1 //===- lib/CodeGen/GlobalISel/LegalizerInfo.cpp - Legalizer ---------------===// 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 // Implement an interface to specify and query how an illegal operation on a 10 // given type should be expanded. 11 // 12 // Issues to be resolved: 13 // + Make it fast. 14 // + Support weird types like i3, <7 x i3>, ... 15 // + Operations with more than one type (ICMP, CMPXCHG, intrinsics, ...) 16 // 17 //===----------------------------------------------------------------------===// 18 19 #include "llvm/CodeGen/GlobalISel/LegalizerInfo.h" 20 #include "llvm/ADT/SmallBitVector.h" 21 #include "llvm/CodeGen/GlobalISel/GISelChangeObserver.h" 22 #include "llvm/CodeGen/MachineInstr.h" 23 #include "llvm/CodeGen/MachineOperand.h" 24 #include "llvm/CodeGen/MachineRegisterInfo.h" 25 #include "llvm/CodeGen/TargetOpcodes.h" 26 #include "llvm/MC/MCInstrDesc.h" 27 #include "llvm/MC/MCInstrInfo.h" 28 #include "llvm/Support/Debug.h" 29 #include "llvm/Support/ErrorHandling.h" 30 #include "llvm/Support/LowLevelTypeImpl.h" 31 #include "llvm/Support/MathExtras.h" 32 #include <algorithm> 33 #include <map> 34 35 using namespace llvm; 36 using namespace LegalizeActions; 37 38 #define DEBUG_TYPE "legalizer-info" 39 40 cl::opt<bool> llvm::DisableGISelLegalityCheck( 41 "disable-gisel-legality-check", 42 cl::desc("Don't verify that MIR is fully legal between GlobalISel passes"), 43 cl::Hidden); 44 45 raw_ostream &llvm::operator<<(raw_ostream &OS, LegalizeAction Action) { 46 switch (Action) { 47 case Legal: 48 OS << "Legal"; 49 break; 50 case NarrowScalar: 51 OS << "NarrowScalar"; 52 break; 53 case WidenScalar: 54 OS << "WidenScalar"; 55 break; 56 case FewerElements: 57 OS << "FewerElements"; 58 break; 59 case MoreElements: 60 OS << "MoreElements"; 61 break; 62 case Bitcast: 63 OS << "Bitcast"; 64 break; 65 case Lower: 66 OS << "Lower"; 67 break; 68 case Libcall: 69 OS << "Libcall"; 70 break; 71 case Custom: 72 OS << "Custom"; 73 break; 74 case Unsupported: 75 OS << "Unsupported"; 76 break; 77 case NotFound: 78 OS << "NotFound"; 79 break; 80 case UseLegacyRules: 81 OS << "UseLegacyRules"; 82 break; 83 } 84 return OS; 85 } 86 87 raw_ostream &LegalityQuery::print(raw_ostream &OS) const { 88 OS << Opcode << ", Tys={"; 89 for (const auto &Type : Types) { 90 OS << Type << ", "; 91 } 92 OS << "}, Opcode="; 93 94 OS << Opcode << ", MMOs={"; 95 for (const auto &MMODescr : MMODescrs) { 96 OS << MMODescr.SizeInBits << ", "; 97 } 98 OS << "}"; 99 100 return OS; 101 } 102 103 #ifndef NDEBUG 104 // Make sure the rule won't (trivially) loop forever. 105 static bool hasNoSimpleLoops(const LegalizeRule &Rule, const LegalityQuery &Q, 106 const std::pair<unsigned, LLT> &Mutation) { 107 switch (Rule.getAction()) { 108 case Custom: 109 case Lower: 110 case MoreElements: 111 case FewerElements: 112 break; 113 default: 114 return Q.Types[Mutation.first] != Mutation.second; 115 } 116 return true; 117 } 118 119 // Make sure the returned mutation makes sense for the match type. 120 static bool mutationIsSane(const LegalizeRule &Rule, 121 const LegalityQuery &Q, 122 std::pair<unsigned, LLT> Mutation) { 123 // If the user wants a custom mutation, then we can't really say much about 124 // it. Return true, and trust that they're doing the right thing. 125 if (Rule.getAction() == Custom) 126 return true; 127 128 const unsigned TypeIdx = Mutation.first; 129 const LLT OldTy = Q.Types[TypeIdx]; 130 const LLT NewTy = Mutation.second; 131 132 switch (Rule.getAction()) { 133 case FewerElements: 134 if (!OldTy.isVector()) 135 return false; 136 LLVM_FALLTHROUGH; 137 case MoreElements: { 138 // MoreElements can go from scalar to vector. 