1 //===- InstructionSimplify.cpp - Fold instruction operands ----------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements routines for folding instructions into simpler forms 10 // that do not require creating new instructions. This does constant folding 11 // ("add i32 1, 1" -> "2") but can also handle non-constant operands, either 12 // returning a constant ("and i32 %x, 0" -> "0") or an already existing value 13 // ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been 14 // simplified: This is usually true and assuming it simplifies the logic (if 15 // they have not been simplified then results are correct but maybe suboptimal). 16 // 17 //===----------------------------------------------------------------------===// 18 19 #include "llvm/Analysis/InstructionSimplify.h" 20 21 #include "llvm/ADT/STLExtras.h" 22 #include "llvm/ADT/SetVector.h" 23 #include "llvm/ADT/Statistic.h" 24 #include "llvm/Analysis/AliasAnalysis.h" 25 #include "llvm/Analysis/AssumptionCache.h" 26 #include "llvm/Analysis/CaptureTracking.h" 27 #include "llvm/Analysis/CmpInstAnalysis.h" 28 #include "llvm/Analysis/ConstantFolding.h" 29 #include "llvm/Analysis/InstSimplifyFolder.h" 30 #include "llvm/Analysis/LoopAnalysisManager.h" 31 #include "llvm/Analysis/MemoryBuiltins.h" 32 #include "llvm/Analysis/OverflowInstAnalysis.h" 33 #include "llvm/Analysis/ValueTracking.h" 34 #include "llvm/Analysis/VectorUtils.h" 35 #include "llvm/IR/ConstantRange.h" 36 #include "llvm/IR/DataLayout.h" 37 #include "llvm/IR/Dominators.h" 38 #include "llvm/IR/InstrTypes.h" 39 #include "llvm/IR/Instructions.h" 40 #include "llvm/IR/Operator.h" 41 #include "llvm/IR/PatternMatch.h" 42 #include "llvm/Support/KnownBits.h" 43 #include <algorithm> 44 #include <optional> 45 using namespace llvm; 46 using namespace llvm::PatternMatch; 47 48 #define DEBUG_TYPE "instsimplify" 49 50 enum { RecursionLimit = 3 }; 51 52 STATISTIC(NumExpand, "Number of expansions"); 53 STATISTIC(NumReassoc, "Number of reassociations"); 54 55 static Value *simplifyAndInst(Value *, Value *, const SimplifyQuery &, 56 unsigned); 57 static Value *simplifyUnOp(unsigned, Value *, const SimplifyQuery &, unsigned); 58 static Value *simplifyFPUnOp(unsigned, Value *, const FastMathFlags &, 59 const SimplifyQuery &, unsigned); 60 static Value *simplifyBinOp(unsigned, Value *, Value *, const SimplifyQuery &, 61 unsigned); 62 static Value *simplifyBinOp(unsigned, Value *, Value *, const FastMathFlags &, 63 const SimplifyQuery &, unsigned); 64 static Value *simplifyCmpInst(unsigned, Value *, Value *, const SimplifyQuery &, 65 unsigned); 66 static Value *simplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 67 const SimplifyQuery &Q, unsigned MaxRecurse); 68 static Value *simplifyOrInst(Value *, Value *, const SimplifyQuery &, unsigned); 69 static Value *simplifyXorInst(Value *, Value *, const SimplifyQuery &, 70 unsigned); 71 static Value *simplifyCastInst(unsigned, Value *, Type *, const SimplifyQuery &, 72 unsigned); 73 static Value *simplifyGEPInst(Type *, Value *, ArrayRef<Value *>, bool, 74 const SimplifyQuery &, unsigned); 75 static Value *simplifySelectInst(Value *, Value *, Value *, 76 const SimplifyQuery &, unsigned); 77 static Value *simplifyInstructionWithOperands(Instruction *I, 78 ArrayRef<Value *> NewOps, 79 const SimplifyQuery &SQ, 80 unsigned MaxRecurse); 81 82 static Value *foldSelectWithBinaryOp(Value *Cond, Value *TrueVal, 83 Value *FalseVal) { 84 BinaryOperator::BinaryOps BinOpCode; 85 if (auto *BO = dyn_cast<BinaryOperator>(Cond)) 86 BinOpCode = BO->getOpcode(); 87 else 88 return nullptr; 89 90 CmpInst::Predicate ExpectedPred, Pred1, Pred2; 91 if (BinOpCode == BinaryOperator::Or) { 92 ExpectedPred = ICmpInst::ICMP_NE; 93 } else if (BinOpCode == BinaryOperator::And) { 94 ExpectedPred = ICmpInst::ICMP_EQ; 95 } else 96 return nullptr; 97 98 // %A = icmp eq %TV, %FV 99 // %B = icmp eq %X, %Y (and one of these is a select operand) 100 // %C = and %A, %B 101 // %D = select %C, %TV, %FV 102 // --> 103 // %FV 104 105 // %A = icmp ne %TV, %FV 106 // %B = icmp ne %X, %Y (and one of these is a select operand) 107 // %C = or %A, %B 108 // %D = select %C, %TV, %FV 109 // --> 110 // %TV 111 Value *X, *Y; 112 if (!match(Cond, m_c_BinOp(m_c_ICmp(Pred1, m_Specific(TrueVal), 113 m_Specific(FalseVal)), 114 m_ICmp(Pred2, m_Value(X), m_Value(Y)))) || 115 Pred1 != Pred2 || Pred1 != ExpectedPred) 116 return nullptr; 117 118 if (X == TrueVal || X == FalseVal || Y == TrueVal || Y == FalseVal) 119 return BinOpCode == BinaryOperator::Or ? TrueVal : FalseVal; 120 121 return nullptr; 122 } 123 124 /// For a boolean type or a vector of boolean type, return false or a vector 125 /// with every element false. 126 static Constant *getFalse(Type *Ty) { return ConstantInt::getFalse(Ty); } 127 128 /// For a boolean type or a vector of boolean type, return true or a vector 129 /// with every element true. 130 static Constant *getTrue(Type *Ty) { return ConstantInt::getTrue(Ty); } 131 132 /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"? 133 static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS, 134 Value *RHS) { 135 CmpInst *Cmp = dyn_cast<CmpInst>(V); 136 if (!Cmp) 137 return false; 138 CmpInst::Predicate CPred = Cmp->getPredicate(); 139 Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1); 140 if (CPred == Pred && CLHS == LHS && CRHS == RHS) 141 return true; 142 return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS && 143 CRHS == LHS; 144 } 145 146 /// Simplify comparison with true or false branch of select: 147 /// %sel = select i1 %cond, i32 %tv, i32 %fv 148 /// %cmp = icmp sle i32 %sel, %rhs 149 /// Compose new comparison by substituting %sel with either %tv or %fv 150 /// and see if it simplifies. 151 static Value *simplifyCmpSelCase(CmpInst::Predicate Pred, Value *LHS, 152 Value *RHS, Value *Cond, 153 const SimplifyQuery &Q, unsigned MaxRecurse, 154 Constant *TrueOrFalse) { 155 Value *SimplifiedCmp = simplifyCmpInst(Pred, LHS, RHS, Q, MaxRecurse); 156 if (SimplifiedCmp == Cond) { 157 // %cmp simplified to the select condition (%cond). 158 return TrueOrFalse; 159 } else if (!SimplifiedCmp && isSameCompare(Cond, Pred, LHS, RHS)) { 160 // It didn't simplify. However, if composed comparison is equivalent 161 // to the select condition (%cond) then we can replace it. 162 return TrueOrFalse; 163 } 164 return SimplifiedCmp; 165 } 166 167 /// Simplify comparison with true branch of select 168 static Value *simplifyCmpSelTrueCase(CmpInst::Predicate Pred, Value *LHS, 169 Value *RHS, Value *Cond, 170 const SimplifyQuery &Q, 171 unsigned MaxRecurse) { 172 return simplifyCmpSelCase(Pred, LHS, RHS, Cond, Q, MaxRecurse, 173 getTrue(Cond->getType())); 174 } 175 176 /// Simplify comparison with false branch of select 177 static Value *simplifyCmpSelFalseCase(CmpInst::Predicate Pred, Value *LHS, 178 Value *RHS, Value *Cond, 179 const SimplifyQuery &Q, 180 unsigned MaxRecurse) { 181 return simplifyCmpSelCase(Pred, LHS, RHS, Cond, Q, MaxRecurse, 182 getFalse(Cond->getType())); 183 } 184 185 /// We know comparison with both branches of select can be simplified, but they 186 /// are not equal. This routine handles some logical simplifications. 187 static Value *handleOtherCmpSelSimplifications(Value *TCmp, Value *FCmp, 188 Value *Cond, 189 const SimplifyQuery &Q, 190 unsigned MaxRecurse) { 191 // If the false value simplified to false, then the result of the compare 192 // is equal to "Cond && TCmp". This also catches the case when the false 193 // value simplified to false and the true value to true, returning "Cond". 194 // Folding select to and/or isn't poison-safe in general; impliesPoison 195 // checks whether folding it does not convert a well-defined value into 196 // poison. 197 if (match(FCmp, m_Zero()) && impliesPoison(TCmp, Cond)) 198 if (Value *V = simplifyAndInst(Cond, TCmp, Q, MaxRecurse)) 199 return V; 200 // If the true value simplified to true, then the result of the compare 201 // is equal to "Cond || FCmp". 202 if (match(TCmp, m_One()) && impliesPoison(FCmp, Cond)) 203 if (Value *V = simplifyOrInst(Cond, FCmp, Q, MaxRecurse)) 204 return V; 205 // Finally, if the false value simplified to true and the true value to 206 // false, then the result of the compare is equal to "!Cond". 207 if (match(FCmp, m_One()) && match(TCmp, m_Zero())) 208 if (Value *V = simplifyXorInst( 209 Cond, Constant::getAllOnesValue(Cond->getType()), Q, MaxRecurse)) 210 return V; 211 return nullptr; 212 } 213 214 /// Does the given value dominate the specified phi node? 215 static bool valueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) { 216 Instruction *I = dyn_cast<Instruction>(V); 217 if (!I) 218 // Arguments and constants dominate all instructions. 219 return true; 220 221 // If we have a DominatorTree then do a precise test. 222 if (DT) 223 return DT->dominates(I, P); 224 225 // Otherwise, if the instruction is in the entry block and is not an invoke, 226 // then it obviously dominates all phi nodes. 227 if (I->getParent()->isEntryBlock() && !isa<InvokeInst>(I) && 228 !isa<CallBrInst>(I)) 229 return true; 230 231 return false; 232 } 233 234 /// Try to simplify a binary operator of form "V op OtherOp" where V is 235 /// "(B0 opex B1)" by distributing 'op' across 'opex' as 236 /// "(B0 op OtherOp) opex (B1 op OtherOp)". 237 static Value *expandBinOp(Instruction::BinaryOps Opcode, Value *V, 238 Value *OtherOp, Instruction::BinaryOps OpcodeToExpand, 239 const SimplifyQuery &Q, unsigned MaxRecurse) { 240 auto *B = dyn_cast<BinaryOperator>(V); 241 if (!B || B->getOpcode() != OpcodeToExpand) 242 return nullptr; 243 Value *B0 = B->getOperand(0), *B1 = B->getOperand(1); 244 Value *L = 245 simplifyBinOp(Opcode, B0, OtherOp, Q.getWithoutUndef(), MaxRecurse); 246 if (!L) 247 return nullptr; 248 Value *R = 249 simplifyBinOp(Opcode, B1, OtherOp, Q.getWithoutUndef(), MaxRecurse); 250 if (!R) 251 return nullptr; 252 253 // Does the expanded pair of binops simplify to the existing binop? 254 if ((L == B0 && R == B1) || 255 (Instruction::isCommutative(OpcodeToExpand) && L == B1 && R == B0)) { 256 ++NumExpand; 257 return B; 258 } 259 260 // Otherwise, return "L op' R" if it simplifies. 261 Value *S = simplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse); 262 if (!S) 263 return nullptr; 264 265 ++NumExpand; 266 return S; 267 } 268 269 /// Try to simplify binops of form "A op (B op' C)" or the commuted variant by 270 /// distributing op over op'. 271 static Value *expandCommutativeBinOp(Instruction::BinaryOps Opcode, Value *L, 272 Value *R, 273 Instruction::BinaryOps OpcodeToExpand, 274 const SimplifyQuery &Q, 275 unsigned MaxRecurse) { 276 // Recursion is always used, so bail out at once if we already hit the limit. 277 if (!MaxRecurse--) 278 return nullptr; 279 280 if (Value *V = expandBinOp(Opcode, L, R, OpcodeToExpand, Q, MaxRecurse)) 281 return V; 282 if (Value *V = expandBinOp(Opcode, R, L, OpcodeToExpand, Q, MaxRecurse)) 283 return V; 284 return nullptr; 285 } 286 287 /// Generic simplifications for associative binary operations. 288 /// Returns the simpler value, or null if none was found. 289 static Value *simplifyAssociativeBinOp(Instruction::BinaryOps Opcode, 290 Value *LHS, Value *RHS, 291 const SimplifyQuery &Q, 292 unsigned MaxRecurse) { 293 assert(Instruction::isAssociative(Opcode) && "Not an associative operation!"); 294 295 // Recursion is always used, so bail out at once if we already hit the limit. 296 if (!MaxRecurse--) 297 return nullptr; 298 299 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS); 300 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS); 301 302 // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely. 303 if (Op0 && Op0->getOpcode() == Opcode) { 304 Value *A = Op0->getOperand(0); 305 Value *B = Op0->getOperand(1); 306 Value *C = RHS; 307 308 // Does "B op C" simplify? 309 if (Value *V = simplifyBinOp(Opcode, B, C, Q, MaxRecurse)) { 310 // It does! Return "A op V" if it simplifies or is already available. 311 // If V equals B then "A op V" is just the LHS. 312 if (V == B) 313 return LHS; 314 // Otherwise return "A op V" if it simplifies. 315 if (Value *W = simplifyBinOp(Opcode, A, V, Q, MaxRecurse)) { 316 ++NumReassoc; 317 return W; 318 } 319 } 320 } 321 322 // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely. 323 if (Op1 && Op1->getOpcode() == Opcode) { 324 Value *A = LHS; 325 Value *B = Op1->getOperand(0); 326 Value *C = Op1->getOperand(1); 327 328 // Does "A op B" simplify? 329 if (Value *V = simplifyBinOp(Opcode, A, B, Q, MaxRecurse)) { 330 // It does! Return "V op C" if it simplifies or is already available. 331 // If V equals B then "V op C" is just the RHS. 332 if (V == B) 333 return RHS; 334 // Otherwise return "V op C" if it simplifies. 335 if (Value *W = simplifyBinOp(Opcode, V, C, Q, MaxRecurse)) { 336 ++NumReassoc; 337 return W; 338 } 339 } 340 } 341 342 // The remaining transforms require commutativity as well as associativity. 343 if (!Instruction::isCommutative(Opcode)) 344 return nullptr; 345 346 // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely. 347 if (Op0 && Op0->getOpcode() == Opcode) { 348 Value *A = Op0->getOperand(0); 349 Value *B = Op0->getOperand(1); 350 Value *C = RHS; 351 352 // Does "C op A" simplify? 353 if (Value *V = simplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { 354 // It does! Return "V op B" if it simplifies or is already available. 355 // If V equals A then "V op B" is just the LHS. 356 if (V == A) 357 return LHS; 358 // Otherwise return "V op B" if it simplifies. 359 if (Value *W = simplifyBinOp(Opcode, V, B, Q, MaxRecurse)) { 360 ++NumReassoc; 361 return W; 362 } 363 } 364 } 365 366 // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely. 367 if (Op1 && Op1->getOpcode() == Opcode) { 368 Value *A = LHS; 369 Value *B = Op1->getOperand(0); 370 Value *C = Op1->getOperand(1); 371 372 // Does "C op A" simplify? 373 if (Value *V = simplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { 374 // It does! Return "B op V" if it simplifies or is already available. 375 // If V equals C then "B op V" is just the RHS. 376 if (V == C) 377 return RHS; 378 // Otherwise return "B op V" if it simplifies. 379 if (Value *W = simplifyBinOp(Opcode, B, V, Q, MaxRecurse)) { 380 ++NumReassoc; 381 return W; 382 } 383 } 384 } 385 386 return nullptr; 387 } 388 389 /// In the case of a binary operation with a select instruction as an operand, 390 /// try to simplify the binop by seeing whether evaluating it on both branches 391 /// of the select results in the same value. Returns the common value if so, 392 /// otherwise returns null. 393 static Value *threadBinOpOverSelect(Instruction::BinaryOps Opcode, Value *LHS, 394 Value *RHS, const SimplifyQuery &Q, 395 unsigned MaxRecurse) { 396 // Recursion is always used, so bail out at once if we already hit the limit. 397 if (!MaxRecurse--) 398 return nullptr; 399 400 SelectInst *SI; 401 if (isa<SelectInst>(LHS)) { 402 SI = cast<SelectInst>(LHS); 403 } else { 404 assert(isa<SelectInst>(RHS) && "No select instruction operand!"); 405 SI = cast<SelectInst>(RHS); 406 } 407 408 // Evaluate the BinOp on the true and false branches of the select. 409 Value *TV; 410 Value *FV; 411 if (SI == LHS) { 412 TV = simplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse); 413 FV = simplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse); 414 } else { 415 TV = simplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse); 416 FV = simplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse); 417 } 418 419 // If they simplified to the same value, then return the common value. 420 // If they both failed to simplify then return null. 421 if (TV == FV) 422 return TV; 423 424 // If one branch simplified to undef, return the other one. 425 if (TV && Q.isUndefValue(TV)) 426 return FV; 427 if (FV && Q.isUndefValue(FV)) 428 return TV; 429 430 // If applying the operation did not change the true and false select values, 431 // then the result of the binop is the select itself. 432 if (TV == SI->getTrueValue() && FV == SI->getFalseValue()) 433 return SI; 434 435 // If one branch simplified and the other did not, and the simplified 436 // value is equal to the unsimplified one, return the simplified value. 437 // For example, select (cond, X, X & Z) & Z -> X & Z. 438 if ((FV && !TV) || (TV && !FV)) { 439 // Check that the simplified value has the form "X op Y" where "op" is the 440 // same as the original operation. 441 Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV); 442 if (Simplified && Simplified->getOpcode() == unsigned(Opcode) && 443 !Simplified->hasPoisonGeneratingFlags()) { 444 // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS". 445 // We already know that "op" is the same as for the simplified value. See 446 // if the operands match too. If so, return the simplified value. 447 Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue(); 448 Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS; 449 Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch; 450 if (Simplified->getOperand(0) == UnsimplifiedLHS && 451 Simplified->getOperand(1) == UnsimplifiedRHS) 452 return Simplified; 453 if (Simplified->isCommutative() && 454 Simplified->getOperand(1) == UnsimplifiedLHS && 455 Simplified->getOperand(0) == UnsimplifiedRHS) 456 return Simplified; 457 } 458 } 459 460 return nullptr; 461 } 462 463 /// In the case of a comparison with a select instruction, try to simplify the 464 /// comparison by seeing whether both branches of the select result in the same 465 /// value. Returns the common value if so, otherwise returns null. 466 /// For example, if we have: 467 /// %tmp = select i1 %cmp, i32 1, i32 2 468 /// %cmp1 = icmp sle i32 %tmp, 3 469 /// We can simplify %cmp1 to true, because both branches of select are 470 /// less than 3. We compose new comparison by substituting %tmp with both 471 /// branches of select and see if it can be simplified. 472 static Value *threadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS, 473 Value *RHS, const SimplifyQuery &Q, 474 unsigned MaxRecurse) { 475 // Recursion is always used, so bail out at once if we already hit the limit. 476 if (!MaxRecurse--) 477 return nullptr; 478 479 // Make sure the select is on the LHS. 480 if (!isa<SelectInst>(LHS)) { 481 std::swap(LHS, RHS); 482 Pred = CmpInst::getSwappedPredicate(Pred); 483 } 484 assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!"); 485 SelectInst *SI = cast<SelectInst>(LHS); 486 Value *Cond = SI->getCondition(); 487 Value *TV = SI->getTrueValue(); 488 Value *FV = SI->getFalseValue(); 489 490 // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it. 491 // Does "cmp TV, RHS" simplify? 492 Value *TCmp = simplifyCmpSelTrueCase(Pred, TV, RHS, Cond, Q, MaxRecurse); 493 if (!TCmp) 494 return nullptr; 495 496 // Does "cmp FV, RHS" simplify? 497 Value *FCmp = simplifyCmpSelFalseCase(Pred, FV, RHS, Cond, Q, MaxRecurse); 498 if (!FCmp) 499 return nullptr; 500 501 // If both sides simplified to the same value, then use it as the result of 502 // the original comparison. 503 if (TCmp == FCmp) 504 return TCmp; 505 506 // The remaining cases only make sense if the select condition has the same 507 // type as the result of the comparison, so bail out if this is not so. 508 if (Cond->getType()->isVectorTy() == RHS->getType()->isVectorTy()) 509 return handleOtherCmpSelSimplifications(TCmp, FCmp, Cond, Q, MaxRecurse); 510 511 return nullptr; 512 } 513 514 /// In the case of a binary operation with an operand that is a PHI instruction, 515 /// try to simplify the binop by seeing whether evaluating it on the incoming 516 /// phi values yields the same result for every value. If so returns the common 517 /// value, otherwise returns null. 518 static Value *threadBinOpOverPHI(Instruction::BinaryOps Opcode, Value *LHS, 519 Value *RHS, const SimplifyQuery &Q, 520 unsigned MaxRecurse) { 521 // Recursion is always used, so bail out at once if we already hit the limit. 522 if (!MaxRecurse--) 523 return nullptr; 524 525 PHINode *PI; 526 if (isa<PHINode>(LHS)) { 527 PI = cast<PHINode>(LHS); 528 // Bail out if RHS and the phi may be mutually interdependent due to a loop. 529 if (!valueDominatesPHI(RHS, PI, Q.DT)) 530 return nullptr; 531 } else { 532 assert(isa<PHINode>(RHS) && "No PHI instruction operand!"); 533 PI = cast<PHINode>(RHS); 534 // Bail out if LHS and the phi may be mutually interdependent due to a loop. 535 if (!valueDominatesPHI(LHS, PI, Q.DT)) 536 return nullptr; 537 } 538 539 // Evaluate the BinOp on the incoming phi values. 540 Value *CommonValue = nullptr; 541 for (Use &Incoming : PI->incoming_values()) { 542 // If the incoming value is the phi node itself, it can safely be skipped. 543 if (Incoming == PI) 544 continue; 545 Instruction *InTI = PI->getIncomingBlock(Incoming)->getTerminator(); 546 Value *V = PI == LHS 547 ? simplifyBinOp(Opcode, Incoming, RHS, 548 Q.getWithInstruction(InTI), MaxRecurse) 549 : simplifyBinOp(Opcode, LHS, Incoming, 550 Q.getWithInstruction(InTI), MaxRecurse); 551 // If the operation failed to simplify, or simplified to a different value 552 // to previously, then give up. 553 if (!V || (CommonValue && V != CommonValue)) 554 return nullptr; 555 CommonValue = V; 556 } 557 558 return CommonValue; 559 } 560 561 /// In the case of a comparison with a PHI instruction, try to simplify the 562 /// comparison by seeing whether comparing with all of the incoming phi values 563 /// yields the same result every time. If so returns the common result, 564 /// otherwise returns null. 565 static Value *threadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS, 566 const SimplifyQuery &Q, unsigned MaxRecurse) { 567 // Recursion is always used, so bail out at once if we already hit the limit. 568 if (!MaxRecurse--) 569 return nullptr; 570 571 // Make sure the phi is on the LHS. 572 if (!isa<PHINode>(LHS)) { 573 std::swap(LHS, RHS); 574 Pred = CmpInst::getSwappedPredicate(Pred); 575 } 576 assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!"); 577 PHINode *PI = cast<PHINode>(LHS); 578 579 // Bail out if RHS and the phi may be mutually interdependent due to a loop. 580 if (!valueDominatesPHI(RHS, PI, Q.DT)) 581 return nullptr; 582 583 // Evaluate the BinOp on the incoming phi values. 584 Value *CommonValue = nullptr; 585 for (unsigned u = 0, e = PI->getNumIncomingValues(); u < e; ++u) { 586 Value *Incoming = PI->getIncomingValue(u); 587 Instruction *InTI = PI->getIncomingBlock(u)->getTerminator(); 588 // If the incoming value is the phi node itself, it can safely be skipped. 589 if (Incoming == PI) 590 continue; 591 // Change the context instruction to the "edge" that flows into the phi. 592 // This is important because that is where incoming is actually "evaluated" 593 // even though it is used later somewhere else. 594 Value *V = simplifyCmpInst(Pred, Incoming, RHS, Q.getWithInstruction(InTI), 595 MaxRecurse); 596 // If the operation failed to simplify, or simplified to a different value 597 // to previously, then give up. 598 if (!V || (CommonValue && V != CommonValue)) 599 return nullptr; 600 CommonValue = V; 601 } 602 603 return CommonValue; 604 } 605 606 static Constant *foldOrCommuteConstant(Instruction::BinaryOps Opcode, 607 Value *&Op0, Value *&Op1, 608 const SimplifyQuery &Q) { 609 if (auto *CLHS = dyn_cast<Constant>(Op0)) { 610 if (auto *CRHS = dyn_cast<Constant>(Op1)) { 611 switch (Opcode) { 612 default: 613 break; 614 case Instruction::FAdd: 615 case Instruction::FSub: 616 case Instruction::FMul: 617 case Instruction::FDiv: 618 case Instruction::FRem: 619 if (Q.CxtI != nullptr) 620 return ConstantFoldFPInstOperands(Opcode, CLHS, CRHS, Q.DL, Q.CxtI); 621 } 622 return ConstantFoldBinaryOpOperands(Opcode, CLHS, CRHS, Q.DL); 623 } 624 625 // Canonicalize the constant to the RHS if this is a commutative operation. 626 if (Instruction::isCommutative(Opcode)) 627 std::swap(Op0, Op1); 628 } 629 return nullptr; 630 } 631 632 /// Given operands for an Add, see if we can fold the result. 633 /// If not, this returns null. 634 static Value *simplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 635 const SimplifyQuery &Q, unsigned MaxRecurse) { 636 if (Constant *C = foldOrCommuteConstant(Instruction::Add, Op0, Op1, Q)) 637 return C; 638 639 // X + poison -> poison 640 if (isa<PoisonValue>(Op1)) 641 return Op1; 642 643 // X + undef -> undef 644 if (Q.isUndefValue(Op1)) 645 return Op1; 646 647 // X + 0 -> X 648 if (match(Op1, m_Zero())) 649 return Op0; 650 651 // If two operands are negative, return 0. 652 if (isKnownNegation(Op0, Op1)) 653 return Constant::getNullValue(Op0->getType()); 654 655 // X + (Y - X) -> Y 656 // (Y - X) + X -> Y 657 // Eg: X + -X -> 0 658 Value *Y = nullptr; 659 if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) || 660 match(Op0, m_Sub(m_Value(Y), m_Specific(Op1)))) 661 return Y; 662 663 // X + ~X -> -1 since ~X = -X-1 664 Type *Ty = Op0->getType(); 665 if (match(Op0, m_Not(m_Specific(Op1))) || match(Op1, m_Not(m_Specific(Op0)))) 666 return Constant::getAllOnesValue(Ty); 667 668 // add nsw/nuw (xor Y, signmask), signmask --> Y 669 // The no-wrapping add guarantees that the top bit will be set by the add. 670 // Therefore, the xor must be clearing the already set sign bit of Y. 671 if ((IsNSW || IsNUW) && match(Op1, m_SignMask()) && 672 match(Op0, m_Xor(m_Value(Y), m_SignMask()))) 673 return Y; 674 675 // add nuw %x, -1 -> -1, because %x can only be 0. 676 if (IsNUW && match(Op1, m_AllOnes())) 677 return Op1; // Which is -1. 678 679 /// i1 add -> xor. 680 if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1)) 681 if (Value *V = simplifyXorInst(Op0, Op1, Q, MaxRecurse - 1)) 682 return V; 683 684 // Try some generic simplifications for associative operations. 685 if (Value *V = 686 simplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q, MaxRecurse)) 687 return V; 688 689 // Threading Add over selects and phi nodes is pointless, so don't bother. 690 // Threading over the select in "A + select(cond, B, C)" means evaluating 691 // "A+B" and "A+C" and seeing if they are equal; but they are equal if and 692 // only if B and C are equal. If B and C are equal then (since we assume 693 // that operands have already been simplified) "select(cond, B, C)" should 694 // have been simplified to the common value of B and C already. Analysing 695 // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly 696 // for threading over phi nodes. 697 698 return nullptr; 699 } 700 701 Value *llvm::simplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 702 const SimplifyQuery &Query) { 703 return ::simplifyAddInst(Op0, Op1, IsNSW, IsNUW, Query, RecursionLimit); 704 } 705 706 /// Compute the base pointer and cumulative constant offsets for V. 707 /// 708 /// This strips all constant offsets off of V, leaving it the base pointer, and 709 /// accumulates the total constant offset applied in the returned constant. 710 /// It returns zero if there are no constant offsets applied. 711 /// 712 /// This is very similar to stripAndAccumulateConstantOffsets(), except it 713 /// normalizes the offset bitwidth to the stripped pointer type, not the 714 /// original pointer type. 715 static APInt stripAndComputeConstantOffsets(const DataLayout &DL, Value *&V, 716 bool AllowNonInbounds = false) { 717 assert(V->getType()->isPtrOrPtrVectorTy()); 718 719 APInt Offset = APInt::getZero(DL.getIndexTypeSizeInBits(V->getType())); 720 V = V->stripAndAccumulateConstantOffsets(DL, Offset, AllowNonInbounds); 721 // As that strip may trace through `addrspacecast`, need to sext or trunc 722 // the offset calculated. 723 return Offset.sextOrTrunc(DL.getIndexTypeSizeInBits(V->getType())); 724 } 725 726 /// Compute the constant difference between two pointer values. 727 /// If the difference is not a constant, returns zero. 728 static Constant *computePointerDifference(const DataLayout &DL, Value *LHS, 729 Value *RHS) { 730 APInt LHSOffset = stripAndComputeConstantOffsets(DL, LHS); 731 APInt RHSOffset = stripAndComputeConstantOffsets(DL, RHS); 732 733 // If LHS and RHS are not related via constant offsets to the same base 734 // value, there is nothing we can do here. 735 if (LHS != RHS) 736 return nullptr; 737 738 // Otherwise, the difference of LHS - RHS can be computed as: 739 // LHS - RHS 740 // = (LHSOffset + Base) - (RHSOffset + Base) 741 // = LHSOffset - RHSOffset 742 Constant *Res = ConstantInt::get(LHS->getContext(), LHSOffset - RHSOffset); 743 if (auto *VecTy = dyn_cast<VectorType>(LHS->getType())) 744 Res = ConstantVector::getSplat(VecTy->getElementCount(), Res); 745 return Res; 746 } 747 748 /// Test if there is a dominating equivalence condition for the 749 /// two operands. If there is, try to reduce the binary operation 750 /// between the two operands. 751 /// Example: Op0 - Op1 --> 0 when Op0 == Op1 752 static Value *simplifyByDomEq(unsigned Opcode, Value *Op0, Value *Op1, 753 const SimplifyQuery &Q, unsigned MaxRecurse) { 754 // Recursive run it can not get any benefit 755 if (MaxRecurse != RecursionLimit) 756 return nullptr; 757 758 std::optional<bool> Imp = 759 isImpliedByDomCondition(CmpInst::ICMP_EQ, Op0, Op1, Q.CxtI, Q.DL); 760 if (Imp && *Imp) { 761 Type *Ty = Op0->getType(); 762 switch (Opcode) { 763 case Instruction::Sub: 764 case Instruction::Xor: 765 case Instruction::URem: 766 case Instruction::SRem: 767 return Constant::getNullValue(Ty); 768 769 case Instruction::SDiv: 770 case Instruction::UDiv: 771 return ConstantInt::get(Ty, 1); 772 773 case Instruction::And: 774 case Instruction::Or: 775 // Could be either one - choose Op1 since that's more likely a constant. 776 return Op1; 777 default: 778 break; 779 } 780 } 781 return nullptr; 782 } 783 784 /// Given operands for a Sub, see if we can fold the result. 785 /// If not, this returns null. 786 static Value *simplifySubInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 787 const SimplifyQuery &Q, unsigned MaxRecurse) { 788 if (Constant *C = foldOrCommuteConstant(Instruction::Sub, Op0, Op1, Q)) 789 return C; 790 791 // X - poison -> poison 792 // poison - X -> poison 793 if (isa<PoisonValue>(Op0) || isa<PoisonValue>(Op1)) 794 return PoisonValue::get(Op0->getType()); 795 796 // X - undef -> undef 797 // undef - X -> undef 798 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 799 return UndefValue::get(Op0->getType()); 800 801 // X - 0 -> X 802 if (match(Op1, m_Zero())) 803 return Op0; 804 805 // X - X -> 0 806 if (Op0 == Op1) 807 return Constant::getNullValue(Op0->getType()); 808 809 // Is this a negation? 810 if (match(Op0, m_Zero())) { 811 // 0 - X -> 0 if the sub is NUW. 812 if (IsNUW) 813 return Constant::getNullValue(Op0->getType()); 814 815 KnownBits Known = computeKnownBits(Op1, /* Depth */ 0, Q); 816 if (Known.Zero.isMaxSignedValue()) { 817 // Op1 is either 0 or the minimum signed value. If the sub is NSW, then 818 // Op1 must be 0 because negating the minimum signed value is undefined. 819 if (IsNSW) 820 return Constant::getNullValue(Op0->getType()); 821 822 // 0 - X -> X if X is 0 or the minimum signed value. 823 return Op1; 824 } 825 } 826 827 // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies. 828 // For example, (X + Y) - Y -> X; (Y + X) - Y -> X 829 Value *X = nullptr, *Y = nullptr, *Z = Op1; 830 if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z 831 // See if "V === Y - Z" simplifies. 832 if (Value *V = simplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse - 1)) 833 // It does! Now see if "X + V" simplifies. 834 if (Value *W = simplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse - 1)) { 835 // It does, we successfully reassociated! 836 ++NumReassoc; 837 return W; 838 } 839 // See if "V === X - Z" simplifies. 840 if (Value *V = simplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse - 1)) 841 // It does! Now see if "Y + V" simplifies. 842 if (Value *W = simplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse - 1)) { 843 // It does, we successfully reassociated! 844 ++NumReassoc; 845 return W; 846 } 847 } 848 849 // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies. 850 // For example, X - (X + 1) -> -1 851 X = Op0; 852 if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z) 853 // See if "V === X - Y" simplifies. 854 if (Value *V = simplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse - 1)) 855 // It does! Now see if "V - Z" simplifies. 856 if (Value *W = simplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse - 1)) { 857 // It does, we successfully reassociated! 858 ++NumReassoc; 859 return W; 860 } 861 // See if "V === X - Z" simplifies. 862 if (Value *V = simplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse - 1)) 863 // It does! Now see if "V - Y" simplifies. 864 if (Value *W = simplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse - 1)) { 865 // It does, we successfully reassociated! 866 ++NumReassoc; 867 return W; 868 } 869 } 870 871 // Z - (X - Y) -> (Z - X) + Y if everything simplifies. 872 // For example, X - (X - Y) -> Y. 873 Z = Op0; 874 if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y) 875 // See if "V === Z - X" simplifies. 876 if (Value *V = simplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse - 1)) 877 // It does! Now see if "V + Y" simplifies. 878 if (Value *W = simplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse - 1)) { 879 // It does, we successfully reassociated! 880 ++NumReassoc; 881 return W; 882 } 883 884 // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies. 885 if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) && 886 match(Op1, m_Trunc(m_Value(Y)))) 887 if (X->getType() == Y->getType()) 888 // See if "V === X - Y" simplifies. 889 if (Value *V = simplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse - 1)) 890 // It does! Now see if "trunc V" simplifies. 891 if (Value *W = simplifyCastInst(Instruction::Trunc, V, Op0->getType(), 892 Q, MaxRecurse - 1)) 893 // It does, return the simplified "trunc V". 894 return W; 895 896 // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...). 