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