139 const unsigned OldElts = OldTy.isVector() ? OldTy.getNumElements() : 1; 140 if (NewTy.isVector()) { 141 if (Rule.getAction() == FewerElements) { 142 // Make sure the element count really decreased. 143 if (NewTy.getNumElements() >= OldElts) 144 return false; 145 } else { 146 // Make sure the element count really increased. 147 if (NewTy.getNumElements() <= OldElts) 148 return false; 149 } 150 } 151 152 // Make sure the element type didn't change. 153 return NewTy.getScalarType() == OldTy.getScalarType(); 154 } 155 case NarrowScalar: 156 case WidenScalar: { 157 if (OldTy.isVector()) { 158 // Number of elements should not change. 159 if (!NewTy.isVector() || OldTy.getNumElements() != NewTy.getNumElements()) 160 return false; 161 } else { 162 // Both types must be vectors 163 if (NewTy.isVector()) 164 return false; 165 } 166 167 if (Rule.getAction() == NarrowScalar) { 168 // Make sure the size really decreased. 169 if (NewTy.getScalarSizeInBits() >= OldTy.getScalarSizeInBits()) 170 return false; 171 } else { 172 // Make sure the size really increased. 173 if (NewTy.getScalarSizeInBits() <= OldTy.getScalarSizeInBits()) 174 return false; 175 } 176 177 return true; 178 } 179 case Bitcast: { 180 return OldTy != NewTy && OldTy.getSizeInBits() == NewTy.getSizeInBits(); 181 } 182 default: 183 return true; 184 } 185 } 186 #endif 187 188 LegalizeActionStep LegalizeRuleSet::apply(const LegalityQuery &Query) const { 189 LLVM_DEBUG(dbgs() << "Applying legalizer ruleset to: "; Query.print(dbgs()); 190 dbgs() << "\n"); 191 if (Rules.empty()) { 192 LLVM_DEBUG(dbgs() << ".. fallback to legacy rules (no rules defined)\n"); 193 return {LegalizeAction::UseLegacyRules, 0, LLT{}}; 194 } 195 for (const LegalizeRule &Rule : Rules) { 196 if (Rule.match(Query)) { 197 LLVM_DEBUG(dbgs() << ".. match\n"); 198 std::pair<unsigned, LLT> Mutation = Rule.determineMutation(Query); 199 LLVM_DEBUG(dbgs() << ".. .. " << Rule.getAction() << ", " 200 << Mutation.first << ", " << Mutation.second << "\n"); 201 assert(mutationIsSane(Rule, Query, Mutation) && 202 "legality mutation invalid for match"); 203 assert(hasNoSimpleLoops(Rule, Query, Mutation) && "Simple loop detected"); 204 return {Rule.getAction(), Mutation.first, Mutation.second}; 205 } else 206 LLVM_DEBUG(dbgs() << ".. no match\n"); 207 } 208 LLVM_DEBUG(dbgs() << ".. unsupported\n"); 209 return {LegalizeAction::Unsupported, 0, LLT{}}; 210 } 211 212 bool LegalizeRuleSet::verifyTypeIdxsCoverage(unsigned NumTypeIdxs) const { 213 #ifndef NDEBUG 214 if (Rules.empty()) { 215 LLVM_DEBUG( 216 dbgs() << ".. type index coverage check SKIPPED: no rules defined\n"); 217 return true; 218 } 219 const int64_t FirstUncovered = TypeIdxsCovered.find_first_unset(); 220 if (FirstUncovered < 0) { 221 LLVM_DEBUG(dbgs() << ".. type index coverage check SKIPPED:" 222 " user-defined predicate detected\n"); 223 return true; 224 } 225 const bool AllCovered = (FirstUncovered >= NumTypeIdxs); 226 if (NumTypeIdxs > 0) 227 LLVM_DEBUG(dbgs() << ".. the first uncovered type index: " << FirstUncovered 228 << ", " << (AllCovered ? "OK" : "FAIL") << "\n"); 229 return AllCovered; 230 #else 231 return true; 232 #endif 233 } 234 235 bool LegalizeRuleSet::verifyImmIdxsCoverage(unsigned NumImmIdxs) const { 236 #ifndef NDEBUG 237 if (Rules.empty()) { 238 LLVM_DEBUG( 239 dbgs() << ".. imm index