897 if (match(Op0, m_PtrToInt(m_Value(X))) && match(Op1, m_PtrToInt(m_Value(Y)))) 898 if (Constant *Result = computePointerDifference(Q.DL, X, Y)) 899 return ConstantFoldIntegerCast(Result, Op0->getType(), /*IsSigned*/ true, 900 Q.DL); 901 902 // i1 sub -> xor. 903 if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1)) 904 if (Value *V = simplifyXorInst(Op0, Op1, Q, MaxRecurse - 1)) 905 return V; 906 907 // Threading Sub over selects and phi nodes is pointless, so don't bother. 908 // Threading over the select in "A - select(cond, B, C)" means evaluating 909 // "A-B" and "A-C" and seeing if they are equal; but they are equal if and 910 // only if B and C are equal. If B and C are equal then (since we assume 911 // that operands have already been simplified) "select(cond, B, C)" should 912 // have been simplified to the common value of B and C already. Analysing 913 // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly 914 // for threading over phi nodes. 915 916 if (Value *V = simplifyByDomEq(Instruction::Sub, Op0, Op1, Q, MaxRecurse)) 917 return V; 918 919 return nullptr; 920 } 921 922 Value *llvm::simplifySubInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 923 const SimplifyQuery &Q) { 924 return ::simplifySubInst(Op0, Op1, IsNSW, IsNUW, Q, RecursionLimit); 925 } 926 927 /// Given operands for a Mul, see if we can fold the result. 928 /// If not, this returns null. 929 static Value *simplifyMulInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 930 const SimplifyQuery &Q, unsigned MaxRecurse) { 931 if (Constant *C = foldOrCommuteConstant(Instruction::Mul, Op0, Op1, Q)) 932 return C; 933 934 // X * poison -> poison 935 if (isa<PoisonValue>(Op1)) 936 return Op1; 937 938 // X * undef -> 0 939 // X * 0 -> 0 940 if (Q.isUndefValue(Op1) || match(Op1, m_Zero())) 941 return Constant::getNullValue(Op0->getType()); 942 943 // X * 1 -> X 944 if (match(Op1, m_One())) 945 return Op0; 946 947 // (X / Y) * Y -> X if the division is exact. 948 Value *X = nullptr; 949 if (Q.IIQ.UseInstrInfo && 950 (match(Op0, 951 m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y 952 match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0)))))) // Y * (X / Y) 953 return X; 954 955 if (Op0->getType()->isIntOrIntVectorTy(1)) { 956 // mul i1 nsw is a special-case because -1 * -1 is poison (+1 is not 957 // representable). All other cases reduce to 0, so just return 0. 958 if (IsNSW) 959 return ConstantInt::getNullValue(Op0->getType()); 960 961 // Treat "mul i1" as "and i1". 962 if (MaxRecurse) 963 if (Value *V = simplifyAndInst(Op0, Op1, Q, MaxRecurse - 1)) 964 return V; 965 } 966 967 // Try some generic simplifications for associative operations. 968 if (Value *V = 969 simplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q, MaxRecurse)) 970 return V; 971 972 // Mul distributes over Add. Try some generic simplifications based on this. 973 if (Value *V = expandCommutativeBinOp(Instruction::Mul, Op0, Op1, 974 Instruction::Add, Q, MaxRecurse)) 975 return V; 976 977 // If the operation is with the result of a select instruction, check whether 978 // operating on either branch of the select always yields the same value. 979 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 980 if (Value *V = 981 threadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q, MaxRecurse)) 982 return V; 983 984 // If the operation is with the result of a phi instruction, check whether 985 // operating on all incoming values of the phi always yields the same value. 986 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 987 if (Value *V = 988 threadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q, MaxRecurse)) 989 return V; 990 991 return nullptr; 992 } 993 994 Value *llvm::simplifyMulInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 995 const SimplifyQuery &Q) { 996 return ::simplifyMulInst(Op0, Op1, IsNSW, IsNUW, Q, RecursionLimit); 997 } 998 999 /// Given a predicate and two operands, return true if the comparison is true. 1000 /// This is a helper for div/rem simplification where we return some other value 1001 /// when we can prove a relationship between the operands. 1002 static bool isICmpTrue(ICmpInst::Predicate Pred, Value *LHS, Value *RHS, 1003 const SimplifyQuery &Q, unsigned MaxRecurse) { 1004 Value *V = simplifyICmpInst(Pred, LHS, RHS, Q, MaxRecurse); 1005 Constant *C = dyn_cast_or_null<Constant>(V); 1006 return (C && C->isAllOnesValue()); 1007 } 1008 1009 /// Return true if we can simplify X / Y to 0. Remainder can adapt that answer 1010 /// to simplify X % Y to X. 1011 static bool isDivZero(Value *X, Value *Y, const SimplifyQuery &Q, 1012 unsigned MaxRecurse, bool IsSigned) { 1013 // Recursion is always used, so bail out at once if we already hit the limit. 1014 if (!MaxRecurse--) 1015 return false; 1016 1017 if (IsSigned) { 1018 // (X srem Y) sdiv Y --> 0 1019 if (match(X, m_SRem(m_Value(), m_Specific(Y)))) 1020 return true; 1021 1022 // |X| / |Y| --> 0 1023 // 1024 // We require that 1 operand is a simple constant. That could be extended to 1025 // 2 variables if we computed the sign bit for each. 1026 // 1027 // Make sure that a constant is not the minimum signed value because taking 1028 // the abs() of that is undefined. 1029 Type *Ty = X->getType(); 1030 const APInt *C; 1031 if (match(X, m_APInt(C)) && !C->isMinSignedValue()) { 1032 // Is the variable divisor magnitude always greater than the constant 1033 // dividend magnitude? 1034 // |Y| > |C| --> Y < -abs(C) or Y > abs(C) 1035 Constant *PosDividendC = ConstantInt::get(Ty, C->abs()); 1036 Constant *NegDividendC = ConstantInt::get(Ty, -C->abs()); 1037 if (isICmpTrue(CmpInst::ICMP_SLT, Y, NegDividendC, Q, MaxRecurse) || 1038 isICmpTrue(CmpInst::ICMP_SGT, Y, PosDividendC, Q, MaxRecurse)) 1039 return true; 1040 } 1041 if (match(Y, m_APInt(C))) { 1042 // Special-case: we can't take the abs() of a minimum signed value. If 1043 // that's the divisor, then all we have to do is prove that the dividend 1044 // is also not the minimum signed value. 1045 if (C->isMinSignedValue()) 1046 return isICmpTrue(CmpInst::ICMP_NE, X, Y, Q, MaxRecurse); 1047 1048 // Is the variable dividend magnitude always less than the constant 1049 // divisor magnitude? 1050 // |X| < |C| --> X > -abs(C) and X < abs(C) 1051 Constant *PosDivisorC = ConstantInt::get(Ty, C->abs()); 1052 Constant *NegDivisorC = ConstantInt::get(Ty, -C->abs()); 1053 if (isICmpTrue(CmpInst::ICMP_SGT, X, NegDivisorC, Q, MaxRecurse) && 1054 isICmpTrue(CmpInst::ICMP_SLT, X, PosDivisorC, Q, MaxRecurse)) 1055 return true; 1056 } 1057 return false; 1058 } 1059 1060 // IsSigned == false. 1061 1062 // Is the unsigned dividend known to be less than a constant divisor? 1063 // TODO: Convert this (and above) to range analysis 1064 // ("computeConstantRangeIncludingKnownBits")? 1065 const APInt *C; 1066 if (match(Y, m_APInt(C)) && 1067 computeKnownBits(X, /* Depth */ 0, Q).getMaxValue().ult(*C)) 1068 return true; 1069 1070 // Try again for any divisor: 1071 // Is the dividend unsigned less than the divisor? 1072 return isICmpTrue(ICmpInst::ICMP_ULT, X, Y, Q, MaxRecurse); 1073 } 1074 1075 /// Check for common or similar folds of integer division or integer remainder. 1076 /// This applies to all 4 opcodes (sdiv/udiv/srem/urem). 1077 static Value *simplifyDivRem(Instruction::BinaryOps Opcode, Value *Op0, 1078 Value *Op1, const SimplifyQuery &Q, 1079 unsigned MaxRecurse) { 1080 bool IsDiv = (Opcode == Instruction::SDiv || Opcode == Instruction::UDiv); 1081 bool IsSigned = (Opcode == Instruction::SDiv || Opcode == Instruction::SRem); 1082 1083 Type *Ty = Op0->getType(); 1084 1085 // X / undef -> poison 1086 // X % undef -> poison 1087 if (Q.isUndefValue(Op1) || isa<PoisonValue>(Op1)) 1088 return PoisonValue::get(Ty); 1089 1090 // X / 0 -> poison 1091 // X % 0 -> poison 1092 // We don't need to preserve faults! 1093 if (match(Op1, m_Zero())) 1094 return PoisonValue::get(Ty); 1095 1096 // If any element of a constant divisor fixed width vector is zero or undef 1097 // the behavior is undefined and we can fold the whole op to poison. 1098 auto *Op1C = dyn_cast<Constant>(Op1); 1099 auto *VTy = dyn_cast<FixedVectorType>(Ty); 1100 if (Op1C && VTy) { 1101 unsigned NumElts = VTy->getNumElements(); 1102 for (unsigned i = 0; i != NumElts; ++i) { 1103 Constant *Elt = Op1C->getAggregateElement(i); 1104 if (Elt && (Elt->isNullValue() || Q.isUndefValue(Elt))) 1105 return PoisonValue::get(Ty); 1106 } 1107 } 1108 1109 // poison / X -> poison 1110 // poison % X -> poison 1111 if (isa<PoisonValue>(Op0)) 1112 return Op0; 1113 1114 // undef / X -> 0 1115 // undef % X -> 0 1116 if (Q.isUndefValue(Op0)) 1117 return Constant::getNullValue(Ty); 1118 1119 // 0 / X -> 0 1120 // 0 % X -> 0 1121 if (match(Op0, m_Zero())) 1122 return Constant::getNullValue(Op0->getType()); 1123 1124 // X / X -> 1 1125 // X % X -> 0 1126 if (Op0 == Op1) 1127 return IsDiv ? ConstantInt::get(Ty, 1) : Constant::getNullValue(Ty); 1128 1129 KnownBits Known = computeKnownBits(Op1, /* Depth */ 0, Q); 1130 // X / 0 -> poison 1131 // X % 0 -> poison 1132 // If the divisor is known to be zero, just return poison. This can happen in 1133 // some cases where its provable indirectly the denominator is zero but it's 1134 // not trivially simplifiable (i.e known zero through a phi node). 1135 if (Known.isZero()) 1136 return PoisonValue::get(Ty); 1137 1138 // X / 1 -> X 1139 // X % 1 -> 0 1140 // If the divisor can only be zero or one, we can't have division-by-zero 1141 // or remainder-by-zero, so assume the divisor is 1. 1142 // e.g. 1, zext (i8 X), sdiv X (Y and 1) 1143 if (Known.countMinLeadingZeros() == Known.getBitWidth() - 1) 1144 return IsDiv ? Op0 : Constant::getNullValue(Ty); 1145 1146 // If X * Y does not overflow, then: 1147 // X * Y / Y -> X 1148 // X * Y % Y -> 0 1149 Value *X; 1150 if (match(Op0, m_c_Mul(m_Value(X), m_Specific(Op1)))) { 1151 auto *Mul = cast<OverflowingBinaryOperator>(Op0); 1152 // The multiplication can't overflow if it is defined not to, or if 1153 // X == A / Y for some A. 1154 if ((IsSigned && Q.IIQ.hasNoSignedWrap(Mul)) || 1155 (!IsSigned && Q.IIQ.hasNoUnsignedWrap(Mul)) || 1156 (IsSigned && match(X, m_SDiv(m_Value(), m_Specific(Op1)))) || 1157 (!IsSigned && match(X, m_UDiv(m_Value(), m_Specific(Op1))))) { 1158 return IsDiv ? X : Constant::getNullValue(Op0->getType()); 1159 } 1160 } 1161 1162 if (isDivZero(Op0, Op1, Q, MaxRecurse, IsSigned)) 1163 return IsDiv ? Constant::getNullValue(Op0->getType()) : Op0; 1164 1165 if (Value *V = simplifyByDomEq(Opcode, Op0, Op1, Q, MaxRecurse)) 1166 return V; 1167 1168 // If the operation is with the result of a select instruction, check whether 1169 // operating on either branch of the select always yields the same value. 1170 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1171 if (Value *V = threadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1172 return V; 1173 1174 // If the operation is with the result of a phi instruction, check whether 1175 // operating on all incoming values of the phi always yields the same value. 1176 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1177 if (Value *V = threadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1178 return V; 1179 1180 return nullptr; 1181 } 1182 1183 /// These are simplifications common to SDiv and UDiv. 1184 static Value *simplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 1185 bool IsExact, const SimplifyQuery &Q, 1186 unsigned MaxRecurse) { 1187 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1188 return C; 1189 1190 if (Value *V = simplifyDivRem(Opcode, Op0, Op1, Q, MaxRecurse)) 1191 return V; 1192 1193 const APInt *DivC; 1194 if (IsExact && match(Op1, m_APInt(DivC))) { 1195 // If this is an exact divide by a constant, then the dividend (Op0) must 1196 // have at least as many trailing zeros as the divisor to divide evenly. If 1197 // it has less trailing zeros, then the result must be poison. 1198 if (DivC->countr_zero()) { 1199 KnownBits KnownOp0 = computeKnownBits(Op0, /* Depth */ 0, Q); 1200 if (KnownOp0.countMaxTrailingZeros() < DivC->countr_zero()) 1201 return PoisonValue::get(Op0->getType()); 1202 } 1203 1204 // udiv exact (mul nsw X, C), C --> X 1205 // sdiv exact (mul nuw X, C), C --> X 1206 // where C is not a power of 2. 1207 Value *X; 1208 if (!DivC->isPowerOf2() && 1209 (Opcode == Instruction::UDiv 1210 ? match(Op0, m_NSWMul(m_Value(X), m_Specific(Op1))) 1211 : match(Op0, m_NUWMul(m_Value(X), m_Specific(Op1))))) 1212 return X; 1213 } 1214 1215 return nullptr; 1216 } 1217 1218 /// These are simplifications common to SRem and URem. 1219 static Value *simplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 1220 const SimplifyQuery &Q, unsigned MaxRecurse) { 1221 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1222 return C; 1223 1224 if (Value *V = simplifyDivRem(Opcode, Op0, Op1, Q, MaxRecurse)) 1225 return V; 1226 1227 // (X << Y) % X -> 0 1228 if (Q.IIQ.UseInstrInfo && 1229 ((Opcode == Instruction::SRem && 1230 match(Op0, m_NSWShl(m_Specific(Op1), m_Value()))) || 1231 (Opcode == Instruction::URem && 1232 match(Op0, m_NUWShl(m_Specific(Op1), m_Value()))))) 1233 return Constant::getNullValue(Op0->getType()); 1234 1235 return nullptr; 1236 } 1237 1238 /// Given operands for an SDiv, see if we can fold the result. 1239 /// If not, this returns null. 1240 static Value *simplifySDivInst(Value *Op0, Value *Op1, bool IsExact, 1241 const SimplifyQuery &Q, unsigned MaxRecurse) { 1242 // If two operands are negated and no signed overflow, return -1. 1243 if (isKnownNegation(Op0, Op1, /*NeedNSW=*/true)) 1244 return Constant::getAllOnesValue(Op0->getType()); 1245 1246 return simplifyDiv(Instruction::SDiv, Op0, Op1, IsExact, Q, MaxRecurse); 1247 } 1248 1249 Value *llvm::simplifySDivInst(Value *Op0, Value *Op1, bool IsExact, 1250 const SimplifyQuery &Q) { 1251 return ::simplifySDivInst(Op0, Op1, IsExact, Q, RecursionLimit); 1252 } 1253 1254 /// Given operands for a UDiv, see if we can fold the result. 1255 /// If not, this returns null. 1256 static Value *simplifyUDivInst(Value *Op0, Value *Op1, bool IsExact, 1257 const SimplifyQuery &Q, unsigned MaxRecurse) { 1258 return simplifyDiv(Instruction::UDiv, Op0, Op1, IsExact, Q, MaxRecurse); 1259 } 1260 1261 Value *llvm::simplifyUDivInst(Value *Op0, Value *Op1, bool IsExact, 1262 const SimplifyQuery &Q) { 1263 return ::simplifyUDivInst(Op0, Op1, IsExact, Q, RecursionLimit); 1264 } 1265 1266 /// Given operands for an SRem, see if we can fold the result. 1267 /// If not, this returns null. 1268 static Value *simplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1269 unsigned MaxRecurse) { 1270 // If the divisor is 0, the result is undefined, so assume the divisor is -1. 1271 // srem Op0, (sext i1 X) --> srem Op0, -1 --> 0 1272 Value *X; 1273 if (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) 1274 return ConstantInt::getNullValue(Op0->getType()); 1275 1276 // If the two operands are negated, return 0. 1277 if (isKnownNegation(Op0, Op1)) 1278 return ConstantInt::getNullValue(Op0->getType()); 1279 1280 return simplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse); 1281 } 1282 1283 Value *llvm::simplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 1284 return ::simplifySRemInst(Op0, Op1, Q, RecursionLimit); 1285 } 1286 1287 /// Given operands for a URem, see if we can fold the result. 1288 /// If not, this returns null. 1289 static Value *simplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 1290 unsigned MaxRecurse) { 1291 return simplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse); 1292 } 1293 1294 Value *llvm::simplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 1295 return ::simplifyURemInst(Op0, Op1, Q, RecursionLimit); 1296 } 1297 1298 /// Returns true if a shift by \c Amount always yields poison. 1299 static bool isPoisonShift(Value *Amount, const SimplifyQuery &Q) { 1300 Constant *C = dyn_cast<Constant>(Amount); 1301 if (!C) 1302 return false; 1303 1304 // X shift by undef -> poison because it may shift by the bitwidth. 1305 if (Q.isUndefValue(C)) 1306 return true; 1307 1308 // Shifting by the bitwidth or more is poison. This covers scalars and 1309 // fixed/scalable vectors with splat constants. 1310 const APInt *AmountC; 1311 if (match(C, m_APInt(AmountC)) && AmountC->uge(AmountC->getBitWidth())) 1312 return true; 1313 1314 // Try harder for fixed-length vectors: 1315 // If all lanes of a vector shift are poison, the whole shift is poison. 1316 if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) { 1317 for (unsigned I = 0, 1318 E = cast<FixedVectorType>(C->getType())->getNumElements(); 1319 I != E; ++I) 1320 if (!isPoisonShift(C->getAggregateElement(I), Q)) 1321 return false; 1322 return true; 1323 } 1324 1325 return false; 1326 } 1327 1328 /// Given operands for an Shl, LShr or AShr, see if we can fold the result. 1329 /// If not, this returns null. 1330 static Value *simplifyShift(Instruction::BinaryOps Opcode, Value *Op0, 1331 Value *Op1, bool IsNSW, const SimplifyQuery &Q, 1332 unsigned MaxRecurse) { 1333 if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) 1334 return C; 1335 1336 // poison shift by X -> poison 1337 if (isa<PoisonValue>(Op0)) 1338 return Op0; 1339 1340 // 0 shift by X -> 0 1341 if (match(Op0, m_Zero())) 1342 return Constant::getNullValue(Op0->getType()); 1343 1344 // X shift by 0 -> X 1345 // Shift-by-sign-extended bool must be shift-by-0 because shift-by-all-ones 1346 // would be poison. 1347 Value *X; 1348 if (match(Op1, m_Zero()) || 1349 (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))) 1350 return Op0; 1351 1352 // Fold undefined shifts. 1353 if (isPoisonShift(Op1, Q)) 1354 return PoisonValue::get(Op0->getType()); 1355 1356 // If the operation is with the result of a select instruction, check whether 1357 // operating on either branch of the select always yields the same value. 1358 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1359 if (Value *V = threadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) 1360 return V; 1361 1362 // If the operation is with the result of a phi instruction, check whether 1363 // operating on all incoming values of the phi always yields the same value. 1364 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1365 if (Value *V = threadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) 1366 return V; 1367 1368 // If any bits in the shift amount make that value greater than or equal to 1369 // the number of bits in the type, the shift is undefined. 1370 KnownBits KnownAmt = computeKnownBits(Op1, /* Depth */ 0, Q); 1371 if (KnownAmt.getMinValue().uge(KnownAmt.getBitWidth())) 1372 return PoisonValue::get(Op0->getType()); 1373 1374 // If all valid bits in the shift amount are known zero, the first operand is 1375 // unchanged. 1376 unsigned NumValidShiftBits = Log2_32_Ceil(KnownAmt.getBitWidth()); 1377 if (KnownAmt.countMinTrailingZeros() >= NumValidShiftBits) 1378 return Op0; 1379 1380 // Check for nsw shl leading to a poison value. 1381 if (IsNSW) { 1382 assert(Opcode == Instruction::Shl && "Expected shl for nsw instruction"); 1383 KnownBits KnownVal = computeKnownBits(Op0, /* Depth */ 0, Q); 1384 KnownBits KnownShl = KnownBits::shl(KnownVal, KnownAmt); 1385 1386 if (KnownVal.Zero.isSignBitSet()) 1387 KnownShl.Zero.setSignBit(); 1388 if (KnownVal.One.isSignBitSet()) 1389 KnownShl.One.setSignBit(); 1390 1391 if (KnownShl.hasConflict()) 1392 return PoisonValue::get(Op0->getType()); 1393 } 1394 1395 return nullptr; 1396 } 1397 1398 /// Given operands for an LShr or AShr, see if we can fold the result. If not, 1399 /// this returns null. 1400 static Value *simplifyRightShift(Instruction::BinaryOps Opcode, Value *Op0, 1401 Value *Op1, bool IsExact, 1402 const SimplifyQuery &Q, unsigned MaxRecurse) { 1403 if (Value *V = 1404 simplifyShift(Opcode, Op0, Op1, /*IsNSW*/ false, Q, MaxRecurse)) 1405 return V; 1406 1407 // X >> X -> 0 1408 if (Op0 == Op1) 1409 return Constant::getNullValue(Op0->getType()); 1410 1411 // undef >> X -> 0 1412 // undef >> X -> undef (if it's exact) 1413 if (Q.isUndefValue(Op0)) 1414 return IsExact ? Op0 : Constant::getNullValue(Op0->getType()); 1415 1416 // The low bit cannot be shifted out of an exact shift if it is set. 1417 // TODO: Generalize by counting trailing zeros (see fold for exact division). 1418 if (IsExact) { 1419 KnownBits Op0Known = computeKnownBits(Op0, /* Depth */ 0, Q); 1420 if (Op0Known.One[0]) 1421 return Op0; 1422 } 1423 1424 return nullptr; 1425 } 1426 1427 /// Given operands for an Shl, see if we can fold the result. 1428 /// If not, this returns null. 1429 static Value *simplifyShlInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 1430 const SimplifyQuery &Q, unsigned MaxRecurse) { 1431 if (Value *V = 1432 simplifyShift(Instruction::Shl, Op0, Op1, IsNSW, Q, MaxRecurse)) 1433 return V; 1434 1435 Type *Ty = Op0->getType(); 1436 // undef << X -> 0 1437 // undef << X -> undef if (if it's NSW/NUW) 1438 if (Q.isUndefValue(Op0)) 1439 return IsNSW || IsNUW ? Op0 : Constant::getNullValue(Ty); 1440 1441 // (X >> A) << A -> X 1442 Value *X; 1443 if (Q.IIQ.UseInstrInfo && 1444 match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1))))) 1445 return X; 1446 1447 // shl nuw i8 C, %x -> C iff C has sign bit set. 1448 if (IsNUW && match(Op0, m_Negative())) 1449 return Op0; 1450 // NOTE: could use computeKnownBits() / LazyValueInfo, 1451 // but the cost-benefit analysis suggests it isn't worth it. 1452 1453 // "nuw" guarantees that only zeros are shifted out, and "nsw" guarantees 1454 // that the sign-bit does not change, so the only input that does not 1455 // produce poison is 0, and "0 << (bitwidth-1) --> 0". 1456 if (IsNSW && IsNUW && 1457 match(Op1, m_SpecificInt(Ty->getScalarSizeInBits() - 1))) 1458 return Constant::getNullValue(Ty); 1459 1460 return nullptr; 1461 } 1462 1463 Value *llvm::simplifyShlInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, 1464 const SimplifyQuery &Q) { 1465 return ::simplifyShlInst(Op0, Op1, IsNSW, IsNUW, Q, RecursionLimit); 1466 } 1467 1468 /// Given operands for an LShr, see if we can fold the result. 1469 /// If not, this returns null. 1470 static Value *simplifyLShrInst(Value *Op0, Value *Op1, bool IsExact, 1471 const SimplifyQuery &Q, unsigned MaxRecurse) { 1472 if (Value *V = simplifyRightShift(Instruction::LShr, Op0, Op1, IsExact, Q, 1473 MaxRecurse)) 1474 return V; 1475 1476 // (X << A) >> A -> X 1477 Value *X; 1478 if (Q.IIQ.UseInstrInfo && match(Op0, m_NUWShl(m_Value(X), m_Specific(Op1)))) 1479 return X; 1480 1481 // ((X << A) | Y) >> A -> X if effective width of Y is not larger than A. 1482 // We can return X as we do in the above case since OR alters no bits in X. 1483 // SimplifyDemandedBits in InstCombine can do more general optimization for 1484 // bit manipulation. This pattern aims to provide opportunities for other 1485 // optimizers by supporting a simple but common case in InstSimplify. 1486 Value *Y; 1487 const APInt *ShRAmt, *ShLAmt; 1488 if (Q.IIQ.UseInstrInfo && match(Op1, m_APInt(ShRAmt)) && 1489 match(Op0, m_c_Or(m_NUWShl(m_Value(X), m_APInt(ShLAmt)), m_Value(Y))) && 1490 *ShRAmt == *ShLAmt) { 1491 const KnownBits YKnown = computeKnownBits(Y, /* Depth */ 0, Q); 1492 const unsigned EffWidthY = YKnown.countMaxActiveBits(); 1493 if (ShRAmt->uge(EffWidthY)) 1494 return X; 1495 } 1496 1497 return nullptr; 1498 } 1499 1500 Value *llvm::simplifyLShrInst(Value *Op0, Value *Op1, bool IsExact, 1501 const SimplifyQuery &Q) { 1502 return ::simplifyLShrInst(Op0, Op1, IsExact, Q, RecursionLimit); 1503 } 1504 1505 /// Given operands for an AShr, see if we can fold the result. 1506 /// If not, this returns null. 1507 static Value *simplifyAShrInst(Value *Op0, Value *Op1, bool IsExact, 1508 const SimplifyQuery &Q, unsigned MaxRecurse) { 1509 if (Value *V = simplifyRightShift(Instruction::AShr, Op0, Op1, IsExact, Q, 1510 MaxRecurse)) 1511 return V; 1512 1513 // -1 >>a X --> -1 1514 // (-1 << X) a>> X --> -1 1515 // Do not return Op0 because it may contain undef elements if it's a vector. 1516 if (match(Op0, m_AllOnes()) || 1517 match(Op0, m_Shl(m_AllOnes(), m_Specific(Op1)))) 1518 return Constant::getAllOnesValue(Op0->getType()); 1519 1520 // (X << A) >> A -> X 1521 Value *X; 1522 if (Q.IIQ.UseInstrInfo && match(Op0, m_NSWShl(m_Value(X), m_Specific(Op1)))) 1523 return X; 1524 1525 // Arithmetic shifting an all-sign-bit value is a no-op. 1526 unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); 1527 if (NumSignBits == Op0->getType()->getScalarSizeInBits()) 1528 return Op0; 1529 1530 return nullptr; 1531 } 1532 1533 Value *llvm::simplifyAShrInst(Value *Op0, Value *Op1, bool IsExact, 1534 const SimplifyQuery &Q) { 1535 return ::simplifyAShrInst(Op0, Op1, IsExact, Q, RecursionLimit); 1536 } 1537 1538 /// Commuted variants are assumed to be handled by calling this function again 1539 /// with the parameters swapped. 1540 static Value *simplifyUnsignedRangeCheck(ICmpInst *ZeroICmp, 1541 ICmpInst *UnsignedICmp, bool IsAnd, 1542 const SimplifyQuery &Q) { 1543 Value *X, *Y; 1544 1545 ICmpInst::Predicate EqPred; 1546 if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(Y), m_Zero())) || 1547 !ICmpInst::isEquality(EqPred)) 1548 return nullptr; 1549 1550 ICmpInst::Predicate UnsignedPred; 1551 1552 Value *A, *B; 1553 // Y = (A - B); 1554 if (match(Y, m_Sub(m_Value(A), m_Value(B)))) { 1555 if (match(UnsignedICmp, 1556 m_c_ICmp(UnsignedPred, m_Specific(A), m_Specific(B))) && 1557 ICmpInst::isUnsigned(UnsignedPred)) { 1558 // A >=/<= B || (A - B) != 0 <--> true 1559 if ((UnsignedPred == ICmpInst::ICMP_UGE || 1560 UnsignedPred == ICmpInst::ICMP_ULE) && 1561 EqPred == ICmpInst::ICMP_NE && !IsAnd) 1562 return ConstantInt::getTrue(UnsignedICmp->getType()); 1563 // A </> B && (A - B) == 0 <--> false 1564 if ((UnsignedPred == ICmpInst::ICMP_ULT || 1565 UnsignedPred == ICmpInst::ICMP_UGT) && 1566 EqPred == ICmpInst::ICMP_EQ && IsAnd) 1567 return ConstantInt::getFalse(UnsignedICmp->getType()); 1568 1569 // A </> B && (A - B) != 0 <--> A </> B 1570 // A </> B || (A - B) != 0 <--> (A - B) != 0 1571 if (EqPred == ICmpInst::ICMP_NE && (UnsignedPred == ICmpInst::ICMP_ULT || 1572 UnsignedPred == ICmpInst::ICMP_UGT)) 1573 return IsAnd ? UnsignedICmp : ZeroICmp; 1574 1575 // A <=/>= B && (A - B) == 0 <--> (A - B) == 0 1576 // A <=/>= B || (A - B) == 0 <--> A <=/>= B 1577 if (EqPred == ICmpInst::ICMP_EQ && (UnsignedPred == ICmpInst::ICMP_ULE || 1578 UnsignedPred == ICmpInst::ICMP_UGE)) 1579 return IsAnd ? ZeroICmp : UnsignedICmp; 1580 } 1581 1582 // Given Y = (A - B) 1583 // Y >= A && Y != 0 --> Y >= A iff B != 0 1584 // Y < A || Y == 0 --> Y < A iff B != 0 1585 if (match(UnsignedICmp, 1586 m_c_ICmp(UnsignedPred, m_Specific(Y), m_Specific(A)))) { 1587 if (UnsignedPred == ICmpInst::ICMP_UGE && IsAnd && 1588 EqPred == ICmpInst::ICMP_NE && 1589 isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1590 return UnsignedICmp; 1591 if (UnsignedPred == ICmpInst::ICMP_ULT && !IsAnd && 1592 EqPred == ICmpInst::ICMP_EQ && 1593 isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1594 return UnsignedICmp; 1595 } 1596 } 1597 1598 if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) && 1599 ICmpInst::isUnsigned(UnsignedPred)) 1600 ; 1601 else if (match(UnsignedICmp, 1602 m_ICmp(UnsignedPred, m_Specific(Y), m_Value(X))) && 1603 ICmpInst::isUnsigned(UnsignedPred)) 1604 UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred); 1605 else 1606 return nullptr; 1607 1608 // X > Y && Y == 0 --> Y == 0 iff X != 0 1609 // X > Y || Y == 0 --> X > Y iff X != 0 1610 if (UnsignedPred == ICmpInst::ICMP_UGT && EqPred == ICmpInst::ICMP_EQ && 1611 isKnownNonZero(X, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1612 return IsAnd ? ZeroICmp : UnsignedICmp; 1613 1614 // X <= Y && Y != 0 --> X <= Y iff X != 0 1615 // X <= Y || Y != 0 --> Y != 0 iff X != 0 1616 if (UnsignedPred == ICmpInst::ICMP_ULE && EqPred == ICmpInst::ICMP_NE && 1617 isKnownNonZero(X, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) 1618 return IsAnd ? UnsignedICmp : ZeroICmp; 1619 1620 // The transforms below here are expected to be handled more generally with 1621 // simplifyAndOrOfICmpsWithLimitConst() or in InstCombine's 1622 // foldAndOrOfICmpsWithConstEq(). If we are looking to trim optimizer overlap, 1623 // these are candidates for removal. 1624 1625 // X < Y && Y != 0 --> X < Y 1626 // X < Y || Y != 0 --> Y != 0 1627 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE) 1628 return IsAnd ? UnsignedICmp : ZeroICmp; 1629 1630 // X >= Y && Y == 0 --> Y == 0 1631 // X >= Y || Y == 0 --> X >= Y 1632 if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_EQ) 1633 return IsAnd ? ZeroICmp : UnsignedICmp; 1634 1635 // X < Y && Y == 0 --> false 1636 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ && 1637 IsAnd) 1638 return getFalse(UnsignedICmp->getType()); 1639 1640 // X >= Y || Y != 0 --> true 1641 if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_NE && 1642 !IsAnd) 1643 return getTrue(UnsignedICmp->getType()); 1644 1645 return nullptr; 1646 } 1647 1648 /// Test if a pair of compares with a shared operand and 2 constants has an 1649 /// empty set intersection, full set union, or if one compare is a superset of 1650 /// the other. 1651 static Value *simplifyAndOrOfICmpsWithConstants(ICmpInst *Cmp0, ICmpInst *Cmp1, 1652 bool IsAnd) { 1653 // Look for this pattern: {and/or} (icmp X, C0), (icmp X, C1)). 1654 if (Cmp0->getOperand(0) != Cmp1->getOperand(0)) 1655 return nullptr; 1656 1657 const APInt *C0, *C1; 1658 if (!match(Cmp0->getOperand(1), m_APInt(C0)) || 1659 !match(Cmp1->getOperand(1), m_APInt(C1))) 1660 return nullptr; 1661 1662 auto Range0 = ConstantRange::makeExactICmpRegion(Cmp0->getPredicate(), *C0); 1663 auto Range1 = ConstantRange::makeExactICmpRegion(Cmp1->getPredicate(), *C1); 1664 1665 // For and-of-compares, check if the intersection is empty: 1666 // (icmp X, C0) && (icmp X, C1) --> empty set --> false 1667 if (IsAnd && Range0.intersectWith(Range1).isEmptySet()) 1668 return getFalse(Cmp0->getType()); 1669 1670 // For or-of-compares, check if the union is full: 1671 // (icmp X, C0) || (icmp X, C1) --> full set --> true 1672 if (!IsAnd && Range0.unionWith(Range1).isFullSet()) 1673 return getTrue(Cmp0->getType()); 1674 1675 // Is one range a superset of the other? 1676 // If this is and-of-compares, take the smaller set: 1677 // (icmp sgt X, 4) && (icmp sgt X, 42) --> icmp sgt X, 42 1678 // If this is or-of-compares, take the larger set: 1679 // (icmp sgt X, 4) || (icmp sgt X, 42) --> icmp sgt X, 4 1680 if (Range0.contains(Range1)) 1681 return IsAnd ? Cmp1 : Cmp0; 1682 if (Range1.contains(Range0)) 1683 return IsAnd ? Cmp0 : Cmp1; 1684 1685 return nullptr; 1686 } 1687 1688 static Value *simplifyAndOfICmpsWithAdd(ICmpInst *Op0, ICmpInst *Op1, 1689 const InstrInfoQuery &IIQ) { 1690 // (icmp (add V, C0), C1) & (icmp V, C0) 1691 ICmpInst::Predicate Pred0, Pred1; 1692 const APInt *C0, *C1; 1693 Value *V; 1694 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1)))) 1695 return nullptr; 1696 1697 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value()))) 1698 return nullptr; 1699 1700 auto *AddInst = cast<OverflowingBinaryOperator>(Op0->getOperand(0)); 1701 if (AddInst->getOperand(1) != Op1->getOperand(1)) 1702 return nullptr; 1703 1704 Type *ITy = Op0->getType(); 1705 bool IsNSW = IIQ.hasNoSignedWrap(AddInst); 1706 bool IsNUW = IIQ.hasNoUnsignedWrap(AddInst); 1707 1708 const APInt Delta = *C1 - *C0; 1709 if (C0->isStrictlyPositive()) { 1710 if (Delta == 2) { 1711 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT) 1712 return getFalse(ITy); 1713 if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && IsNSW) 1714 return getFalse(ITy); 1715 } 1716 if (Delta == 1) { 1717 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT) 1718 return getFalse(ITy); 1719 if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && IsNSW) 1720 return getFalse(ITy); 1721 } 1722 } 1723 if (C0->getBoolValue() && IsNUW) { 1724 if (Delta == 2) 1725 if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT) 1726 return getFalse(ITy); 1727 if (Delta == 1) 1728 if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT) 1729 return getFalse(ITy); 1730 } 1731 1732 return nullptr; 1733 } 1734 1735 /// Try to simplify and/or of icmp with ctpop intrinsic. 