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 if (!OldTy.isVector()) 132 return false; 133 LLVM_FALLTHROUGH; 134 case MoreElements: { 135 // MoreElements can go from scalar to vector. 136 const unsigned OldElts = OldTy.isVector() ? OldTy.getNumElements() : 1; 137 if (NewTy.isVector()) { 138 if (Rule.getAction() == FewerElements) { 139 // Make sure the element count really decreased. 140 if (NewTy.getNumElements() >= OldElts) 141 return false; 142 } else { 143 // Make sure the element count really increased. 144 if (NewTy.getNumElements() <= OldElts) 145 return false; 146 } 147 } 148 149 // Make sure the element type didn't change. 150 return NewTy.getScalarType() == OldTy.getScalarType(); 151 } 152 case NarrowScalar: 153 case WidenScalar: { 154 if (OldTy.isVector()) { 155 // Number of elements should not change. 156 if (!NewTy.isVector() || OldTy.getNumElements() != NewTy.getNumElements()) 157 return false; 158 } else { 159 // Both types must be vectors 160 if (NewTy.isVector()) 161 return false; 162 } 163 164 if (Rule.getAction() == NarrowScalar) { 165 // Make sure the size really decreased. 166 if (NewTy.getScalarSizeInBits() >= OldTy.getScalarSizeInBits()) 167 return false; 168 } else { 169 // Make sure the size really increased. 170 if (NewTy.getScalarSizeInBits() <= OldTy.getScalarSizeInBits()) 171 return false; 172 } 173 174 return true; 175 } 176 default: 177 return true; 178 } 179 } 180 #endif 181 182 LegalizeActionStep LegalizeRuleSet::apply(const LegalityQuery &Query) const { 183 LLVM_DEBUG(dbgs() << "Applying legalizer ruleset to: "; Query.print(dbgs()); 184 dbgs() << "\n"); 185 if (Rules.empty()) { 186 LLVM_DEBUG(dbgs() << ".. fallback to legacy rules (no rules defined)\n"); 187 return {LegalizeAction::UseLegacyRules, 0, LLT{}}; 188 } 189 for (const LegalizeRule &Rule : Rules) { 190 if (Rule.match(Query)) { 191 LLVM_DEBUG(dbgs() << ".. match\n"); 192 std::pair<unsigned, LLT> Mutation = Rule.determineMutation(Query); 193 LLVM_DEBUG(dbgs() << ".. .. " << Rule.getAction() << ", " 194 << Mutation.first << ", " << Mutation.second << "\n"); 195 assert(mutationIsSane(Rule, Query, Mutation) && 196 "legality mutation invalid for match"); 197 assert(hasNoSimpleLoops(Rule, Query, Mutation) && "Simple loop detected"); 198 return {Rule.getAction(), Mutation.first, Mutation.second}; 199 } else 200 LLVM_DEBUG(dbgs() << ".. no match\n"); 201 } 202 LLVM_DEBUG(dbgs() << ".. unsupported\n"); 203 return {LegalizeAction::Unsupported, 0, LLT{}}; 204 } 205 206 bool LegalizeRuleSet::verifyTypeIdxsCoverage(unsigned NumTypeIdxs) const { 207 #ifndef NDEBUG 208 if (Rules.empty()) { 209 LLVM_DEBUG( 210 dbgs() << ".. type index coverage check SKIPPED: no rules defined\n"); 211 return true; 212 } 213 const int64_t FirstUncovered = TypeIdxsCovered.find_first_unset(); 214 if (FirstUncovered < 0) { 215 LLVM_DEBUG(dbgs() << ".. type index coverage check SKIPPED:" 216 " user-defined predicate detected\n"); 217 return true; 218 } 219 const bool AllCovered = (FirstUncovered >= NumTypeIdxs); 220 if (NumTypeIdxs > 0) 221 LLVM_DEBUG(dbgs() << ".. the first uncovered type index: " << FirstUncovered 222 << ", " << (AllCovered ? "OK" : "FAIL") << "\n"); 223 return AllCovered; 224 #else 225 return true; 226 #endif 227 } 228 229 bool LegalizeRuleSet::verifyImmIdxsCoverage(unsigned NumImmIdxs) const { 230 #ifndef NDEBUG 231 if (Rules.empty()) { 232 LLVM_DEBUG( 233 dbgs() << ".. imm index coverage check SKIPPED: no