coverage check SKIPPED: no rules defined\n"); 240 return true; 241 } 242 const int64_t FirstUncovered = ImmIdxsCovered.find_first_unset(); 243 if (FirstUncovered < 0) { 244 LLVM_DEBUG(dbgs() << ".. imm index coverage check SKIPPED:" 245 " user-defined predicate detected\n"); 246 return true; 247 } 248 const bool AllCovered = (FirstUncovered >= NumImmIdxs); 249 LLVM_DEBUG(dbgs() << ".. the first uncovered imm index: " << FirstUncovered 250 << ", " << (AllCovered ? "OK" : "FAIL") << "\n"); 251 return AllCovered; 252 #else 253 return true; 254 #endif 255 } 256 257 LegalizerInfo::LegalizerInfo() : TablesInitialized(false) { 258 // Set defaults. 259 // FIXME: these two (G_ANYEXT and G_TRUNC?) can be legalized to the 260 // fundamental load/store Jakob proposed. Once loads & stores are supported. 261 setScalarAction(TargetOpcode::G_ANYEXT, 1, {{1, Legal}}); 262 setScalarAction(TargetOpcode::G_ZEXT, 1, {{1, Legal}}); 263 setScalarAction(TargetOpcode::G_SEXT, 1, {{1, Legal}}); 264 setScalarAction(TargetOpcode::G_TRUNC, 0, {{1, Legal}}); 265 setScalarAction(TargetOpcode::G_TRUNC, 1, {{1, Legal}}); 266 267 setScalarAction(TargetOpcode::G_INTRINSIC, 0, {{1, Legal}}); 268 setScalarAction(TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS, 0, {{1, Legal}}); 269 270 setLegalizeScalarToDifferentSizeStrategy( 271 TargetOpcode::G_IMPLICIT_DEF, 0, narrowToSmallerAndUnsupportedIfTooSmall); 272 setLegalizeScalarToDifferentSizeStrategy( 273 TargetOpcode::G_ADD, 0, widenToLargerTypesAndNarrowToLargest); 274 setLegalizeScalarToDifferentSizeStrategy( 275 TargetOpcode::G_OR, 0, widenToLargerTypesAndNarrowToLargest); 276 setLegalizeScalarToDifferentSizeStrategy( 277 TargetOpcode::G_LOAD, 0, narrowToSmallerAndUnsupportedIfTooSmall); 278 setLegalizeScalarToDifferentSizeStrategy( 279 TargetOpcode::G_STORE, 0, narrowToSmallerAndUnsupportedIfTooSmall); 280 281 setLegalizeScalarToDifferentSizeStrategy( 282 TargetOpcode::G_BRCOND, 0, widenToLargerTypesUnsupportedOtherwise); 283 setLegalizeScalarToDifferentSizeStrategy( 284 TargetOpcode::G_INSERT, 0, narrowToSmallerAndUnsupportedIfTooSmall); 285 setLegalizeScalarToDifferentSizeStrategy( 286 TargetOpcode::G_EXTRACT, 0, narrowToSmallerAndUnsupportedIfTooSmall); 287 setLegalizeScalarToDifferentSizeStrategy( 288 TargetOpcode::G_EXTRACT, 1, narrowToSmallerAndUnsupportedIfTooSmall); 289 setScalarAction(TargetOpcode::G_FNEG, 0, {{1, Lower}}); 290 } 291 292 void LegalizerInfo::computeTables() { 293 assert(TablesInitialized == false); 294 295 for (unsigned OpcodeIdx = 0; OpcodeIdx <= LastOp - FirstOp; ++OpcodeIdx) { 296 const unsigned Opcode = FirstOp + OpcodeIdx; 297 for (unsigned TypeIdx = 0; TypeIdx != SpecifiedActions[OpcodeIdx].size(); 298 ++TypeIdx) { 299 // 0. Collect information specified through the setAction API, i.e. 300 // for specific bit sizes. 301 // For scalar types: 302 SizeAndActionsVec ScalarSpecifiedActions; 303 // For pointer types: 304 std::map<uint16_t, SizeAndActionsVec> AddressSpace2SpecifiedActions; 305 // For vector types: 306 std::map<uint16_t, SizeAndActionsVec> ElemSize2SpecifiedActions; 307 for (auto LLT2Action : SpecifiedActions[OpcodeIdx][TypeIdx]) { 308 const LLT Type = LLT2Action.first; 309 const LegalizeAction Action = LLT2Action.second; 310 311 auto SizeAction = std::make_pair(Type.getSizeInBits(), Action); 312 if (Type.isPointer()) 313 AddressSpace2SpecifiedActions[Type.getAddressSpace()].push_back( 314 SizeAction); 315 else if (Type.isVector()) 316 ElemSize2SpecifiedActions[Type.getElementType().getSizeInBits()] 317 .push_back(SizeAction); 318 else 319 ScalarSpecifiedActions.push_back(SizeAction); 320 } 321 322 // 1. Handle scalar types 323 { 324 // Decide how to handle bit sizes for which no explicit specification 325 // was given. 