1736 static Value *simplifyAndOrOfICmpsWithCtpop(ICmpInst *Cmp0, ICmpInst *Cmp1, 1737 bool IsAnd) { 1738 ICmpInst::Predicate Pred0, Pred1; 1739 Value *X; 1740 const APInt *C; 1741 if (!match(Cmp0, m_ICmp(Pred0, m_Intrinsic<Intrinsic::ctpop>(m_Value(X)), 1742 m_APInt(C))) || 1743 !match(Cmp1, m_ICmp(Pred1, m_Specific(X), m_ZeroInt())) || C->isZero()) 1744 return nullptr; 1745 1746 // (ctpop(X) == C) || (X != 0) --> X != 0 where C > 0 1747 if (!IsAnd && Pred0 == ICmpInst::ICMP_EQ && Pred1 == ICmpInst::ICMP_NE) 1748 return Cmp1; 1749 // (ctpop(X) != C) && (X == 0) --> X == 0 where C > 0 1750 if (IsAnd && Pred0 == ICmpInst::ICMP_NE && Pred1 == ICmpInst::ICMP_EQ) 1751 return Cmp1; 1752 1753 return nullptr; 1754 } 1755 1756 static Value *simplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1, 1757 const SimplifyQuery &Q) { 1758 if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true, Q)) 1759 return X; 1760 if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/true, Q)) 1761 return X; 1762 1763 if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, true)) 1764 return X; 1765 1766 if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op0, Op1, true)) 1767 return X; 1768 if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op1, Op0, true)) 1769 return X; 1770 1771 if (Value *X = simplifyAndOfICmpsWithAdd(Op0, Op1, Q.IIQ)) 1772 return X; 1773 if (Value *X = simplifyAndOfICmpsWithAdd(Op1, Op0, Q.IIQ)) 1774 return X; 1775 1776 return nullptr; 1777 } 1778 1779 static Value *simplifyOrOfICmpsWithAdd(ICmpInst *Op0, ICmpInst *Op1, 1780 const InstrInfoQuery &IIQ) { 1781 // (icmp (add V, C0), C1) | (icmp V, C0) 1782 ICmpInst::Predicate Pred0, Pred1; 1783 const APInt *C0, *C1; 1784 Value *V; 1785 if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1)))) 1786 return nullptr; 1787 1788 if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value()))) 1789 return nullptr; 1790 1791 auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0)); 1792 if (AddInst->getOperand(1) != Op1->getOperand(1)) 1793 return nullptr; 1794 1795 Type *ITy = Op0->getType(); 1796 bool IsNSW = IIQ.hasNoSignedWrap(AddInst); 1797 bool IsNUW = IIQ.hasNoUnsignedWrap(AddInst); 1798 1799 const APInt Delta = *C1 - *C0; 1800 if (C0->isStrictlyPositive()) { 1801 if (Delta == 2) { 1802 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE) 1803 return getTrue(ITy); 1804 if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && IsNSW) 1805 return getTrue(ITy); 1806 } 1807 if (Delta == 1) { 1808 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE) 1809 return getTrue(ITy); 1810 if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && IsNSW) 1811 return getTrue(ITy); 1812 } 1813 } 1814 if (C0->getBoolValue() && IsNUW) { 1815 if (Delta == 2) 1816 if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE) 1817 return getTrue(ITy); 1818 if (Delta == 1) 1819 if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE) 1820 return getTrue(ITy); 1821 } 1822 1823 return nullptr; 1824 } 1825 1826 static Value *simplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1, 1827 const SimplifyQuery &Q) { 1828 if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false, Q)) 1829 return X; 1830 if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/false, Q)) 1831 return X; 1832 1833 if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, false)) 1834 return X; 1835 1836 if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op0, Op1, false)) 1837 return X; 1838 if (Value *X = simplifyAndOrOfICmpsWithCtpop(Op1, Op0, false)) 1839 return X; 1840 1841 if (Value *X = simplifyOrOfICmpsWithAdd(Op0, Op1, Q.IIQ)) 1842 return X; 1843 if (Value *X = simplifyOrOfICmpsWithAdd(Op1, Op0, Q.IIQ)) 1844 return X; 1845 1846 return nullptr; 1847 } 1848 1849 static Value *simplifyAndOrOfFCmps(const SimplifyQuery &Q, FCmpInst *LHS, 1850 FCmpInst *RHS, bool IsAnd) { 1851 Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1); 1852 Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1); 1853 if (LHS0->getType() != RHS0->getType()) 1854 return nullptr; 1855 1856 const DataLayout &DL = Q.DL; 1857 const TargetLibraryInfo *TLI = Q.TLI; 1858 1859 FCmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); 1860 if ((PredL == FCmpInst::FCMP_ORD && PredR == FCmpInst::FCMP_ORD && IsAnd) || 1861 (PredL == FCmpInst::FCMP_UNO && PredR == FCmpInst::FCMP_UNO && !IsAnd)) { 1862 // (fcmp ord NNAN, X) & (fcmp ord X, Y) --> fcmp ord X, Y 1863 // (fcmp ord NNAN, X) & (fcmp ord Y, X) --> fcmp ord Y, X 1864 // (fcmp ord X, NNAN) & (fcmp ord X, Y) --> fcmp ord X, Y 1865 // (fcmp ord X, NNAN) & (fcmp ord Y, X) --> fcmp ord Y, X 1866 // (fcmp uno NNAN, X) | (fcmp uno X, Y) --> fcmp uno X, Y 1867 // (fcmp uno NNAN, X) | (fcmp uno Y, X) --> fcmp uno Y, X 1868 // (fcmp uno X, NNAN) | (fcmp uno X, Y) --> fcmp uno X, Y 1869 // (fcmp uno X, NNAN) | (fcmp uno Y, X) --> fcmp uno Y, X 1870 if (((LHS1 == RHS0 || LHS1 == RHS1) && 1871 isKnownNeverNaN(LHS0, DL, TLI, 0, Q.AC, Q.CxtI, Q.DT)) || 1872 ((LHS0 == RHS0 || LHS0 == RHS1) && 1873 isKnownNeverNaN(LHS1, DL, TLI, 0, Q.AC, Q.CxtI, Q.DT))) 1874 return RHS; 1875 1876 // (fcmp ord X, Y) & (fcmp ord NNAN, X) --> fcmp ord X, Y 1877 // (fcmp ord Y, X) & (fcmp ord NNAN, X) --> fcmp ord Y, X 1878 // (fcmp ord X, Y) & (fcmp ord X, NNAN) --> fcmp ord X, Y 1879 // (fcmp ord Y, X) & (fcmp ord X, NNAN) --> fcmp ord Y, X 1880 // (fcmp uno X, Y) | (fcmp uno NNAN, X) --> fcmp uno X, Y 1881 // (fcmp uno Y, X) | (fcmp uno NNAN, X) --> fcmp uno Y, X 1882 // (fcmp uno X, Y) | (fcmp uno X, NNAN) --> fcmp uno X, Y 1883 // (fcmp uno Y, X) | (fcmp uno X, NNAN) --> fcmp uno Y, X 1884 if (((RHS1 == LHS0 || RHS1 == LHS1) && 1885 isKnownNeverNaN(RHS0, DL, TLI, 0, Q.AC, Q.CxtI, Q.DT)) || 1886 ((RHS0 == LHS0 || RHS0 == LHS1) && 1887 isKnownNeverNaN(RHS1, DL, TLI, 0, Q.AC, Q.CxtI, Q.DT))) 1888 return LHS; 1889 } 1890 1891 return nullptr; 1892 } 1893 1894 static Value *simplifyAndOrOfCmps(const SimplifyQuery &Q, Value *Op0, 1895 Value *Op1, bool IsAnd) { 1896 // Look through casts of the 'and' operands to find compares. 1897 auto *Cast0 = dyn_cast<CastInst>(Op0); 1898 auto *Cast1 = dyn_cast<CastInst>(Op1); 1899 if (Cast0 && Cast1 && Cast0->getOpcode() == Cast1->getOpcode() && 1900 Cast0->getSrcTy() == Cast1->getSrcTy()) { 1901 Op0 = Cast0->getOperand(0); 1902 Op1 = Cast1->getOperand(0); 1903 } 1904 1905 Value *V = nullptr; 1906 auto *ICmp0 = dyn_cast<ICmpInst>(Op0); 1907 auto *ICmp1 = dyn_cast<ICmpInst>(Op1); 1908 if (ICmp0 && ICmp1) 1909 V = IsAnd ? simplifyAndOfICmps(ICmp0, ICmp1, Q) 1910 : simplifyOrOfICmps(ICmp0, ICmp1, Q); 1911 1912 auto *FCmp0 = dyn_cast<FCmpInst>(Op0); 1913 auto *FCmp1 = dyn_cast<FCmpInst>(Op1); 1914 if (FCmp0 && FCmp1) 1915 V = simplifyAndOrOfFCmps(Q, FCmp0, FCmp1, IsAnd); 1916 1917 if (!V) 1918 return nullptr; 1919 if (!Cast0) 1920 return V; 1921 1922 // If we looked through casts, we can only handle a constant simplification 1923 // because we are not allowed to create a cast instruction here. 1924 if (auto *C = dyn_cast<Constant>(V)) 1925 return ConstantFoldCastOperand(Cast0->getOpcode(), C, Cast0->getType(), 1926 Q.DL); 1927 1928 return nullptr; 1929 } 1930 1931 static Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, 1932 const SimplifyQuery &Q, 1933 bool AllowRefinement, 1934 SmallVectorImpl<Instruction *> *DropFlags, 1935 unsigned MaxRecurse); 1936 1937 static Value *simplifyAndOrWithICmpEq(unsigned Opcode, Value *Op0, Value *Op1, 1938 const SimplifyQuery &Q, 1939 unsigned MaxRecurse) { 1940 assert((Opcode == Instruction::And || Opcode == Instruction::Or) && 1941 "Must be and/or"); 1942 ICmpInst::Predicate Pred; 1943 Value *A, *B; 1944 if (!match(Op0, m_ICmp(Pred, m_Value(A), m_Value(B))) || 1945 !ICmpInst::isEquality(Pred)) 1946 return nullptr; 1947 1948 auto Simplify = [&](Value *Res) -> Value * { 1949 Constant *Absorber = ConstantExpr::getBinOpAbsorber(Opcode, Res->getType()); 1950 1951 // and (icmp eq a, b), x implies (a==b) inside x. 1952 // or (icmp ne a, b), x implies (a==b) inside x. 1953 // If x simplifies to true/false, we can simplify the and/or. 1954 if (Pred == 1955 (Opcode == Instruction::And ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE)) { 1956 if (Res == Absorber) 1957 return Absorber; 1958 if (Res == ConstantExpr::getBinOpIdentity(Opcode, Res->getType())) 1959 return Op0; 1960 return nullptr; 1961 } 1962 1963 // If we have and (icmp ne a, b), x and for a==b we can simplify x to false, 1964 // then we can drop the icmp, as x will already be false in the case where 1965 // the icmp is false. Similar for or and true. 1966 if (Res == Absorber) 1967 return Op1; 1968 return nullptr; 1969 }; 1970 1971 if (Value *Res = 1972 simplifyWithOpReplaced(Op1, A, B, Q, /* AllowRefinement */ true, 1973 /* DropFlags */ nullptr, MaxRecurse)) 1974 return Simplify(Res); 1975 if (Value *Res = 1976 simplifyWithOpReplaced(Op1, B, A, Q, /* AllowRefinement */ true, 1977 /* DropFlags */ nullptr, MaxRecurse)) 1978 return Simplify(Res); 1979 1980 return nullptr; 1981 } 1982 1983 /// Given a bitwise logic op, check if the operands are add/sub with a common 1984 /// source value and inverted constant (identity: C - X -> ~(X + ~C)). 1985 static Value *simplifyLogicOfAddSub(Value *Op0, Value *Op1, 1986 Instruction::BinaryOps Opcode) { 1987 assert(Op0->getType() == Op1->getType() && "Mismatched binop types"); 1988 assert(BinaryOperator::isBitwiseLogicOp(Opcode) && "Expected logic op"); 1989 Value *X; 1990 Constant *C1, *C2; 1991 if ((match(Op0, m_Add(m_Value(X), m_Constant(C1))) && 1992 match(Op1, m_Sub(m_Constant(C2), m_Specific(X)))) || 1993 (match(Op1, m_Add(m_Value(X), m_Constant(C1))) && 1994 match(Op0, m_Sub(m_Constant(C2), m_Specific(X))))) { 1995 if (ConstantExpr::getNot(C1) == C2) { 1996 // (X + C) & (~C - X) --> (X + C) & ~(X + C) --> 0 1997 // (X + C) | (~C - X) --> (X + C) | ~(X + C) --> -1 1998 // (X + C) ^ (~C - X) --> (X + C) ^ ~(X + C) --> -1 1999 Type *Ty = Op0->getType(); 2000 return Opcode == Instruction::And ? ConstantInt::getNullValue(Ty) 2001 : ConstantInt::getAllOnesValue(Ty); 2002 } 2003 } 2004 return nullptr; 2005 } 2006 2007 // Commutative patterns for and that will be tried with both operand orders. 2008 static Value *simplifyAndCommutative(Value *Op0, Value *Op1, 2009 const SimplifyQuery &Q, 2010 unsigned MaxRecurse) { 2011 // ~A & A = 0 2012 if (match(Op0, m_Not(m_Specific(Op1)))) 2013 return Constant::getNullValue(Op0->getType()); 2014 2015 // (A | ?) & A = A 2016 if (match(Op0, m_c_Or(m_Specific(Op1), m_Value()))) 2017 return Op1; 2018 2019 // (X | ~Y) & (X | Y) --> X 2020 Value *X, *Y; 2021 if (match(Op0, m_c_Or(m_Value(X), m_Not(m_Value(Y)))) && 2022 match(Op1, m_c_Or(m_Deferred(X), m_Deferred(Y)))) 2023 return X; 2024 2025 // If we have a multiplication overflow check that is being 'and'ed with a 2026 // check that one of the multipliers is not zero, we can omit the 'and', and 2027 // only keep the overflow check. 2028 if (isCheckForZeroAndMulWithOverflow(Op0, Op1, true)) 2029 return Op1; 2030 2031 // -A & A = A if A is a power of two or zero. 2032 if (match(Op0, m_Neg(m_Specific(Op1))) && 2033 isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT)) 2034 return Op1; 2035 2036 // This is a similar pattern used for checking if a value is a power-of-2: 2037 // (A - 1) & A --> 0 (if A is a power-of-2 or 0) 2038 if (match(Op0, m_Add(m_Specific(Op1), m_AllOnes())) && 2039 isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT)) 2040 return Constant::getNullValue(Op1->getType()); 2041 2042 // (x << N) & ((x << M) - 1) --> 0, where x is known to be a power of 2 and 2043 // M <= N. 2044 const APInt *Shift1, *Shift2; 2045 if (match(Op0, m_Shl(m_Value(X), m_APInt(Shift1))) && 2046 match(Op1, m_Add(m_Shl(m_Specific(X), m_APInt(Shift2)), m_AllOnes())) && 2047 isKnownToBeAPowerOfTwo(X, Q.DL, /*OrZero*/ true, /*Depth*/ 0, Q.AC, 2048 Q.CxtI) && 2049 Shift1->uge(*Shift2)) 2050 return Constant::getNullValue(Op0->getType()); 2051 2052 if (Value *V = 2053 simplifyAndOrWithICmpEq(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2054 return V; 2055 2056 return nullptr; 2057 } 2058 2059 /// Given operands for an And, see if we can fold the result. 2060 /// If not, this returns null. 2061 static Value *simplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 2062 unsigned MaxRecurse) { 2063 if (Constant *C = foldOrCommuteConstant(Instruction::And, Op0, Op1, Q)) 2064 return C; 2065 2066 // X & poison -> poison 2067 if (isa<PoisonValue>(Op1)) 2068 return Op1; 2069 2070 // X & undef -> 0 2071 if (Q.isUndefValue(Op1)) 2072 return Constant::getNullValue(Op0->getType()); 2073 2074 // X & X = X 2075 if (Op0 == Op1) 2076 return Op0; 2077 2078 // X & 0 = 0 2079 if (match(Op1, m_Zero())) 2080 return Constant::getNullValue(Op0->getType()); 2081 2082 // X & -1 = X 2083 if (match(Op1, m_AllOnes())) 2084 return Op0; 2085 2086 if (Value *Res = simplifyAndCommutative(Op0, Op1, Q, MaxRecurse)) 2087 return Res; 2088 if (Value *Res = simplifyAndCommutative(Op1, Op0, Q, MaxRecurse)) 2089 return Res; 2090 2091 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::And)) 2092 return V; 2093 2094 // A mask that only clears known zeros of a shifted value is a no-op. 2095 const APInt *Mask; 2096 const APInt *ShAmt; 2097 Value *X, *Y; 2098 if (match(Op1, m_APInt(Mask))) { 2099 // If all bits in the inverted and shifted mask are clear: 2100 // and (shl X, ShAmt), Mask --> shl X, ShAmt 2101 if (match(Op0, m_Shl(m_Value(X), m_APInt(ShAmt))) && 2102 (~(*Mask)).lshr(*ShAmt).isZero()) 2103 return Op0; 2104 2105 // If all bits in the inverted and shifted mask are clear: 2106 // and (lshr X, ShAmt), Mask --> lshr X, ShAmt 2107 if (match(Op0, m_LShr(m_Value(X), m_APInt(ShAmt))) && 2108 (~(*Mask)).shl(*ShAmt).isZero()) 2109 return Op0; 2110 } 2111 2112 // and 2^x-1, 2^C --> 0 where x <= C. 2113 const APInt *PowerC; 2114 Value *Shift; 2115 if (match(Op1, m_Power2(PowerC)) && 2116 match(Op0, m_Add(m_Value(Shift), m_AllOnes())) && 2117 isKnownToBeAPowerOfTwo(Shift, Q.DL, /*OrZero*/ false, 0, Q.AC, Q.CxtI, 2118 Q.DT)) { 2119 KnownBits Known = computeKnownBits(Shift, /* Depth */ 0, Q); 2120 // Use getActiveBits() to make use of the additional power of two knowledge 2121 if (PowerC->getActiveBits() >= Known.getMaxValue().getActiveBits()) 2122 return ConstantInt::getNullValue(Op1->getType()); 2123 } 2124 2125 if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, true)) 2126 return V; 2127 2128 // Try some generic simplifications for associative operations. 2129 if (Value *V = 2130 simplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2131 return V; 2132 2133 // And distributes over Or. Try some generic simplifications based on this. 2134 if (Value *V = expandCommutativeBinOp(Instruction::And, Op0, Op1, 2135 Instruction::Or, Q, MaxRecurse)) 2136 return V; 2137 2138 // And distributes over Xor. Try some generic simplifications based on this. 2139 if (Value *V = expandCommutativeBinOp(Instruction::And, Op0, Op1, 2140 Instruction::Xor, Q, MaxRecurse)) 2141 return V; 2142 2143 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) { 2144 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2145 // A & (A && B) -> A && B 2146 if (match(Op1, m_Select(m_Specific(Op0), m_Value(), m_Zero()))) 2147 return Op1; 2148 else if (match(Op0, m_Select(m_Specific(Op1), m_Value(), m_Zero()))) 2149 return Op0; 2150 } 2151 // If the operation is with the result of a select instruction, check 2152 // whether operating on either branch of the select always yields the same 2153 // value. 2154 if (Value *V = 2155 threadBinOpOverSelect(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2156 return V; 2157 } 2158 2159 // If the operation is with the result of a phi instruction, check whether 2160 // operating on all incoming values of the phi always yields the same value. 2161 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 2162 if (Value *V = 2163 threadBinOpOverPHI(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2164 return V; 2165 2166 // Assuming the effective width of Y is not larger than A, i.e. all bits 2167 // from X and Y are disjoint in (X << A) | Y, 2168 // if the mask of this AND op covers all bits of X or Y, while it covers 2169 // no bits from the other, we can bypass this AND op. E.g., 2170 // ((X << A) | Y) & Mask -> Y, 2171 // if Mask = ((1 << effective_width_of(Y)) - 1) 2172 // ((X << A) | Y) & Mask -> X << A, 2173 // if Mask = ((1 << effective_width_of(X)) - 1) << A 2174 // SimplifyDemandedBits in InstCombine can optimize the general case. 2175 // This pattern aims to help other passes for a common case. 2176 Value *XShifted; 2177 if (Q.IIQ.UseInstrInfo && match(Op1, m_APInt(Mask)) && 2178 match(Op0, m_c_Or(m_CombineAnd(m_NUWShl(m_Value(X), m_APInt(ShAmt)), 2179 m_Value(XShifted)), 2180 m_Value(Y)))) { 2181 const unsigned Width = Op0->getType()->getScalarSizeInBits(); 2182 const unsigned ShftCnt = ShAmt->getLimitedValue(Width); 2183 const KnownBits YKnown = computeKnownBits(Y, /* Depth */ 0, Q); 2184 const unsigned EffWidthY = YKnown.countMaxActiveBits(); 2185 if (EffWidthY <= ShftCnt) { 2186 const KnownBits XKnown = computeKnownBits(X, /* Depth */ 0, Q); 2187 const unsigned EffWidthX = XKnown.countMaxActiveBits(); 2188 const APInt EffBitsY = APInt::getLowBitsSet(Width, EffWidthY); 2189 const APInt EffBitsX = APInt::getLowBitsSet(Width, EffWidthX) << ShftCnt; 2190 // If the mask is extracting all bits from X or Y as is, we can skip 2191 // this AND op. 2192 if (EffBitsY.isSubsetOf(*Mask) && !EffBitsX.intersects(*Mask)) 2193 return Y; 2194 if (EffBitsX.isSubsetOf(*Mask) && !EffBitsY.intersects(*Mask)) 2195 return XShifted; 2196 } 2197 } 2198 2199 // ((X | Y) ^ X ) & ((X | Y) ^ Y) --> 0 2200 // ((X | Y) ^ Y ) & ((X | Y) ^ X) --> 0 2201 BinaryOperator *Or; 2202 if (match(Op0, m_c_Xor(m_Value(X), 2203 m_CombineAnd(m_BinOp(Or), 2204 m_c_Or(m_Deferred(X), m_Value(Y))))) && 2205 match(Op1, m_c_Xor(m_Specific(Or), m_Specific(Y)))) 2206 return Constant::getNullValue(Op0->getType()); 2207 2208 const APInt *C1; 2209 Value *A; 2210 // (A ^ C) & (A ^ ~C) -> 0 2211 if (match(Op0, m_Xor(m_Value(A), m_APInt(C1))) && 2212 match(Op1, m_Xor(m_Specific(A), m_SpecificInt(~*C1)))) 2213 return Constant::getNullValue(Op0->getType()); 2214 2215 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2216 if (std::optional<bool> Implied = isImpliedCondition(Op0, Op1, Q.DL)) { 2217 // If Op0 is true implies Op1 is true, then Op0 is a subset of Op1. 2218 if (*Implied == true) 2219 return Op0; 2220 // If Op0 is true implies Op1 is false, then they are not true together. 2221 if (*Implied == false) 2222 return ConstantInt::getFalse(Op0->getType()); 2223 } 2224 if (std::optional<bool> Implied = isImpliedCondition(Op1, Op0, Q.DL)) { 2225 // If Op1 is true implies Op0 is true, then Op1 is a subset of Op0. 2226 if (*Implied) 2227 return Op1; 2228 // If Op1 is true implies Op0 is false, then they are not true together. 2229 if (!*Implied) 2230 return ConstantInt::getFalse(Op1->getType()); 2231 } 2232 } 2233 2234 if (Value *V = simplifyByDomEq(Instruction::And, Op0, Op1, Q, MaxRecurse)) 2235 return V; 2236 2237 return nullptr; 2238 } 2239 2240 Value *llvm::simplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2241 return ::simplifyAndInst(Op0, Op1, Q, RecursionLimit); 2242 } 2243 2244 // TODO: Many of these folds could use LogicalAnd/LogicalOr. 2245 static Value *simplifyOrLogic(Value *X, Value *Y) { 2246 assert(X->getType() == Y->getType() && "Expected same type for 'or' ops"); 2247 Type *Ty = X->getType(); 2248 2249 // X | ~X --> -1 2250 if (match(Y, m_Not(m_Specific(X)))) 2251 return ConstantInt::getAllOnesValue(Ty); 2252 2253 // X | ~(X & ?) = -1 2254 if (match(Y, m_Not(m_c_And(m_Specific(X), m_Value())))) 2255 return ConstantInt::getAllOnesValue(Ty); 2256 2257 // X | (X & ?) --> X 2258 if (match(Y, m_c_And(m_Specific(X), m_Value()))) 2259 return X; 2260 2261 Value *A, *B; 2262 2263 // (A ^ B) | (A | B) --> A | B 2264 // (A ^ B) | (B | A) --> B | A 2265 if (match(X, m_Xor(m_Value(A), m_Value(B))) && 2266 match(Y, m_c_Or(m_Specific(A), m_Specific(B)))) 2267 return Y; 2268 2269 // ~(A ^ B) | (A | B) --> -1 2270 // ~(A ^ B) | (B | A) --> -1 2271 if (match(X, m_Not(m_Xor(m_Value(A), m_Value(B)))) && 2272 match(Y, m_c_Or(m_Specific(A), m_Specific(B)))) 2273 return ConstantInt::getAllOnesValue(Ty); 2274 2275 // (A & ~B) | (A ^ B) --> A ^ B 2276 // (~B & A) | (A ^ B) --> A ^ B 2277 // (A & ~B) | (B ^ A) --> B ^ A 2278 // (~B & A) | (B ^ A) --> B ^ A 2279 if (match(X, m_c_And(m_Value(A), m_Not(m_Value(B)))) && 2280 match(Y, m_c_Xor(m_Specific(A), m_Specific(B)))) 2281 return Y; 2282 2283 // (~A ^ B) | (A & B) --> ~A ^ B 2284 // (B ^ ~A) | (A & B) --> B ^ ~A 2285 // (~A ^ B) | (B & A) --> ~A ^ B 2286 // (B ^ ~A) | (B & A) --> B ^ ~A 2287 if (match(X, m_c_Xor(m_NotForbidUndef(m_Value(A)), m_Value(B))) && 2288 match(Y, m_c_And(m_Specific(A), m_Specific(B)))) 2289 return X; 2290 2291 // (~A | B) | (A ^ B) --> -1 2292 // (~A | B) | (B ^ A) --> -1 2293 // (B | ~A) | (A ^ B) --> -1 2294 // (B | ~A) | (B ^ A) --> -1 2295 if (match(X, m_c_Or(m_Not(m_Value(A)), m_Value(B))) && 2296 match(Y, m_c_Xor(m_Specific(A), m_Specific(B)))) 2297 return ConstantInt::getAllOnesValue(Ty); 2298 2299 // (~A & B) | ~(A | B) --> ~A 2300 // (~A & B) | ~(B | A) --> ~A 2301 // (B & ~A) | ~(A | B) --> ~A 2302 // (B & ~A) | ~(B | A) --> ~A 2303 Value *NotA; 2304 if (match(X, 2305 m_c_And(m_CombineAnd(m_Value(NotA), m_NotForbidUndef(m_Value(A))), 2306 m_Value(B))) && 2307 match(Y, m_Not(m_c_Or(m_Specific(A), m_Specific(B))))) 2308 return NotA; 2309 // The same is true of Logical And 2310 // TODO: This could share the logic of the version above if there was a 2311 // version of LogicalAnd that allowed more than just i1 types. 2312 if (match(X, m_c_LogicalAnd( 2313 m_CombineAnd(m_Value(NotA), m_NotForbidUndef(m_Value(A))), 2314 m_Value(B))) && 2315 match(Y, m_Not(m_c_LogicalOr(m_Specific(A), m_Specific(B))))) 2316 return NotA; 2317 2318 // ~(A ^ B) | (A & B) --> ~(A ^ B) 2319 // ~(A ^ B) | (B & A) --> ~(A ^ B) 2320 Value *NotAB; 2321 if (match(X, m_CombineAnd(m_NotForbidUndef(m_Xor(m_Value(A), m_Value(B))), 2322 m_Value(NotAB))) && 2323 match(Y, m_c_And(m_Specific(A), m_Specific(B)))) 2324 return NotAB; 2325 2326 // ~(A & B) | (A ^ B) --> ~(A & B) 2327 // ~(A & B) | (B ^ A) --> ~(A & B) 2328 if (match(X, m_CombineAnd(m_NotForbidUndef(m_And(m_Value(A), m_Value(B))), 2329 m_Value(NotAB))) && 2330 match(Y, m_c_Xor(m_Specific(A), m_Specific(B)))) 2331 return NotAB; 2332 2333 return nullptr; 2334 } 2335 2336 /// Given operands for an Or, see if we can fold the result. 2337 /// If not, this returns null. 2338 static Value *simplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 2339 unsigned MaxRecurse) { 2340 if (Constant *C = foldOrCommuteConstant(Instruction::Or, Op0, Op1, Q)) 2341 return C; 2342 2343 // X | poison -> poison 2344 if (isa<PoisonValue>(Op1)) 2345 return Op1; 2346 2347 // X | undef -> -1 2348 // X | -1 = -1 2349 // Do not return Op1 because it may contain undef elements if it's a vector. 2350 if (Q.isUndefValue(Op1) || match(Op1, m_AllOnes())) 2351 return Constant::getAllOnesValue(Op0->getType()); 2352 2353 // X | X = X 2354 // X | 0 = X 2355 if (Op0 == Op1 || match(Op1, m_Zero())) 2356 return Op0; 2357 2358 if (Value *R = simplifyOrLogic(Op0, Op1)) 2359 return R; 2360 if (Value *R = simplifyOrLogic(Op1, Op0)) 2361 return R; 2362 2363 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Or)) 2364 return V; 2365 2366 // Rotated -1 is still -1: 2367 // (-1 << X) | (-1 >> (C - X)) --> -1 2368 // (-1 >> X) | (-1 << (C - X)) --> -1 2369 // ...with C <= bitwidth (and commuted variants). 2370 Value *X, *Y; 2371 if ((match(Op0, m_Shl(m_AllOnes(), m_Value(X))) && 2372 match(Op1, m_LShr(m_AllOnes(), m_Value(Y)))) || 2373 (match(Op1, m_Shl(m_AllOnes(), m_Value(X))) && 2374 match(Op0, m_LShr(m_AllOnes(), m_Value(Y))))) { 2375 const APInt *C; 2376 if ((match(X, m_Sub(m_APInt(C), m_Specific(Y))) || 2377 match(Y, m_Sub(m_APInt(C), m_Specific(X)))) && 2378 C->ule(X->getType()->getScalarSizeInBits())) { 2379 return ConstantInt::getAllOnesValue(X->getType()); 2380 } 2381 } 2382 2383 // A funnel shift (rotate) can be decomposed into simpler shifts. See if we 2384 // are mixing in another shift that is redundant with the funnel shift. 2385 2386 // (fshl X, ?, Y) | (shl X, Y) --> fshl X, ?, Y 2387 // (shl X, Y) | (fshl X, ?, Y) --> fshl X, ?, Y 2388 if (match(Op0, 2389 m_Intrinsic<Intrinsic::fshl>(m_Value(X), m_Value(), m_Value(Y))) && 2390 match(Op1, m_Shl(m_Specific(X), m_Specific(Y)))) 2391 return Op0; 2392 if (match(Op1, 2393 m_Intrinsic<Intrinsic::fshl>(m_Value(X), m_Value(), m_Value(Y))) && 2394 match(Op0, m_Shl(m_Specific(X), m_Specific(Y)))) 2395 return Op1; 2396 2397 // (fshr ?, X, Y) | (lshr X, Y) --> fshr ?, X, Y 2398 // (lshr X, Y) | (fshr ?, X, Y) --> fshr ?, X, Y 2399 if (match(Op0, 2400 m_Intrinsic<Intrinsic::fshr>(m_Value(), m_Value(X), m_Value(Y))) && 2401 match(Op1, m_LShr(m_Specific(X), m_Specific(Y)))) 2402 return Op0; 2403 if (match(Op1, 2404 m_Intrinsic<Intrinsic::fshr>(m_Value(), m_Value(X), m_Value(Y))) && 2405 match(Op0, m_LShr(m_Specific(X), m_Specific(Y)))) 2406 return Op1; 2407 2408 if (Value *V = 2409 simplifyAndOrWithICmpEq(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2410 return V; 2411 if (Value *V = 2412 simplifyAndOrWithICmpEq(Instruction::Or, Op1, Op0, Q, MaxRecurse)) 2413 return V; 2414 2415 if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, false)) 2416 return V; 2417 2418 // If we have a multiplication overflow check that is being 'and'ed with a 2419 // check that one of the multipliers is not zero, we can omit the 'and', and 2420 // only keep the overflow check. 2421 if (isCheckForZeroAndMulWithOverflow(Op0, Op1, false)) 2422 return Op1; 2423 if (isCheckForZeroAndMulWithOverflow(Op1, Op0, false)) 2424 return Op0; 2425 2426 // Try some generic simplifications for associative operations. 2427 if (Value *V = 2428 simplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2429 return V; 2430 2431 // Or distributes over And. Try some generic simplifications based on this. 2432 if (Value *V = expandCommutativeBinOp(Instruction::Or, Op0, Op1, 2433 Instruction::And, Q, MaxRecurse)) 2434 return V; 2435 2436 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) { 2437 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2438 // A | (A || B) -> A || B 2439 if (match(Op1, m_Select(m_Specific(Op0), m_One(), m_Value()))) 2440 return Op1; 2441 else if (match(Op0, m_Select(m_Specific(Op1), m_One(), m_Value()))) 2442 return Op0; 2443 } 2444 // If the operation is with the result of a select instruction, check 2445 // whether operating on either branch of the select always yields the same 2446 // value. 2447 if (Value *V = 2448 threadBinOpOverSelect(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2449 return V; 2450 } 2451 2452 // (A & C1)|(B & C2) 2453 Value *A, *B; 2454 const APInt *C1, *C2; 2455 if (match(Op0, m_And(m_Value(A), m_APInt(C1))) && 2456 match(Op1, m_And(m_Value(B), m_APInt(C2)))) { 2457 if (*C1 == ~*C2) { 2458 // (A & C1)|(B & C2) 2459 // If we have: ((V + N) & C1) | (V & C2) 2460 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0 2461 // replace with V+N. 2462 Value *N; 2463 if (C2->isMask() && // C2 == 0+1+ 2464 match(A, m_c_Add(m_Specific(B), m_Value(N)))) { 2465 // Add commutes, try both ways. 2466 if (MaskedValueIsZero(N, *C2, Q)) 2467 return A; 2468 } 2469 // Or commutes, try both ways. 2470 if (C1->isMask() && match(B, m_c_Add(m_Specific(A), m_Value(N)))) { 2471 // Add commutes, try both ways. 2472 if (MaskedValueIsZero(N, *C1, Q)) 2473 return B; 2474 } 2475 } 2476 } 2477 2478 // If the operation is with the result of a phi instruction, check whether 2479 // operating on all incoming values of the phi always yields the same value. 2480 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 2481 if (Value *V = threadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2482 return V; 2483 2484 // (A ^ C) | (A ^ ~C) -> -1, i.e. all bits set to one. 2485 if (match(Op0, m_Xor(m_Value(A), m_APInt(C1))) && 2486 match(Op1, m_Xor(m_Specific(A), m_SpecificInt(~*C1)))) 2487 return Constant::getAllOnesValue(Op0->getType()); 2488 2489 if (Op0->getType()->isIntOrIntVectorTy(1)) { 2490 if (std::optional<bool> Implied = 2491 isImpliedCondition(Op0, Op1, Q.DL, false)) { 2492 // If Op0 is false implies Op1 is false, then Op1 is a subset of Op0. 2493 if (*Implied == false) 2494 return Op0; 2495 // If Op0 is false implies Op1 is true, then at least one is always true. 2496 if (*Implied == true) 2497 return ConstantInt::getTrue(Op0->getType()); 2498 } 2499 if (std::optional<bool> Implied = 2500 isImpliedCondition(Op1, Op0, Q.DL, false)) { 2501 // If Op1 is false implies Op0 is false, then Op0 is a subset of Op1. 2502 if (*Implied == false) 2503 return Op1; 2504 // If Op1 is false implies Op0 is true, then at least one is always true. 2505 if (*Implied == true) 2506 return ConstantInt::getTrue(Op1->getType()); 2507 } 2508 } 2509 2510 if (Value *V = simplifyByDomEq(Instruction::Or, Op0, Op1, Q, MaxRecurse)) 2511 return V; 2512 2513 return nullptr; 2514 } 2515 2516 Value *llvm::simplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2517 return ::simplifyOrInst(Op0, Op1, Q, RecursionLimit); 2518 } 2519 2520 /// Given operands for a Xor, see if we can fold the result. 2521 /// If not, this returns null. 2522 static Value *simplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, 2523 unsigned MaxRecurse) { 2524 if (Constant *C = foldOrCommuteConstant(Instruction::Xor, Op0, Op1, Q)) 2525 return C; 2526 2527 // X ^ poison -> poison 2528 if (isa<PoisonValue>(Op1)) 2529 return Op1; 2530 2531 // A ^ undef -> undef 2532 if (Q.isUndefValue(Op1)) 2533 return Op1; 2534 2535 // A ^ 0 = A 2536 if (match(Op1, m_Zero())) 2537 return Op0; 2538 2539 // A ^ A = 0 2540 if (Op0 == Op1) 2541 return Constant::getNullValue(Op0->getType()); 2542 2543 // A ^ ~A = ~A ^ A = -1 2544 if (match(Op0, m_Not(m_Specific(Op1))) || match(Op1, m_Not(m_Specific(Op0)))) 2545 return Constant::getAllOnesValue(Op0->getType()); 2546 2547 auto foldAndOrNot = [](Value *X, Value *Y) -> Value * { 2548 Value *A, *B; 2549 // (~A & B) ^ (A | B) --> A -- There are 8 commuted variants. 2550 if (match(X, m_c_And(m_Not(m_Value(A)), m_Value(B))) && 2551 match(Y, m_c_Or(m_Specific(A), m_Specific(B)))) 2552 return A; 2553 2554 // (~A | B) ^ (A & B) --> ~A -- There are 8 commuted variants. 2555 // The 'not' op must contain a complete -1 operand (no undef elements for 2556 // vector) for the transform to be safe. 2557 Value *NotA; 2558 if (match(X, 2559 m_c_Or(m_CombineAnd(m_NotForbidUndef(m_Value(A)), m_Value(NotA)), 2560 m_Value(B))) && 2561 match(Y, m_c_And(m_Specific(A), m_Specific(B)))) 2562 return NotA; 2563 2564 return nullptr; 2565 }; 2566 if (Value *R = foldAndOrNot(Op0, Op1)) 2567 return R; 2568 if (Value *R = foldAndOrNot(Op1, Op0)) 2569 return R; 2570 2571 if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Xor)) 2572 return V; 2573 2574 // Try some generic simplifications for associative operations. 2575 if (Value *V = 2576 simplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q, MaxRecurse)) 2577 return V; 2578 2579 // Threading Xor over selects and phi nodes is pointless, so don't bother. 2580 // Threading over the select in "A ^ select(cond, B, C)" means evaluating 2581 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and 2582 // only if B and C are equal. If B and C are equal then (since we assume 2583 // that operands have already been simplified) "select(cond, B, C)" should 2584 // have been simplified to the common value of B and C already. Analysing 2585 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly 2586 // for threading over phi nodes. 2587 2588 if (Value *V = simplifyByDomEq(Instruction::Xor, Op0, Op1, Q, MaxRecurse)) 2589 return V; 2590 2591 return nullptr; 2592 } 2593 2594 Value *llvm::simplifyXorInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { 2595 return ::simplifyXorInst(Op0, Op1, Q, RecursionLimit); 2596 } 2597 2598 static Type *getCompareTy(Value *Op) { 2599 return CmpInst::makeCmpResultType(Op->getType()); 2600 } 2601 2602 /// Rummage around inside V looking for something equivalent to the comparison 2603 /// "LHS Pred RHS". Return such a value if found, otherwise return null. 2604 /// Helper function for analyzing max/min idioms. 2605 static Value *extractEquivalentCondition(Value *V, CmpInst::Predicate Pred, 2606 Value *LHS, Value *RHS) { 2607 SelectInst *SI = dyn_cast<SelectInst>(V); 2608 if (!SI) 2609 return nullptr; 2610 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition()); 2611 if (!Cmp) 2612 return nullptr; 2613 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1); 2614 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS) 2615 return Cmp; 2616 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) && 2617 LHS == CmpRHS && RHS == CmpLHS) 2618 return Cmp; 2619 return nullptr; 2620 } 2621 2622 /// Return true if the underlying object (storage) must be disjoint from 2623 /// storage returned by any noalias return call. 2624 static bool isAllocDisjoint(const Value *V) { 2625 // For allocas, we consider only static ones (dynamic 2626 // allocas might be transformed into calls to malloc not simultaneously 2627 // live with the compared-to allocation). For globals, we exclude symbols 2628 // that might be resolve lazily to symbols in another dynamically-loaded 2629 // library (and, thus, could be malloc'ed by the implementation). 2630 if (const AllocaInst *AI = dyn_cast<AllocaInst>(V)) 2631 return AI->isStaticAlloca(); 2632 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) 2633 return (GV->hasLocalLinkage() || GV->hasHiddenVisibility() || 2634 GV->hasProtectedVisibility() || GV->hasGlobalUnnamedAddr()) && 2635 !GV->isThreadLocal(); 2636 if (const Argument *A = dyn_cast<Argument>(V)) 2637 return A->hasByValAttr(); 2638 return false; 2639 } 2640 2641 /// Return true if V1 and V2 are each the base of some distict storage region 2642 /// [V, object_size(V)] which do not overlap. Note that zero sized regions 2643 /// *are* possible, and that zero sized regions do not overlap with any other. 2644 static bool haveNonOverlappingStorage(const Value *V1, const Value *V2) { 2645 // Global variables always exist, so they always exist during the lifetime 2646 // of each other and all allocas. Global variables themselves usually have 2647 // non-overlapping storage, but since their addresses are constants, the 2648 // case involving two globals does not reach here and is instead handled in 2649 // constant folding. 2650 // 2651 // Two different allocas usually have different addresses... 2652 // 2653 // However, if there's an @llvm.stackrestore dynamically in between two 2654 // allocas, they may have the same address. It's tempting to reduce the 2655 // scope of the problem by only looking at *static* allocas here. That would 2656 // cover the majority of allocas while significantly reducing the likelihood 2657 // of having an @llvm.stackrestore pop up in the middle. However, it's not 2658 // actually impossible for an @llvm.stackrestore to pop up in the middle of 2659 // an entry block. Also, if we have a block that's not attached to a 2660 // function, we can't tell if it's "static" under the current definition. 2661 // Theoretically, this problem could be fixed by creating a new kind of 2662 // instruction kind specifically for static allocas. Such a new instruction 2663 // could be required to be at the top of the entry block, thus preventing it 2664 // from being subject to a @llvm.stackrestore. Instcombine could even 2665 // convert regular allocas into these special allocas. It'd be nifty. 