rules defined\n"); 234 return true; 235 } 236 const int64_t FirstUncovered = ImmIdxsCovered.find_first_unset(); 237 if (FirstUncovered < 0) { 238 LLVM_DEBUG(dbgs() << ".. imm index coverage check SKIPPED:" 239 " user-defined predicate detected\n"); 240 return true; 241 } 242 const bool AllCovered = (FirstUncovered >= NumImmIdxs); 243 LLVM_DEBUG(dbgs() << ".. the first uncovered imm index: " << FirstUncovered 244 << ", " << (AllCovered ? "OK" : "FAIL") << "\n"); 245 return AllCovered; 246 #else 247 return true; 248 #endif 249 } 250 251 LegalizerInfo::LegalizerInfo() : TablesInitialized(false) { 252 // Set defaults. 253 // FIXME: these two (G_ANYEXT and G_TRUNC?) can be legalized to the 254 // fundamental load/store Jakob proposed. Once loads & stores are supported. 255 setScalarAction(TargetOpcode::G_ANYEXT, 1, {{1, Legal}}); 256 setScalarAction(TargetOpcode::G_ZEXT, 1, {{1, Legal}}); 257 setScalarAction(TargetOpcode::G_SEXT, 1, {{1, Legal}}); 258 setScalarAction(TargetOpcode::G_TRUNC, 0, {{1, Legal}}); 259 setScalarAction(TargetOpcode::G_TRUNC, 1, {{1, Legal}}); 260 261 setScalarAction(TargetOpcode::G_INTRINSIC, 0, {{1, Legal}}); 262 setScalarAction(TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS, 0, {{1, Legal}}); 263 264 setLegalizeScalarToDifferentSizeStrategy( 265 TargetOpcode::G_IMPLICIT_DEF, 0, narrowToSmallerAndUnsupportedIfTooSmall); 266 setLegalizeScalarToDifferentSizeStrategy( 267 TargetOpcode::G_ADD, 0, widenToLargerTypesAndNarrowToLargest); 268 setLegalizeScalarToDifferentSizeStrategy( 269 TargetOpcode::G_OR, 0, widenToLargerTypesAndNarrowToLargest); 270 setLegalizeScalarToDifferentSizeStrategy( 271 TargetOpcode::G_LOAD, 0, narrowToSmallerAndUnsupportedIfTooSmall); 272 setLegalizeScalarToDifferentSizeStrategy( 273 TargetOpcode::G_STORE, 0, narrowToSmallerAndUnsupportedIfTooSmall); 274 275 setLegalizeScalarToDifferentSizeStrategy( 276 TargetOpcode::G_BRCOND, 0, widenToLargerTypesUnsupportedOtherwise); 277 setLegalizeScalarToDifferentSizeStrategy( 278 TargetOpcode::G_INSERT, 0, narrowToSmallerAndUnsupportedIfTooSmall); 279 setLegalizeScalarToDifferentSizeStrategy( 280 TargetOpcode::G_EXTRACT, 0, narrowToSmallerAndUnsupportedIfTooSmall); 281 setLegalizeScalarToDifferentSizeStrategy( 282 TargetOpcode::G_EXTRACT, 1, narrowToSmallerAndUnsupportedIfTooSmall); 283 setScalarAction(TargetOpcode::G_FNEG, 0, {{1, Lower}}); 284 } 285 286 void LegalizerInfo::computeTables() { 287 assert(TablesInitialized == false); 288 289 for (unsigned OpcodeIdx = 0; OpcodeIdx <= LastOp - FirstOp; ++OpcodeIdx) { 290 const unsigned Opcode = FirstOp + OpcodeIdx; 291 for (unsigned TypeIdx = 0; TypeIdx != SpecifiedActions[OpcodeIdx].size(); 292 ++TypeIdx) { 293 // 0. Collect information specified through the setAction API, i.e. 294 // for specific bit sizes. 295 // For scalar types: 296 SizeAndActionsVec ScalarSpecifiedActions; 297 // For pointer types: 298 std::map<uint16_t, SizeAndActionsVec> AddressSpace2SpecifiedActions; 299 // For vector types: 300 std::map<uint16_t, SizeAndActionsVec> ElemSize2SpecifiedActions; 301 for (auto LLT2Action : SpecifiedActions[OpcodeIdx][TypeIdx]) { 302 const LLT Type = LLT2Action.first; 303 const LegalizeAction Action = LLT2Action.second; 304 305 auto SizeAction = std::make_pair(Type.getSizeInBits(), Action); 306 if (Type.isPointer()) 307 AddressSpace2SpecifiedActions[Type.getAddressSpace()].push_back( 308 SizeAction); 309 else if (Type.isVector()) 310 ElemSize2SpecifiedActions[Type.getElementType().getSizeInBits()] 311 .push_back(SizeAction); 312 else 313 ScalarSpecifiedActions.push_back(SizeAction); 314 } 315 316 // 1. Handle scalar types 317 { 318 // Decide how to handle bit sizes for which no explicit specification 319 // was given. 