326 SizeChangeStrategy S = &unsupportedForDifferentSizes; 327 if (TypeIdx < ScalarSizeChangeStrategies[OpcodeIdx].size() && 328 ScalarSizeChangeStrategies[OpcodeIdx][TypeIdx] != nullptr) 329 S = ScalarSizeChangeStrategies[OpcodeIdx][TypeIdx]; 330 llvm::sort(ScalarSpecifiedActions); 331 checkPartialSizeAndActionsVector(ScalarSpecifiedActions); 332 setScalarAction(Opcode, TypeIdx, S(ScalarSpecifiedActions)); 333 } 334 335 // 2. Handle pointer types 336 for (auto PointerSpecifiedActions : AddressSpace2SpecifiedActions) { 337 llvm::sort(PointerSpecifiedActions.second); 338 checkPartialSizeAndActionsVector(PointerSpecifiedActions.second); 339 // For pointer types, we assume that there isn't a meaningfull way 340 // to change the number of bits used in the pointer. 341 setPointerAction( 342 Opcode, TypeIdx, PointerSpecifiedActions.first, 343 unsupportedForDifferentSizes(PointerSpecifiedActions.second)); 344 } 345 346 // 3. Handle vector types 347 SizeAndActionsVec ElementSizesSeen; 348 for (auto VectorSpecifiedActions : ElemSize2SpecifiedActions) { 349 llvm::sort(VectorSpecifiedActions.second); 350 const uint16_t ElementSize = VectorSpecifiedActions.first; 351 ElementSizesSeen.push_back({ElementSize, Legal}); 352 checkPartialSizeAndActionsVector(VectorSpecifiedActions.second); 353 // For vector types, we assume that the best way to adapt the number 354 // of elements is to the next larger number of elements type for which 355 // the vector type is legal, unless there is no such type. In that case, 356 // legalize towards a vector type with a smaller number of elements. 357 SizeAndActionsVec NumElementsActions; 358 for (SizeAndAction BitsizeAndAction : VectorSpecifiedActions.second) { 359 assert(BitsizeAndAction.first % ElementSize == 0); 360 const uint16_t NumElements = BitsizeAndAction.first / ElementSize; 361 NumElementsActions.push_back({NumElements, BitsizeAndAction.second}); 362 } 363 setVectorNumElementAction( 364 Opcode, TypeIdx, ElementSize, 365 moreToWiderTypesAndLessToWidest(NumElementsActions)); 366 } 367 llvm::sort(ElementSizesSeen); 368 SizeChangeStrategy VectorElementSizeChangeStrategy = 369 &unsupportedForDifferentSizes; 370 if (TypeIdx < VectorElementSizeChangeStrategies[OpcodeIdx].size() && 371 VectorElementSizeChangeStrategies[OpcodeIdx][TypeIdx] != nullptr) 372 VectorElementSizeChangeStrategy = 373 VectorElementSizeChangeStrategies[OpcodeIdx][TypeIdx]; 374 setScalarInVectorAction( 375 Opcode, TypeIdx, VectorElementSizeChangeStrategy(ElementSizesSeen)); 376 } 377 } 378 379 TablesInitialized = true; 380 } 381 382 // FIXME: inefficient implementation for now. Without ComputeValueVTs we're 383 // probably going to need specialized lookup structures for various types before 384 // we have any hope of doing well with something like <13 x i3>. Even the common 385 // cases should do better than what we have now. 386 std::pair<LegalizeAction, LLT> 387 LegalizerInfo::getAspectAction(const InstrAspect &Aspect) const { 388 assert(TablesInitialized && "backend forgot to call computeTables"); 389 // These *have* to be implemented for now, they're the fundamental basis of 390 // how everything else is transformed. 