2666 // However, until then, this problem remains open. 2667 // 2668 // So, we'll assume that two non-empty allocas have different addresses 2669 // for now. 2670 auto isByValArg = [](const Value *V) { 2671 const Argument *A = dyn_cast<Argument>(V); 2672 return A && A->hasByValAttr(); 2673 }; 2674 2675 // Byval args are backed by store which does not overlap with each other, 2676 // allocas, or globals. 2677 if (isByValArg(V1)) 2678 return isa<AllocaInst>(V2) || isa<GlobalVariable>(V2) || isByValArg(V2); 2679 if (isByValArg(V2)) 2680 return isa<AllocaInst>(V1) || isa<GlobalVariable>(V1) || isByValArg(V1); 2681 2682 return isa<AllocaInst>(V1) && 2683 (isa<AllocaInst>(V2) || isa<GlobalVariable>(V2)); 2684 } 2685 2686 // A significant optimization not implemented here is assuming that alloca 2687 // addresses are not equal to incoming argument values. They don't *alias*, 2688 // as we say, but that doesn't mean they aren't equal, so we take a 2689 // conservative approach. 2690 // 2691 // This is inspired in part by C++11 5.10p1: 2692 // "Two pointers of the same type compare equal if and only if they are both 2693 // null, both point to the same function, or both represent the same 2694 // address." 2695 // 2696 // This is pretty permissive. 2697 // 2698 // It's also partly due to C11 6.5.9p6: 2699 // "Two pointers compare equal if and only if both are null pointers, both are 2700 // pointers to the same object (including a pointer to an object and a 2701 // subobject at its beginning) or function, both are pointers to one past the 2702 // last element of the same array object, or one is a pointer to one past the 2703 // end of one array object and the other is a pointer to the start of a 2704 // different array object that happens to immediately follow the first array 2705 // object in the address space.) 2706 // 2707 // C11's version is more restrictive, however there's no reason why an argument 2708 // couldn't be a one-past-the-end value for a stack object in the caller and be 2709 // equal to the beginning of a stack object in the callee. 2710 // 2711 // If the C and C++ standards are ever made sufficiently restrictive in this 2712 // area, it may be possible to update LLVM's semantics accordingly and reinstate 2713 // this optimization. 2714 static Constant *computePointerICmp(CmpInst::Predicate Pred, Value *LHS, 2715 Value *RHS, const SimplifyQuery &Q) { 2716 assert(LHS->getType() == RHS->getType() && "Must have same types"); 2717 const DataLayout &DL = Q.DL; 2718 const TargetLibraryInfo *TLI = Q.TLI; 2719 const DominatorTree *DT = Q.DT; 2720 const Instruction *CxtI = Q.CxtI; 2721 2722 // We can only fold certain predicates on pointer comparisons. 2723 switch (Pred) { 2724 default: 2725 return nullptr; 2726 2727 // Equality comparisons are easy to fold. 2728 case CmpInst::ICMP_EQ: 2729 case CmpInst::ICMP_NE: 2730 break; 2731 2732 // We can only handle unsigned relational comparisons because 'inbounds' on 2733 // a GEP only protects against unsigned wrapping. 2734 case CmpInst::ICMP_UGT: 2735 case CmpInst::ICMP_UGE: 2736 case CmpInst::ICMP_ULT: 2737 case CmpInst::ICMP_ULE: 2738 // However, we have to switch them to their signed variants to handle 2739 // negative indices from the base pointer. 2740 Pred = ICmpInst::getSignedPredicate(Pred); 2741 break; 2742 } 2743 2744 // Strip off any constant offsets so that we can reason about them. 2745 // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets 2746 // here and compare base addresses like AliasAnalysis does, however there are 2747 // numerous hazards. AliasAnalysis and its utilities rely on special rules 2748 // governing loads and stores which don't apply to icmps. Also, AliasAnalysis 2749 // doesn't need to guarantee pointer inequality when it says NoAlias. 2750 2751 // Even if an non-inbounds GEP occurs along the path we can still optimize 2752 // equality comparisons concerning the result. 2753 bool AllowNonInbounds = ICmpInst::isEquality(Pred); 2754 unsigned IndexSize = DL.getIndexTypeSizeInBits(LHS->getType()); 2755 APInt LHSOffset(IndexSize, 0), RHSOffset(IndexSize, 0); 2756 LHS = LHS->stripAndAccumulateConstantOffsets(DL, LHSOffset, AllowNonInbounds); 2757 RHS = RHS->stripAndAccumulateConstantOffsets(DL, RHSOffset, AllowNonInbounds); 2758 2759 // If LHS and RHS are related via constant offsets to the same base 2760 // value, we can replace it with an icmp which just compares the offsets. 2761 if (LHS == RHS) 2762 return ConstantInt::get(getCompareTy(LHS), 2763 ICmpInst::compare(LHSOffset, RHSOffset, Pred)); 2764 2765 // Various optimizations for (in)equality comparisons. 2766 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) { 2767 // Different non-empty allocations that exist at the same time have 2768 // different addresses (if the program can tell). If the offsets are 2769 // within the bounds of their allocations (and not one-past-the-end! 2770 // so we can't use inbounds!), and their allocations aren't the same, 2771 // the pointers are not equal. 2772 if (haveNonOverlappingStorage(LHS, RHS)) { 2773 uint64_t LHSSize, RHSSize; 2774 ObjectSizeOpts Opts; 2775 Opts.EvalMode = ObjectSizeOpts::Mode::Min; 2776 auto *F = [](Value *V) -> Function * { 2777 if (auto *I = dyn_cast<Instruction>(V)) 2778 return I->getFunction(); 2779 if (auto *A = dyn_cast<Argument>(V)) 2780 return A->getParent(); 2781 return nullptr; 2782 }(LHS); 2783 Opts.NullIsUnknownSize = F ? NullPointerIsDefined(F) : true; 2784 if (getObjectSize(LHS, LHSSize, DL, TLI, Opts) && 2785 getObjectSize(RHS, RHSSize, DL, TLI, Opts)) { 2786 APInt Dist = LHSOffset - RHSOffset; 2787 if (Dist.isNonNegative() ? Dist.ult(LHSSize) : (-Dist).ult(RHSSize)) 2788 return ConstantInt::get(getCompareTy(LHS), 2789 !CmpInst::isTrueWhenEqual(Pred)); 2790 } 2791 } 2792 2793 // If one side of the equality comparison must come from a noalias call 2794 // (meaning a system memory allocation function), and the other side must 2795 // come from a pointer that cannot overlap with dynamically-allocated 2796 // memory within the lifetime of the current function (allocas, byval 2797 // arguments, globals), then determine the comparison result here. 2798 SmallVector<const Value *, 8> LHSUObjs, RHSUObjs; 2799 getUnderlyingObjects(LHS, LHSUObjs); 2800 getUnderlyingObjects(RHS, RHSUObjs); 2801 2802 // Is the set of underlying objects all noalias calls? 2803 auto IsNAC = [](ArrayRef<const Value *> Objects) { 2804 return all_of(Objects, isNoAliasCall); 2805 }; 2806 2807 // Is the set of underlying objects all things which must be disjoint from 2808 // noalias calls. We assume that indexing from such disjoint storage 2809 // into the heap is undefined, and thus offsets can be safely ignored. 2810 auto IsAllocDisjoint = [](ArrayRef<const Value *> Objects) { 2811 return all_of(Objects, ::isAllocDisjoint); 2812 }; 2813 2814 if ((IsNAC(LHSUObjs) && IsAllocDisjoint(RHSUObjs)) || 2815 (IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs))) 2816 return ConstantInt::get(getCompareTy(LHS), 2817 !CmpInst::isTrueWhenEqual(Pred)); 2818 2819 // Fold comparisons for non-escaping pointer even if the allocation call 2820 // cannot be elided. We cannot fold malloc comparison to null. Also, the 2821 // dynamic allocation call could be either of the operands. Note that 2822 // the other operand can not be based on the alloc - if it were, then 2823 // the cmp itself would be a capture. 2824 Value *MI = nullptr; 2825 if (isAllocLikeFn(LHS, TLI) && 2826 llvm::isKnownNonZero(RHS, DL, 0, nullptr, CxtI, DT)) 2827 MI = LHS; 2828 else if (isAllocLikeFn(RHS, TLI) && 2829 llvm::isKnownNonZero(LHS, DL, 0, nullptr, CxtI, DT)) 2830 MI = RHS; 2831 if (MI) { 2832 // FIXME: This is incorrect, see PR54002. While we can assume that the 2833 // allocation is at an address that makes the comparison false, this 2834 // requires that *all* comparisons to that address be false, which 2835 // InstSimplify cannot guarantee. 2836 struct CustomCaptureTracker : public CaptureTracker { 2837 bool Captured = false; 2838 void tooManyUses() override { Captured = true; } 2839 bool captured(const Use *U) override { 2840 if (auto *ICmp = dyn_cast<ICmpInst>(U->getUser())) { 2841 // Comparison against value stored in global variable. Given the 2842 // pointer does not escape, its value cannot be guessed and stored 2843 // separately in a global variable. 2844 unsigned OtherIdx = 1 - U->getOperandNo(); 2845 auto *LI = dyn_cast<LoadInst>(ICmp->getOperand(OtherIdx)); 2846 if (LI && isa<GlobalVariable>(LI->getPointerOperand())) 2847 return false; 2848 } 2849 2850 Captured = true; 2851 return true; 2852 } 2853 }; 2854 CustomCaptureTracker Tracker; 2855 PointerMayBeCaptured(MI, &Tracker); 2856 if (!Tracker.Captured) 2857 return ConstantInt::get(getCompareTy(LHS), 2858 CmpInst::isFalseWhenEqual(Pred)); 2859 } 2860 } 2861 2862 // Otherwise, fail. 2863 return nullptr; 2864 } 2865 2866 /// Fold an icmp when its operands have i1 scalar type. 2867 static Value *simplifyICmpOfBools(CmpInst::Predicate Pred, Value *LHS, 2868 Value *RHS, const SimplifyQuery &Q) { 2869 Type *ITy = getCompareTy(LHS); // The return type. 2870 Type *OpTy = LHS->getType(); // The operand type. 2871 if (!OpTy->isIntOrIntVectorTy(1)) 2872 return nullptr; 2873 2874 // A boolean compared to true/false can be reduced in 14 out of the 20 2875 // (10 predicates * 2 constants) possible combinations. The other 2876 // 6 cases require a 'not' of the LHS. 2877 2878 auto ExtractNotLHS = [](Value *V) -> Value * { 2879 Value *X; 2880 if (match(V, m_Not(m_Value(X)))) 2881 return X; 2882 return nullptr; 2883 }; 2884 2885 if (match(RHS, m_Zero())) { 2886 switch (Pred) { 2887 case CmpInst::ICMP_NE: // X != 0 -> X 2888 case CmpInst::ICMP_UGT: // X >u 0 -> X 2889 case CmpInst::ICMP_SLT: // X <s 0 -> X 2890 return LHS; 2891 2892 case CmpInst::ICMP_EQ: // not(X) == 0 -> X != 0 -> X 2893 case CmpInst::ICMP_ULE: // not(X) <=u 0 -> X >u 0 -> X 2894 case CmpInst::ICMP_SGE: // not(X) >=s 0 -> X <s 0 -> X 2895 if (Value *X = ExtractNotLHS(LHS)) 2896 return X; 2897 break; 2898 2899 case CmpInst::ICMP_ULT: // X <u 0 -> false 2900 case CmpInst::ICMP_SGT: // X >s 0 -> false 2901 return getFalse(ITy); 2902 2903 case CmpInst::ICMP_UGE: // X >=u 0 -> true 2904 case CmpInst::ICMP_SLE: // X <=s 0 -> true 2905 return getTrue(ITy); 2906 2907 default: 2908 break; 2909 } 2910 } else if (match(RHS, m_One())) { 2911 switch (Pred) { 2912 case CmpInst::ICMP_EQ: // X == 1 -> X 2913 case CmpInst::ICMP_UGE: // X >=u 1 -> X 2914 case CmpInst::ICMP_SLE: // X <=s -1 -> X 2915 return LHS; 2916 2917 case CmpInst::ICMP_NE: // not(X) != 1 -> X == 1 -> X 2918 case CmpInst::ICMP_ULT: // not(X) <=u 1 -> X >=u 1 -> X 2919 case CmpInst::ICMP_SGT: // not(X) >s 1 -> X <=s -1 -> X 2920 if (Value *X = ExtractNotLHS(LHS)) 2921 return X; 2922 break; 2923 2924 case CmpInst::ICMP_UGT: // X >u 1 -> false 2925 case CmpInst::ICMP_SLT: // X <s -1 -> false 2926 return getFalse(ITy); 2927 2928 case CmpInst::ICMP_ULE: // X <=u 1 -> true 2929 case CmpInst::ICMP_SGE: // X >=s -1 -> true 2930 return getTrue(ITy); 2931 2932 default: 2933 break; 2934 } 2935 } 2936 2937 switch (Pred) { 2938 default: 2939 break; 2940 case ICmpInst::ICMP_UGE: 2941 if (isImpliedCondition(RHS, LHS, Q.DL).value_or(false)) 2942 return getTrue(ITy); 2943 break; 2944 case ICmpInst::ICMP_SGE: 2945 /// For signed comparison, the values for an i1 are 0 and -1 2946 /// respectively. This maps into a truth table of: 2947 /// LHS | RHS | LHS >=s RHS | LHS implies RHS 2948 /// 0 | 0 | 1 (0 >= 0) | 1 2949 /// 0 | 1 | 1 (0 >= -1) | 1 2950 /// 1 | 0 | 0 (-1 >= 0) | 0 2951 /// 1 | 1 | 1 (-1 >= -1) | 1 2952 if (isImpliedCondition(LHS, RHS, Q.DL).value_or(false)) 2953 return getTrue(ITy); 2954 break; 2955 case ICmpInst::ICMP_ULE: 2956 if (isImpliedCondition(LHS, RHS, Q.DL).value_or(false)) 2957 return getTrue(ITy); 2958 break; 2959 case ICmpInst::ICMP_SLE: 2960 /// SLE follows the same logic as SGE with the LHS and RHS swapped. 2961 if (isImpliedCondition(RHS, LHS, Q.DL).value_or(false)) 2962 return getTrue(ITy); 2963 break; 2964 } 2965 2966 return nullptr; 2967 } 2968 2969 /// Try hard to fold icmp with zero RHS because this is a common case. 2970 static Value *simplifyICmpWithZero(CmpInst::Predicate Pred, Value *LHS, 2971 Value *RHS, const SimplifyQuery &Q) { 2972 if (!match(RHS, m_Zero())) 2973 return nullptr; 2974 2975 Type *ITy = getCompareTy(LHS); // The return type. 2976 switch (Pred) { 2977 default: 2978 llvm_unreachable("Unknown ICmp predicate!"); 2979 case ICmpInst::ICMP_ULT: 2980 return getFalse(ITy); 2981 case ICmpInst::ICMP_UGE: 2982 return getTrue(ITy); 2983 case ICmpInst::ICMP_EQ: 2984 case ICmpInst::ICMP_ULE: 2985 if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) 2986 return getFalse(ITy); 2987 break; 2988 case ICmpInst::ICMP_NE: 2989 case ICmpInst::ICMP_UGT: 2990 if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) 2991 return getTrue(ITy); 2992 break; 2993 case ICmpInst::ICMP_SLT: { 2994 KnownBits LHSKnown = computeKnownBits(LHS, /* Depth */ 0, Q); 2995 if (LHSKnown.isNegative()) 2996 return getTrue(ITy); 2997 if (LHSKnown.isNonNegative()) 2998 return getFalse(ITy); 2999 break; 3000 } 3001 case ICmpInst::ICMP_SLE: { 3002 KnownBits LHSKnown = computeKnownBits(LHS, /* Depth */ 0, Q); 3003 if (LHSKnown.isNegative()) 3004 return getTrue(ITy); 3005 if (LHSKnown.isNonNegative() && 3006 isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) 3007 return getFalse(ITy); 3008 break; 3009 } 3010 case ICmpInst::ICMP_SGE: { 3011 KnownBits LHSKnown = computeKnownBits(LHS, /* Depth */ 0, Q); 3012 if (LHSKnown.isNegative()) 3013 return getFalse(ITy); 3014 if (LHSKnown.isNonNegative()) 3015 return getTrue(ITy); 3016 break; 3017 } 3018 case ICmpInst::ICMP_SGT: { 3019 KnownBits LHSKnown = computeKnownBits(LHS, /* Depth */ 0, Q); 3020 if (LHSKnown.isNegative()) 3021 return getFalse(ITy); 3022 if (LHSKnown.isNonNegative() && 3023 isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) 3024 return getTrue(ITy); 3025 break; 3026 } 3027 } 3028 3029 return nullptr; 3030 } 3031 3032 static Value *simplifyICmpWithConstant(CmpInst::Predicate Pred, Value *LHS, 3033 Value *RHS, const InstrInfoQuery &IIQ) { 3034 Type *ITy = getCompareTy(RHS); // The return type. 3035 3036 Value *X; 3037 // Sign-bit checks can be optimized to true/false after unsigned 3038 // floating-point casts: 3039 // icmp slt (bitcast (uitofp X)), 0 --> false 3040 // icmp sgt (bitcast (uitofp X)), -1 --> true 3041 if (match(LHS, m_BitCast(m_UIToFP(m_Value(X))))) { 3042 if (Pred == ICmpInst::ICMP_SLT && match(RHS, m_Zero())) 3043 return ConstantInt::getFalse(ITy); 3044 if (Pred == ICmpInst::ICMP_SGT && match(RHS, m_AllOnes())) 3045 return ConstantInt::getTrue(ITy); 3046 } 3047 3048 const APInt *C; 3049 if (!match(RHS, m_APIntAllowUndef(C))) 3050 return nullptr; 3051 3052 // Rule out tautological comparisons (eg., ult 0 or uge 0). 3053 ConstantRange RHS_CR = ConstantRange::makeExactICmpRegion(Pred, *C); 3054 if (RHS_CR.isEmptySet()) 3055 return ConstantInt::getFalse(ITy); 3056 if (RHS_CR.isFullSet()) 3057 return ConstantInt::getTrue(ITy); 3058 3059 ConstantRange LHS_CR = 3060 computeConstantRange(LHS, CmpInst::isSigned(Pred), IIQ.UseInstrInfo); 3061 if (!LHS_CR.isFullSet()) { 3062 if (RHS_CR.contains(LHS_CR)) 3063 return ConstantInt::getTrue(ITy); 3064 if (RHS_CR.inverse().contains(LHS_CR)) 3065 return ConstantInt::getFalse(ITy); 3066 } 3067 3068 // (mul nuw/nsw X, MulC) != C --> true (if C is not a multiple of MulC) 3069 // (mul nuw/nsw X, MulC) == C --> false (if C is not a multiple of MulC) 3070 const APInt *MulC; 3071 if (IIQ.UseInstrInfo && ICmpInst::isEquality(Pred) && 3072 ((match(LHS, m_NUWMul(m_Value(), m_APIntAllowUndef(MulC))) && 3073 *MulC != 0 && C->urem(*MulC) != 0) || 3074 (match(LHS, m_NSWMul(m_Value(), m_APIntAllowUndef(MulC))) && 3075 *MulC != 0 && C->srem(*MulC) != 0))) 3076 return ConstantInt::get(ITy, Pred == ICmpInst::ICMP_NE); 3077 3078 return nullptr; 3079 } 3080 3081 static Value *simplifyICmpWithBinOpOnLHS(CmpInst::Predicate Pred, 3082 BinaryOperator *LBO, Value *RHS, 3083 const SimplifyQuery &Q, 3084 unsigned MaxRecurse) { 3085 Type *ITy = getCompareTy(RHS); // The return type. 3086 3087 Value *Y = nullptr; 3088 // icmp pred (or X, Y), X 3089 if (match(LBO, m_c_Or(m_Value(Y), m_Specific(RHS)))) { 3090 if (Pred == ICmpInst::ICMP_ULT) 3091 return getFalse(ITy); 3092 if (Pred == ICmpInst::ICMP_UGE) 3093 return getTrue(ITy); 3094 3095 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGE) { 3096 KnownBits RHSKnown = computeKnownBits(RHS, /* Depth */ 0, Q); 3097 KnownBits YKnown = computeKnownBits(Y, /* Depth */ 0, Q); 3098 if (RHSKnown.isNonNegative() && YKnown.isNegative()) 3099 return Pred == ICmpInst::ICMP_SLT ? getTrue(ITy) : getFalse(ITy); 3100 if (RHSKnown.isNegative() || YKnown.isNonNegative()) 3101 return Pred == ICmpInst::ICMP_SLT ? getFalse(ITy) : getTrue(ITy); 3102 } 3103 } 3104 3105 // icmp pred (and X, Y), X 3106 if (match(LBO, m_c_And(m_Value(), m_Specific(RHS)))) { 3107 if (Pred == ICmpInst::ICMP_UGT) 3108 return getFalse(ITy); 3109 if (Pred == ICmpInst::ICMP_ULE) 3110 return getTrue(ITy); 3111 } 3112 3113 // icmp pred (urem X, Y), Y 3114 if (match(LBO, m_URem(m_Value(), m_Specific(RHS)))) { 3115 switch (Pred) { 3116 default: 3117 break; 3118 case ICmpInst::ICMP_SGT: 3119 case ICmpInst::ICMP_SGE: { 3120 KnownBits Known = computeKnownBits(RHS, /* Depth */ 0, Q); 3121 if (!Known.isNonNegative()) 3122 break; 3123 [[fallthrough]]; 3124 } 3125 case ICmpInst::ICMP_EQ: 3126 case ICmpInst::ICMP_UGT: 3127 case ICmpInst::ICMP_UGE: 3128 return getFalse(ITy); 3129 case ICmpInst::ICMP_SLT: 3130 case ICmpInst::ICMP_SLE: { 3131 KnownBits Known = computeKnownBits(RHS, /* Depth */ 0, Q); 3132 if (!Known.isNonNegative()) 3133 break; 3134 [[fallthrough]]; 3135 } 3136 case ICmpInst::ICMP_NE: 3137 case ICmpInst::ICMP_ULT: 3138 case ICmpInst::ICMP_ULE: 3139 return getTrue(ITy); 3140 } 3141 } 3142 3143 // icmp pred (urem X, Y), X 3144 if (match(LBO, m_URem(m_Specific(RHS), m_Value()))) { 3145 if (Pred == ICmpInst::ICMP_ULE) 3146 return getTrue(ITy); 3147 if (Pred == ICmpInst::ICMP_UGT) 3148 return getFalse(ITy); 3149 } 3150 3151 // x >>u y <=u x --> true. 3152 // x >>u y >u x --> false. 3153 // x udiv y <=u x --> true. 3154 // x udiv y >u x --> false. 3155 if (match(LBO, m_LShr(m_Specific(RHS), m_Value())) || 3156 match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) { 3157 // icmp pred (X op Y), X 3158 if (Pred == ICmpInst::ICMP_UGT) 3159 return getFalse(ITy); 3160 if (Pred == ICmpInst::ICMP_ULE) 3161 return getTrue(ITy); 3162 } 3163 3164 // If x is nonzero: 3165 // x >>u C <u x --> true for C != 0. 3166 // x >>u C != x --> true for C != 0. 3167 // x >>u C >=u x --> false for C != 0. 3168 // x >>u C == x --> false for C != 0. 3169 // x udiv C <u x --> true for C != 1. 3170 // x udiv C != x --> true for C != 1. 3171 // x udiv C >=u x --> false for C != 1. 3172 // x udiv C == x --> false for C != 1. 3173 // TODO: allow non-constant shift amount/divisor 3174 const APInt *C; 3175 if ((match(LBO, m_LShr(m_Specific(RHS), m_APInt(C))) && *C != 0) || 3176 (match(LBO, m_UDiv(m_Specific(RHS), m_APInt(C))) && *C != 1)) { 3177 if (isKnownNonZero(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT)) { 3178 switch (Pred) { 3179 default: 3180 break; 3181 case ICmpInst::ICMP_EQ: 3182 case ICmpInst::ICMP_UGE: 3183 return getFalse(ITy); 3184 case ICmpInst::ICMP_NE: 3185 case ICmpInst::ICMP_ULT: 3186 return getTrue(ITy); 3187 case ICmpInst::ICMP_UGT: 3188 case ICmpInst::ICMP_ULE: 3189 // UGT/ULE are handled by the more general case just above 3190 llvm_unreachable("Unexpected UGT/ULE, should have been handled"); 3191 } 3192 } 3193 } 3194 3195 // (x*C1)/C2 <= x for C1 <= C2. 3196 // This holds even if the multiplication overflows: Assume that x != 0 and 3197 // arithmetic is modulo M. For overflow to occur we must have C1 >= M/x and 3198 // thus C2 >= M/x. It follows that (x*C1)/C2 <= (M-1)/C2 <= ((M-1)*x)/M < x. 3199 // 3200 // Additionally, either the multiplication and division might be represented 3201 // as shifts: 3202 // (x*C1)>>C2 <= x for C1 < 2**C2. 3203 // (x<<C1)/C2 <= x for 2**C1 < C2. 3204 const APInt *C1, *C2; 3205 if ((match(LBO, m_UDiv(m_Mul(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 3206 C1->ule(*C2)) || 3207 (match(LBO, m_LShr(m_Mul(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 3208 C1->ule(APInt(C2->getBitWidth(), 1) << *C2)) || 3209 (match(LBO, m_UDiv(m_Shl(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) && 3210 (APInt(C1->getBitWidth(), 1) << *C1).ule(*C2))) { 3211 if (Pred == ICmpInst::ICMP_UGT) 3212 return getFalse(ITy); 3213 if (Pred == ICmpInst::ICMP_ULE) 3214 return getTrue(ITy); 3215 } 3216 3217 // (sub C, X) == X, C is odd --> false 3218 // (sub C, X) != X, C is odd --> true 3219 if (match(LBO, m_Sub(m_APIntAllowUndef(C), m_Specific(RHS))) && 3220 (*C & 1) == 1 && ICmpInst::isEquality(Pred)) 3221 return (Pred == ICmpInst::ICMP_EQ) ? getFalse(ITy) : getTrue(ITy); 3222 3223 return nullptr; 3224 } 3225 3226 // If only one of the icmp's operands has NSW flags, try to prove that: 3227 // 3228 // icmp slt (x + C1), (x +nsw C2) 3229 // 3230 // is equivalent to: 3231 // 3232 // icmp slt C1, C2 3233 // 3234 // which is true if x + C2 has the NSW flags set and: 3235 // *) C1 < C2 && C1 >= 0, or 3236 // *) C2 < C1 && C1 <= 0. 3237 // 3238 static bool trySimplifyICmpWithAdds(CmpInst::Predicate Pred, Value *LHS, 3239 Value *RHS, const InstrInfoQuery &IIQ) { 3240 // TODO: only support icmp slt for now. 3241 if (Pred != CmpInst::ICMP_SLT || !IIQ.UseInstrInfo) 3242 return false; 3243 3244 // Canonicalize nsw add as RHS. 3245 if (!match(RHS, m_NSWAdd(m_Value(), m_Value()))) 3246 std::swap(LHS, RHS); 3247 if (!match(RHS, m_NSWAdd(m_Value(), m_Value()))) 3248 return false; 3249 3250 Value *X; 3251 const APInt *C1, *C2; 3252 if (!match(LHS, m_c_Add(m_Value(X), m_APInt(C1))) || 3253 !match(RHS, m_c_Add(m_Specific(X), m_APInt(C2)))) 3254 return false; 3255 3256 return (C1->slt(*C2) && C1->isNonNegative()) || 3257 (C2->slt(*C1) && C1->isNonPositive()); 3258 } 3259 3260 /// TODO: A large part of this logic is duplicated in InstCombine's 3261 /// foldICmpBinOp(). We should be able to share that and avoid the code 3262 /// duplication. 3263 static Value *simplifyICmpWithBinOp(CmpInst::Predicate Pred, Value *LHS, 3264 Value *RHS, const SimplifyQuery &Q, 3265 unsigned MaxRecurse) { 3266 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS); 3267 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS); 3268 if (MaxRecurse && (LBO || RBO)) { 3269 // Analyze the case when either LHS or RHS is an add instruction. 3270 Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr; 3271 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null). 3272 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false; 3273 if (LBO && LBO->getOpcode() == Instruction::Add) { 3274 A = LBO->getOperand(0); 3275 B = LBO->getOperand(1); 3276 NoLHSWrapProblem = 3277 ICmpInst::isEquality(Pred) || 3278 (CmpInst::isUnsigned(Pred) && 3279 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO))) || 3280 (CmpInst::isSigned(Pred) && 3281 Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO))); 3282 } 3283 if (RBO && RBO->getOpcode() == Instruction::Add) { 3284 C = RBO->getOperand(0); 3285 D = RBO->getOperand(1); 3286 NoRHSWrapProblem = 3287 ICmpInst::isEquality(Pred) || 3288 (CmpInst::isUnsigned(Pred) && 3289 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(RBO))) || 3290 (CmpInst::isSigned(Pred) && 3291 Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(RBO))); 3292 } 3293 3294 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow. 3295 if ((A == RHS || B == RHS) && NoLHSWrapProblem) 3296 if (Value *V = simplifyICmpInst(Pred, A == RHS ? B : A, 3297 Constant::getNullValue(RHS->getType()), Q, 3298 MaxRecurse - 1)) 3299 return V; 3300 3301 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow. 3302 if ((C == LHS || D == LHS) && NoRHSWrapProblem) 3303 if (Value *V = 3304 simplifyICmpInst(Pred, Constant::getNullValue(LHS->getType()), 3305 C == LHS ? D : C, Q, MaxRecurse - 1)) 3306 return V; 3307 3308 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow. 3309 bool CanSimplify = (NoLHSWrapProblem && NoRHSWrapProblem) || 3310 trySimplifyICmpWithAdds(Pred, LHS, RHS, Q.IIQ); 3311 if (A && C && (A == C || A == D || B == C || B == D) && CanSimplify) { 3312 // Determine Y and Z in the form icmp (X+Y), (X+Z). 3313 Value *Y, *Z; 3314 if (A == C) { 3315 // C + B == C + D -> B == D 3316 Y = B; 3317 Z = D; 3318 } else if (A == D) { 3319 // D + B == C + D -> B == C 3320 Y = B; 3321 Z = C; 3322 } else if (B == C) { 3323 // A + C == C + D -> A == D 3324 Y = A; 3325 Z = D; 3326 } else { 3327 assert(B == D); 3328 // A + D == C + D -> A == C 3329 Y = A; 3330 Z = C; 3331 } 3332 if (Value *V = simplifyICmpInst(Pred, Y, Z, Q, MaxRecurse - 1)) 3333 return V; 3334 } 3335 } 3336 3337 if (LBO) 3338 if (Value *V = simplifyICmpWithBinOpOnLHS(Pred, LBO, RHS, Q, MaxRecurse)) 3339 return V; 3340 3341 if (RBO) 3342 if (Value *V = simplifyICmpWithBinOpOnLHS( 3343 ICmpInst::getSwappedPredicate(Pred), RBO, LHS, Q, MaxRecurse)) 3344 return V; 3345 3346 // 0 - (zext X) pred C 3347 if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) { 3348 const APInt *C; 3349 if (match(RHS, m_APInt(C))) { 3350 if (C->isStrictlyPositive()) { 3351 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_NE) 3352 return ConstantInt::getTrue(getCompareTy(RHS)); 3353 if (Pred == ICmpInst::ICMP_SGE || Pred == ICmpInst::ICMP_EQ) 3354 return ConstantInt::getFalse(getCompareTy(RHS)); 3355 } 3356 if (C->isNonNegative()) { 3357 if (Pred == ICmpInst::ICMP_SLE) 3358 return ConstantInt::getTrue(getCompareTy(RHS)); 3359 if (Pred == ICmpInst::ICMP_SGT) 3360 return ConstantInt::getFalse(getCompareTy(RHS)); 3361 } 3362 } 3363 } 3364 3365 // If C2 is a power-of-2 and C is not: 3366 // (C2 << X) == C --> false 3367 // (C2 << X) != C --> true 3368 const APInt *C; 3369 if (match(LHS, m_Shl(m_Power2(), m_Value())) && 3370 match(RHS, m_APIntAllowUndef(C)) && !C->isPowerOf2()) { 3371 // C2 << X can equal zero in some circumstances. 3372 // This simplification might be unsafe if C is zero. 3373 // 3374 // We know it is safe if: 3375 // - The shift is nsw. We can't shift out the one bit. 3376 // - The shift is nuw. We can't shift out the one bit. 3377 // - C2 is one. 3378 // - C isn't zero. 3379 if (Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO)) || 3380 Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO)) || 3381 match(LHS, m_Shl(m_One(), m_Value())) || !C->isZero()) { 3382 if (Pred == ICmpInst::ICMP_EQ) 3383 return ConstantInt::getFalse(getCompareTy(RHS)); 3384 if (Pred == ICmpInst::ICMP_NE) 3385 return ConstantInt::getTrue(getCompareTy(RHS)); 3386 } 3387 } 3388 3389 // If C is a power-of-2: 3390 // (C << X) >u 0x8000 --> false 3391 // (C << X) <=u 0x8000 --> true 3392 if (match(LHS, m_Shl(m_Power2(), m_Value())) && match(RHS, m_SignMask())) { 3393 if (Pred == ICmpInst::ICMP_UGT) 3394 return ConstantInt::getFalse(getCompareTy(RHS)); 3395 if (Pred == ICmpInst::ICMP_ULE) 3396 return ConstantInt::getTrue(getCompareTy(RHS)); 3397 } 3398 3399 if (!MaxRecurse || !LBO || !RBO || LBO->getOpcode() != RBO->getOpcode()) 3400 return nullptr; 3401 3402 if (LBO->getOperand(0) == RBO->getOperand(0)) { 3403 switch (LBO->getOpcode()) { 3404 default: 3405 break; 3406 case Instruction::Shl: { 3407 bool NUW = Q.IIQ.hasNoUnsignedWrap(LBO) && Q.IIQ.hasNoUnsignedWrap(RBO); 3408 bool NSW = Q.IIQ.hasNoSignedWrap(LBO) && Q.IIQ.hasNoSignedWrap(RBO); 3409 if (!NUW || (ICmpInst::isSigned(Pred) && !NSW) || 3410 !isKnownNonZero(LBO->getOperand(0), Q.DL)) 3411 break; 3412 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(1), 3413 RBO->getOperand(1), Q, MaxRecurse - 1)) 3414 return V; 3415 break; 3416 } 3417 // If C1 & C2 == C1, A = X and/or C1, B = X and/or C2: 3418 // icmp ule A, B -> true 3419 // icmp ugt A, B -> false 3420 // icmp sle A, B -> true (C1 and C2 are the same sign) 3421 // icmp sgt A, B -> false (C1 and C2 are the same sign) 3422 case Instruction::And: 3423 case Instruction::Or: { 3424 const APInt *C1, *C2; 3425 if (ICmpInst::isRelational(Pred) && 3426 match(LBO->getOperand(1), m_APInt(C1)) && 3427 match(RBO->getOperand(1), m_APInt(C2))) { 3428 if (!C1->isSubsetOf(*C2)) { 3429 std::swap(C1, C2); 3430 Pred = ICmpInst::getSwappedPredicate(Pred); 3431 } 3432 if (C1->isSubsetOf(*C2)) { 3433 if (Pred == ICmpInst::ICMP_ULE) 3434 return ConstantInt::getTrue(getCompareTy(LHS)); 3435 if (Pred == ICmpInst::ICMP_UGT) 3436 return ConstantInt::getFalse(getCompareTy(LHS)); 3437 if (C1->isNonNegative() == C2->isNonNegative()) { 3438 if (Pred == ICmpInst::ICMP_SLE) 3439 return ConstantInt::getTrue(getCompareTy(LHS)); 3440 if (Pred == ICmpInst::ICMP_SGT) 3441 return ConstantInt::getFalse(getCompareTy(LHS)); 3442 } 3443 } 3444 } 3445 break; 3446 } 3447 } 3448 } 3449 3450 if (LBO->getOperand(1) == RBO->getOperand(1)) { 3451 switch (LBO->getOpcode()) { 3452 default: 3453 break; 3454 case Instruction::UDiv: 3455 case Instruction::LShr: 3456 if (ICmpInst::isSigned(Pred) || !Q.IIQ.isExact(LBO) || 3457 !Q.IIQ.isExact(RBO)) 3458 break; 3459 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0), 3460 RBO->getOperand(0), Q, MaxRecurse - 1)) 3461 return V; 3462 break; 3463 case Instruction::SDiv: 3464 if (!ICmpInst::isEquality(Pred) || !Q.IIQ.isExact(LBO) || 3465 !Q.IIQ.isExact(RBO)) 3466 break; 3467 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0), 3468 RBO->getOperand(0), Q, MaxRecurse - 1)) 3469 return V; 3470 break; 3471 case Instruction::AShr: 3472 if (!Q.IIQ.isExact(LBO) || !Q.IIQ.isExact(RBO)) 3473 break; 3474 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0), 3475 RBO->getOperand(0), Q, MaxRecurse - 1)) 3476 return V; 3477 break; 3478 case Instruction::Shl: { 3479 bool NUW = Q.IIQ.hasNoUnsignedWrap(LBO) && Q.IIQ.hasNoUnsignedWrap(RBO); 3480 bool NSW = Q.IIQ.hasNoSignedWrap(LBO) && Q.IIQ.hasNoSignedWrap(RBO); 3481 if (!NUW && !NSW) 3482 break; 3483 if (!NSW && ICmpInst::isSigned(Pred)) 3484 break; 3485 if (Value *V = simplifyICmpInst(Pred, LBO->getOperand(0), 3486 RBO->getOperand(0), Q, MaxRecurse - 1)) 3487 return V; 3488 break; 3489 } 3490 } 3491 } 3492 return nullptr; 3493 } 3494 3495 /// simplify integer comparisons where at least one operand of the compare 3496 /// matches an integer min/max idiom. 3497 static Value *simplifyICmpWithMinMax(CmpInst::Predicate Pred, Value *LHS, 3498 Value *RHS, const SimplifyQuery &Q, 3499 unsigned MaxRecurse) { 3500 Type *ITy = getCompareTy(LHS); // The return type. 3501 Value *A, *B; 3502 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE; 3503 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B". 3504 3505 // Signed variants on "max(a,b)>=a -> true". 3506 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 3507 if (A != RHS) 3508 std::swap(A, B); // smax(A, B) pred A. 3509 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 3510 // We analyze this as smax(A, B) pred A. 3511 P = Pred; 3512 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) && 3513 (A == LHS || B == LHS)) { 3514 if (A != LHS) 3515 std::swap(A, B); // A pred smax(A, B). 3516 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 3517 // We analyze this as smax(A, B) swapped-pred A. 3518 P = CmpInst::getSwappedPredicate(Pred); 3519 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) && 3520 (A == RHS || B == RHS)) { 3521 if (A != RHS) 3522 std::swap(A, B); // smin(A, B) pred A. 3523 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 3524 // We analyze this as smax(-A, -B) swapped-pred -A. 3525 // Note that we do not need to actually form -A or -B thanks to EqP. 3526 P = CmpInst::getSwappedPredicate(Pred); 3527 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) && 3528 (A == LHS || B == LHS)) { 3529 if (A != LHS) 3530 std::swap(A, B); // A pred smin(A, B). 3531 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 3532 // We analyze this as smax(-A, -B) pred -A. 3533 // Note that we do not need to actually form -A or -B thanks to EqP. 3534 P = Pred; 3535 } 3536 if (P != CmpInst::BAD_ICMP_PREDICATE) { 3537 // Cases correspond to "max(A, B) p A". 3538 switch (P) { 3539 default: 3540 break; 3541 case CmpInst::ICMP_EQ: 3542 case CmpInst::ICMP_SLE: 3543 // Equivalent to "A EqP B". This may be the same as the condition tested 3544 // in the max/min; if so, we can just return that. 3545 if (Value *V = extractEquivalentCondition(LHS, EqP, A, B)) 3546 return V; 3547 if (Value *V = extractEquivalentCondition(RHS, EqP, A, B)) 3548 return V; 3549 // Otherwise, see if "A EqP B" simplifies. 3550 if (MaxRecurse) 3551 if (Value *V = simplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1)) 3552 return V; 3553 break; 3554 case CmpInst::ICMP_NE: 3555 case CmpInst::ICMP_SGT: { 3556 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 3557 // Equivalent to "A InvEqP B". This may be the same as the condition 3558 // tested in the max/min; if so, we can just return that. 3559 if (Value *V = extractEquivalentCondition(LHS, InvEqP, A, B)) 3560 return V; 3561 if (Value *V = extractEquivalentCondition(RHS, InvEqP, A, B)) 3562 return V; 3563 // Otherwise, see if "A InvEqP B" simplifies. 3564 if (MaxRecurse) 3565 if (Value *V = simplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1)) 3566 return V; 3567 break; 3568 } 3569 case CmpInst::ICMP_SGE: 3570 // Always true. 3571 return getTrue(ITy); 3572 case CmpInst::ICMP_SLT: 3573 // Always false. 3574 return getFalse(ITy); 3575 } 3576 } 3577 3578 // Unsigned variants on "max(a,b)>=a -> true". 3579 P = CmpInst::BAD_ICMP_PREDICATE; 3580 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 3581 if (A != RHS) 3582 std::swap(A, B); // umax(A, B) pred A. 3583 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 3584 // We analyze this as umax(A, B) pred A. 3585 P = Pred; 3586 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) && 3587 (A == LHS || B == LHS)) { 3588 if (A != LHS) 3589 std::swap(A, B); // A pred umax(A, B). 