320 SizeChangeStrategy S = &unsupportedForDifferentSizes; 321 if (TypeIdx < ScalarSizeChangeStrategies[OpcodeIdx].size() && 322 ScalarSizeChangeStrategies[OpcodeIdx][TypeIdx] != nullptr) 323 S = ScalarSizeChangeStrategies[OpcodeIdx][TypeIdx]; 324 llvm::sort(ScalarSpecifiedActions); 325 checkPartialSizeAndActionsVector(ScalarSpecifiedActions); 326 setScalarAction(Opcode, TypeIdx, S(ScalarSpecifiedActions)); 327 } 328 329 // 2. Handle pointer types 330 for (auto PointerSpecifiedActions : AddressSpace2SpecifiedActions) { 331 llvm::sort(PointerSpecifiedActions.second); 332 checkPartialSizeAndActionsVector(PointerSpecifiedActions.second); 333 // For pointer types, we assume that there isn't a meaningfull way 334 // to change the number of bits used in the pointer. 335 setPointerAction( 336 Opcode, TypeIdx, PointerSpecifiedActions.first, 337 unsupportedForDifferentSizes(PointerSpecifiedActions.second)); 338 } 339 340 // 3. Handle vector types 341 SizeAndActionsVec ElementSizesSeen; 342 for (auto VectorSpecifiedActions : ElemSize2SpecifiedActions) { 343 llvm::sort(VectorSpecifiedActions.second); 344 const uint16_t ElementSize = VectorSpecifiedActions.first; 345 ElementSizesSeen.push_back({ElementSize, Legal}); 346 checkPartialSizeAndActionsVector(VectorSpecifiedActions.second); 347 // For vector types, we assume that the best way to adapt the number 348 // of elements is to the next larger number of elements type for which 349 // the vector type is legal, unless there is no such type. In that case, 350 // legalize towards a vector type with a smaller number of elements. 351 SizeAndActionsVec NumElementsActions; 352 for (SizeAndAction BitsizeAndAction : VectorSpecifiedActions.second) { 353 assert(BitsizeAndAction.first % ElementSize == 0); 354 const uint16_t NumElements = BitsizeAndAction.first / ElementSize; 355 NumElementsActions.push_back({NumElements, BitsizeAndAction.second}); 356 } 357 setVectorNumElementAction( 358 Opcode, TypeIdx, ElementSize, 359 moreToWiderTypesAndLessToWidest(NumElementsActions)); 360 } 361 llvm::sort(ElementSizesSeen); 362 SizeChangeStrategy VectorElementSizeChangeStrategy = 363 &unsupportedForDifferentSizes; 364 if (TypeIdx < VectorElementSizeChangeStrategies[OpcodeIdx].size() && 365 VectorElementSizeChangeStrategies[OpcodeIdx][TypeIdx] != nullptr) 366 VectorElementSizeChangeStrategy = 367 VectorElementSizeChangeStrategies[OpcodeIdx][TypeIdx]; 368 setScalarInVectorAction( 369 Opcode, TypeIdx, VectorElementSizeChangeStrategy(ElementSizesSeen)); 370 } 371 } 372 373 TablesInitialized = true; 374 } 375 376 // FIXME: inefficient implementation for now. Without ComputeValueVTs we're 377 // probably going to need specialized lookup structures for various types before 378 // we have any hope of doing well with something like <13 x i3>. Even the common 379 // cases should do better than what we have now. 380 std::pair<LegalizeAction, LLT> 381 LegalizerInfo::getAspectAction(const InstrAspect &Aspect) const { 382 assert(TablesInitialized && "backend forgot to call computeTables"); 383 // These *have* to be implemented for now, they're the fundamental basis of 384 // how everything else is transformed. 