391 if (Aspect.Type.isScalar() || Aspect.Type.isPointer()) 392 return findScalarLegalAction(Aspect); 393 assert(Aspect.Type.isVector()); 394 return findVectorLegalAction(Aspect); 395 } 396 397 /// Helper function to get LLT for the given type index. 398 static LLT getTypeFromTypeIdx(const MachineInstr &MI, 399 const MachineRegisterInfo &MRI, unsigned OpIdx, 400 unsigned TypeIdx) { 401 assert(TypeIdx < MI.getNumOperands() && "Unexpected TypeIdx"); 402 // G_UNMERGE_VALUES has variable number of operands, but there is only 403 // one source type and one destination type as all destinations must be the 404 // same type. So, get the last operand if TypeIdx == 1. 405 if (MI.getOpcode() == TargetOpcode::G_UNMERGE_VALUES && TypeIdx == 1) 406 return MRI.getType(MI.getOperand(MI.getNumOperands() - 1).getReg()); 407 return MRI.getType(MI.getOperand(OpIdx).getReg()); 408 } 409 410 unsigned LegalizerInfo::getOpcodeIdxForOpcode(unsigned Opcode) const { 411 assert(Opcode >= FirstOp && Opcode <= LastOp && "Unsupported opcode"); 412 return Opcode - FirstOp; 413 } 414 415 unsigned LegalizerInfo::getActionDefinitionsIdx(unsigned Opcode) const { 416 unsigned OpcodeIdx = getOpcodeIdxForOpcode(Opcode); 417 if (unsigned Alias = RulesForOpcode[OpcodeIdx].getAlias()) { 418 LLVM_DEBUG(dbgs() << ".. opcode " << Opcode << " is aliased to " << Alias 419 << "\n"); 420 OpcodeIdx = getOpcodeIdxForOpcode(Alias); 421 assert(RulesForOpcode[OpcodeIdx].getAlias() == 0 && "Cannot chain aliases"); 422 } 423 424 return OpcodeIdx; 425 } 426 427 const LegalizeRuleSet & 428 LegalizerInfo::getActionDefinitions(unsigned Opcode) const { 429 unsigned OpcodeIdx = getActionDefinitionsIdx(Opcode); 430 return RulesForOpcode[OpcodeIdx]; 431 } 432 433 LegalizeRuleSet &LegalizerInfo::getActionDefinitionsBuilder(unsigned Opcode) { 434 unsigned OpcodeIdx = getActionDefinitionsIdx(Opcode); 435 auto &Result = RulesForOpcode[OpcodeIdx]; 436 assert(!Result.isAliasedByAnother() && "Modifying this opcode will modify aliases"); 437 return Result; 438 } 439 440 LegalizeRuleSet &LegalizerInfo::getActionDefinitionsBuilder( 441 std::initializer_list<unsigned> Opcodes) { 442 unsigned Representative = *Opcodes.begin(); 443 444 assert(!llvm::empty(Opcodes) && Opcodes.begin() + 1 != Opcodes.end() && 445 "Initializer list must have at least two opcodes"); 446 447 for (auto I = Opcodes.begin() + 1, E = Opcodes.end(); I != E; ++I) 448 aliasActionDefinitions(Representative, *I); 449 450 auto &Return = getActionDefinitionsBuilder(Representative); 451 Return.setIsAliasedByAnother(); 452 return Return; 453 } 454 455 void LegalizerInfo::aliasActionDefinitions(unsigned OpcodeTo, 456 unsigned OpcodeFrom) { 457 assert(OpcodeTo != OpcodeFrom && "Cannot alias to self"); 458 assert(OpcodeTo >= FirstOp && OpcodeTo <= LastOp && "Unsupported opcode"); 459 const unsigned OpcodeFromIdx = getOpcodeIdxForOpcode(OpcodeFrom); 460 RulesForOpcode[OpcodeFromIdx].aliasTo(OpcodeTo); 461 } 462 463 LegalizeActionStep 464 LegalizerInfo::getAction(const LegalityQuery &Query) const { 465 LegalizeActionStep Step = getActionDefinitions(Query.Opcode).apply(Query); 466 if (Step.Action != LegalizeAction::UseLegacyRules) { 467 return Step; 468 } 469 470 for (unsigned i = 0; i < Query.Types.size(); ++i) { 471 auto Action = getAspectAction({Query.Opcode, i, Query.Types[i]}); 472 if (Action.first != Legal) { 473 LLVM_DEBUG(dbgs() << ".. (legacy) Type " << i << " Action=" 474 << Action.first << ", " << Action.second << "\n"); 475 return {Action.first, i, Action.second}; 476 } else 477 LLVM_DEBUG(dbgs() << ".. (legacy) Type " << i << " Legal\n"); 478 } 479 LLVM_DEBUG(dbgs() << ".. (legacy) Legal\n"); 480 return {Legal, 0, LLT{}}; 481 } 482 483 LegalizeActionStep 484 LegalizerInfo::getAction(const MachineInstr &MI, 485 const MachineRegisterInfo &MRI) const { 486 SmallVector<LLT, 2> Types; 487 SmallBitVector SeenTypes(8); 488 const MCOperandInfo *OpInfo = MI.getDesc().OpInfo; 489 // FIXME: probably we'll need to cache the results here somehow? 