3590 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 3591 // We analyze this as umax(A, B) swapped-pred A. 3592 P = CmpInst::getSwappedPredicate(Pred); 3593 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) && 3594 (A == RHS || B == RHS)) { 3595 if (A != RHS) 3596 std::swap(A, B); // umin(A, B) pred A. 3597 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 3598 // We analyze this as umax(-A, -B) swapped-pred -A. 3599 // Note that we do not need to actually form -A or -B thanks to EqP. 3600 P = CmpInst::getSwappedPredicate(Pred); 3601 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) && 3602 (A == LHS || B == LHS)) { 3603 if (A != LHS) 3604 std::swap(A, B); // A pred umin(A, B). 3605 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 3606 // We analyze this as umax(-A, -B) pred -A. 3607 // Note that we do not need to actually form -A or -B thanks to EqP. 3608 P = Pred; 3609 } 3610 if (P != CmpInst::BAD_ICMP_PREDICATE) { 3611 // Cases correspond to "max(A, B) p A". 3612 switch (P) { 3613 default: 3614 break; 3615 case CmpInst::ICMP_EQ: 3616 case CmpInst::ICMP_ULE: 3617 // Equivalent to "A EqP B". This may be the same as the condition tested 3618 // in the max/min; if so, we can just return that. 3619 if (Value *V = extractEquivalentCondition(LHS, EqP, A, B)) 3620 return V; 3621 if (Value *V = extractEquivalentCondition(RHS, EqP, A, B)) 3622 return V; 3623 // Otherwise, see if "A EqP B" simplifies. 3624 if (MaxRecurse) 3625 if (Value *V = simplifyICmpInst(EqP, A, B, Q, MaxRecurse - 1)) 3626 return V; 3627 break; 3628 case CmpInst::ICMP_NE: 3629 case CmpInst::ICMP_UGT: { 3630 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 3631 // Equivalent to "A InvEqP B". This may be the same as the condition 3632 // tested in the max/min; if so, we can just return that. 3633 if (Value *V = extractEquivalentCondition(LHS, InvEqP, A, B)) 3634 return V; 3635 if (Value *V = extractEquivalentCondition(RHS, InvEqP, A, B)) 3636 return V; 3637 // Otherwise, see if "A InvEqP B" simplifies. 3638 if (MaxRecurse) 3639 if (Value *V = simplifyICmpInst(InvEqP, A, B, Q, MaxRecurse - 1)) 3640 return V; 3641 break; 3642 } 3643 case CmpInst::ICMP_UGE: 3644 return getTrue(ITy); 3645 case CmpInst::ICMP_ULT: 3646 return getFalse(ITy); 3647 } 3648 } 3649 3650 // Comparing 1 each of min/max with a common operand? 3651 // Canonicalize min operand to RHS. 3652 if (match(LHS, m_UMin(m_Value(), m_Value())) || 3653 match(LHS, m_SMin(m_Value(), m_Value()))) { 3654 std::swap(LHS, RHS); 3655 Pred = ICmpInst::getSwappedPredicate(Pred); 3656 } 3657 3658 Value *C, *D; 3659 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && 3660 match(RHS, m_SMin(m_Value(C), m_Value(D))) && 3661 (A == C || A == D || B == C || B == D)) { 3662 // smax(A, B) >=s smin(A, D) --> true 3663 if (Pred == CmpInst::ICMP_SGE) 3664 return getTrue(ITy); 3665 // smax(A, B) <s smin(A, D) --> false 3666 if (Pred == CmpInst::ICMP_SLT) 3667 return getFalse(ITy); 3668 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && 3669 match(RHS, m_UMin(m_Value(C), m_Value(D))) && 3670 (A == C || A == D || B == C || B == D)) { 3671 // umax(A, B) >=u umin(A, D) --> true 3672 if (Pred == CmpInst::ICMP_UGE) 3673 return getTrue(ITy); 3674 // umax(A, B) <u umin(A, D) --> false 3675 if (Pred == CmpInst::ICMP_ULT) 3676 return getFalse(ITy); 3677 } 3678 3679 return nullptr; 3680 } 3681 3682 static Value *simplifyICmpWithDominatingAssume(CmpInst::Predicate Predicate, 3683 Value *LHS, Value *RHS, 3684 const SimplifyQuery &Q) { 3685 // Gracefully handle instructions that have not been inserted yet. 3686 if (!Q.AC || !Q.CxtI) 3687 return nullptr; 3688 3689 for (Value *AssumeBaseOp : {LHS, RHS}) { 3690 for (auto &AssumeVH : Q.AC->assumptionsFor(AssumeBaseOp)) { 3691 if (!AssumeVH) 3692 continue; 3693 3694 CallInst *Assume = cast<CallInst>(AssumeVH); 3695 if (std::optional<bool> Imp = isImpliedCondition( 3696 Assume->getArgOperand(0), Predicate, LHS, RHS, Q.DL)) 3697 if (isValidAssumeForContext(Assume, Q.CxtI, Q.DT)) 3698 return ConstantInt::get(getCompareTy(LHS), *Imp); 3699 } 3700 } 3701 3702 return nullptr; 3703 } 3704 3705 static Value *simplifyICmpWithIntrinsicOnLHS(CmpInst::Predicate Pred, 3706 Value *LHS, Value *RHS) { 3707 auto *II = dyn_cast<IntrinsicInst>(LHS); 3708 if (!II) 3709 return nullptr; 3710 3711 switch (II->getIntrinsicID()) { 3712 case Intrinsic::uadd_sat: 3713 // uadd.sat(X, Y) uge X, uadd.sat(X, Y) uge Y 3714 if (II->getArgOperand(0) == RHS || II->getArgOperand(1) == RHS) { 3715 if (Pred == ICmpInst::ICMP_UGE) 3716 return ConstantInt::getTrue(getCompareTy(II)); 3717 if (Pred == ICmpInst::ICMP_ULT) 3718 return ConstantInt::getFalse(getCompareTy(II)); 3719 } 3720 return nullptr; 3721 case Intrinsic::usub_sat: 3722 // usub.sat(X, Y) ule X 3723 if (II->getArgOperand(0) == RHS) { 3724 if (Pred == ICmpInst::ICMP_ULE) 3725 return ConstantInt::getTrue(getCompareTy(II)); 3726 if (Pred == ICmpInst::ICMP_UGT) 3727 return ConstantInt::getFalse(getCompareTy(II)); 3728 } 3729 return nullptr; 3730 default: 3731 return nullptr; 3732 } 3733 } 3734 3735 /// Given operands for an ICmpInst, see if we can fold the result. 3736 /// If not, this returns null. 3737 static Value *simplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 3738 const SimplifyQuery &Q, unsigned MaxRecurse) { 3739 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 3740 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!"); 3741 3742 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 3743 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 3744 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI); 3745 3746 // If we have a constant, make sure it is on the RHS. 3747 std::swap(LHS, RHS); 3748 Pred = CmpInst::getSwappedPredicate(Pred); 3749 } 3750 assert(!isa<UndefValue>(LHS) && "Unexpected icmp undef,%X"); 3751 3752 Type *ITy = getCompareTy(LHS); // The return type. 3753 3754 // icmp poison, X -> poison 3755 if (isa<PoisonValue>(RHS)) 3756 return PoisonValue::get(ITy); 3757 3758 // For EQ and NE, we can always pick a value for the undef to make the 3759 // predicate pass or fail, so we can return undef. 3760 // Matches behavior in llvm::ConstantFoldCompareInstruction. 3761 if (Q.isUndefValue(RHS) && ICmpInst::isEquality(Pred)) 3762 return UndefValue::get(ITy); 3763 3764 // icmp X, X -> true/false 3765 // icmp X, undef -> true/false because undef could be X. 3766 if (LHS == RHS || Q.isUndefValue(RHS)) 3767 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred)); 3768 3769 if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q)) 3770 return V; 3771 3772 // TODO: Sink/common this with other potentially expensive calls that use 3773 // ValueTracking? See comment below for isKnownNonEqual(). 3774 if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q)) 3775 return V; 3776 3777 if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS, Q.IIQ)) 3778 return V; 3779 3780 // If both operands have range metadata, use the metadata 3781 // to simplify the comparison. 3782 if (isa<Instruction>(RHS) && isa<Instruction>(LHS)) { 3783 auto RHS_Instr = cast<Instruction>(RHS); 3784 auto LHS_Instr = cast<Instruction>(LHS); 3785 3786 if (Q.IIQ.getMetadata(RHS_Instr, LLVMContext::MD_range) && 3787 Q.IIQ.getMetadata(LHS_Instr, LLVMContext::MD_range)) { 3788 auto RHS_CR = getConstantRangeFromMetadata( 3789 *RHS_Instr->getMetadata(LLVMContext::MD_range)); 3790 auto LHS_CR = getConstantRangeFromMetadata( 3791 *LHS_Instr->getMetadata(LLVMContext::MD_range)); 3792 3793 if (LHS_CR.icmp(Pred, RHS_CR)) 3794 return ConstantInt::getTrue(RHS->getContext()); 3795 3796 if (LHS_CR.icmp(CmpInst::getInversePredicate(Pred), RHS_CR)) 3797 return ConstantInt::getFalse(RHS->getContext()); 3798 } 3799 } 3800 3801 // Compare of cast, for example (zext X) != 0 -> X != 0 3802 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) { 3803 Instruction *LI = cast<CastInst>(LHS); 3804 Value *SrcOp = LI->getOperand(0); 3805 Type *SrcTy = SrcOp->getType(); 3806 Type *DstTy = LI->getType(); 3807 3808 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input 3809 // if the integer type is the same size as the pointer type. 3810 if (MaxRecurse && isa<PtrToIntInst>(LI) && 3811 Q.DL.getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) { 3812 if (Constant *RHSC = dyn_cast<Constant>(RHS)) { 3813 // Transfer the cast to the constant. 3814 if (Value *V = simplifyICmpInst(Pred, SrcOp, 3815 ConstantExpr::getIntToPtr(RHSC, SrcTy), 3816 Q, MaxRecurse - 1)) 3817 return V; 3818 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) { 3819 if (RI->getOperand(0)->getType() == SrcTy) 3820 // Compare without the cast. 3821 if (Value *V = simplifyICmpInst(Pred, SrcOp, RI->getOperand(0), Q, 3822 MaxRecurse - 1)) 3823 return V; 3824 } 3825 } 3826 3827 if (isa<ZExtInst>(LHS)) { 3828 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the 3829 // same type. 3830 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { 3831 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 3832 // Compare X and Y. Note that signed predicates become unsigned. 3833 if (Value *V = 3834 simplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), SrcOp, 3835 RI->getOperand(0), Q, MaxRecurse - 1)) 3836 return V; 3837 } 3838 // Fold (zext X) ule (sext X), (zext X) sge (sext X) to true. 3839 else if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { 3840 if (SrcOp == RI->getOperand(0)) { 3841 if (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_SGE) 3842 return ConstantInt::getTrue(ITy); 3843 if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SLT) 3844 return ConstantInt::getFalse(ITy); 3845 } 3846 } 3847 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended 3848 // too. If not, then try to deduce the result of the comparison. 3849 else if (match(RHS, m_ImmConstant())) { 3850 Constant *C = dyn_cast<Constant>(RHS); 3851 assert(C != nullptr); 3852 3853 // Compute the constant that would happen if we truncated to SrcTy then 3854 // reextended to DstTy. 3855 Constant *Trunc = 3856 ConstantFoldCastOperand(Instruction::Trunc, C, SrcTy, Q.DL); 3857 assert(Trunc && "Constant-fold of ImmConstant should not fail"); 3858 Constant *RExt = 3859 ConstantFoldCastOperand(CastInst::ZExt, Trunc, DstTy, Q.DL); 3860 assert(RExt && "Constant-fold of ImmConstant should not fail"); 3861 Constant *AnyEq = 3862 ConstantFoldCompareInstOperands(ICmpInst::ICMP_EQ, RExt, C, Q.DL); 3863 assert(AnyEq && "Constant-fold of ImmConstant should not fail"); 3864 3865 // If the re-extended constant didn't change any of the elements then 3866 // this is effectively also a case of comparing two zero-extended 3867 // values. 3868 if (AnyEq->isAllOnesValue() && MaxRecurse) 3869 if (Value *V = simplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), 3870 SrcOp, Trunc, Q, MaxRecurse - 1)) 3871 return V; 3872 3873 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit 3874 // there. Use this to work out the result of the comparison. 3875 if (AnyEq->isNullValue()) { 3876 switch (Pred) { 3877 default: 3878 llvm_unreachable("Unknown ICmp predicate!"); 3879 // LHS <u RHS. 3880 case ICmpInst::ICMP_EQ: 3881 case ICmpInst::ICMP_UGT: 3882 case ICmpInst::ICMP_UGE: 3883 return Constant::getNullValue(ITy); 3884 3885 case ICmpInst::ICMP_NE: 3886 case ICmpInst::ICMP_ULT: 3887 case ICmpInst::ICMP_ULE: 3888 return Constant::getAllOnesValue(ITy); 3889 3890 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS 3891 // is non-negative then LHS <s RHS. 3892 case ICmpInst::ICMP_SGT: 3893 case ICmpInst::ICMP_SGE: 3894 return ConstantFoldCompareInstOperands( 3895 ICmpInst::ICMP_SLT, C, Constant::getNullValue(C->getType()), 3896 Q.DL); 3897 case ICmpInst::ICMP_SLT: 3898 case ICmpInst::ICMP_SLE: 3899 return ConstantFoldCompareInstOperands( 3900 ICmpInst::ICMP_SGE, C, Constant::getNullValue(C->getType()), 3901 Q.DL); 3902 } 3903 } 3904 } 3905 } 3906 3907 if (isa<SExtInst>(LHS)) { 3908 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the 3909 // same type. 3910 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { 3911 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 3912 // Compare X and Y. Note that the predicate does not change. 3913 if (Value *V = simplifyICmpInst(Pred, SrcOp, RI->getOperand(0), Q, 3914 MaxRecurse - 1)) 3915 return V; 3916 } 3917 // Fold (sext X) uge (zext X), (sext X) sle (zext X) to true. 3918 else if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { 3919 if (SrcOp == RI->getOperand(0)) { 3920 if (Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_SLE) 3921 return ConstantInt::getTrue(ITy); 3922 if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SGT) 3923 return ConstantInt::getFalse(ITy); 3924 } 3925 } 3926 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended 3927 // too. If not, then try to deduce the result of the comparison. 3928 else if (match(RHS, m_ImmConstant())) { 3929 Constant *C = cast<Constant>(RHS); 3930 3931 // Compute the constant that would happen if we truncated to SrcTy then 3932 // reextended to DstTy. 3933 Constant *Trunc = 3934 ConstantFoldCastOperand(Instruction::Trunc, C, SrcTy, Q.DL); 3935 assert(Trunc && "Constant-fold of ImmConstant should not fail"); 3936 Constant *RExt = 3937 ConstantFoldCastOperand(CastInst::SExt, Trunc, DstTy, Q.DL); 3938 assert(RExt && "Constant-fold of ImmConstant should not fail"); 3939 Constant *AnyEq = 3940 ConstantFoldCompareInstOperands(ICmpInst::ICMP_EQ, RExt, C, Q.DL); 3941 assert(AnyEq && "Constant-fold of ImmConstant should not fail"); 3942 3943 // If the re-extended constant didn't change then this is effectively 3944 // also a case of comparing two sign-extended values. 3945 if (AnyEq->isAllOnesValue() && MaxRecurse) 3946 if (Value *V = 3947 simplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse - 1)) 3948 return V; 3949 3950 // Otherwise the upper bits of LHS are all equal, while RHS has varying 3951 // bits there. Use this to work out the result of the comparison. 3952 if (AnyEq->isNullValue()) { 3953 switch (Pred) { 3954 default: 3955 llvm_unreachable("Unknown ICmp predicate!"); 3956 case ICmpInst::ICMP_EQ: 3957 return Constant::getNullValue(ITy); 3958 case ICmpInst::ICMP_NE: 3959 return Constant::getAllOnesValue(ITy); 3960 3961 // If RHS is non-negative then LHS <s RHS. If RHS is negative then 3962 // LHS >s RHS. 3963 case ICmpInst::ICMP_SGT: 3964 case ICmpInst::ICMP_SGE: 3965 return ConstantExpr::getICmp(ICmpInst::ICMP_SLT, C, 3966 Constant::getNullValue(C->getType())); 3967 case ICmpInst::ICMP_SLT: 3968 case ICmpInst::ICMP_SLE: 3969 return ConstantExpr::getICmp(ICmpInst::ICMP_SGE, C, 3970 Constant::getNullValue(C->getType())); 3971 3972 // If LHS is non-negative then LHS <u RHS. If LHS is negative then 3973 // LHS >u RHS. 3974 case ICmpInst::ICMP_UGT: 3975 case ICmpInst::ICMP_UGE: 3976 // Comparison is true iff the LHS <s 0. 3977 if (MaxRecurse) 3978 if (Value *V = simplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp, 3979 Constant::getNullValue(SrcTy), Q, 3980 MaxRecurse - 1)) 3981 return V; 3982 break; 3983 case ICmpInst::ICMP_ULT: 3984 case ICmpInst::ICMP_ULE: 3985 // Comparison is true iff the LHS >=s 0. 3986 if (MaxRecurse) 3987 if (Value *V = simplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp, 3988 Constant::getNullValue(SrcTy), Q, 3989 MaxRecurse - 1)) 3990 return V; 3991 break; 3992 } 3993 } 3994 } 3995 } 3996 } 3997 3998 // icmp eq|ne X, Y -> false|true if X != Y 3999 // This is potentially expensive, and we have already computedKnownBits for 4000 // compares with 0 above here, so only try this for a non-zero compare. 4001 if (ICmpInst::isEquality(Pred) && !match(RHS, m_Zero()) && 4002 isKnownNonEqual(LHS, RHS, Q.DL, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) { 4003 return Pred == ICmpInst::ICMP_NE ? getTrue(ITy) : getFalse(ITy); 4004 } 4005 4006 if (Value *V = simplifyICmpWithBinOp(Pred, LHS, RHS, Q, MaxRecurse)) 4007 return V; 4008 4009 if (Value *V = simplifyICmpWithMinMax(Pred, LHS, RHS, Q, MaxRecurse)) 4010 return V; 4011 4012 if (Value *V = simplifyICmpWithIntrinsicOnLHS(Pred, LHS, RHS)) 4013 return V; 4014 if (Value *V = simplifyICmpWithIntrinsicOnLHS( 4015 ICmpInst::getSwappedPredicate(Pred), RHS, LHS)) 4016 return V; 4017 4018 if (Value *V = simplifyICmpWithDominatingAssume(Pred, LHS, RHS, Q)) 4019 return V; 4020 4021 if (std::optional<bool> Res = 4022 isImpliedByDomCondition(Pred, LHS, RHS, Q.CxtI, Q.DL)) 4023 return ConstantInt::getBool(ITy, *Res); 4024 4025 // Simplify comparisons of related pointers using a powerful, recursive 4026 // GEP-walk when we have target data available.. 4027 if (LHS->getType()->isPointerTy()) 4028 if (auto *C = computePointerICmp(Pred, LHS, RHS, Q)) 4029 return C; 4030 if (auto *CLHS = dyn_cast<PtrToIntOperator>(LHS)) 4031 if (auto *CRHS = dyn_cast<PtrToIntOperator>(RHS)) 4032 if (CLHS->getPointerOperandType() == CRHS->getPointerOperandType() && 4033 Q.DL.getTypeSizeInBits(CLHS->getPointerOperandType()) == 4034 Q.DL.getTypeSizeInBits(CLHS->getType())) 4035 if (auto *C = computePointerICmp(Pred, CLHS->getPointerOperand(), 4036 CRHS->getPointerOperand(), Q)) 4037 return C; 4038 4039 // If the comparison is with the result of a select instruction, check whether 4040 // comparing with either branch of the select always yields the same value. 4041 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 4042 if (Value *V = threadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) 4043 return V; 4044 4045 // If the comparison is with the result of a phi instruction, check whether 4046 // doing the compare with each incoming phi value yields a common result. 4047 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 4048 if (Value *V = threadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) 4049 return V; 4050 4051 return nullptr; 4052 } 4053 4054 Value *llvm::simplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 4055 const SimplifyQuery &Q) { 4056 return ::simplifyICmpInst(Predicate, LHS, RHS, Q, RecursionLimit); 4057 } 4058 4059 /// Given operands for an FCmpInst, see if we can fold the result. 4060 /// If not, this returns null. 4061 static Value *simplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 4062 FastMathFlags FMF, const SimplifyQuery &Q, 4063 unsigned MaxRecurse) { 4064 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 4065 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!"); 4066 4067 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 4068 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 4069 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI, 4070 Q.CxtI); 4071 4072 // If we have a constant, make sure it is on the RHS. 4073 std::swap(LHS, RHS); 4074 Pred = CmpInst::getSwappedPredicate(Pred); 4075 } 4076 4077 // Fold trivial predicates. 4078 Type *RetTy = getCompareTy(LHS); 4079 if (Pred == FCmpInst::FCMP_FALSE) 4080 return getFalse(RetTy); 4081 if (Pred == FCmpInst::FCMP_TRUE) 4082 return getTrue(RetTy); 4083 4084 // fcmp pred x, poison and fcmp pred poison, x 4085 // fold to poison 4086 if (isa<PoisonValue>(LHS) || isa<PoisonValue>(RHS)) 4087 return PoisonValue::get(RetTy); 4088 4089 // fcmp pred x, undef and fcmp pred undef, x 4090 // fold to true if unordered, false if ordered 4091 if (Q.isUndefValue(LHS) || Q.isUndefValue(RHS)) { 4092 // Choosing NaN for the undef will always make unordered comparison succeed 4093 // and ordered comparison fail. 4094 return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred)); 4095 } 4096 4097 // fcmp x,x -> true/false. Not all compares are foldable. 4098 if (LHS == RHS) { 4099 if (CmpInst::isTrueWhenEqual(Pred)) 4100 return getTrue(RetTy); 4101 if (CmpInst::isFalseWhenEqual(Pred)) 4102 return getFalse(RetTy); 4103 } 4104 4105 // Fold (un)ordered comparison if we can determine there are no NaNs. 4106 // 4107 // This catches the 2 variable input case, constants are handled below as a 4108 // class-like compare. 4109 if (Pred == FCmpInst::FCMP_ORD || Pred == FCmpInst::FCMP_UNO) { 4110 if (FMF.noNaNs() || 4111 (isKnownNeverNaN(RHS, Q.DL, Q.TLI, 0, Q.AC, Q.CxtI, Q.DT) && 4112 isKnownNeverNaN(LHS, Q.DL, Q.TLI, 0, Q.AC, Q.CxtI, Q.DT))) 4113 return ConstantInt::get(RetTy, Pred == FCmpInst::FCMP_ORD); 4114 } 4115 4116 const APFloat *C = nullptr; 4117 match(RHS, m_APFloatAllowUndef(C)); 4118 std::optional<KnownFPClass> FullKnownClassLHS; 4119 4120 // Lazily compute the possible classes for LHS. Avoid computing it twice if 4121 // RHS is a 0. 4122 auto computeLHSClass = [=, &FullKnownClassLHS](FPClassTest InterestedFlags = 4123 fcAllFlags) { 4124 if (FullKnownClassLHS) 4125 return *FullKnownClassLHS; 4126 return computeKnownFPClass(LHS, FMF, Q.DL, InterestedFlags, 0, Q.TLI, Q.AC, 4127 Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo); 4128 }; 4129 4130 if (C && Q.CxtI) { 4131 // Fold out compares that express a class test. 4132 // 4133 // FIXME: Should be able to perform folds without context 4134 // instruction. Always pass in the context function? 4135 4136 const Function *ParentF = Q.CxtI->getFunction(); 4137 auto [ClassVal, ClassTest] = fcmpToClassTest(Pred, *ParentF, LHS, C); 4138 if (ClassVal) { 4139 FullKnownClassLHS = computeLHSClass(); 4140 if ((FullKnownClassLHS->KnownFPClasses & ClassTest) == fcNone) 4141 return getFalse(RetTy); 4142 if ((FullKnownClassLHS->KnownFPClasses & ~ClassTest) == fcNone) 4143 return getTrue(RetTy); 4144 } 4145 } 4146 4147 // Handle fcmp with constant RHS. 4148 if (C) { 4149 // TODO: If we always required a context function, we wouldn't need to 4150 // special case nans. 4151 if (C->isNaN()) 4152 return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred)); 4153 4154 // TODO: Need version fcmpToClassTest which returns implied class when the 4155 // compare isn't a complete class test. e.g. > 1.0 implies fcPositive, but 4156 // isn't implementable as a class call. 4157 if (C->isNegative() && !C->isNegZero()) { 4158 FPClassTest Interested = KnownFPClass::OrderedLessThanZeroMask; 4159 4160 // TODO: We can catch more cases by using a range check rather than 4161 // relying on CannotBeOrderedLessThanZero. 4162 switch (Pred) { 4163 case FCmpInst::FCMP_UGE: 4164 case FCmpInst::FCMP_UGT: 4165 case FCmpInst::FCMP_UNE: { 4166 KnownFPClass KnownClass = computeLHSClass(Interested); 4167 4168 // (X >= 0) implies (X > C) when (C < 0) 4169 if (KnownClass.cannotBeOrderedLessThanZero()) 4170 return getTrue(RetTy); 4171 break; 4172 } 4173 case FCmpInst::FCMP_OEQ: 4174 case FCmpInst::FCMP_OLE: 4175 case FCmpInst::FCMP_OLT: { 4176 KnownFPClass KnownClass = computeLHSClass(Interested); 4177 4178 // (X >= 0) implies !(X < C) when (C < 0) 4179 if (KnownClass.cannotBeOrderedLessThanZero()) 4180 return getFalse(RetTy); 4181 break; 4182 } 4183 default: 4184 break; 4185 } 4186 } 4187 // Check comparison of [minnum/maxnum with constant] with other constant. 4188 const APFloat *C2; 4189 if ((match(LHS, m_Intrinsic<Intrinsic::minnum>(m_Value(), m_APFloat(C2))) && 4190 *C2 < *C) || 4191 (match(LHS, m_Intrinsic<Intrinsic::maxnum>(m_Value(), m_APFloat(C2))) && 4192 *C2 > *C)) { 4193 bool IsMaxNum = 4194 cast<IntrinsicInst>(LHS)->getIntrinsicID() == Intrinsic::maxnum; 4195 // The ordered relationship and minnum/maxnum guarantee that we do not 4196 // have NaN constants, so ordered/unordered preds are handled the same. 4197 switch (Pred) { 4198 case FCmpInst::FCMP_OEQ: 4199 case FCmpInst::FCMP_UEQ: 4200 // minnum(X, LesserC) == C --> false 4201 // maxnum(X, GreaterC) == C --> false 4202 return getFalse(RetTy); 4203 case FCmpInst::FCMP_ONE: 4204 case FCmpInst::FCMP_UNE: 4205 // minnum(X, LesserC) != C --> true 4206 // maxnum(X, GreaterC) != C --> true 4207 return getTrue(RetTy); 4208 case FCmpInst::FCMP_OGE: 4209 case FCmpInst::FCMP_UGE: 4210 case FCmpInst::FCMP_OGT: 4211 case FCmpInst::FCMP_UGT: 4212 // minnum(X, LesserC) >= C --> false 4213 // minnum(X, LesserC) > C --> false 4214 // maxnum(X, GreaterC) >= C --> true 4215 // maxnum(X, GreaterC) > C --> true 4216 return ConstantInt::get(RetTy, IsMaxNum); 4217 case FCmpInst::FCMP_OLE: 4218 case FCmpInst::FCMP_ULE: 4219 case FCmpInst::FCMP_OLT: 4220 case FCmpInst::FCMP_ULT: 4221 // minnum(X, LesserC) <= C --> true 4222 // minnum(X, LesserC) < C --> true 4223 // maxnum(X, GreaterC) <= C --> false 4224 // maxnum(X, GreaterC) < C --> false 4225 return ConstantInt::get(RetTy, !IsMaxNum); 4226 default: 4227 // TRUE/FALSE/ORD/UNO should be handled before this. 4228 llvm_unreachable("Unexpected fcmp predicate"); 4229 } 4230 } 4231 } 4232 4233 // TODO: Could fold this with above if there were a matcher which returned all 4234 // classes in a non-splat vector. 4235 if (match(RHS, m_AnyZeroFP())) { 4236 switch (Pred) { 4237 case FCmpInst::FCMP_OGE: 4238 case FCmpInst::FCMP_ULT: { 4239 FPClassTest Interested = KnownFPClass::OrderedLessThanZeroMask; 4240 if (!FMF.noNaNs()) 4241 Interested |= fcNan; 4242 4243 KnownFPClass Known = computeLHSClass(Interested); 4244 4245 // Positive or zero X >= 0.0 --> true 4246 // Positive or zero X < 0.0 --> false 4247 if ((FMF.noNaNs() || Known.isKnownNeverNaN()) && 4248 Known.cannotBeOrderedLessThanZero()) 4249 return Pred == FCmpInst::FCMP_OGE ? getTrue(RetTy) : getFalse(RetTy); 4250 break; 4251 } 4252 case FCmpInst::FCMP_UGE: 4253 case FCmpInst::FCMP_OLT: { 4254 FPClassTest Interested = KnownFPClass::OrderedLessThanZeroMask; 4255 KnownFPClass Known = computeLHSClass(Interested); 4256 4257 // Positive or zero or nan X >= 0.0 --> true 4258 // Positive or zero or nan X < 0.0 --> false 4259 if (Known.cannotBeOrderedLessThanZero()) 4260 return Pred == FCmpInst::FCMP_UGE ? getTrue(RetTy) : getFalse(RetTy); 4261 break; 4262 } 4263 default: 4264 break; 4265 } 4266 } 4267 4268 // If the comparison is with the result of a select instruction, check whether 4269 // comparing with either branch of the select always yields the same value. 4270 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 4271 if (Value *V = threadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) 4272 return V; 4273 4274 // If the comparison is with the result of a phi instruction, check whether 4275 // doing the compare with each incoming phi value yields a common result. 4276 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 4277 if (Value *V = threadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) 4278 return V; 4279 4280 return nullptr; 4281 } 4282 4283 Value *llvm::simplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 4284 FastMathFlags FMF, const SimplifyQuery &Q) { 4285 return ::simplifyFCmpInst(Predicate, LHS, RHS, FMF, Q, RecursionLimit); 4286 } 4287 4288 static Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, 4289 const SimplifyQuery &Q, 4290 bool AllowRefinement, 4291 SmallVectorImpl<Instruction *> *DropFlags, 4292 unsigned MaxRecurse) { 4293 // Trivial replacement. 4294 if (V == Op) 4295 return RepOp; 4296 4297 if (!MaxRecurse--) 4298 return nullptr; 4299 4300 // We cannot replace a constant, and shouldn't even try. 4301 if (isa<Constant>(Op)) 4302 return nullptr; 4303 4304 auto *I = dyn_cast<Instruction>(V); 4305 if (!I) 4306 return nullptr; 4307 4308 // The arguments of a phi node might refer to a value from a previous 4309 // cycle iteration. 4310 if (isa<PHINode>(I)) 4311 return nullptr; 4312 4313 if (Op->getType()->isVectorTy()) { 4314 // For vector types, the simplification must hold per-lane, so forbid 4315 // potentially cross-lane operations like shufflevector. 4316 if (!I->getType()->isVectorTy() || isa<ShuffleVectorInst>(I) || 4317 isa<CallBase>(I) || isa<BitCastInst>(I)) 4318 return nullptr; 4319 } 4320 4321 // Don't fold away llvm.is.constant checks based on assumptions. 4322 if (match(I, m_Intrinsic<Intrinsic::is_constant>())) 4323 return nullptr; 4324 4325 // Don't simplify freeze. 4326 if (isa<FreezeInst>(I)) 4327 return nullptr; 4328 4329 // Replace Op with RepOp in instruction operands. 4330 SmallVector<Value *, 8> NewOps; 4331 bool AnyReplaced = false; 4332 for (Value *InstOp : I->operands()) { 4333 if (Value *NewInstOp = simplifyWithOpReplaced( 4334 InstOp, Op, RepOp, Q, AllowRefinement, DropFlags, MaxRecurse)) { 4335 NewOps.push_back(NewInstOp); 4336 AnyReplaced = InstOp != NewInstOp; 4337 } else { 4338 NewOps.push_back(InstOp); 4339 } 4340 } 4341 4342 if (!AnyReplaced) 4343 return nullptr; 4344 4345 if (!AllowRefinement) { 4346 // General InstSimplify functions may refine the result, e.g. by returning 4347 // a constant for a potentially poison value. To avoid this, implement only 4348 // a few non-refining but profitable transforms here. 4349 4350 if (auto *BO = dyn_cast<BinaryOperator>(I)) { 4351 unsigned Opcode = BO->getOpcode(); 4352 // id op x -> x, x op id -> x 4353 if (NewOps[0] == ConstantExpr::getBinOpIdentity(Opcode, I->getType())) 4354 return NewOps[1]; 4355 if (NewOps[1] == ConstantExpr::getBinOpIdentity(Opcode, I->getType(), 4356 /* RHS */ true)) 4357 return NewOps[0]; 4358 4359 // x & x -> x, x | x -> x 4360 if ((Opcode == Instruction::And || Opcode == Instruction::Or) && 4361 NewOps[0] == NewOps[1]) { 4362 // or disjoint x, x results in poison. 4363 if (auto *PDI = dyn_cast<PossiblyDisjointInst>(BO)) { 4364 if (PDI->isDisjoint()) { 4365 if (!DropFlags) 4366 return nullptr; 4367 DropFlags->push_back(BO); 4368 } 4369 } 4370 return NewOps[0]; 4371 } 4372 4373 // x - x -> 0, x ^ x -> 0. This is non-refining, because x is non-poison 4374 // by assumption and this case never wraps, so nowrap flags can be 4375 // ignored. 4376 if ((Opcode == Instruction::Sub || Opcode == Instruction::Xor) && 4377 NewOps[0] == RepOp && NewOps[1] == RepOp) 4378 return Constant::getNullValue(I->getType()); 4379 4380 // If we are substituting an absorber constant into a binop and extra 4381 // poison can't leak if we remove the select -- because both operands of 4382 // the binop are based on the same value -- then it may be safe to replace 4383 // the value with the absorber constant. Examples: 4384 // (Op == 0) ? 0 : (Op & -Op) --> Op & -Op 4385 // (Op == 0) ? 0 : (Op * (binop Op, C)) --> Op * (binop Op, C) 4386 // (Op == -1) ? -1 : (Op | (binop C, Op) --> Op | (binop C, Op) 4387 Constant *Absorber = 4388 ConstantExpr::getBinOpAbsorber(Opcode, I->getType()); 4389 if ((NewOps[0] == Absorber || NewOps[1] == Absorber) && 4390 impliesPoison(BO, Op)) 4391 return Absorber; 4392 } 4393 4394 if (isa<GetElementPtrInst>(I)) { 4395 // getelementptr x, 0 -> x. 4396 // This never returns poison, even if inbounds is set. 4397 if (NewOps.size() == 2 && match(NewOps[1], m_Zero())) 4398 return NewOps[0]; 4399 } 4400 } else { 4401 // The simplification queries below may return the original value. Consider: 4402 // %div = udiv i32 %arg, %arg2 4403 // %mul = mul nsw i32 %div, %arg2 4404 // %cmp = icmp eq i32 %mul, %arg 4405 // %sel = select i1 %cmp, i32 %div, i32 undef 4406 // Replacing %arg by %mul, %div becomes "udiv i32 %mul, %arg2", which 4407 // simplifies back to %arg. This can only happen because %mul does not 4408 // dominate %div. To ensure a consistent return value contract, we make sure 4409 // that this case returns nullptr as well. 4410 auto PreventSelfSimplify = [V](Value *Simplified) { 4411 return Simplified != V ? Simplified : nullptr; 4412 }; 4413 4414 return PreventSelfSimplify( 4415 ::simplifyInstructionWithOperands(I, NewOps, Q, MaxRecurse)); 4416 } 4417 4418 // If all operands are constant after substituting Op for RepOp then we can 4419 // constant fold the instruction. 4420 SmallVector<Constant *, 8> ConstOps; 4421 for (Value *NewOp : NewOps) { 4422 if (Constant *ConstOp = dyn_cast<Constant>(NewOp)) 4423 ConstOps.push_back(ConstOp); 4424 else 4425 return nullptr; 4426 } 4427 4428 // Consider: 4429 // %cmp = icmp eq i32 %x, 2147483647 4430 // %add = add nsw i32 %x, 1 4431 // %sel = select i1 %cmp, i32 -2147483648, i32 %add 4432 // 4433 // We can't replace %sel with %add unless we strip away the flags (which 4434 // will be done in InstCombine). 4435 // TODO: This may be unsound, because it only catches some forms of 4436 // refinement. 4437 if (!AllowRefinement) { 4438 if (canCreatePoison(cast<Operator>(I), !DropFlags)) { 4439 // abs cannot create poison if the value is known to never be int_min. 4440 if (auto *II = dyn_cast<IntrinsicInst>(I); 4441 II && II->getIntrinsicID() == Intrinsic::abs) { 4442 if (!ConstOps[0]->isNotMinSignedValue()) 4443 return nullptr; 4444 } else 4445 return nullptr; 4446 } 4447 Constant *Res = ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI); 4448 if (DropFlags && Res && I->hasPoisonGeneratingFlagsOrMetadata()) 4449 DropFlags->push_back(I); 4450 return Res; 4451 } 4452 4453 return ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI); 4454 } 4455 4456 Value *llvm::simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, 4457 const SimplifyQuery &Q, 4458 bool AllowRefinement, 4459 SmallVectorImpl<Instruction *> *DropFlags) { 4460 return ::simplifyWithOpReplaced(V, Op, RepOp, Q, AllowRefinement, DropFlags, 4461 RecursionLimit); 4462 } 4463 4464 /// Try to simplify a select instruction when its condition operand is an 4465 /// integer comparison where one operand of the compare is a constant. 4466 static Value *simplifySelectBitTest(Value *TrueVal, Value *FalseVal, Value *X, 4467 const APInt *Y, bool TrueWhenUnset) { 4468 const APInt *C; 4469 4470 // (X & Y) == 0 ? X & ~Y : X --> X 4471 // (X & Y) != 0 ? X & ~Y : X --> X & ~Y 4472 if (FalseVal == X && match(TrueVal, m_And(m_Specific(X), m_APInt(C))) && 4473 *Y == ~*C) 4474 return TrueWhenUnset ? FalseVal : TrueVal; 4475 4476 // (X & Y) == 0 ? X : X & ~Y --> X & ~Y 4477 // (X & Y) != 0 ? X : X & ~Y --> X 4478 if (TrueVal == X && match(FalseVal, m_And(m_Specific(X), m_APInt(C))) && 4479 *Y == ~*C) 4480 return TrueWhenUnset ? FalseVal : TrueVal; 4481 4482 if (Y->isPowerOf2()) { 4483 // (X & Y) == 0 ? X | Y : X --> X | Y 4484 // (X & Y) != 0 ? X | Y : X --> X 4485 if (FalseVal == X && match(TrueVal, m_Or(m_Specific(X), m_APInt(C))) && 4486 *Y == *C) { 4487 // We can't return the or if it has the disjoint flag. 4488 if (TrueWhenUnset && cast<PossiblyDisjointInst>(TrueVal)->isDisjoint()) 4489 return nullptr; 4490 return TrueWhenUnset ? TrueVal : FalseVal; 4491 } 4492 4493 // (X & Y) == 0 ? X : X | Y --> X 4494 // (X & Y) != 0 ? X : X | Y --> X | Y 4495 if (TrueVal == X && match(FalseVal, m_Or(m_Specific(X), m_APInt(C))) && 4496 *Y == *C) { 4497 // We can't return the or if it has the disjoint flag. 4498 if (!TrueWhenUnset && cast<PossiblyDisjointInst>(FalseVal)->isDisjoint()) 4499 return nullptr; 4500 return TrueWhenUnset ? TrueVal : FalseVal; 4501 } 4502 } 4503 4504 return nullptr; 4505 } 4506 4507 static Value *simplifyCmpSelOfMaxMin(Value *CmpLHS, Value *CmpRHS, 4508 ICmpInst::Predicate Pred, Value *TVal, 4509 Value *FVal) { 4510 // Canonicalize common cmp+sel operand as CmpLHS. 