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