490 for (unsigned i = 0; i < MI.getDesc().getNumOperands(); ++i) { 491 if (!OpInfo[i].isGenericType()) 492 continue; 493 494 // We must only record actions once for each TypeIdx; otherwise we'd 495 // try to legalize operands multiple times down the line. 496 unsigned TypeIdx = OpInfo[i].getGenericTypeIndex(); 497 if (SeenTypes[TypeIdx]) 498 continue; 499 500 SeenTypes.set(TypeIdx); 501 502 LLT Ty = getTypeFromTypeIdx(MI, MRI, i, TypeIdx); 503 Types.push_back(Ty); 504 } 505 506 SmallVector<LegalityQuery::MemDesc, 2> MemDescrs; 507 for (const auto &MMO : MI.memoperands()) 508 MemDescrs.push_back({8 * MMO->getSize() /* in bits */, 509 8 * MMO->getAlign().value(), MMO->getOrdering()}); 510 511 return getAction({MI.getOpcode(), Types, MemDescrs}); 512 } 513 514 bool LegalizerInfo::isLegal(const MachineInstr &MI, 515 const MachineRegisterInfo &MRI) const { 516 return getAction(MI, MRI).Action == Legal; 517 } 518 519 bool LegalizerInfo::isLegalOrCustom(const MachineInstr &MI, 520 const MachineRegisterInfo &MRI) const { 521 auto Action = getAction(MI, MRI).Action; 522 // If the action is custom, it may not necessarily modify the instruction, 523 // so we have to assume it's legal. 524 return Action == Legal || Action == Custom; 525 } 526 527 LegalizerInfo::SizeAndActionsVec 528 LegalizerInfo::increaseToLargerTypesAndDecreaseToLargest( 529 const SizeAndActionsVec &v, LegalizeAction IncreaseAction, 530 LegalizeAction DecreaseAction) { 531 SizeAndActionsVec result; 532 unsigned LargestSizeSoFar = 0; 533 if (v.size() >= 1 && v[0].first != 1) 534 result.push_back({1, IncreaseAction}); 535 for (size_t i = 0; i < v.size(); ++i) { 536 result.push_back(v[i]); 537 LargestSizeSoFar = v[i].first; 538 if (i + 1 < v.size() && v[i + 1].first != v[i].first + 1) { 539 result.push_back({LargestSizeSoFar + 1, IncreaseAction}); 540 LargestSizeSoFar = v[i].first + 1; 541 } 542 } 543 result.push_back({LargestSizeSoFar + 1, DecreaseAction}); 544 return result; 545 } 546 547 LegalizerInfo::SizeAndActionsVec 548 LegalizerInfo::decreaseToSmallerTypesAndIncreaseToSmallest( 549 const SizeAndActionsVec &v, LegalizeAction DecreaseAction, 550 LegalizeAction IncreaseAction) { 551 SizeAndActionsVec result; 552 if (v.size() == 0 || v[0].first != 1) 553 result.push_back({1, IncreaseAction}); 554 for (size_t i = 0; i < v.size(); ++i) { 555 result.push_back(v[i]); 556 if (i + 1 == v.size() || v[i + 1].first != v[i].first + 1) { 557 result.push_back({v[i].first + 1, DecreaseAction}); 558 } 559 } 560 return result; 561 } 562 563 LegalizerInfo::SizeAndAction 564 LegalizerInfo::findAction(const SizeAndActionsVec &Vec, const uint32_t Size) { 565 assert(Size >= 1); 566 // Find the last element in Vec that has a bitsize equal to or smaller than 567 // the requested bit size. 568 // That is the element just before the first element that is bigger than Size. 569 auto It = partition_point( 570 Vec, [=](const SizeAndAction &A) { return A.first <= Size; }); 571 assert(It != Vec.begin() && "Does Vec not start with size 1?"); 572 int VecIdx = It - Vec.begin() - 1; 573 574 LegalizeAction Action = Vec[VecIdx].second; 575 switch (Action) { 576 case Legal: 577 case Bitcast: 578 case Lower: 579 case Libcall: 580 case Custom: 581 return {Size, Action}; 582 case FewerElements: 583 // FIXME: is this special case still needed and correct? 