4511 if (CmpRHS == TVal || CmpRHS == FVal) { 4512 std::swap(CmpLHS, CmpRHS); 4513 Pred = ICmpInst::getSwappedPredicate(Pred); 4514 } 4515 4516 // Canonicalize common cmp+sel operand as TVal. 4517 if (CmpLHS == FVal) { 4518 std::swap(TVal, FVal); 4519 Pred = ICmpInst::getInversePredicate(Pred); 4520 } 4521 4522 // A vector select may be shuffling together elements that are equivalent 4523 // based on the max/min/select relationship. 4524 Value *X = CmpLHS, *Y = CmpRHS; 4525 bool PeekedThroughSelectShuffle = false; 4526 auto *Shuf = dyn_cast<ShuffleVectorInst>(FVal); 4527 if (Shuf && Shuf->isSelect()) { 4528 if (Shuf->getOperand(0) == Y) 4529 FVal = Shuf->getOperand(1); 4530 else if (Shuf->getOperand(1) == Y) 4531 FVal = Shuf->getOperand(0); 4532 else 4533 return nullptr; 4534 PeekedThroughSelectShuffle = true; 4535 } 4536 4537 // (X pred Y) ? X : max/min(X, Y) 4538 auto *MMI = dyn_cast<MinMaxIntrinsic>(FVal); 4539 if (!MMI || TVal != X || 4540 !match(FVal, m_c_MaxOrMin(m_Specific(X), m_Specific(Y)))) 4541 return nullptr; 4542 4543 // (X > Y) ? X : max(X, Y) --> max(X, Y) 4544 // (X >= Y) ? X : max(X, Y) --> max(X, Y) 4545 // (X < Y) ? X : min(X, Y) --> min(X, Y) 4546 // (X <= Y) ? X : min(X, Y) --> min(X, Y) 4547 // 4548 // The equivalence allows a vector select (shuffle) of max/min and Y. Ex: 4549 // (X > Y) ? X : (Z ? max(X, Y) : Y) 4550 // If Z is true, this reduces as above, and if Z is false: 4551 // (X > Y) ? X : Y --> max(X, Y) 4552 ICmpInst::Predicate MMPred = MMI->getPredicate(); 4553 if (MMPred == CmpInst::getStrictPredicate(Pred)) 4554 return MMI; 4555 4556 // Other transforms are not valid with a shuffle. 4557 if (PeekedThroughSelectShuffle) 4558 return nullptr; 4559 4560 // (X == Y) ? X : max/min(X, Y) --> max/min(X, Y) 4561 if (Pred == CmpInst::ICMP_EQ) 4562 return MMI; 4563 4564 // (X != Y) ? X : max/min(X, Y) --> X 4565 if (Pred == CmpInst::ICMP_NE) 4566 return X; 4567 4568 // (X < Y) ? X : max(X, Y) --> X 4569 // (X <= Y) ? X : max(X, Y) --> X 4570 // (X > Y) ? X : min(X, Y) --> X 4571 // (X >= Y) ? X : min(X, Y) --> X 4572 ICmpInst::Predicate InvPred = CmpInst::getInversePredicate(Pred); 4573 if (MMPred == CmpInst::getStrictPredicate(InvPred)) 4574 return X; 4575 4576 return nullptr; 4577 } 4578 4579 /// An alternative way to test if a bit is set or not uses sgt/slt instead of 4580 /// eq/ne. 4581 static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *CmpRHS, 4582 ICmpInst::Predicate Pred, 4583 Value *TrueVal, Value *FalseVal) { 4584 Value *X; 4585 APInt Mask; 4586 if (!decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask)) 4587 return nullptr; 4588 4589 return simplifySelectBitTest(TrueVal, FalseVal, X, &Mask, 4590 Pred == ICmpInst::ICMP_EQ); 4591 } 4592 4593 /// Try to simplify a select instruction when its condition operand is an 4594 /// integer equality comparison. 4595 static Value *simplifySelectWithICmpEq(Value *CmpLHS, Value *CmpRHS, 4596 Value *TrueVal, Value *FalseVal, 4597 const SimplifyQuery &Q, 4598 unsigned MaxRecurse) { 4599 if (simplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, 4600 /* AllowRefinement */ false, 4601 /* DropFlags */ nullptr, MaxRecurse) == TrueVal) 4602 return FalseVal; 4603 if (simplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, 4604 /* AllowRefinement */ true, 4605 /* DropFlags */ nullptr, MaxRecurse) == FalseVal) 4606 return FalseVal; 4607 4608 return nullptr; 4609 } 4610 4611 /// Try to simplify a select instruction when its condition operand is an 4612 /// integer comparison. 4613 static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal, 4614 Value *FalseVal, 4615 const SimplifyQuery &Q, 4616 unsigned MaxRecurse) { 4617 ICmpInst::Predicate Pred; 4618 Value *CmpLHS, *CmpRHS; 4619 if (!match(CondVal, m_ICmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS)))) 4620 return nullptr; 4621 4622 if (Value *V = simplifyCmpSelOfMaxMin(CmpLHS, CmpRHS, Pred, TrueVal, FalseVal)) 4623 return V; 4624 4625 // Canonicalize ne to eq predicate. 4626 if (Pred == ICmpInst::ICMP_NE) { 4627 Pred = ICmpInst::ICMP_EQ; 4628 std::swap(TrueVal, FalseVal); 4629 } 4630 4631 // Check for integer min/max with a limit constant: 4632 // X > MIN_INT ? X : MIN_INT --> X 4633 // X < MAX_INT ? X : MAX_INT --> X 4634 if (TrueVal->getType()->isIntOrIntVectorTy()) { 4635 Value *X, *Y; 4636 SelectPatternFlavor SPF = 4637 matchDecomposedSelectPattern(cast<ICmpInst>(CondVal), TrueVal, FalseVal, 4638 X, Y) 4639 .Flavor; 4640 if (SelectPatternResult::isMinOrMax(SPF) && Pred == getMinMaxPred(SPF)) { 4641 APInt LimitC = getMinMaxLimit(getInverseMinMaxFlavor(SPF), 4642 X->getType()->getScalarSizeInBits()); 4643 if (match(Y, m_SpecificInt(LimitC))) 4644 return X; 4645 } 4646 } 4647 4648 if (Pred == ICmpInst::ICMP_EQ && match(CmpRHS, m_Zero())) { 4649 Value *X; 4650 const APInt *Y; 4651 if (match(CmpLHS, m_And(m_Value(X), m_APInt(Y)))) 4652 if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, Y, 4653 /*TrueWhenUnset=*/true)) 4654 return V; 4655 4656 // Test for a bogus zero-shift-guard-op around funnel-shift or rotate. 4657 Value *ShAmt; 4658 auto isFsh = m_CombineOr(m_FShl(m_Value(X), m_Value(), m_Value(ShAmt)), 4659 m_FShr(m_Value(), m_Value(X), m_Value(ShAmt))); 4660 // (ShAmt == 0) ? fshl(X, *, ShAmt) : X --> X 4661 // (ShAmt == 0) ? fshr(*, X, ShAmt) : X --> X 4662 if (match(TrueVal, isFsh) && FalseVal == X && CmpLHS == ShAmt) 4663 return X; 4664 4665 // Test for a zero-shift-guard-op around rotates. These are used to 4666 // avoid UB from oversized shifts in raw IR rotate patterns, but the 4667 // intrinsics do not have that problem. 4668 // We do not allow this transform for the general funnel shift case because 4669 // that would not preserve the poison safety of the original code. 4670 auto isRotate = 4671 m_CombineOr(m_FShl(m_Value(X), m_Deferred(X), m_Value(ShAmt)), 4672 m_FShr(m_Value(X), m_Deferred(X), m_Value(ShAmt))); 4673 // (ShAmt == 0) ? X : fshl(X, X, ShAmt) --> fshl(X, X, ShAmt) 4674 // (ShAmt == 0) ? X : fshr(X, X, ShAmt) --> fshr(X, X, ShAmt) 4675 if (match(FalseVal, isRotate) && TrueVal == X && CmpLHS == ShAmt && 4676 Pred == ICmpInst::ICMP_EQ) 4677 return FalseVal; 4678 4679 // X == 0 ? abs(X) : -abs(X) --> -abs(X) 4680 // X == 0 ? -abs(X) : abs(X) --> abs(X) 4681 if (match(TrueVal, m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS))) && 4682 match(FalseVal, m_Neg(m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS))))) 4683 return FalseVal; 4684 if (match(TrueVal, 4685 m_Neg(m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS)))) && 4686 match(FalseVal, m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS)))) 4687 return FalseVal; 4688 } 4689 4690 // Check for other compares that behave like bit test. 4691 if (Value *V = 4692 simplifySelectWithFakeICmpEq(CmpLHS, CmpRHS, Pred, TrueVal, FalseVal)) 4693 return V; 4694 4695 // If we have a scalar equality comparison, then we know the value in one of 4696 // the arms of the select. See if substituting this value into the arm and 4697 // simplifying the result yields the same value as the other arm. 4698 if (Pred == ICmpInst::ICMP_EQ) { 4699 if (Value *V = simplifySelectWithICmpEq(CmpLHS, CmpRHS, TrueVal, FalseVal, 4700 Q, MaxRecurse)) 4701 return V; 4702 if (Value *V = simplifySelectWithICmpEq(CmpRHS, CmpLHS, TrueVal, FalseVal, 4703 Q, MaxRecurse)) 4704 return V; 4705 4706 Value *X; 4707 Value *Y; 4708 // select((X | Y) == 0 ? X : 0) --> 0 (commuted 2 ways) 4709 if (match(CmpLHS, m_Or(m_Value(X), m_Value(Y))) && 4710 match(CmpRHS, m_Zero())) { 4711 // (X | Y) == 0 implies X == 0 and Y == 0. 4712 if (Value *V = simplifySelectWithICmpEq(X, CmpRHS, TrueVal, FalseVal, Q, 4713 MaxRecurse)) 4714 return V; 4715 if (Value *V = simplifySelectWithICmpEq(Y, CmpRHS, TrueVal, FalseVal, Q, 4716 MaxRecurse)) 4717 return V; 4718 } 4719 4720 // select((X & Y) == -1 ? X : -1) --> -1 (commuted 2 ways) 4721 if (match(CmpLHS, m_And(m_Value(X), m_Value(Y))) && 4722 match(CmpRHS, m_AllOnes())) { 4723 // (X & Y) == -1 implies X == -1 and Y == -1. 4724 if (Value *V = simplifySelectWithICmpEq(X, CmpRHS, TrueVal, FalseVal, Q, 4725 MaxRecurse)) 4726 return V; 4727 if (Value *V = simplifySelectWithICmpEq(Y, CmpRHS, TrueVal, FalseVal, Q, 4728 MaxRecurse)) 4729 return V; 4730 } 4731 } 4732 4733 return nullptr; 4734 } 4735 4736 /// Try to simplify a select instruction when its condition operand is a 4737 /// floating-point comparison. 4738 static Value *simplifySelectWithFCmp(Value *Cond, Value *T, Value *F, 4739 const SimplifyQuery &Q) { 4740 FCmpInst::Predicate Pred; 4741 if (!match(Cond, m_FCmp(Pred, m_Specific(T), m_Specific(F))) && 4742 !match(Cond, m_FCmp(Pred, m_Specific(F), m_Specific(T)))) 4743 return nullptr; 4744 4745 // This transform is safe if we do not have (do not care about) -0.0 or if 4746 // at least one operand is known to not be -0.0. Otherwise, the select can 4747 // change the sign of a zero operand. 4748 bool HasNoSignedZeros = 4749 Q.CxtI && isa<FPMathOperator>(Q.CxtI) && Q.CxtI->hasNoSignedZeros(); 4750 const APFloat *C; 4751 if (HasNoSignedZeros || (match(T, m_APFloat(C)) && C->isNonZero()) || 4752 (match(F, m_APFloat(C)) && C->isNonZero())) { 4753 // (T == F) ? T : F --> F 4754 // (F == T) ? T : F --> F 4755 if (Pred == FCmpInst::FCMP_OEQ) 4756 return F; 4757 4758 // (T != F) ? T : F --> T 4759 // (F != T) ? T : F --> T 4760 if (Pred == FCmpInst::FCMP_UNE) 4761 return T; 4762 } 4763 4764 return nullptr; 4765 } 4766 4767 /// Given operands for a SelectInst, see if we can fold the result. 4768 /// If not, this returns null. 4769 static Value *simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 4770 const SimplifyQuery &Q, unsigned MaxRecurse) { 4771 if (auto *CondC = dyn_cast<Constant>(Cond)) { 4772 if (auto *TrueC = dyn_cast<Constant>(TrueVal)) 4773 if (auto *FalseC = dyn_cast<Constant>(FalseVal)) 4774 if (Constant *C = ConstantFoldSelectInstruction(CondC, TrueC, FalseC)) 4775 return C; 4776 4777 // select poison, X, Y -> poison 4778 if (isa<PoisonValue>(CondC)) 4779 return PoisonValue::get(TrueVal->getType()); 4780 4781 // select undef, X, Y -> X or Y 4782 if (Q.isUndefValue(CondC)) 4783 return isa<Constant>(FalseVal) ? FalseVal : TrueVal; 4784 4785 // select true, X, Y --> X 4786 // select false, X, Y --> Y 4787 // For vectors, allow undef/poison elements in the condition to match the 4788 // defined elements, so we can eliminate the select. 4789 if (match(CondC, m_One())) 4790 return TrueVal; 4791 if (match(CondC, m_Zero())) 4792 return FalseVal; 4793 } 4794 4795 assert(Cond->getType()->isIntOrIntVectorTy(1) && 4796 "Select must have bool or bool vector condition"); 4797 assert(TrueVal->getType() == FalseVal->getType() && 4798 "Select must have same types for true/false ops"); 4799 4800 if (Cond->getType() == TrueVal->getType()) { 4801 // select i1 Cond, i1 true, i1 false --> i1 Cond 4802 if (match(TrueVal, m_One()) && match(FalseVal, m_ZeroInt())) 4803 return Cond; 4804 4805 // (X && Y) ? X : Y --> Y (commuted 2 ways) 4806 if (match(Cond, m_c_LogicalAnd(m_Specific(TrueVal), m_Specific(FalseVal)))) 4807 return FalseVal; 4808 4809 // (X || Y) ? X : Y --> X (commuted 2 ways) 4810 if (match(Cond, m_c_LogicalOr(m_Specific(TrueVal), m_Specific(FalseVal)))) 4811 return TrueVal; 4812 4813 // (X || Y) ? false : X --> false (commuted 2 ways) 4814 if (match(Cond, m_c_LogicalOr(m_Specific(FalseVal), m_Value())) && 4815 match(TrueVal, m_ZeroInt())) 4816 return ConstantInt::getFalse(Cond->getType()); 4817 4818 // Match patterns that end in logical-and. 4819 if (match(FalseVal, m_ZeroInt())) { 4820 // !(X || Y) && X --> false (commuted 2 ways) 4821 if (match(Cond, m_Not(m_c_LogicalOr(m_Specific(TrueVal), m_Value())))) 4822 return ConstantInt::getFalse(Cond->getType()); 4823 // X && !(X || Y) --> false (commuted 2 ways) 4824 if (match(TrueVal, m_Not(m_c_LogicalOr(m_Specific(Cond), m_Value())))) 4825 return ConstantInt::getFalse(Cond->getType()); 4826 4827 // (X || Y) && Y --> Y (commuted 2 ways) 4828 if (match(Cond, m_c_LogicalOr(m_Specific(TrueVal), m_Value()))) 4829 return TrueVal; 4830 // Y && (X || Y) --> Y (commuted 2 ways) 4831 if (match(TrueVal, m_c_LogicalOr(m_Specific(Cond), m_Value()))) 4832 return Cond; 4833 4834 // (X || Y) && (X || !Y) --> X (commuted 8 ways) 4835 Value *X, *Y; 4836 if (match(Cond, m_c_LogicalOr(m_Value(X), m_Not(m_Value(Y)))) && 4837 match(TrueVal, m_c_LogicalOr(m_Specific(X), m_Specific(Y)))) 4838 return X; 4839 if (match(TrueVal, m_c_LogicalOr(m_Value(X), m_Not(m_Value(Y)))) && 4840 match(Cond, m_c_LogicalOr(m_Specific(X), m_Specific(Y)))) 4841 return X; 4842 } 4843 4844 // Match patterns that end in logical-or. 4845 if (match(TrueVal, m_One())) { 4846 // !(X && Y) || X --> true (commuted 2 ways) 4847 if (match(Cond, m_Not(m_c_LogicalAnd(m_Specific(FalseVal), m_Value())))) 4848 return ConstantInt::getTrue(Cond->getType()); 4849 // X || !(X && Y) --> true (commuted 2 ways) 4850 if (match(FalseVal, m_Not(m_c_LogicalAnd(m_Specific(Cond), m_Value())))) 4851 return ConstantInt::getTrue(Cond->getType()); 4852 4853 // (X && Y) || Y --> Y (commuted 2 ways) 4854 if (match(Cond, m_c_LogicalAnd(m_Specific(FalseVal), m_Value()))) 4855 return FalseVal; 4856 // Y || (X && Y) --> Y (commuted 2 ways) 4857 if (match(FalseVal, m_c_LogicalAnd(m_Specific(Cond), m_Value()))) 4858 return Cond; 4859 } 4860 } 4861 4862 // select ?, X, X -> X 4863 if (TrueVal == FalseVal) 4864 return TrueVal; 4865 4866 if (Cond == TrueVal) { 4867 // select i1 X, i1 X, i1 false --> X (logical-and) 4868 if (match(FalseVal, m_ZeroInt())) 4869 return Cond; 4870 // select i1 X, i1 X, i1 true --> true 4871 if (match(FalseVal, m_One())) 4872 return ConstantInt::getTrue(Cond->getType()); 4873 } 4874 if (Cond == FalseVal) { 4875 // select i1 X, i1 true, i1 X --> X (logical-or) 4876 if (match(TrueVal, m_One())) 4877 return Cond; 4878 // select i1 X, i1 false, i1 X --> false 4879 if (match(TrueVal, m_ZeroInt())) 4880 return ConstantInt::getFalse(Cond->getType()); 4881 } 4882 4883 // If the true or false value is poison, we can fold to the other value. 4884 // If the true or false value is undef, we can fold to the other value as 4885 // long as the other value isn't poison. 4886 // select ?, poison, X -> X 4887 // select ?, undef, X -> X 4888 if (isa<PoisonValue>(TrueVal) || 4889 (Q.isUndefValue(TrueVal) && impliesPoison(FalseVal, Cond))) 4890 return FalseVal; 4891 // select ?, X, poison -> X 4892 // select ?, X, undef -> X 4893 if (isa<PoisonValue>(FalseVal) || 4894 (Q.isUndefValue(FalseVal) && impliesPoison(TrueVal, Cond))) 4895 return TrueVal; 4896 4897 // Deal with partial undef vector constants: select ?, VecC, VecC' --> VecC'' 4898 Constant *TrueC, *FalseC; 4899 if (isa<FixedVectorType>(TrueVal->getType()) && 4900 match(TrueVal, m_Constant(TrueC)) && 4901 match(FalseVal, m_Constant(FalseC))) { 4902 unsigned NumElts = 4903 cast<FixedVectorType>(TrueC->getType())->getNumElements(); 4904 SmallVector<Constant *, 16> NewC; 4905 for (unsigned i = 0; i != NumElts; ++i) { 4906 // Bail out on incomplete vector constants. 4907 Constant *TEltC = TrueC->getAggregateElement(i); 4908 Constant *FEltC = FalseC->getAggregateElement(i); 4909 if (!TEltC || !FEltC) 4910 break; 4911 4912 // If the elements match (undef or not), that value is the result. If only 4913 // one element is undef, choose the defined element as the safe result. 4914 if (TEltC == FEltC) 4915 NewC.push_back(TEltC); 4916 else if (isa<PoisonValue>(TEltC) || 4917 (Q.isUndefValue(TEltC) && isGuaranteedNotToBePoison(FEltC))) 4918 NewC.push_back(FEltC); 4919 else if (isa<PoisonValue>(FEltC) || 4920 (Q.isUndefValue(FEltC) && isGuaranteedNotToBePoison(TEltC))) 4921 NewC.push_back(TEltC); 4922 else 4923 break; 4924 } 4925 if (NewC.size() == NumElts) 4926 return ConstantVector::get(NewC); 4927 } 4928 4929 if (Value *V = 4930 simplifySelectWithICmpCond(Cond, TrueVal, FalseVal, Q, MaxRecurse)) 4931 return V; 4932 4933 if (Value *V = simplifySelectWithFCmp(Cond, TrueVal, FalseVal, Q)) 4934 return V; 4935 4936 if (Value *V = foldSelectWithBinaryOp(Cond, TrueVal, FalseVal)) 4937 return V; 4938 4939 std::optional<bool> Imp = isImpliedByDomCondition(Cond, Q.CxtI, Q.DL); 4940 if (Imp) 4941 return *Imp ? TrueVal : FalseVal; 4942 4943 return nullptr; 4944 } 4945 4946 Value *llvm::simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 4947 const SimplifyQuery &Q) { 4948 return ::simplifySelectInst(Cond, TrueVal, FalseVal, Q, RecursionLimit); 4949 } 4950 4951 /// Given operands for an GetElementPtrInst, see if we can fold the result. 4952 /// If not, this returns null. 4953 static Value *simplifyGEPInst(Type *SrcTy, Value *Ptr, 4954 ArrayRef<Value *> Indices, bool InBounds, 4955 const SimplifyQuery &Q, unsigned) { 4956 // The type of the GEP pointer operand. 4957 unsigned AS = 4958 cast<PointerType>(Ptr->getType()->getScalarType())->getAddressSpace(); 4959 4960 // getelementptr P -> P. 4961 if (Indices.empty()) 4962 return Ptr; 4963 4964 // Compute the (pointer) type returned by the GEP instruction. 4965 Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Indices); 4966 Type *GEPTy = Ptr->getType(); 4967 if (!GEPTy->isVectorTy()) { 4968 for (Value *Op : Indices) { 4969 // If one of the operands is a vector, the result type is a vector of 4970 // pointers. All vector operands must have the same number of elements. 4971 if (VectorType *VT = dyn_cast<VectorType>(Op->getType())) { 4972 GEPTy = VectorType::get(GEPTy, VT->getElementCount()); 4973 break; 4974 } 4975 } 4976 } 4977 4978 // All-zero GEP is a no-op, unless it performs a vector splat. 4979 if (Ptr->getType() == GEPTy && 4980 all_of(Indices, [](const auto *V) { return match(V, m_Zero()); })) 4981 return Ptr; 4982 4983 // getelementptr poison, idx -> poison 4984 // getelementptr baseptr, poison -> poison 4985 if (isa<PoisonValue>(Ptr) || 4986 any_of(Indices, [](const auto *V) { return isa<PoisonValue>(V); })) 4987 return PoisonValue::get(GEPTy); 4988 4989 // getelementptr undef, idx -> undef 4990 if (Q.isUndefValue(Ptr)) 4991 return UndefValue::get(GEPTy); 4992 4993 bool IsScalableVec = 4994 SrcTy->isScalableTy() || any_of(Indices, [](const Value *V) { 4995 return isa<ScalableVectorType>(V->getType()); 4996 }); 4997 4998 if (Indices.size() == 1) { 4999 Type *Ty = SrcTy; 5000 if (!IsScalableVec && Ty->isSized()) { 5001 Value *P; 5002 uint64_t C; 5003 uint64_t TyAllocSize = Q.DL.getTypeAllocSize(Ty); 5004 // getelementptr P, N -> P if P points to a type of zero size. 5005 if (TyAllocSize == 0 && Ptr->getType() == GEPTy) 5006 return Ptr; 5007 5008 // The following transforms are only safe if the ptrtoint cast 5009 // doesn't truncate the pointers. 5010 if (Indices[0]->getType()->getScalarSizeInBits() == 5011 Q.DL.getPointerSizeInBits(AS)) { 5012 auto CanSimplify = [GEPTy, &P, Ptr]() -> bool { 5013 return P->getType() == GEPTy && 5014 getUnderlyingObject(P) == getUnderlyingObject(Ptr); 5015 }; 5016 // getelementptr V, (sub P, V) -> P if P points to a type of size 1. 5017 if (TyAllocSize == 1 && 5018 match(Indices[0], 5019 m_Sub(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Specific(Ptr)))) && 5020 CanSimplify()) 5021 return P; 5022 5023 // getelementptr V, (ashr (sub P, V), C) -> P if P points to a type of 5024 // size 1 << C. 5025 if (match(Indices[0], m_AShr(m_Sub(m_PtrToInt(m_Value(P)), 5026 m_PtrToInt(m_Specific(Ptr))), 5027 m_ConstantInt(C))) && 5028 TyAllocSize == 1ULL << C && CanSimplify()) 5029 return P; 5030 5031 // getelementptr V, (sdiv (sub P, V), C) -> P if P points to a type of 5032 // size C. 5033 if (match(Indices[0], m_SDiv(m_Sub(m_PtrToInt(m_Value(P)), 5034 m_PtrToInt(m_Specific(Ptr))), 5035 m_SpecificInt(TyAllocSize))) && 5036 CanSimplify()) 5037 return P; 5038 } 5039 } 5040 } 5041 5042 if (!IsScalableVec && Q.DL.getTypeAllocSize(LastType) == 1 && 5043 all_of(Indices.drop_back(1), 5044 [](Value *Idx) { return match(Idx, m_Zero()); })) { 5045 unsigned IdxWidth = 5046 Q.DL.getIndexSizeInBits(Ptr->getType()->getPointerAddressSpace()); 5047 if (Q.DL.getTypeSizeInBits(Indices.back()->getType()) == IdxWidth) { 5048 APInt BasePtrOffset(IdxWidth, 0); 5049 Value *StrippedBasePtr = 5050 Ptr->stripAndAccumulateInBoundsConstantOffsets(Q.DL, BasePtrOffset); 5051 5052 // Avoid creating inttoptr of zero here: While LLVMs treatment of 5053 // inttoptr is generally conservative, this particular case is folded to 5054 // a null pointer, which will have incorrect provenance. 5055 5056 // gep (gep V, C), (sub 0, V) -> C 5057 if (match(Indices.back(), 5058 m_Sub(m_Zero(), m_PtrToInt(m_Specific(StrippedBasePtr)))) && 5059 !BasePtrOffset.isZero()) { 5060 auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset); 5061 return ConstantExpr::getIntToPtr(CI, GEPTy); 5062 } 5063 // gep (gep V, C), (xor V, -1) -> C-1 5064 if (match(Indices.back(), 5065 m_Xor(m_PtrToInt(m_Specific(StrippedBasePtr)), m_AllOnes())) && 5066 !BasePtrOffset.isOne()) { 5067 auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset - 1); 5068 return ConstantExpr::getIntToPtr(CI, GEPTy); 5069 } 5070 } 5071 } 5072 5073 // Check to see if this is constant foldable. 5074 if (!isa<Constant>(Ptr) || 5075 !all_of(Indices, [](Value *V) { return isa<Constant>(V); })) 5076 return nullptr; 5077 5078 if (!ConstantExpr::isSupportedGetElementPtr(SrcTy)) 5079 return ConstantFoldGetElementPtr(SrcTy, cast<Constant>(Ptr), InBounds, 5080 std::nullopt, Indices); 5081 5082 auto *CE = ConstantExpr::getGetElementPtr(SrcTy, cast<Constant>(Ptr), Indices, 5083 InBounds); 5084 return ConstantFoldConstant(CE, Q.DL); 5085 } 5086 5087 Value *llvm::simplifyGEPInst(Type *SrcTy, Value *Ptr, ArrayRef<Value *> Indices, 5088 bool InBounds, const SimplifyQuery &Q) { 5089 return ::simplifyGEPInst(SrcTy, Ptr, Indices, InBounds, Q, RecursionLimit); 5090 } 5091 5092 /// Given operands for an InsertValueInst, see if we can fold the result. 5093 /// If not, this returns null. 5094 static Value *simplifyInsertValueInst(Value *Agg, Value *Val, 5095 ArrayRef<unsigned> Idxs, 5096 const SimplifyQuery &Q, unsigned) { 5097 if (Constant *CAgg = dyn_cast<Constant>(Agg)) 5098 if (Constant *CVal = dyn_cast<Constant>(Val)) 5099 return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs); 5100 5101 // insertvalue x, poison, n -> x 5102 // insertvalue x, undef, n -> x if x cannot be poison 5103 if (isa<PoisonValue>(Val) || 5104 (Q.isUndefValue(Val) && isGuaranteedNotToBePoison(Agg))) 5105 return Agg; 5106 5107 // insertvalue x, (extractvalue y, n), n 5108 if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val)) 5109 if (EV->getAggregateOperand()->getType() == Agg->getType() && 5110 EV->getIndices() == Idxs) { 5111 // insertvalue poison, (extractvalue y, n), n -> y 5112 // insertvalue undef, (extractvalue y, n), n -> y if y cannot be poison 5113 if (isa<PoisonValue>(Agg) || 5114 (Q.isUndefValue(Agg) && 5115 isGuaranteedNotToBePoison(EV->getAggregateOperand()))) 5116 return EV->getAggregateOperand(); 5117 5118 // insertvalue y, (extractvalue y, n), n -> y 5119 if (Agg == EV->getAggregateOperand()) 5120 return Agg; 5121 } 5122 5123 return nullptr; 5124 } 5125 5126 Value *llvm::simplifyInsertValueInst(Value *Agg, Value *Val, 5127 ArrayRef<unsigned> Idxs, 5128 const SimplifyQuery &Q) { 5129 return ::simplifyInsertValueInst(Agg, Val, Idxs, Q, RecursionLimit); 5130 } 5131 5132 Value *llvm::simplifyInsertElementInst(Value *Vec, Value *Val, Value *Idx, 5133 const SimplifyQuery &Q) { 5134 // Try to constant fold. 5135 auto *VecC = dyn_cast<Constant>(Vec); 5136 auto *ValC = dyn_cast<Constant>(Val); 5137 auto *IdxC = dyn_cast<Constant>(Idx); 5138 if (VecC && ValC && IdxC) 5139 return ConstantExpr::getInsertElement(VecC, ValC, IdxC); 5140 5141 // For fixed-length vector, fold into poison if index is out of bounds. 5142 if (auto *CI = dyn_cast<ConstantInt>(Idx)) { 5143 if (isa<FixedVectorType>(Vec->getType()) && 5144 CI->uge(cast<FixedVectorType>(Vec->getType())->getNumElements())) 5145 return PoisonValue::get(Vec->getType()); 5146 } 5147 5148 // If index is undef, it might be out of bounds (see above case) 5149 if (Q.isUndefValue(Idx)) 5150 return PoisonValue::get(Vec->getType()); 5151 5152 // If the scalar is poison, or it is undef and there is no risk of 5153 // propagating poison from the vector value, simplify to the vector value. 5154 if (isa<PoisonValue>(Val) || 5155 (Q.isUndefValue(Val) && isGuaranteedNotToBePoison(Vec))) 5156 return Vec; 5157 5158 // If we are extracting a value from a vector, then inserting it into the same 5159 // place, that's the input vector: 5160 // insertelt Vec, (extractelt Vec, Idx), Idx --> Vec 5161 if (match(Val, m_ExtractElt(m_Specific(Vec), m_Specific(Idx)))) 5162 return Vec; 5163 5164 return nullptr; 5165 } 5166 5167 /// Given operands for an ExtractValueInst, see if we can fold the result. 5168 /// If not, this returns null. 5169 static Value *simplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, 5170 const SimplifyQuery &, unsigned) { 5171 if (auto *CAgg = dyn_cast<Constant>(Agg)) 5172 return ConstantFoldExtractValueInstruction(CAgg, Idxs); 5173 5174 // extractvalue x, (insertvalue y, elt, n), n -> elt 5175 unsigned NumIdxs = Idxs.size(); 5176 for (auto *IVI = dyn_cast<InsertValueInst>(Agg); IVI != nullptr; 5177 IVI = dyn_cast<InsertValueInst>(IVI->getAggregateOperand())) { 5178 ArrayRef<unsigned> InsertValueIdxs = IVI->getIndices(); 5179 unsigned NumInsertValueIdxs = InsertValueIdxs.size(); 5180 unsigned NumCommonIdxs = std::min(NumInsertValueIdxs, NumIdxs); 5181 if (InsertValueIdxs.slice(0, NumCommonIdxs) == 5182 Idxs.slice(0, NumCommonIdxs)) { 5183 if (NumIdxs == NumInsertValueIdxs) 5184 return IVI->getInsertedValueOperand(); 5185 break; 5186 } 5187 } 5188 5189 return nullptr; 5190 } 5191 5192 Value *llvm::simplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, 5193 const SimplifyQuery &Q) { 5194 return ::simplifyExtractValueInst(Agg, Idxs, Q, RecursionLimit); 5195 } 5196 5197 /// Given operands for an ExtractElementInst, see if we can fold the result. 5198 /// If not, this returns null. 5199 static Value *simplifyExtractElementInst(Value *Vec, Value *Idx, 5200 const SimplifyQuery &Q, unsigned) { 5201 auto *VecVTy = cast<VectorType>(Vec->getType()); 5202 if (auto *CVec = dyn_cast<Constant>(Vec)) { 5203 if (auto *CIdx = dyn_cast<Constant>(Idx)) 5204 return ConstantExpr::getExtractElement(CVec, CIdx); 5205 5206 if (Q.isUndefValue(Vec)) 5207 return UndefValue::get(VecVTy->getElementType()); 5208 } 5209 5210 // An undef extract index can be arbitrarily chosen to be an out-of-range 5211 // index value, which would result in the instruction being poison. 5212 if (Q.isUndefValue(Idx)) 5213 return PoisonValue::get(VecVTy->getElementType()); 5214 5215 // If extracting a specified index from the vector, see if we can recursively 5216 // find a previously computed scalar that was inserted into the vector. 5217 if (auto *IdxC = dyn_cast<ConstantInt>(Idx)) { 5218 // For fixed-length vector, fold into undef if index is out of bounds. 5219 unsigned MinNumElts = VecVTy->getElementCount().getKnownMinValue(); 5220 if (isa<FixedVectorType>(VecVTy) && IdxC->getValue().uge(MinNumElts)) 5221 return PoisonValue::get(VecVTy->getElementType()); 5222 // Handle case where an element is extracted from a splat. 5223 if (IdxC->getValue().ult(MinNumElts)) 5224 if (auto *Splat = getSplatValue(Vec)) 5225 return Splat; 5226 if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue())) 5227 return Elt; 5228 } else { 5229 // extractelt x, (insertelt y, elt, n), n -> elt 5230 // If the possibly-variable indices are trivially known to be equal 5231 // (because they are the same operand) then use the value that was 5232 // inserted directly. 5233 auto *IE = dyn_cast<InsertElementInst>(Vec); 5234 if (IE && IE->getOperand(2) == Idx) 5235 return IE->getOperand(1); 5236 5237 // The index is not relevant if our vector is a splat. 5238 if (Value *Splat = getSplatValue(Vec)) 5239 return Splat; 5240 } 5241 return nullptr; 5242 } 5243 5244 Value *llvm::simplifyExtractElementInst(Value *Vec, Value *Idx, 5245 const SimplifyQuery &Q) { 5246 return ::simplifyExtractElementInst(Vec, Idx, Q, RecursionLimit); 5247 } 5248 5249 /// See if we can fold the given phi. If not, returns null. 5250 static Value *simplifyPHINode(PHINode *PN, ArrayRef<Value *> IncomingValues, 5251 const SimplifyQuery &Q) { 5252 // WARNING: no matter how worthwhile it may seem, we can not perform PHI CSE 5253 // here, because the PHI we may succeed simplifying to was not 5254 // def-reachable from the original PHI! 5255 5256 // If all of the PHI's incoming values are the same then replace the PHI node 5257 // with the common value. 5258 Value *CommonValue = nullptr; 5259 bool HasUndefInput = false; 5260 for (Value *Incoming : IncomingValues) { 5261 // If the incoming value is the phi node itself, it can safely be skipped. 5262 if (Incoming == PN) 5263 continue; 5264 if (Q.isUndefValue(Incoming)) { 5265 // Remember that we saw an undef value, but otherwise ignore them. 5266 HasUndefInput = true; 5267 continue; 5268 } 5269 if (CommonValue && Incoming != CommonValue) 5270 return nullptr; // Not the same, bail out. 5271 CommonValue = Incoming; 5272 } 5273 5274 // If CommonValue is null then all of the incoming values were either undef or 5275 // equal to the phi node itself. 5276 if (!CommonValue) 5277 return UndefValue::get(PN->getType()); 5278 5279 if (HasUndefInput) { 5280 // If we have a PHI node like phi(X, undef, X), where X is defined by some 5281 // instruction, we cannot return X as the result of the PHI node unless it 5282 // dominates the PHI block. 5283 return valueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : nullptr; 5284 } 5285 5286 return CommonValue; 5287 } 5288 5289 static Value *simplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty, 5290 const SimplifyQuery &Q, unsigned MaxRecurse) { 5291 if (auto *C = dyn_cast<Constant>(Op)) 5292 return ConstantFoldCastOperand(CastOpc, C, Ty, Q.DL); 5293 5294 if (auto *CI = dyn_cast<CastInst>(Op)) { 5295 auto *Src = CI->getOperand(0); 5296 Type *SrcTy = Src->getType(); 5297 Type *MidTy = CI->getType(); 5298 Type *DstTy = Ty; 5299 if (Src->getType() == Ty) { 5300 auto FirstOp = static_cast<Instruction::CastOps>(CI->getOpcode()); 5301 auto SecondOp = static_cast<Instruction::CastOps>(CastOpc); 5302 Type *SrcIntPtrTy = 5303 SrcTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(SrcTy) : nullptr; 5304 Type *MidIntPtrTy = 5305 MidTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(MidTy) : nullptr; 5306 Type *DstIntPtrTy = 5307 DstTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(DstTy) : nullptr; 5308 if (CastInst::isEliminableCastPair(FirstOp, SecondOp, SrcTy, MidTy, DstTy, 5309 SrcIntPtrTy, MidIntPtrTy, 5310 DstIntPtrTy) == Instruction::BitCast) 5311 return Src; 5312 } 5313 } 5314 5315 // bitcast x -> x 5316 if (CastOpc == Instruction::BitCast) 5317 if (Op->getType() == Ty) 5318 return Op; 5319 5320 return nullptr; 5321 } 5322 5323 Value *llvm::simplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty, 5324 const SimplifyQuery &Q) { 5325 return ::simplifyCastInst(CastOpc, Op, Ty, Q, RecursionLimit); 5326 } 5327 5328 /// For the given destination element of a shuffle, peek through shuffles to 5329 /// match a root vector source operand that contains that element in the same 5330 /// vector lane (ie, the same mask index), so we can eliminate the shuffle(s). 5331 static Value *foldIdentityShuffles(int DestElt, Value *Op0, Value *Op1, 5332 int MaskVal, Value *RootVec, 5333 unsigned MaxRecurse) { 5334 if (!MaxRecurse--) 5335 return nullptr; 5336 5337 // Bail out if any mask value is undefined. That kind of shuffle may be 5338 // simplified further based on demanded bits or other folds. 5339 if (MaskVal == -1) 5340 return nullptr; 5341 5342 // The mask value chooses which source operand we need to look at next. 5343 int InVecNumElts = cast<FixedVectorType>(Op0->getType())->getNumElements(); 5344 int RootElt = MaskVal; 5345 Value *SourceOp = Op0; 5346 if (MaskVal >= InVecNumElts) { 5347 RootElt = MaskVal - InVecNumElts; 5348 SourceOp = Op1; 5349 } 5350 5351 // If the source operand is a shuffle itself, look through it to find the 5352 // matching root vector. 5353 if (auto *SourceShuf = dyn_cast<ShuffleVectorInst>(SourceOp)) { 5354 return foldIdentityShuffles( 5355 DestElt, SourceShuf->getOperand(0), SourceShuf->getOperand(1), 5356 SourceShuf->getMaskValue(RootElt), RootVec, MaxRecurse); 5357 } 5358 5359 // TODO: Look through bitcasts? What if the bitcast changes the vector element 5360 // size? 5361 5362 // The source operand is not a shuffle. Initialize the root vector value for 5363 // this shuffle if that has not been done yet. 5364 if (!RootVec) 5365 RootVec = SourceOp; 5366 5367 // Give up as soon as a source operand does not match the existing root value. 5368 if (RootVec != SourceOp) 5369 return nullptr; 5370 5371 // The element must be coming from the same lane in the source vector 5372 // (although it may have crossed lanes in intermediate shuffles). 5373 if (RootElt != DestElt) 5374 return nullptr; 5375 5376 return RootVec; 5377 } 5378 5379 static Value *simplifyShuffleVectorInst(Value *Op0, Value *Op1, 5380 ArrayRef<int> Mask, Type *RetTy, 5381 const SimplifyQuery &Q, 5382 unsigned MaxRecurse) { 5383 if (all_of(Mask, [](int Elem) { return Elem == PoisonMaskElem; })) 5384 return PoisonValue::get(RetTy); 5385 5386 auto *InVecTy = cast<VectorType>(Op0->getType()); 5387 unsigned MaskNumElts = Mask.size(); 5388 ElementCount InVecEltCount = InVecTy->getElementCount(); 5389 5390 bool Scalable = InVecEltCount.isScalable(); 5391 5392 SmallVector<int, 32> Indices; 5393 Indices.assign(Mask.begin(), Mask.end()); 5394 5395 // Canonicalization: If mask does not select elements from an input vector, 5396 // replace that input vector with poison. 