584 // Special case for scalarization: 585 if (Vec == SizeAndActionsVec({{1, FewerElements}})) 586 return {1, FewerElements}; 587 LLVM_FALLTHROUGH; 588 case NarrowScalar: { 589 // The following needs to be a loop, as for now, we do allow needing to 590 // go over "Unsupported" bit sizes before finding a legalizable bit size. 591 // e.g. (s8, WidenScalar), (s9, Unsupported), (s32, Legal). if Size==8, 592 // we need to iterate over s9, and then to s32 to return (s32, Legal). 593 // If we want to get rid of the below loop, we should have stronger asserts 594 // when building the SizeAndActionsVecs, probably not allowing 595 // "Unsupported" unless at the ends of the vector. 596 for (int i = VecIdx - 1; i >= 0; --i) 597 if (!needsLegalizingToDifferentSize(Vec[i].second) && 598 Vec[i].second != Unsupported) 599 return {Vec[i].first, Action}; 600 llvm_unreachable(""); 601 } 602 case WidenScalar: 603 case MoreElements: { 604 // See above, the following needs to be a loop, at least for now. 605 for (std::size_t i = VecIdx + 1; i < Vec.size(); ++i) 606 if (!needsLegalizingToDifferentSize(Vec[i].second) && 607 Vec[i].second != Unsupported) 608 return {Vec[i].first, Action}; 609 llvm_unreachable(""); 610 } 611 case Unsupported: 612 return {Size, Unsupported}; 613 case NotFound: 614 case UseLegacyRules: 615 llvm_unreachable("NotFound"); 616 } 617 llvm_unreachable("Action has an unknown enum value"); 618 } 619 620 std::pair<LegalizeAction, LLT> 621 LegalizerInfo::findScalarLegalAction(const InstrAspect &Aspect) const { 622 assert(Aspect.Type.isScalar() || Aspect.Type.isPointer()); 623 if (Aspect.Opcode < FirstOp || Aspect.Opcode > LastOp) 624 return {NotFound, LLT()}; 625 const unsigned OpcodeIdx = getOpcodeIdxForOpcode(Aspect.Opcode); 626 if (Aspect.Type.isPointer() && 627 AddrSpace2PointerActions[OpcodeIdx].find(Aspect.Type.getAddressSpace()) == 628 AddrSpace2PointerActions[OpcodeIdx].end()) { 629 return {NotFound, LLT()}; 630 } 631 const SmallVector<SizeAndActionsVec, 1> &Actions = 632 Aspect.Type.isPointer() 633 ? AddrSpace2PointerActions[OpcodeIdx] 634 .find(Aspect.Type.getAddressSpace()) 635 ->second 636 : ScalarActions[OpcodeIdx]; 637 if (Aspect.Idx >= Actions.size()) 638 return {NotFound, LLT()}; 639 const SizeAndActionsVec &Vec = Actions[Aspect.Idx]; 640 // FIXME: speed up this search, e.g. by using a results cache for repeated 641 // queries? 642 auto SizeAndAction = findAction(Vec, Aspect.Type.getSizeInBits()); 643 return {SizeAndAction.second, 644 Aspect.Type.isScalar() ? LLT::scalar(SizeAndAction.first) 645 : LLT::pointer(Aspect.Type.getAddressSpace(), 646 SizeAndAction.first)}; 647 } 648 649 std::pair<LegalizeAction, LLT> 650 LegalizerInfo::findVectorLegalAction(const InstrAspect &Aspect) const { 651 assert(Aspect.Type.isVector()); 652 // First legalize the vector element size, then legalize the number of 653 // lanes in the vector. 654 if (Aspect.Opcode < FirstOp || Aspect.Opcode > LastOp) 655 return {NotFound, Aspect.Type}; 656 const unsigned OpcodeIdx = getOpcodeIdxForOpcode(Aspect.Opcode); 657 const unsigned TypeIdx = Aspect.Idx; 658 if (TypeIdx >= ScalarInVectorActions[OpcodeIdx].size()) 659 return {NotFound, Aspect.Type}; 660 const SizeAndActionsVec &ElemSizeVec = 661 ScalarInVectorActions[OpcodeIdx][TypeIdx]; 662 663 LLT IntermediateType; 664 auto ElementSizeAndAction = 665 findAction(ElemSizeVec, Aspect.Type.getScalarSizeInBits()); 666 IntermediateType = 667 LLT::vector(Aspect.Type.getNumElements(), ElementSizeAndAction.first); 668 if (ElementSizeAndAction.second != Legal) 669 return {ElementSizeAndAction.second, IntermediateType}; 670 671 auto i = NumElements2Actions[OpcodeIdx].find( 672 IntermediateType.getScalarSizeInBits()); 673 if (i == NumElements2Actions[OpcodeIdx].end()) { 674 return {NotFound, IntermediateType}; 675 } 676 const SizeAndActionsVec &NumElementsVec = (*i).second[TypeIdx]; 677 auto NumElementsAndAction = 678 findAction(NumElementsVec, IntermediateType.getNumElements()); 679 return {NumElementsAndAction.second, 680 LLT::vector(NumElementsAndAction.first, 681 IntermediateType.getScalarSizeInBits())}; 682 } 683 684 unsigned LegalizerInfo::getExtOpcodeForWideningConstant(LLT SmallTy) const { 685 return SmallTy.isByteSized() ? TargetOpcode::G_SEXT : TargetOpcode::G_ZEXT; 686 } 687 688 /// \pre Type indices of every opcode form a dense set starting from 0. 689 void LegalizerInfo::verify(const MCInstrInfo &MII) const { 690 #ifndef NDEBUG 691 std::vector<unsigned> FailedOpcodes; 692 for (unsigned Opcode = FirstOp; Opcode <= LastOp; ++Opcode) { 693 const MCInstrDesc &MCID = MII.get(Opcode); 694 const unsigned NumTypeIdxs = std::accumulate( 695 MCID.opInfo_begin(), MCID.opInfo_end(), 0U, 696 [](unsigned Acc, const MCOperandInfo &OpInfo) { 697 return OpInfo.isGenericType() 698 ? std::max(OpInfo.getGenericTypeIndex() + 1U, Acc) 699 : Acc; 700 }); 701 const unsigned NumImmIdxs = std::accumulate( 702 MCID.opInfo_begin(), MCID.opInfo_end(), 0U, 703 [](unsigned Acc, const MCOperandInfo &OpInfo) { 704 return OpInfo.isGenericImm() 705 ? std::max(OpInfo.getGenericImmIndex() + 1U, Acc) 706 : Acc; 707 }); 708 LLVM_DEBUG(dbgs() << MII.getName(Opcode) << " (opcode " << Opcode 709 << "): " << NumTypeIdxs << " type ind" 710 << (NumTypeIdxs == 1 ? "ex" : "ices") << ", " 711 << NumImmIdxs << " imm ind" 712 << (NumImmIdxs == 1 ? "ex" : "ices") << "\n"); 713 const LegalizeRuleSet &RuleSet = getActionDefinitions(Opcode); 714 if (!RuleSet.verifyTypeIdxsCoverage(NumTypeIdxs)) 715 FailedOpcodes.push_back(Opcode); 716 else if (!RuleSet.verifyImmIdxsCoverage(NumImmIdxs)) 717 FailedOpcodes.push_back(Opcode); 718 } 719 if (!FailedOpcodes.empty()) { 720 errs() << "The following opcodes have ill-defined legalization rules:"; 721 for (unsigned Opcode : FailedOpcodes) 722 errs() << " " << MII.getName(Opcode); 723 errs() << "\n"; 724 725 report_fatal_error("ill-defined LegalizerInfo" 726 ", try -debug-only=legalizer-info for details"); 727 } 728 #endif 729 } 730 731 #ifndef NDEBUG 732 // FIXME: This should be in the MachineVerifier, but it can't use the 733 // LegalizerInfo as it's currently in the separate GlobalISel library. 734 // Note that RegBankSelected property already checked in the verifier 735 // has the same layering problem, but we only use inline methods so 736 // end up not needing to link against the GlobalISel library. 737 const MachineInstr *llvm::machineFunctionIsIllegal(const MachineFunction &MF) { 738 if (const LegalizerInfo *MLI = MF.getSubtarget().getLegalizerInfo()) { 739 const MachineRegisterInfo &MRI = MF.getRegInfo(); 740 for (const MachineBasicBlock &MBB : MF) 741 for (const MachineInstr &MI : MBB) 742 if (isPreISelGenericOpcode(MI.getOpcode()) && 743 !MLI->isLegalOrCustom(MI, MRI)) 744 return &MI; 745 } 746 return nullptr; 747 } 748 #endif 749