5397 if (!Scalable) { 5398 bool MaskSelects0 = false, MaskSelects1 = false; 5399 unsigned InVecNumElts = InVecEltCount.getKnownMinValue(); 5400 for (unsigned i = 0; i != MaskNumElts; ++i) { 5401 if (Indices[i] == -1) 5402 continue; 5403 if ((unsigned)Indices[i] < InVecNumElts) 5404 MaskSelects0 = true; 5405 else 5406 MaskSelects1 = true; 5407 } 5408 if (!MaskSelects0) 5409 Op0 = PoisonValue::get(InVecTy); 5410 if (!MaskSelects1) 5411 Op1 = PoisonValue::get(InVecTy); 5412 } 5413 5414 auto *Op0Const = dyn_cast<Constant>(Op0); 5415 auto *Op1Const = dyn_cast<Constant>(Op1); 5416 5417 // If all operands are constant, constant fold the shuffle. This 5418 // transformation depends on the value of the mask which is not known at 5419 // compile time for scalable vectors 5420 if (Op0Const && Op1Const) 5421 return ConstantExpr::getShuffleVector(Op0Const, Op1Const, Mask); 5422 5423 // Canonicalization: if only one input vector is constant, it shall be the 5424 // second one. This transformation depends on the value of the mask which 5425 // is not known at compile time for scalable vectors 5426 if (!Scalable && Op0Const && !Op1Const) { 5427 std::swap(Op0, Op1); 5428 ShuffleVectorInst::commuteShuffleMask(Indices, 5429 InVecEltCount.getKnownMinValue()); 5430 } 5431 5432 // A splat of an inserted scalar constant becomes a vector constant: 5433 // shuf (inselt ?, C, IndexC), undef, <IndexC, IndexC...> --> <C, C...> 5434 // NOTE: We may have commuted above, so analyze the updated Indices, not the 5435 // original mask constant. 5436 // NOTE: This transformation depends on the value of the mask which is not 5437 // known at compile time for scalable vectors 5438 Constant *C; 5439 ConstantInt *IndexC; 5440 if (!Scalable && match(Op0, m_InsertElt(m_Value(), m_Constant(C), 5441 m_ConstantInt(IndexC)))) { 5442 // Match a splat shuffle mask of the insert index allowing undef elements. 5443 int InsertIndex = IndexC->getZExtValue(); 5444 if (all_of(Indices, [InsertIndex](int MaskElt) { 5445 return MaskElt == InsertIndex || MaskElt == -1; 5446 })) { 5447 assert(isa<UndefValue>(Op1) && "Expected undef operand 1 for splat"); 5448 5449 // Shuffle mask poisons become poison constant result elements. 5450 SmallVector<Constant *, 16> VecC(MaskNumElts, C); 5451 for (unsigned i = 0; i != MaskNumElts; ++i) 5452 if (Indices[i] == -1) 5453 VecC[i] = PoisonValue::get(C->getType()); 5454 return ConstantVector::get(VecC); 5455 } 5456 } 5457 5458 // A shuffle of a splat is always the splat itself. Legal if the shuffle's 5459 // value type is same as the input vectors' type. 5460 if (auto *OpShuf = dyn_cast<ShuffleVectorInst>(Op0)) 5461 if (Q.isUndefValue(Op1) && RetTy == InVecTy && 5462 all_equal(OpShuf->getShuffleMask())) 5463 return Op0; 5464 5465 // All remaining transformation depend on the value of the mask, which is 5466 // not known at compile time for scalable vectors. 5467 if (Scalable) 5468 return nullptr; 5469 5470 // Don't fold a shuffle with undef mask elements. This may get folded in a 5471 // better way using demanded bits or other analysis. 5472 // TODO: Should we allow this? 5473 if (is_contained(Indices, -1)) 5474 return nullptr; 5475 5476 // Check if every element of this shuffle can be mapped back to the 5477 // corresponding element of a single root vector. If so, we don't need this 5478 // shuffle. This handles simple identity shuffles as well as chains of 5479 // shuffles that may widen/narrow and/or move elements across lanes and back. 5480 Value *RootVec = nullptr; 5481 for (unsigned i = 0; i != MaskNumElts; ++i) { 5482 // Note that recursion is limited for each vector element, so if any element 5483 // exceeds the limit, this will fail to simplify. 5484 RootVec = 5485 foldIdentityShuffles(i, Op0, Op1, Indices[i], RootVec, MaxRecurse); 5486 5487 // We can't replace a widening/narrowing shuffle with one of its operands. 5488 if (!RootVec || RootVec->getType() != RetTy) 5489 return nullptr; 5490 } 5491 return RootVec; 5492 } 5493 5494 /// Given operands for a ShuffleVectorInst, fold the result or return null. 5495 Value *llvm::simplifyShuffleVectorInst(Value *Op0, Value *Op1, 5496 ArrayRef<int> Mask, Type *RetTy, 5497 const SimplifyQuery &Q) { 5498 return ::simplifyShuffleVectorInst(Op0, Op1, Mask, RetTy, Q, RecursionLimit); 5499 } 5500 5501 static Constant *foldConstant(Instruction::UnaryOps Opcode, Value *&Op, 5502 const SimplifyQuery &Q) { 5503 if (auto *C = dyn_cast<Constant>(Op)) 5504 return ConstantFoldUnaryOpOperand(Opcode, C, Q.DL); 5505 return nullptr; 5506 } 5507 5508 /// Given the operand for an FNeg, see if we can fold the result. If not, this 5509 /// returns null. 5510 static Value *simplifyFNegInst(Value *Op, FastMathFlags FMF, 5511 const SimplifyQuery &Q, unsigned MaxRecurse) { 5512 if (Constant *C = foldConstant(Instruction::FNeg, Op, Q)) 5513 return C; 5514 5515 Value *X; 5516 // fneg (fneg X) ==> X 5517 if (match(Op, m_FNeg(m_Value(X)))) 5518 return X; 5519 5520 return nullptr; 5521 } 5522 5523 Value *llvm::simplifyFNegInst(Value *Op, FastMathFlags FMF, 5524 const SimplifyQuery &Q) { 5525 return ::simplifyFNegInst(Op, FMF, Q, RecursionLimit); 5526 } 5527 5528 /// Try to propagate existing NaN values when possible. If not, replace the 5529 /// constant or elements in the constant with a canonical NaN. 5530 static Constant *propagateNaN(Constant *In) { 5531 Type *Ty = In->getType(); 5532 if (auto *VecTy = dyn_cast<FixedVectorType>(Ty)) { 5533 unsigned NumElts = VecTy->getNumElements(); 5534 SmallVector<Constant *, 32> NewC(NumElts); 5535 for (unsigned i = 0; i != NumElts; ++i) { 5536 Constant *EltC = In->getAggregateElement(i); 5537 // Poison elements propagate. NaN propagates except signaling is quieted. 5538 // Replace unknown or undef elements with canonical NaN. 5539 if (EltC && isa<PoisonValue>(EltC)) 5540 NewC[i] = EltC; 5541 else if (EltC && EltC->isNaN()) 5542 NewC[i] = ConstantFP::get( 5543 EltC->getType(), cast<ConstantFP>(EltC)->getValue().makeQuiet()); 5544 else 5545 NewC[i] = ConstantFP::getNaN(VecTy->getElementType()); 5546 } 5547 return ConstantVector::get(NewC); 5548 } 5549 5550 // If it is not a fixed vector, but not a simple NaN either, return a 5551 // canonical NaN. 5552 if (!In->isNaN()) 5553 return ConstantFP::getNaN(Ty); 5554 5555 // If we known this is a NaN, and it's scalable vector, we must have a splat 5556 // on our hands. Grab that before splatting a QNaN constant. 5557 if (isa<ScalableVectorType>(Ty)) { 5558 auto *Splat = In->getSplatValue(); 5559 assert(Splat && Splat->isNaN() && 5560 "Found a scalable-vector NaN but not a splat"); 5561 In = Splat; 5562 } 5563 5564 // Propagate an existing QNaN constant. If it is an SNaN, make it quiet, but 5565 // preserve the sign/payload. 5566 return ConstantFP::get(Ty, cast<ConstantFP>(In)->getValue().makeQuiet()); 5567 } 5568 5569 /// Perform folds that are common to any floating-point operation. This implies 5570 /// transforms based on poison/undef/NaN because the operation itself makes no 5571 /// difference to the result. 5572 static Constant *simplifyFPOp(ArrayRef<Value *> Ops, FastMathFlags FMF, 5573 const SimplifyQuery &Q, 5574 fp::ExceptionBehavior ExBehavior, 5575 RoundingMode Rounding) { 5576 // Poison is independent of anything else. It always propagates from an 5577 // operand to a math result. 5578 if (any_of(Ops, [](Value *V) { return match(V, m_Poison()); })) 5579 return PoisonValue::get(Ops[0]->getType()); 5580 5581 for (Value *V : Ops) { 5582 bool IsNan = match(V, m_NaN()); 5583 bool IsInf = match(V, m_Inf()); 5584 bool IsUndef = Q.isUndefValue(V); 5585 5586 // If this operation has 'nnan' or 'ninf' and at least 1 disallowed operand 5587 // (an undef operand can be chosen to be Nan/Inf), then the result of 5588 // this operation is poison. 5589 if (FMF.noNaNs() && (IsNan || IsUndef)) 5590 return PoisonValue::get(V->getType()); 5591 if (FMF.noInfs() && (IsInf || IsUndef)) 5592 return PoisonValue::get(V->getType()); 5593 5594 if (isDefaultFPEnvironment(ExBehavior, Rounding)) { 5595 // Undef does not propagate because undef means that all bits can take on 5596 // any value. If this is undef * NaN for example, then the result values 5597 // (at least the exponent bits) are limited. Assume the undef is a 5598 // canonical NaN and propagate that. 5599 if (IsUndef) 5600 return ConstantFP::getNaN(V->getType()); 5601 if (IsNan) 5602 return propagateNaN(cast<Constant>(V)); 5603 } else if (ExBehavior != fp::ebStrict) { 5604 if (IsNan) 5605 return propagateNaN(cast<Constant>(V)); 5606 } 5607 } 5608 return nullptr; 5609 } 5610 5611 /// Given operands for an FAdd, see if we can fold the result. If not, this 5612 /// returns null. 5613 static Value * 5614 simplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5615 const SimplifyQuery &Q, unsigned MaxRecurse, 5616 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5617 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5618 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5619 if (Constant *C = foldOrCommuteConstant(Instruction::FAdd, Op0, Op1, Q)) 5620 return C; 5621 5622 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5623 return C; 5624 5625 // fadd X, -0 ==> X 5626 // With strict/constrained FP, we have these possible edge cases that do 5627 // not simplify to Op0: 5628 // fadd SNaN, -0.0 --> QNaN 5629 // fadd +0.0, -0.0 --> -0.0 (but only with round toward negative) 5630 if (canIgnoreSNaN(ExBehavior, FMF) && 5631 (!canRoundingModeBe(Rounding, RoundingMode::TowardNegative) || 5632 FMF.noSignedZeros())) 5633 if (match(Op1, m_NegZeroFP())) 5634 return Op0; 5635 5636 // fadd X, 0 ==> X, when we know X is not -0 5637 if (canIgnoreSNaN(ExBehavior, FMF)) 5638 if (match(Op1, m_PosZeroFP()) && 5639 (FMF.noSignedZeros() || cannotBeNegativeZero(Op0, Q.DL, Q.TLI))) 5640 return Op0; 5641 5642 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 5643 return nullptr; 5644 5645 if (FMF.noNaNs()) { 5646 // With nnan: X + {+/-}Inf --> {+/-}Inf 5647 if (match(Op1, m_Inf())) 5648 return Op1; 5649 5650 // With nnan: -X + X --> 0.0 (and commuted variant) 5651 // We don't have to explicitly exclude infinities (ninf): INF + -INF == NaN. 5652 // Negative zeros are allowed because we always end up with positive zero: 5653 // X = -0.0: (-0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0 5654 // X = -0.0: ( 0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0 5655 // X = 0.0: (-0.0 - ( 0.0)) + ( 0.0) == (-0.0) + ( 0.0) == 0.0 5656 // X = 0.0: ( 0.0 - ( 0.0)) + ( 0.0) == ( 0.0) + ( 0.0) == 0.0 5657 if (match(Op0, m_FSub(m_AnyZeroFP(), m_Specific(Op1))) || 5658 match(Op1, m_FSub(m_AnyZeroFP(), m_Specific(Op0)))) 5659 return ConstantFP::getZero(Op0->getType()); 5660 5661 if (match(Op0, m_FNeg(m_Specific(Op1))) || 5662 match(Op1, m_FNeg(m_Specific(Op0)))) 5663 return ConstantFP::getZero(Op0->getType()); 5664 } 5665 5666 // (X - Y) + Y --> X 5667 // Y + (X - Y) --> X 5668 Value *X; 5669 if (FMF.noSignedZeros() && FMF.allowReassoc() && 5670 (match(Op0, m_FSub(m_Value(X), m_Specific(Op1))) || 5671 match(Op1, m_FSub(m_Value(X), m_Specific(Op0))))) 5672 return X; 5673 5674 return nullptr; 5675 } 5676 5677 /// Given operands for an FSub, see if we can fold the result. If not, this 5678 /// returns null. 5679 static Value * 5680 simplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5681 const SimplifyQuery &Q, unsigned MaxRecurse, 5682 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5683 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5684 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5685 if (Constant *C = foldOrCommuteConstant(Instruction::FSub, Op0, Op1, Q)) 5686 return C; 5687 5688 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5689 return C; 5690 5691 // fsub X, +0 ==> X 5692 if (canIgnoreSNaN(ExBehavior, FMF) && 5693 (!canRoundingModeBe(Rounding, RoundingMode::TowardNegative) || 5694 FMF.noSignedZeros())) 5695 if (match(Op1, m_PosZeroFP())) 5696 return Op0; 5697 5698 // fsub X, -0 ==> X, when we know X is not -0 5699 if (canIgnoreSNaN(ExBehavior, FMF)) 5700 if (match(Op1, m_NegZeroFP()) && 5701 (FMF.noSignedZeros() || cannotBeNegativeZero(Op0, Q.DL, Q.TLI))) 5702 return Op0; 5703 5704 // fsub -0.0, (fsub -0.0, X) ==> X 5705 // fsub -0.0, (fneg X) ==> X 5706 Value *X; 5707 if (canIgnoreSNaN(ExBehavior, FMF)) 5708 if (match(Op0, m_NegZeroFP()) && match(Op1, m_FNeg(m_Value(X)))) 5709 return X; 5710 5711 // fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored. 5712 // fsub 0.0, (fneg X) ==> X if signed zeros are ignored. 5713 if (canIgnoreSNaN(ExBehavior, FMF)) 5714 if (FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()) && 5715 (match(Op1, m_FSub(m_AnyZeroFP(), m_Value(X))) || 5716 match(Op1, m_FNeg(m_Value(X))))) 5717 return X; 5718 5719 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 5720 return nullptr; 5721 5722 if (FMF.noNaNs()) { 5723 // fsub nnan x, x ==> 0.0 5724 if (Op0 == Op1) 5725 return Constant::getNullValue(Op0->getType()); 5726 5727 // With nnan: {+/-}Inf - X --> {+/-}Inf 5728 if (match(Op0, m_Inf())) 5729 return Op0; 5730 5731 // With nnan: X - {+/-}Inf --> {-/+}Inf 5732 if (match(Op1, m_Inf())) 5733 return foldConstant(Instruction::FNeg, Op1, Q); 5734 } 5735 5736 // Y - (Y - X) --> X 5737 // (X + Y) - Y --> X 5738 if (FMF.noSignedZeros() && FMF.allowReassoc() && 5739 (match(Op1, m_FSub(m_Specific(Op0), m_Value(X))) || 5740 match(Op0, m_c_FAdd(m_Specific(Op1), m_Value(X))))) 5741 return X; 5742 5743 return nullptr; 5744 } 5745 5746 static Value *simplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF, 5747 const SimplifyQuery &Q, unsigned MaxRecurse, 5748 fp::ExceptionBehavior ExBehavior, 5749 RoundingMode Rounding) { 5750 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5751 return C; 5752 5753 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 5754 return nullptr; 5755 5756 // Canonicalize special constants as operand 1. 5757 if (match(Op0, m_FPOne()) || match(Op0, m_AnyZeroFP())) 5758 std::swap(Op0, Op1); 5759 5760 // X * 1.0 --> X 5761 if (match(Op1, m_FPOne())) 5762 return Op0; 5763 5764 if (match(Op1, m_AnyZeroFP())) { 5765 // X * 0.0 --> 0.0 (with nnan and nsz) 5766 if (FMF.noNaNs() && FMF.noSignedZeros()) 5767 return ConstantFP::getZero(Op0->getType()); 5768 5769 // +normal number * (-)0.0 --> (-)0.0 5770 if (isKnownNeverInfOrNaN(Op0, Q.DL, Q.TLI, 0, Q.AC, Q.CxtI, Q.DT) && 5771 // TODO: Check SignBit from computeKnownFPClass when it's more complete. 5772 SignBitMustBeZero(Op0, Q.DL, Q.TLI)) 5773 return Op1; 5774 } 5775 5776 // sqrt(X) * sqrt(X) --> X, if we can: 5777 // 1. Remove the intermediate rounding (reassociate). 5778 // 2. Ignore non-zero negative numbers because sqrt would produce NAN. 5779 // 3. Ignore -0.0 because sqrt(-0.0) == -0.0, but -0.0 * -0.0 == 0.0. 5780 Value *X; 5781 if (Op0 == Op1 && match(Op0, m_Sqrt(m_Value(X))) && FMF.allowReassoc() && 5782 FMF.noNaNs() && FMF.noSignedZeros()) 5783 return X; 5784 5785 return nullptr; 5786 } 5787 5788 /// Given the operands for an FMul, see if we can fold the result 5789 static Value * 5790 simplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5791 const SimplifyQuery &Q, unsigned MaxRecurse, 5792 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5793 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5794 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5795 if (Constant *C = foldOrCommuteConstant(Instruction::FMul, Op0, Op1, Q)) 5796 return C; 5797 5798 // Now apply simplifications that do not require rounding. 5799 return simplifyFMAFMul(Op0, Op1, FMF, Q, MaxRecurse, ExBehavior, Rounding); 5800 } 5801 5802 Value *llvm::simplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5803 const SimplifyQuery &Q, 5804 fp::ExceptionBehavior ExBehavior, 5805 RoundingMode Rounding) { 5806 return ::simplifyFAddInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5807 Rounding); 5808 } 5809 5810 Value *llvm::simplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5811 const SimplifyQuery &Q, 5812 fp::ExceptionBehavior ExBehavior, 5813 RoundingMode Rounding) { 5814 return ::simplifyFSubInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5815 Rounding); 5816 } 5817 5818 Value *llvm::simplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5819 const SimplifyQuery &Q, 5820 fp::ExceptionBehavior ExBehavior, 5821 RoundingMode Rounding) { 5822 return ::simplifyFMulInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5823 Rounding); 5824 } 5825 5826 Value *llvm::simplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF, 5827 const SimplifyQuery &Q, 5828 fp::ExceptionBehavior ExBehavior, 5829 RoundingMode Rounding) { 5830 return ::simplifyFMAFMul(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5831 Rounding); 5832 } 5833 5834 static Value * 5835 simplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5836 const SimplifyQuery &Q, unsigned, 5837 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5838 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5839 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5840 if (Constant *C = foldOrCommuteConstant(Instruction::FDiv, Op0, Op1, Q)) 5841 return C; 5842 5843 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5844 return C; 5845 5846 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 5847 return nullptr; 5848 5849 // X / 1.0 -> X 5850 if (match(Op1, m_FPOne())) 5851 return Op0; 5852 5853 // 0 / X -> 0 5854 // Requires that NaNs are off (X could be zero) and signed zeroes are 5855 // ignored (X could be positive or negative, so the output sign is unknown). 5856 if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZeroFP())) 5857 return ConstantFP::getZero(Op0->getType()); 5858 5859 if (FMF.noNaNs()) { 5860 // X / X -> 1.0 is legal when NaNs are ignored. 5861 // We can ignore infinities because INF/INF is NaN. 5862 if (Op0 == Op1) 5863 return ConstantFP::get(Op0->getType(), 1.0); 5864 5865 // (X * Y) / Y --> X if we can reassociate to the above form. 5866 Value *X; 5867 if (FMF.allowReassoc() && match(Op0, m_c_FMul(m_Value(X), m_Specific(Op1)))) 5868 return X; 5869 5870 // -X / X -> -1.0 and 5871 // X / -X -> -1.0 are legal when NaNs are ignored. 5872 // We can ignore signed zeros because +-0.0/+-0.0 is NaN and ignored. 5873 if (match(Op0, m_FNegNSZ(m_Specific(Op1))) || 5874 match(Op1, m_FNegNSZ(m_Specific(Op0)))) 5875 return ConstantFP::get(Op0->getType(), -1.0); 5876 5877 // nnan ninf X / [-]0.0 -> poison 5878 if (FMF.noInfs() && match(Op1, m_AnyZeroFP())) 5879 return PoisonValue::get(Op1->getType()); 5880 } 5881 5882 return nullptr; 5883 } 5884 5885 Value *llvm::simplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5886 const SimplifyQuery &Q, 5887 fp::ExceptionBehavior ExBehavior, 5888 RoundingMode Rounding) { 5889 return ::simplifyFDivInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5890 Rounding); 5891 } 5892 5893 static Value * 5894 simplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5895 const SimplifyQuery &Q, unsigned, 5896 fp::ExceptionBehavior ExBehavior = fp::ebIgnore, 5897 RoundingMode Rounding = RoundingMode::NearestTiesToEven) { 5898 if (isDefaultFPEnvironment(ExBehavior, Rounding)) 5899 if (Constant *C = foldOrCommuteConstant(Instruction::FRem, Op0, Op1, Q)) 5900 return C; 5901 5902 if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding)) 5903 return C; 5904 5905 if (!isDefaultFPEnvironment(ExBehavior, Rounding)) 5906 return nullptr; 5907 5908 // Unlike fdiv, the result of frem always matches the sign of the dividend. 5909 // The constant match may include undef elements in a vector, so return a full 5910 // zero constant as the result. 5911 if (FMF.noNaNs()) { 5912 // +0 % X -> 0 5913 if (match(Op0, m_PosZeroFP())) 5914 return ConstantFP::getZero(Op0->getType()); 5915 // -0 % X -> -0 5916 if (match(Op0, m_NegZeroFP())) 5917 return ConstantFP::getNegativeZero(Op0->getType()); 5918 } 5919 5920 return nullptr; 5921 } 5922 5923 Value *llvm::simplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF, 5924 const SimplifyQuery &Q, 5925 fp::ExceptionBehavior ExBehavior, 5926 RoundingMode Rounding) { 5927 return ::simplifyFRemInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior, 5928 Rounding); 5929 } 5930 5931 //=== Helper functions for higher up the class hierarchy. 5932 5933 /// Given the operand for a UnaryOperator, see if we can fold the result. 5934 /// If not, this returns null. 5935 static Value *simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q, 5936 unsigned MaxRecurse) { 5937 switch (Opcode) { 5938 case Instruction::FNeg: 5939 return simplifyFNegInst(Op, FastMathFlags(), Q, MaxRecurse); 5940 default: 5941 llvm_unreachable("Unexpected opcode"); 5942 } 5943 } 5944 5945 /// Given the operand for a UnaryOperator, see if we can fold the result. 5946 /// If not, this returns null. 5947 /// Try to use FastMathFlags when folding the result. 5948 static Value *simplifyFPUnOp(unsigned Opcode, Value *Op, 5949 const FastMathFlags &FMF, const SimplifyQuery &Q, 5950 unsigned MaxRecurse) { 5951 switch (Opcode) { 5952 case Instruction::FNeg: 5953 return simplifyFNegInst(Op, FMF, Q, MaxRecurse); 5954 default: 5955 return simplifyUnOp(Opcode, Op, Q, MaxRecurse); 5956 } 5957 } 5958 5959 Value *llvm::simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q) { 5960 return ::simplifyUnOp(Opcode, Op, Q, RecursionLimit); 5961 } 5962 5963 Value *llvm::simplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF, 5964 const SimplifyQuery &Q) { 5965 return ::simplifyFPUnOp(Opcode, Op, FMF, Q, RecursionLimit); 5966 } 5967 5968 /// Given operands for a BinaryOperator, see if we can fold the result. 5969 /// If not, this returns null. 5970 static Value *simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 5971 const SimplifyQuery &Q, unsigned MaxRecurse) { 5972 switch (Opcode) { 5973 case Instruction::Add: 5974 return simplifyAddInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q, 5975 MaxRecurse); 5976 case Instruction::Sub: 5977 return simplifySubInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q, 5978 MaxRecurse); 5979 case Instruction::Mul: 5980 return simplifyMulInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q, 5981 MaxRecurse); 5982 case Instruction::SDiv: 5983 return simplifySDivInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse); 5984 case Instruction::UDiv: 5985 return simplifyUDivInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse); 5986 case Instruction::SRem: 5987 return simplifySRemInst(LHS, RHS, Q, MaxRecurse); 5988 case Instruction::URem: 5989 return simplifyURemInst(LHS, RHS, Q, MaxRecurse); 5990 case Instruction::Shl: 5991 return simplifyShlInst(LHS, RHS, /* IsNSW */ false, /* IsNUW */ false, Q, 5992 MaxRecurse); 5993 case Instruction::LShr: 5994 return simplifyLShrInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse); 5995 case Instruction::AShr: 5996 return simplifyAShrInst(LHS, RHS, /* IsExact */ false, Q, MaxRecurse); 5997 case Instruction::And: 5998 return simplifyAndInst(LHS, RHS, Q, MaxRecurse); 5999 case Instruction::Or: 6000 return simplifyOrInst(LHS, RHS, Q, MaxRecurse); 6001 case Instruction::Xor: 6002 return simplifyXorInst(LHS, RHS, Q, MaxRecurse); 6003 case Instruction::FAdd: 6004 return simplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 6005 case Instruction::FSub: 6006 return simplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 6007 case Instruction::FMul: 6008 return simplifyFMulInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 6009 case Instruction::FDiv: 6010 return simplifyFDivInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 6011 case Instruction::FRem: 6012 return simplifyFRemInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); 6013 default: 6014 llvm_unreachable("Unexpected opcode"); 6015 } 6016 } 6017 6018 /// Given operands for a BinaryOperator, see if we can fold the result. 6019 /// If not, this returns null. 6020 /// Try to use FastMathFlags when folding the result. 6021 static Value *simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 6022 const FastMathFlags &FMF, const SimplifyQuery &Q, 6023 unsigned MaxRecurse) { 6024 switch (Opcode) { 6025 case Instruction::FAdd: 6026 return simplifyFAddInst(LHS, RHS, FMF, Q, MaxRecurse); 6027 case Instruction::FSub: 6028 return simplifyFSubInst(LHS, RHS, FMF, Q, MaxRecurse); 6029 case Instruction::FMul: 6030 return simplifyFMulInst(LHS, RHS, FMF, Q, MaxRecurse); 6031 case Instruction::FDiv: 6032 return simplifyFDivInst(LHS, RHS, FMF, Q, MaxRecurse); 6033 default: 6034 return simplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse); 6035 } 6036 } 6037 6038 Value *llvm::simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 6039 const SimplifyQuery &Q) { 6040 return ::simplifyBinOp(Opcode, LHS, RHS, Q, RecursionLimit); 6041 } 6042 6043 Value *llvm::simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 6044 FastMathFlags FMF, const SimplifyQuery &Q) { 6045 return ::simplifyBinOp(Opcode, LHS, RHS, FMF, Q, RecursionLimit); 6046 } 6047 6048 /// Given operands for a CmpInst, see if we can fold the result. 6049 static Value *simplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 6050 const SimplifyQuery &Q, unsigned MaxRecurse) { 6051 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate)) 6052 return simplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse); 6053 return simplifyFCmpInst(Predicate, LHS, RHS, FastMathFlags(), Q, MaxRecurse); 6054 } 6055 6056 Value *llvm::simplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 6057 const SimplifyQuery &Q) { 6058 return ::simplifyCmpInst(Predicate, LHS, RHS, Q, RecursionLimit); 6059 } 6060 6061 static bool isIdempotent(Intrinsic::ID ID) { 6062 switch (ID) { 6063 default: 6064 return false; 6065 6066 // Unary idempotent: f(f(x)) = f(x) 6067 case Intrinsic::fabs: 6068 case Intrinsic::floor: 6069 case Intrinsic::ceil: 6070 case Intrinsic::trunc: 6071 case Intrinsic::rint: 6072 case Intrinsic::nearbyint: 6073 case Intrinsic::round: 6074 case Intrinsic::roundeven: 6075 case Intrinsic::canonicalize: 6076 case Intrinsic::arithmetic_fence: 6077 return true; 6078 } 6079 } 6080 6081 /// Return true if the intrinsic rounds a floating-point value to an integral 6082 /// floating-point value (not an integer type). 6083 static bool removesFPFraction(Intrinsic::ID ID) { 6084 switch (ID) { 6085 default: 6086 return false; 6087 6088 case Intrinsic::floor: 6089 case Intrinsic::ceil: 6090 case Intrinsic::trunc: 6091 case Intrinsic::rint: 6092 case Intrinsic::nearbyint: 6093 case Intrinsic::round: 6094 case Intrinsic::roundeven: 6095 return true; 6096 } 6097 } 6098 6099 static Value *simplifyRelativeLoad(Constant *Ptr, Constant *Offset, 6100 const DataLayout &DL) { 6101 GlobalValue *PtrSym; 6102 APInt PtrOffset; 6103 if (!IsConstantOffsetFromGlobal(Ptr, PtrSym, PtrOffset, DL)) 6104 return nullptr; 6105 6106 Type *Int32Ty = Type::getInt32Ty(Ptr->getContext()); 6107 6108 auto *OffsetConstInt = dyn_cast<ConstantInt>(Offset); 6109 if (!OffsetConstInt || OffsetConstInt->getBitWidth() > 64) 6110 return nullptr; 6111 6112 APInt OffsetInt = OffsetConstInt->getValue().sextOrTrunc( 6113 DL.getIndexTypeSizeInBits(Ptr->getType())); 6114 if (OffsetInt.srem(4) != 0) 6115 return nullptr; 6116 6117 Constant *Loaded = ConstantFoldLoadFromConstPtr(Ptr, Int32Ty, OffsetInt, DL); 6118 if (!Loaded) 6119 return nullptr; 6120 6121 auto *LoadedCE = dyn_cast<ConstantExpr>(Loaded); 6122 if (!LoadedCE) 6123 return nullptr; 6124 6125 if (LoadedCE->getOpcode() == Instruction::Trunc) { 6126 LoadedCE = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0)); 6127 if (!LoadedCE) 6128 return nullptr; 6129 } 6130 6131 if (LoadedCE->getOpcode() != Instruction::Sub) 6132 return nullptr; 6133 6134 auto *LoadedLHS = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0)); 6135 if (!LoadedLHS || LoadedLHS->getOpcode() != Instruction::PtrToInt) 6136 return nullptr; 6137 auto *LoadedLHSPtr = LoadedLHS->getOperand(0); 6138 6139 Constant *LoadedRHS = LoadedCE->getOperand(1); 6140 GlobalValue *LoadedRHSSym; 6141 APInt LoadedRHSOffset; 6142 if (!IsConstantOffsetFromGlobal(LoadedRHS, LoadedRHSSym, LoadedRHSOffset, 6143 DL) || 6144 PtrSym != LoadedRHSSym || PtrOffset != LoadedRHSOffset) 6145 return nullptr; 6146 6147 return LoadedLHSPtr; 6148 } 6149 6150 // TODO: Need to pass in FastMathFlags 6151 static Value *simplifyLdexp(Value *Op0, Value *Op1, const SimplifyQuery &Q, 6152 bool IsStrict) { 6153 // ldexp(poison, x) -> poison 6154 // ldexp(x, poison) -> poison 6155 if (isa<PoisonValue>(Op0) || isa<PoisonValue>(Op1)) 6156 return Op0; 6157 6158 // ldexp(undef, x) -> nan 6159 if (Q.isUndefValue(Op0)) 6160 return ConstantFP::getNaN(Op0->getType()); 6161 6162 if (!IsStrict) { 6163 // TODO: Could insert a canonicalize for strict 6164 6165 // ldexp(x, undef) -> x 6166 if (Q.isUndefValue(Op1)) 6167 return Op0; 6168 } 6169 6170 const APFloat *C = nullptr; 6171 match(Op0, PatternMatch::m_APFloat(C)); 6172 6173 // These cases should be safe, even with strictfp. 6174 // ldexp(0.0, x) -> 0.0 6175 // ldexp(-0.0, x) -> -0.0 6176 // ldexp(inf, x) -> inf 6177 // ldexp(-inf, x) -> -inf 6178 if (C && (C->isZero() || C->isInfinity())) 6179 return Op0; 6180 6181 // These are canonicalization dropping, could do it if we knew how we could 6182 // ignore denormal flushes and target handling of nan payload bits. 6183 if (IsStrict) 6184 return nullptr; 6185 6186 // TODO: Could quiet this with strictfp if the exception mode isn't strict. 6187 if (C && C->isNaN()) 6188 return ConstantFP::get(Op0->getType(), C->makeQuiet()); 6189 6190 // ldexp(x, 0) -> x 6191 6192 // TODO: Could fold this if we know the exception mode isn't 6193 // strict, we know the denormal mode and other target modes. 6194 if (match(Op1, PatternMatch::m_ZeroInt())) 6195 return Op0; 6196 6197 return nullptr; 6198 } 6199 6200 static Value *simplifyUnaryIntrinsic(Function *F, Value *Op0, 6201 const SimplifyQuery &Q, 6202 const CallBase *Call) { 6203 // Idempotent functions return the same result when called repeatedly. 6204 Intrinsic::ID IID = F->getIntrinsicID(); 6205 if (isIdempotent(IID)) 6206 if (auto *II = dyn_cast<IntrinsicInst>(Op0)) 6207 if (II->getIntrinsicID() == IID) 6208 return II; 6209 6210 if (removesFPFraction(IID)) { 6211 // Converting from int or calling a rounding function always results in a 6212 // finite integral number or infinity. For those inputs, rounding functions 6213 // always return the same value, so the (2nd) rounding is eliminated. Ex: 6214 // floor (sitofp x) -> sitofp x 6215 // round (ceil x) -> ceil x 6216 auto *II = dyn_cast<IntrinsicInst>(Op0); 6217 if ((II && removesFPFraction(II->getIntrinsicID())) || 6218 match(Op0, m_SIToFP(m_Value())) || match(Op0, m_UIToFP(m_Value()))) 6219 return Op0; 6220 } 6221 6222 Value *X; 6223 switch (IID) { 6224 case Intrinsic::fabs: 6225 if (SignBitMustBeZero(Op0, Q.DL, Q.TLI)) 6226 return Op0; 6227 break; 6228 case Intrinsic::bswap: 6229 // bswap(bswap(x)) -> x 6230 if (match(Op0, m_BSwap(m_Value(X)))) 6231 return X; 6232 break; 6233 case Intrinsic::bitreverse: 6234 // bitreverse(bitreverse(x)) -> x 6235 if (match(Op0, m_BitReverse(m_Value(X)))) 6236 return X; 6237 break; 6238 case Intrinsic::ctpop: { 6239 // ctpop(X) -> 1 iff X is non-zero power of 2. 6240 if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ false, 0, Q.AC, Q.CxtI, 6241 Q.DT)) 6242 return ConstantInt::get(Op0->getType(), 1); 6243 // If everything but the lowest bit is zero, that bit is the pop-count. Ex: 6244 // ctpop(and X, 1) --> and X, 1 6245 unsigned BitWidth = Op0->getType()->getScalarSizeInBits(); 6246 if (MaskedValueIsZero(Op0, APInt::getHighBitsSet(BitWidth, BitWidth - 1), 6247 Q)) 6248 return Op0; 6249 break; 6250 } 6251 case Intrinsic::exp: 6252 // exp(log(x)) -> x 6253 if (Call->hasAllowReassoc() && 6254 match(Op0, m_Intrinsic<Intrinsic::log>(m_Value(X)))) 6255 return X; 6256 break; 6257 case Intrinsic::exp2: 6258 // exp2(log2(x)) -> x 6259 if (Call->hasAllowReassoc() && 6260 match(Op0, m_Intrinsic<Intrinsic::log2>(m_Value(X)))) 6261 return X; 6262 break; 6263 case Intrinsic::exp10: 6264 // exp10(log10(x)) -> x 6265 if (Call->hasAllowReassoc() && 6266 match(Op0, m_Intrinsic<Intrinsic::log10>(m_Value(X)))) 6267 return X; 6268 break; 6269 case Intrinsic::log: 6270 // log(exp(x)) -> x 6271 if (Call->hasAllowReassoc() && 6272 match(Op0, m_Intrinsic<Intrinsic::exp>(m_Value(X)))) 6273 return X; 6274 break; 6275 case Intrinsic::log2: 6276 // log2(exp2(x)) -> x 6277 if (Call->hasAllowReassoc() && 6278 (match(Op0, m_Intrinsic<Intrinsic::exp2>(m_Value(X))) || 6279 match(Op0, 6280 m_Intrinsic<Intrinsic::pow>(m_SpecificFP(2.0), m_Value(X))))) 6281 return X; 6282 break; 6283 case Intrinsic::log10: 6284 // log10(pow(10.0, x)) -> x 6285 // log10(exp10(x)) -> x 6286 if (Call->hasAllowReassoc() && 6287 (match(Op0, m_Intrinsic<Intrinsic::exp10>(m_Value(X))) || 6288 match(Op0, 6289 m_Intrinsic<Intrinsic::pow>(m_SpecificFP(10.0), m_Value(X))))) 6290 return X; 6291 break; 6292 case Intrinsic::experimental_vector_reverse: 6293 // experimental.vector.reverse(experimental.vector.reverse(x)) -> x 6294 if (match(Op0, m_VecReverse(m_Value(X)))) 6295 return X; 6296 // experimental.vector.reverse(splat(X)) -> splat(X) 6297 if (isSplatValue(Op0)) 6298 return Op0; 6299 break; 6300 case Intrinsic::frexp: { 6301 // Frexp is idempotent with the added complication of the struct return. 6302 if (match(Op0, m_ExtractValue<0>(m_Value(X)))) { 6303 if (match(X, m_Intrinsic<Intrinsic::frexp>(m_Value()))) 6304 return X; 6305 } 6306 6307 break; 6308 } 6309 default: 6310 break; 6311 } 6312 6313 return nullptr; 6314 } 6315 6316 /// Given a min/max intrinsic, see if it can be removed based on having an 6317 /// operand that is another min/max intrinsic with shared operand(s). The caller 6318 /// is expected to swap the operand arguments to handle commutation. 6319 static Value *foldMinMaxSharedOp(Intrinsic::ID IID, Value *Op0, Value *Op1) { 6320 Value *X, *Y; 6321 if (!match(Op0, m_MaxOrMin(m_Value(X), m_Value(Y)))) 6322 return nullptr; 6323 6324 auto *MM0 = dyn_cast<IntrinsicInst>(Op0); 6325 if (!MM0) 6326 return nullptr; 6327 Intrinsic::ID IID0 = MM0->getIntrinsicID(); 6328 6329 if (Op1 == X || Op1 == Y || 6330 match(Op1, m_c_MaxOrMin(m_Specific(X), m_Specific(Y)))) { 6331 // max (max X, Y), X --> max X, Y 6332 if (IID0 == IID) 6333 return MM0; 6334 // max (min X, Y), X --> X 6335 if (IID0 == getInverseMinMaxIntrinsic(IID)) 6336 return Op1; 6337 } 6338 return nullptr; 6339 } 6340 6341 /// Given a min/max intrinsic, see if it can be removed based on having an 6342 /// operand that is another min/max intrinsic with shared operand(s). The caller 6343 /// is expected to swap the operand arguments to handle commutation. 6344 static Value *foldMinimumMaximumSharedOp(Intrinsic::ID IID, Value *Op0, 6345 Value *Op1) { 6346 assert((IID == Intrinsic::maxnum || IID == Intrinsic::minnum || 6347 IID == Intrinsic::maximum || IID == Intrinsic::minimum) && 6348 "Unsupported intrinsic"); 6349 6350 auto *M0 = dyn_cast<IntrinsicInst>(Op0); 6351 // If Op0 is not the same intrinsic as IID, do not process. 6352 // This is a difference with integer min/max handling. We do not process the 6353 // case like max(min(X,Y),min(X,Y)) => min(X,Y). But it can be handled by GVN. 6354 if (!M0 || M0->getIntrinsicID() != IID) 6355 return nullptr; 6356 Value *X0 = M0->getOperand(0); 6357 Value *Y0 = M0->getOperand(1); 6358 // Simple case, m(m(X,Y), X) => m(X, Y) 6359 // m(m(X,Y), Y) => m(X, Y) 6360 // For minimum/maximum, X is NaN => m(NaN, Y) == NaN and m(NaN, NaN) == NaN. 6361 // For minimum/maximum, Y is NaN => m(X, NaN) == NaN and m(NaN, NaN) == NaN. 6362 // For minnum/maxnum, X is NaN => m(NaN, Y) == Y and m(Y, Y) == Y. 6363 // For minnum/maxnum, Y is NaN => m(X, NaN) == X and m(X, NaN) == X. 6364 if (X0 == Op1 || Y0 == Op1) 6365 return M0; 6366 6367 auto *M1 = dyn_cast<IntrinsicInst>(Op1); 6368 if (!M1) 6369 return nullptr; 6370 Value *X1 = M1->getOperand(0); 6371 Value *Y1 = M1->getOperand(1); 6372 Intrinsic::ID IID1 = M1->getIntrinsicID(); 6373 // we have a case m(m(X,Y),m'(X,Y)) taking into account m' is commutative. 6374 // if m' is m or inversion of m => m(m(X,Y),m'(X,Y)) == m(X,Y). 6375 // For minimum/maximum, X is NaN => m(NaN,Y) == m'(NaN, Y) == NaN. 6376 // For minimum/maximum, Y is NaN => m(X,NaN) == m'(X, NaN) == NaN. 6377 // For minnum/maxnum, X is NaN => m(NaN,Y) == m'(NaN, Y) == Y. 6378 // For minnum/maxnum, Y is NaN => m(X,NaN) == m'(X, NaN) == X. 6379 if ((X0 == X1 && Y0 == Y1) || (X0 == Y1 && Y0 == X1)) 6380 if (IID1 == IID || getInverseMinMaxIntrinsic(IID1) == IID) 6381 return M0; 6382 6383 return nullptr; 6384 } 6385 6386 static Value *simplifyBinaryIntrinsic(Function *F, Value *Op0, Value *Op1, 6387 const SimplifyQuery &Q, 6388 const CallBase *Call) { 6389 Intrinsic::ID IID = F->getIntrinsicID(); 6390 Type *ReturnType = F->getReturnType(); 6391 unsigned BitWidth = ReturnType->getScalarSizeInBits(); 6392 switch (IID) { 6393 case Intrinsic::abs: 6394 // abs(abs(x)) -> abs(x). We don't need to worry about the nsw arg here. 6395 // It is always ok to pick the earlier abs. We'll just lose nsw if its only 6396 // on the outer abs. 6397 if (match(Op0, m_Intrinsic<Intrinsic::abs>(m_Value(), m_Value()))) 6398 return Op0; 6399 break; 6400 6401 case Intrinsic::cttz: { 6402 Value *X; 6403 if (match(Op0, m_Shl(m_One(), m_Value(X)))) 6404 return X; 6405 break; 6406 } 6407 case Intrinsic::ctlz: { 6408 Value *X; 6409 if (match(Op0, m_LShr(m_Negative(), m_Value(X)))) 6410 return X; 6411 if (match(Op0, m_AShr(m_Negative(), m_Value()))) 6412 return Constant::getNullValue(ReturnType); 6413 break; 6414 } 6415 case Intrinsic::ptrmask: { 6416 if (isa<PoisonValue>(Op0) || isa<PoisonValue>(Op1)) 6417 return PoisonValue::get(Op0->getType()); 6418 6419 // NOTE: We can't apply this simplifications based on the value of Op1 6420 // because we need to preserve provenance. 6421 if (Q.isUndefValue(Op0) || match(Op0, m_Zero())) 6422 return Constant::getNullValue(Op0->getType()); 6423 6424 assert(Op1->getType()->getScalarSizeInBits() == 6425 Q.DL.getIndexTypeSizeInBits(Op0->getType()) && 6426 "Invalid mask width"); 6427 // If index-width (mask size) is less than pointer-size then mask is 6428 // 1-extended. 6429 if (match(Op1, m_PtrToInt(m_Specific(Op0)))) 6430 return Op0; 6431 6432 // NOTE: We may have attributes associated with the return value of the 6433 // llvm.ptrmask intrinsic that will be lost when we just return the 6434 // operand. We should try to preserve them. 6435 if (match(Op1, m_AllOnes()) || Q.isUndefValue(Op1)) 6436 return Op0; 6437 6438 Constant *C; 6439 if (match(Op1, m_ImmConstant(C))) { 6440 KnownBits PtrKnown = computeKnownBits(Op0, /*Depth=*/0, Q); 6441 // See if we only masking off bits we know are already zero due to 6442 // alignment. 6443 APInt IrrelevantPtrBits = 6444 PtrKnown.Zero.zextOrTrunc(C->getType()->getScalarSizeInBits()); 6445 C = ConstantFoldBinaryOpOperands( 6446 Instruction::Or, C, ConstantInt::get(C->getType(), IrrelevantPtrBits), 6447 Q.DL); 6448 if (C != nullptr && C->isAllOnesValue()) 6449 return Op0; 6450 } 6451 break; 6452 } 6453 case Intrinsic::smax: 6454 case Intrinsic::smin: 6455 case Intrinsic::umax: 6456 case Intrinsic::umin: { 6457 // If the arguments are the same, this is a no-op. 6458 if (Op0 == Op1) 6459 return Op0; 6460 6461 // Canonicalize immediate constant operand as Op1. 6462 if (match(Op0, m_ImmConstant())) 6463 std::swap(Op0, Op1); 6464 6465 // Assume undef is the limit value. 6466 if (Q.isUndefValue(Op1)) 6467 return ConstantInt::get( 6468 ReturnType, MinMaxIntrinsic::getSaturationPoint(IID, BitWidth)); 6469 6470 const APInt *C; 6471 if (match(Op1, m_APIntAllowUndef(C))) { 6472 // Clamp to limit value. For example: 6473 // umax(i8 %x, i8 255) --> 255 6474 if (*C == MinMaxIntrinsic::getSaturationPoint(IID, BitWidth)) 6475 return ConstantInt::get(ReturnType, *C); 6476 6477 // If the constant op is the opposite of the limit value, the other must 6478 // be larger/smaller or equal. For example: 6479 // umin(i8 %x, i8 255) --> %x 6480 if (*C == MinMaxIntrinsic::getSaturationPoint( 6481 getInverseMinMaxIntrinsic(IID), BitWidth)) 6482 return Op0; 6483 6484 // Remove nested call if constant operands allow it. Example: 6485 // max (max X, 7), 5 -> max X, 7 6486 auto *MinMax0 = dyn_cast<IntrinsicInst>(Op0); 6487 if (MinMax0 && MinMax0->getIntrinsicID() == IID) { 6488 // TODO: loosen undef/splat restrictions for vector constants. 6489 Value *M00 = MinMax0->getOperand(0), *M01 = MinMax0->getOperand(1); 6490 const APInt *InnerC; 6491 if ((match(M00, m_APInt(InnerC)) || match(M01, m_APInt(InnerC))) && 6492 ICmpInst::compare(*InnerC, *C, 6493 ICmpInst::getNonStrictPredicate( 6494 MinMaxIntrinsic::getPredicate(IID)))) 6495 return Op0; 6496 } 6497 } 6498 6499 if (Value *V = foldMinMaxSharedOp(IID, Op0, Op1)) 6500 return V; 6501 if (Value *V = foldMinMaxSharedOp(IID, Op1, Op0)) 6502 return V; 6503 6504 ICmpInst::Predicate Pred = 6505 ICmpInst::getNonStrictPredicate(MinMaxIntrinsic::getPredicate(IID)); 6506 if (isICmpTrue(Pred, Op0, Op1, Q.getWithoutUndef(), RecursionLimit)) 6507 return Op0; 6508 if (isICmpTrue(Pred, Op1, Op0, Q.getWithoutUndef(), RecursionLimit)) 6509 return Op1; 6510 6511 break; 6512 } 6513 case Intrinsic::usub_with_overflow: 6514 case Intrinsic::ssub_with_overflow: 6515 // X - X -> { 0, false } 6516 // X - undef -> { 0, false } 6517 // undef - X -> { 0, false } 6518 if (Op0 == Op1 || Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 6519 return Constant::getNullValue(ReturnType); 6520 break; 6521 case Intrinsic::uadd_with_overflow: 6522 case Intrinsic::sadd_with_overflow: 6523 // X + undef -> { -1, false } 6524 // undef + x -> { -1, false } 6525 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) { 6526 return ConstantStruct::get( 6527 cast<StructType>(ReturnType), 6528 {Constant::getAllOnesValue(ReturnType->getStructElementType(0)), 6529 Constant::getNullValue(ReturnType->getStructElementType(1))}); 6530 } 6531 break; 6532 case Intrinsic::umul_with_overflow: 6533 case Intrinsic::smul_with_overflow: 6534 // 0 * X -> { 0, false } 6535 // X * 0 -> { 0, false } 6536 if (match(Op0, m_Zero()) || match(Op1, m_Zero())) 6537 return Constant::getNullValue(ReturnType); 6538 // undef * X -> { 0, false } 6539 // X * undef -> { 0, false } 6540 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 6541 return Constant::getNullValue(ReturnType); 6542 break; 6543 case Intrinsic::uadd_sat: 6544 // sat(MAX + X) -> MAX 6545 // sat(X + MAX) -> MAX 6546 if (match(Op0, m_AllOnes()) || match(Op1, m_AllOnes())) 6547 return Constant::getAllOnesValue(ReturnType); 6548 [[fallthrough]]; 6549 case Intrinsic::sadd_sat: 6550 // sat(X + undef) -> -1 6551 // sat(undef + X) -> -1 6552 // For unsigned: Assume undef is MAX, thus we saturate to MAX (-1). 6553 // For signed: Assume undef is ~X, in which case X + ~X = -1. 6554 if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 6555 return Constant::getAllOnesValue(ReturnType); 6556 6557 // X + 0 -> X 6558 if (match(Op1, m_Zero())) 6559 return Op0; 6560 // 0 + X -> X 6561 if (match(Op0, m_Zero())) 6562 return Op1; 6563 break; 6564 case Intrinsic::usub_sat: 6565 // sat(0 - X) -> 0, sat(X - MAX) -> 0 6566 if (match(Op0, m_Zero()) || match(Op1, m_AllOnes())) 6567 return Constant::getNullValue(ReturnType); 6568 [[fallthrough]]; 6569 case Intrinsic::ssub_sat: 6570 // X - X -> 0, X - undef -> 0, undef - X -> 0 6571 if (Op0 == Op1 || Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) 6572 return Constant::getNullValue(ReturnType); 6573 // X - 0 -> X 6574 if (match(Op1, m_Zero())) 6575 return Op0; 6576 break; 6577 case Intrinsic::load_relative: 6578 if (auto *C0 = dyn_cast<Constant>(Op0)) 6579 if (auto *C1 = dyn_cast<Constant>(Op1)) 6580 return simplifyRelativeLoad(C0, C1, Q.DL); 6581 break; 6582 case Intrinsic::powi: 6583 if (auto *Power = dyn_cast<ConstantInt>(Op1)) { 6584 // powi(x, 0) -> 1.0 6585 if (Power->isZero()) 6586 return ConstantFP::get(Op0->getType(), 1.0); 6587 // powi(x, 1) -> x 6588 if (Power->isOne()) 6589 return Op0; 6590 } 6591 break; 6592 case Intrinsic::ldexp: 6593 return simplifyLdexp(Op0, Op1, Q, false); 6594 case Intrinsic::copysign: 6595 // copysign X, X --> X 6596 if (Op0 == Op1) 6597 return Op0; 6598 // copysign -X, X --> X 6599 // copysign X, -X --> -X 6600 if (match(Op0, m_FNeg(m_Specific(Op1))) || 6601 match(Op1, m_FNeg(m_Specific(Op0)))) 6602 return Op1; 6603 break; 6604 case Intrinsic::is_fpclass: { 6605 if (isa<PoisonValue>(Op0)) 6606 return PoisonValue::get(ReturnType); 6607 6608 uint64_t Mask = cast<ConstantInt>(Op1)->getZExtValue(); 6609 // If all tests are made, it doesn't matter what the value is. 6610 if ((Mask & fcAllFlags) == fcAllFlags) 6611 return ConstantInt::get(ReturnType, true); 6612 if ((Mask & fcAllFlags) == 0) 6613 return ConstantInt::get(ReturnType, false); 6614 if (Q.isUndefValue(Op0)) 6615 return UndefValue::get(ReturnType); 6616 break; 6617 } 6618 case Intrinsic::maxnum: 6619 case Intrinsic::minnum: 6620 case Intrinsic::maximum: 6621 case Intrinsic::minimum: { 6622 // If the arguments are the same, this is a no-op. 6623 if (Op0 == Op1) 6624 return Op0; 6625 6626 // Canonicalize constant operand as Op1. 6627 if (isa<Constant>(Op0)) 6628 std::swap(Op0, Op1); 6629 6630 // If an argument is undef, return the other argument. 6631 if (Q.isUndefValue(Op1)) 6632 return Op0; 6633 6634 bool PropagateNaN = IID == Intrinsic::minimum || IID == Intrinsic::maximum; 6635 bool IsMin = IID == Intrinsic::minimum || IID == Intrinsic::minnum; 6636 6637 // minnum(X, nan) -> X 6638 // maxnum(X, nan) -> X 6639 // minimum(X, nan) -> nan 6640 // maximum(X, nan) -> nan 6641 if (match(Op1, m_NaN())) 6642 return PropagateNaN ? propagateNaN(cast<Constant>(Op1)) : Op0; 6643 6644 // In the following folds, inf can be replaced with the largest finite 6645 // float, if the ninf flag is set. 6646 const APFloat *C; 6647 if (match(Op1, m_APFloat(C)) && 6648 (C->isInfinity() || (Call->hasNoInfs() && C->isLargest()))) { 6649 // minnum(X, -inf) -> -inf 6650 // maxnum(X, +inf) -> +inf 6651 // minimum(X, -inf) -> -inf if nnan 6652 // maximum(X, +inf) -> +inf if nnan 6653 if (C->isNegative() == IsMin && (!PropagateNaN || Call->hasNoNaNs())) 6654 return ConstantFP::get(ReturnType, *C); 6655 6656 // minnum(X, +inf) -> X if nnan 6657 // maxnum(X, -inf) -> X if nnan 6658 // minimum(X, +inf) -> X 6659 // maximum(X, -inf) -> X 6660 if (C->isNegative() != IsMin && (PropagateNaN || Call->hasNoNaNs())) 6661 return Op0; 6662 } 6663 6664 // Min/max of the same operation with common operand: 6665 // m(m(X, Y)), X --> m(X, Y) (4 commuted variants) 6666 if (Value *V = foldMinimumMaximumSharedOp(IID, Op0, Op1)) 6667 return V; 6668 if (Value *V = foldMinimumMaximumSharedOp(IID, Op1, Op0)) 6669 return V; 6670 6671 break; 6672 } 6673 case Intrinsic::vector_extract: { 6674 Type *ReturnType = F->getReturnType(); 6675 6676 // (extract_vector (insert_vector _, X, 0), 0) -> X 6677 unsigned IdxN = cast<ConstantInt>(Op1)->getZExtValue(); 6678 Value *X = nullptr; 6679 if (match(Op0, m_Intrinsic<Intrinsic::vector_insert>(m_Value(), m_Value(X), 6680 m_Zero())) && 6681 IdxN == 0 && X->getType() == ReturnType) 6682 return X; 6683 6684 break; 6685 } 6686 default: 6687 break; 6688 } 6689 6690 return nullptr; 6691 } 6692 6693 static Value *simplifyIntrinsic(CallBase *Call, Value *Callee, 6694 ArrayRef<Value *> Args, 6695 const SimplifyQuery &Q) { 6696 // Operand bundles should not be in Args. 6697 assert(Call->arg_size() == Args.size()); 6698 unsigned NumOperands = Args.size(); 6699 Function *F = cast<Function>(Callee); 6700 Intrinsic::ID IID = F->getIntrinsicID(); 6701 6702 // Most of the intrinsics with no operands have some kind of side effect. 6703 // Don't simplify. 6704 if (!NumOperands) { 6705 switch (IID) { 6706 case Intrinsic::vscale: { 6707 Type *RetTy = F->getReturnType(); 6708 ConstantRange CR = getVScaleRange(Call->getFunction(), 64); 6709 if (const APInt *C = CR.getSingleElement()) 6710 return ConstantInt::get(RetTy, C->getZExtValue()); 6711 return nullptr; 6712 } 6713 default: 6714 return nullptr; 6715 } 6716 } 6717 6718 if (NumOperands == 1) 6719 return simplifyUnaryIntrinsic(F, Args[0], Q, Call); 6720 6721 if (NumOperands == 2) 6722 return simplifyBinaryIntrinsic(F, Args[0], Args[1], Q, Call); 6723 6724 // Handle intrinsics with 3 or more arguments. 6725 switch (IID) { 6726 case Intrinsic::masked_load: 6727 case Intrinsic::masked_gather: { 6728 Value *MaskArg = Args[2]; 6729 Value *PassthruArg = Args[3]; 6730 // If the mask is all zeros or undef, the "passthru" argument is the result. 6731 if (maskIsAllZeroOrUndef(MaskArg)) 6732 return PassthruArg; 6733 return nullptr; 6734 } 6735 case Intrinsic::fshl: 6736 case Intrinsic::fshr: { 6737 Value *Op0 = Args[0], *Op1 = Args[1], *ShAmtArg = Args[2]; 6738 6739 // If both operands are undef, the result is undef. 6740 if (Q.isUndefValue(Op0) && Q.isUndefValue(Op1)) 6741 return UndefValue::get(F->getReturnType()); 6742 6743 // If shift amount is undef, assume it is zero. 6744 if (Q.isUndefValue(ShAmtArg)) 6745 return Args[IID == Intrinsic::fshl ? 0 : 1]; 6746 6747 const APInt *ShAmtC; 6748 if (match(ShAmtArg, m_APInt(ShAmtC))) { 6749 // If there's effectively no shift, return the 1st arg or 2nd arg. 6750 APInt BitWidth = APInt(ShAmtC->getBitWidth(), ShAmtC->getBitWidth()); 6751 if (ShAmtC->urem(BitWidth).isZero()) 6752 return Args[IID == Intrinsic::fshl ? 0 : 1]; 6753 } 6754 6755 // Rotating zero by anything is zero. 6756 if (match(Op0, m_Zero()) && match(Op1, m_Zero())) 6757 return ConstantInt::getNullValue(F->getReturnType()); 6758 6759 // Rotating -1 by anything is -1. 6760 if (match(Op0, m_AllOnes()) && match(Op1, m_AllOnes())) 6761 return ConstantInt::getAllOnesValue(F->getReturnType()); 6762 6763 return nullptr; 6764 } 6765 case Intrinsic::experimental_constrained_fma: { 6766 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6767 if (Value *V = simplifyFPOp(Args, {}, Q, *FPI->getExceptionBehavior(), 6768 *FPI->getRoundingMode())) 6769 return V; 6770 return nullptr; 6771 } 6772 case Intrinsic::fma: 6773 case Intrinsic::fmuladd: { 6774 if (Value *V = simplifyFPOp(Args, {}, Q, fp::ebIgnore, 6775 RoundingMode::NearestTiesToEven)) 6776 return V; 6777 return nullptr; 6778 } 6779 case Intrinsic::smul_fix: 6780 case Intrinsic::smul_fix_sat: { 6781 Value *Op0 = Args[0]; 6782 Value *Op1 = Args[1]; 6783 Value *Op2 = Args[2]; 6784 Type *ReturnType = F->getReturnType(); 6785 6786 // Canonicalize constant operand as Op1 (ConstantFolding handles the case 6787 // when both Op0 and Op1 are constant so we do not care about that special 6788 // case here). 6789 if (isa<Constant>(Op0)) 6790 std::swap(Op0, Op1); 6791 6792 // X * 0 -> 0 6793 if (match(Op1, m_Zero())) 6794 return Constant::getNullValue(ReturnType); 6795 6796 // X * undef -> 0 6797 if (Q.isUndefValue(Op1)) 6798 return Constant::getNullValue(ReturnType); 6799 6800 // X * (1 << Scale) -> X 6801 APInt ScaledOne = 6802 APInt::getOneBitSet(ReturnType->getScalarSizeInBits(), 6803 cast<ConstantInt>(Op2)->getZExtValue()); 6804 if (ScaledOne.isNonNegative() && match(Op1, m_SpecificInt(ScaledOne))) 6805 return Op0; 6806 6807 return nullptr; 6808 } 6809 case Intrinsic::vector_insert: { 6810 Value *Vec = Args[0]; 6811 Value *SubVec = Args[1]; 6812 Value *Idx = Args[2]; 6813 Type *ReturnType = F->getReturnType(); 6814 6815 // (insert_vector Y, (extract_vector X, 0), 0) -> X 6816 // where: Y is X, or Y is undef 6817 unsigned IdxN = cast<ConstantInt>(Idx)->getZExtValue(); 6818 Value *X = nullptr; 6819 if (match(SubVec, 6820 m_Intrinsic<Intrinsic::vector_extract>(m_Value(X), m_Zero())) && 6821 (Q.isUndefValue(Vec) || Vec == X) && IdxN == 0 && 6822 X->getType() == ReturnType) 6823 return X; 6824 6825 return nullptr; 6826 } 6827 case Intrinsic::experimental_constrained_fadd: { 6828 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6829 return simplifyFAddInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6830 *FPI->getExceptionBehavior(), 6831 *FPI->getRoundingMode()); 6832 } 6833 case Intrinsic::experimental_constrained_fsub: { 6834 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6835 return simplifyFSubInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6836 *FPI->getExceptionBehavior(), 6837 *FPI->getRoundingMode()); 6838 } 6839 case Intrinsic::experimental_constrained_fmul: { 6840 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6841 return simplifyFMulInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6842 *FPI->getExceptionBehavior(), 6843 *FPI->getRoundingMode()); 6844 } 6845 case Intrinsic::experimental_constrained_fdiv: { 6846 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6847 return simplifyFDivInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6848 *FPI->getExceptionBehavior(), 6849 *FPI->getRoundingMode()); 6850 } 6851 case Intrinsic::experimental_constrained_frem: { 6852 auto *FPI = cast<ConstrainedFPIntrinsic>(Call); 6853 return simplifyFRemInst(Args[0], Args[1], FPI->getFastMathFlags(), Q, 6854 *FPI->getExceptionBehavior(), 6855 *FPI->getRoundingMode()); 6856 } 6857 case Intrinsic::experimental_constrained_ldexp: 6858 return simplifyLdexp(Args[0], Args[1], Q, true); 6859 default: 6860 return nullptr; 6861 } 6862 } 6863 6864 static Value *tryConstantFoldCall(CallBase *Call, Value *Callee, 6865 ArrayRef<Value *> Args, 6866 const SimplifyQuery &Q) { 6867 auto *F = dyn_cast<Function>(Callee); 6868 if (!F || !canConstantFoldCallTo(Call, F)) 6869 return nullptr; 6870 6871 SmallVector<Constant *, 4> ConstantArgs; 6872 ConstantArgs.reserve(Args.size()); 6873 for (Value *Arg : Args) { 6874 Constant *C = dyn_cast<Constant>(Arg); 6875 if (!C) { 6876 if (isa<MetadataAsValue>(Arg)) 6877 continue; 6878 return nullptr; 6879 } 6880 ConstantArgs.push_back(C); 6881 } 6882 6883 return ConstantFoldCall(Call, F, ConstantArgs, Q.TLI); 6884 } 6885 6886 Value *llvm::simplifyCall(CallBase *Call, Value *Callee, ArrayRef<Value *> Args, 6887 const SimplifyQuery &Q) { 6888 // Args should not contain operand bundle operands. 6889 assert(Call->arg_size() == Args.size()); 6890 6891 // musttail calls can only be simplified if they are also DCEd. 6892 // As we can't guarantee this here, don't simplify them. 6893 if (Call->isMustTailCall()) 6894 return nullptr; 6895 6896 // call undef -> poison 6897 // call null -> poison 6898 if (isa<UndefValue>(Callee) || isa<ConstantPointerNull>(Callee)) 6899 return PoisonValue::get(Call->getType()); 6900 6901 if (Value *V = tryConstantFoldCall(Call, Callee, Args, Q)) 6902 return V; 6903 6904 auto *F = dyn_cast<Function>(Callee); 6905 if (F && F->isIntrinsic()) 6906 if (Value *Ret = simplifyIntrinsic(Call, Callee, Args, Q)) 6907 return Ret; 6908 6909 return nullptr; 6910 } 6911 6912 Value *llvm::simplifyConstrainedFPCall(CallBase *Call, const SimplifyQuery &Q) { 6913 assert(isa<ConstrainedFPIntrinsic>(Call)); 6914 SmallVector<Value *, 4> Args(Call->args()); 6915 if (Value *V = tryConstantFoldCall(Call, Call->getCalledOperand(), Args, Q)) 6916 return V; 6917 if (Value *Ret = simplifyIntrinsic(Call, Call->getCalledOperand(), Args, Q)) 6918 return Ret; 6919 return nullptr; 6920 } 6921 6922 /// Given operands for a Freeze, see if we can fold the result. 6923 static Value *simplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) { 6924 // Use a utility function defined in ValueTracking. 6925 if (llvm::isGuaranteedNotToBeUndefOrPoison(Op0, Q.AC, Q.CxtI, Q.DT)) 6926 return Op0; 6927 // We have room for improvement. 6928 return nullptr; 6929 } 6930 6931 Value *llvm::simplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) { 6932 return ::simplifyFreezeInst(Op0, Q); 6933 } 6934 6935 Value *llvm::simplifyLoadInst(LoadInst *LI, Value *PtrOp, 6936 const SimplifyQuery &Q) { 6937 if (LI->isVolatile()) 6938 return nullptr; 6939 6940 if (auto *PtrOpC = dyn_cast<Constant>(PtrOp)) 6941 return ConstantFoldLoadFromConstPtr(PtrOpC, LI->getType(), Q.DL); 6942 6943 // We can only fold the load if it is from a constant global with definitive 6944 // initializer. Skip expensive logic if this is not the case. 6945 auto *GV = dyn_cast<GlobalVariable>(getUnderlyingObject(PtrOp)); 6946 if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer()) 6947 return nullptr; 6948 6949 // If GlobalVariable's initializer is uniform, then return the constant 6950 // regardless of its offset. 6951 if (Constant *C = 6952 ConstantFoldLoadFromUniformValue(GV->getInitializer(), LI->getType())) 6953 return C; 6954 6955 // Try to convert operand into a constant by stripping offsets while looking 6956 // through invariant.group intrinsics. 6957 APInt Offset(Q.DL.getIndexTypeSizeInBits(PtrOp->getType()), 0); 6958 PtrOp = PtrOp->stripAndAccumulateConstantOffsets( 6959 Q.DL, Offset, /* AllowNonInbounts */ true, 6960 /* AllowInvariantGroup */ true); 6961 if (PtrOp == GV) { 6962 // Index size may have changed due to address space casts. 6963 Offset = Offset.sextOrTrunc(Q.DL.getIndexTypeSizeInBits(PtrOp->getType())); 6964 return ConstantFoldLoadFromConstPtr(GV, LI->getType(), Offset, Q.DL); 6965 } 6966 6967 return nullptr; 6968 } 6969 6970 /// See if we can compute a simplified version of this instruction. 6971 /// If not, this returns null. 6972 6973 static Value *simplifyInstructionWithOperands(Instruction *I, 6974 ArrayRef<Value *> NewOps, 6975 const SimplifyQuery &SQ, 6976 unsigned MaxRecurse) { 6977 assert(I->getFunction() && "instruction should be inserted in a function"); 6978 assert((!SQ.CxtI || SQ.CxtI->getFunction() == I->getFunction()) && 6979 "context instruction should be in the same function"); 6980 6981 const SimplifyQuery Q = SQ.CxtI ? SQ : SQ.getWithInstruction(I); 6982 6983 switch (I->getOpcode()) { 6984 default: 6985 if (llvm::all_of(NewOps, [](Value *V) { return isa<Constant>(V); })) { 6986 SmallVector<Constant *, 8> NewConstOps(NewOps.size()); 6987 transform(NewOps, NewConstOps.begin(), 6988 [](Value *V) { return cast<Constant>(V); }); 6989 return ConstantFoldInstOperands(I, NewConstOps, Q.DL, Q.TLI); 6990 } 6991 return nullptr; 6992 case Instruction::FNeg: 6993 return simplifyFNegInst(NewOps[0], I->getFastMathFlags(), Q, MaxRecurse); 6994 case Instruction::FAdd: 6995 return simplifyFAddInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 6996 MaxRecurse); 6997 case Instruction::Add: 6998 return simplifyAddInst( 6999 NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 7000 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse); 7001 case Instruction::FSub: 7002 return simplifyFSubInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 7003 MaxRecurse); 7004 case Instruction::Sub: 7005 return simplifySubInst( 7006 NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 7007 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse); 7008 case Instruction::FMul: 7009 return simplifyFMulInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 7010 MaxRecurse); 7011 case Instruction::Mul: 7012 return simplifyMulInst( 7013 NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 7014 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse); 7015 case Instruction::SDiv: 7016 return simplifySDivInst(NewOps[0], NewOps[1], 7017 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q, 7018 MaxRecurse); 7019 case Instruction::UDiv: 7020 return simplifyUDivInst(NewOps[0], NewOps[1], 7021 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q, 7022 MaxRecurse); 7023 case Instruction::FDiv: 7024 return simplifyFDivInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 7025 MaxRecurse); 7026 case Instruction::SRem: 7027 return simplifySRemInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7028 case Instruction::URem: 7029 return simplifyURemInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7030 case Instruction::FRem: 7031 return simplifyFRemInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q, 7032 MaxRecurse); 7033 case Instruction::Shl: 7034 return simplifyShlInst( 7035 NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), 7036 Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q, MaxRecurse); 7037 case Instruction::LShr: 7038 return simplifyLShrInst(NewOps[0], NewOps[1], 7039 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q, 7040 MaxRecurse); 7041 case Instruction::AShr: 7042 return simplifyAShrInst(NewOps[0], NewOps[1], 7043 Q.IIQ.isExact(cast<BinaryOperator>(I)), Q, 7044 MaxRecurse); 7045 case Instruction::And: 7046 return simplifyAndInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7047 case Instruction::Or: 7048 return simplifyOrInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7049 case Instruction::Xor: 7050 return simplifyXorInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7051 case Instruction::ICmp: 7052 return simplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), NewOps[0], 7053 NewOps[1], Q, MaxRecurse); 7054 case Instruction::FCmp: 7055 return simplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), NewOps[0], 7056 NewOps[1], I->getFastMathFlags(), Q, MaxRecurse); 7057 case Instruction::Select: 7058 return simplifySelectInst(NewOps[0], NewOps[1], NewOps[2], Q, MaxRecurse); 7059 break; 7060 case Instruction::GetElementPtr: { 7061 auto *GEPI = cast<GetElementPtrInst>(I); 7062 return simplifyGEPInst(GEPI->getSourceElementType(), NewOps[0], 7063 ArrayRef(NewOps).slice(1), GEPI->isInBounds(), Q, 7064 MaxRecurse); 7065 } 7066 case Instruction::InsertValue: { 7067 InsertValueInst *IV = cast<InsertValueInst>(I); 7068 return simplifyInsertValueInst(NewOps[0], NewOps[1], IV->getIndices(), Q, 7069 MaxRecurse); 7070 } 7071 case Instruction::InsertElement: 7072 return simplifyInsertElementInst(NewOps[0], NewOps[1], NewOps[2], Q); 7073 case Instruction::ExtractValue: { 7074 auto *EVI = cast<ExtractValueInst>(I); 7075 return simplifyExtractValueInst(NewOps[0], EVI->getIndices(), Q, 7076 MaxRecurse); 7077 } 7078 case Instruction::ExtractElement: 7079 return simplifyExtractElementInst(NewOps[0], NewOps[1], Q, MaxRecurse); 7080 case Instruction::ShuffleVector: { 7081 auto *SVI = cast<ShuffleVectorInst>(I); 7082 return simplifyShuffleVectorInst(NewOps[0], NewOps[1], 7083 SVI->getShuffleMask(), SVI->getType(), Q, 7084 MaxRecurse); 7085 } 7086 case Instruction::PHI: 7087 return simplifyPHINode(cast<PHINode>(I), NewOps, Q); 7088 case Instruction::Call: 7089 return simplifyCall( 7090 cast<CallInst>(I), NewOps.back(), 7091 NewOps.drop_back(1 + cast<CallInst>(I)->getNumTotalBundleOperands()), Q); 7092 case Instruction::Freeze: 7093 return llvm::simplifyFreezeInst(NewOps[0], Q); 7094 #define HANDLE_CAST_INST(num, opc, clas) case Instruction::opc: 7095 #include "llvm/IR/Instruction.def" 7096 #undef HANDLE_CAST_INST 7097 return simplifyCastInst(I->getOpcode(), NewOps[0], I->getType(), Q, 7098 MaxRecurse); 7099 case Instruction::Alloca: 7100 // No simplifications for Alloca and it can't be constant folded. 7101 return nullptr; 7102 case Instruction::Load: 7103 return simplifyLoadInst(cast<LoadInst>(I), NewOps[0], Q); 7104 } 7105 } 7106 7107 Value *llvm::simplifyInstructionWithOperands(Instruction *I, 7108 ArrayRef<Value *> NewOps, 7109 const SimplifyQuery &SQ) { 7110 assert(NewOps.size() == I->getNumOperands() && 7111 "Number of operands should match the instruction!"); 7112 return ::simplifyInstructionWithOperands(I, NewOps, SQ, RecursionLimit); 7113 } 7114 7115 Value *llvm::simplifyInstruction(Instruction *I, const SimplifyQuery &SQ) { 7116 SmallVector<Value *, 8> Ops(I->operands()); 7117 Value *Result = ::simplifyInstructionWithOperands(I, Ops, SQ, RecursionLimit); 7118 7119 /// If called on unreachable code, the instruction may simplify to itself. 7120 /// Make life easier for users by detecting that case here, and returning a 7121 /// safe value instead. 7122 return Result == I ? UndefValue::get(I->getType()) : Result; 7123 } 7124 7125 /// Implementation of recursive simplification through an instruction's 7126 /// uses. 7127 /// 7128 /// This is the common implementation of the recursive simplification routines. 7129 /// If we have a pre-simplified value in 'SimpleV', that is forcibly used to 7130 /// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of 7131 /// instructions to process and attempt to simplify it using 7132 /// InstructionSimplify. Recursively visited users which could not be 7133 /// simplified themselves are to the optional UnsimplifiedUsers set for 7134 /// further processing by the caller. 7135 /// 7136 /// This routine returns 'true' only when *it* simplifies something. The passed 7137 /// in simplified value does not count toward this. 7138 static bool replaceAndRecursivelySimplifyImpl( 7139 Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI, 7140 const DominatorTree *DT, AssumptionCache *AC, 7141 SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr) { 7142 bool Simplified = false; 7143 SmallSetVector<Instruction *, 8> Worklist; 7144 const DataLayout &DL = I->getModule()->getDataLayout(); 7145 7146 // If we have an explicit value to collapse to, do that round of the 7147 // simplification loop by hand initially. 7148 if (SimpleV) { 7149 for (User *U : I->users()) 7150 if (U != I) 7151 Worklist.insert(cast<Instruction>(U)); 7152 7153 // Replace the instruction with its simplified value. 7154 I->replaceAllUsesWith(SimpleV); 7155 7156 if (!I->isEHPad() && !I->isTerminator() && !I->mayHaveSideEffects()) 7157 I->eraseFromParent(); 7158 } else { 7159 Worklist.insert(I); 7160 } 7161 7162 // Note that we must test the size on each iteration, the worklist can grow. 7163 for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) { 7164 I = Worklist[Idx]; 7165 7166 // See if this instruction simplifies. 7167 SimpleV = simplifyInstruction(I, {DL, TLI, DT, AC}); 7168 if (!SimpleV) { 7169 if (UnsimplifiedUsers) 7170 UnsimplifiedUsers->insert(I); 7171 continue; 7172 } 7173 7174 Simplified = true; 7175 7176 // Stash away all the uses of the old instruction so we can check them for 7177 // recursive simplifications after a RAUW. This is cheaper than checking all 7178 // uses of To on the recursive step in most cases. 7179 for (User *U : I->users()) 7180 Worklist.insert(cast<Instruction>(U)); 7181 7182 // Replace the instruction with its simplified value. 7183 I->replaceAllUsesWith(SimpleV); 7184 7185 if (!I->isEHPad() && !I->isTerminator() && !I->mayHaveSideEffects()) 7186 I->eraseFromParent(); 7187 } 7188 return Simplified; 7189 } 7190 7191 bool llvm::replaceAndRecursivelySimplify( 7192 Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI, 7193 const DominatorTree *DT, AssumptionCache *AC, 7194 SmallSetVector<Instruction *, 8> *UnsimplifiedUsers) { 7195 assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!"); 7196 assert(SimpleV && "Must provide a simplified value."); 7197 return replaceAndRecursivelySimplifyImpl(I, SimpleV, TLI, DT, AC, 7198 UnsimplifiedUsers); 7199 } 7200 7201 namespace llvm { 7202 const SimplifyQuery getBestSimplifyQuery(Pass &P, Function &F) { 7203 auto *DTWP = P.getAnalysisIfAvailable<DominatorTreeWrapperPass>(); 7204 auto *DT = DTWP ? &DTWP->getDomTree() : nullptr; 7205 auto *TLIWP = P.getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>(); 7206 auto *TLI = TLIWP ? &TLIWP->getTLI(F) : nullptr; 7207 auto *ACWP = P.getAnalysisIfAvailable<AssumptionCacheTracker>(); 7208 auto *AC = ACWP ? &ACWP->getAssumptionCache(F) : nullptr; 7209 return {F.getParent()->getDataLayout(), TLI, DT, AC}; 7210 } 7211 7212 const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &AR, 7213 const DataLayout &DL) { 7214 return {DL, &AR.TLI, &AR.DT, &AR.AC}; 7215 } 7216 7217 template <class T, class... TArgs> 7218 const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &AM, 7219 Function &F) { 7220 auto *DT = AM.template getCachedResult<DominatorTreeAnalysis>(F); 7221 auto *TLI = AM.template getCachedResult<TargetLibraryAnalysis>(F); 7222 auto *AC = AM.template getCachedResult<AssumptionAnalysis>(F); 7223 return {F.getParent()->getDataLayout(), TLI, DT, AC}; 7224 } 7225 template const SimplifyQuery getBestSimplifyQuery(AnalysisManager<Function> &, 7226 Function &); 7227 } // namespace llvm 7228 7229 void InstSimplifyFolder::anchor() {} 7230