385 if (Aspect.Type.isScalar() || Aspect.Type.isPointer()) 386 return findScalarLegalAction(Aspect); 387 assert(Aspect.Type.isVector()); 388 return findVectorLegalAction(Aspect); 389 } 390 391 /// Helper function to get LLT for the given type index. 392 static LLT getTypeFromTypeIdx(const MachineInstr &MI, 393 const MachineRegisterInfo &MRI, unsigned OpIdx, 394 unsigned TypeIdx) { 395 assert(TypeIdx < MI.getNumOperands() && "Unexpected TypeIdx"); 396 // G_UNMERGE_VALUES has variable number of operands, but there is only 397 // one source type and one destination type as all destinations must be the 398 // same type. So, get the last operand if TypeIdx == 1. 399 if (MI.getOpcode() == TargetOpcode::G_UNMERGE_VALUES && TypeIdx == 1) 400 return MRI.getType(MI.getOperand(MI.getNumOperands() - 1).getReg()); 401 return MRI.getType(MI.getOperand(OpIdx).getReg()); 402 } 403 404 unsigned LegalizerInfo::getOpcodeIdxForOpcode(unsigned Opcode) const { 405 assert(Opcode >= FirstOp && Opcode <= LastOp && "Unsupported opcode"); 406 return Opcode - FirstOp; 407 } 408 409 unsigned LegalizerInfo::getActionDefinitionsIdx(unsigned Opcode) const { 410 unsigned OpcodeIdx = getOpcodeIdxForOpcode(Opcode); 411 if (unsigned Alias = RulesForOpcode[OpcodeIdx].getAlias()) { 412 LLVM_DEBUG(dbgs() << ".. opcode " << Opcode << " is aliased to " << Alias 413 << "\n"); 414 OpcodeIdx = getOpcodeIdxForOpcode(Alias); 415 assert(RulesForOpcode[OpcodeIdx].getAlias() == 0 && "Cannot chain aliases"); 416 } 417 418 return OpcodeIdx; 419 } 420 421 const LegalizeRuleSet & 422 LegalizerInfo::getActionDefinitions(unsigned Opcode) const { 423 unsigned OpcodeIdx = getActionDefinitionsIdx(Opcode); 424 return RulesForOpcode[OpcodeIdx]; 425 } 426 427 LegalizeRuleSet &LegalizerInfo::getActionDefinitionsBuilder(unsigned Opcode) { 428 unsigned OpcodeIdx = getActionDefinitionsIdx(Opcode); 429 auto &Result = RulesForOpcode[OpcodeIdx]; 430 assert(!Result.isAliasedByAnother() && "Modifying this opcode will modify aliases"); 431 return Result; 432 } 433 434 LegalizeRuleSet &LegalizerInfo::getActionDefinitionsBuilder( 435 std::initializer_list<unsigned> Opcodes) { 436 unsigned Representative = *Opcodes.begin(); 437 438 assert(!llvm::empty(Opcodes) && Opcodes.begin() + 1 != Opcodes.end() && 439 "Initializer list must have at least two opcodes"); 440 441 for (auto I = Opcodes.begin() + 1, E = Opcodes.end(); I != E; ++I) 442 aliasActionDefinitions(Representative, *I); 443 444 auto &Return = getActionDefinitionsBuilder(Representative); 445 Return.setIsAliasedByAnother(); 446 return Return; 447 } 448 449 void LegalizerInfo::aliasActionDefinitions(unsigned OpcodeTo, 450 unsigned OpcodeFrom) { 451 assert(OpcodeTo != OpcodeFrom && "Cannot alias to self"); 452 assert(OpcodeTo >= FirstOp && OpcodeTo <= LastOp && "Unsupported opcode"); 453 const unsigned OpcodeFromIdx = getOpcodeIdxForOpcode(OpcodeFrom); 454 RulesForOpcode[OpcodeFromIdx].aliasTo(OpcodeTo); 455 } 456 457 LegalizeActionStep 458 LegalizerInfo::getAction(const LegalityQuery &Query) const { 459 LegalizeActionStep Step = getActionDefinitions(Query.Opcode).apply(Query); 460 if (Step.Action != LegalizeAction::UseLegacyRules) { 461 return Step; 462 } 463 464 for (unsigned i = 0; i < Query.Types.size(); ++i) { 465 auto Action = getAspectAction({Query.Opcode, i, Query.Types[i]}); 466 if (Action.first != Legal) { 467 LLVM_DEBUG(dbgs() << ".. (legacy) Type " << i << " Action=" 468 << Action.first << ", " << Action.second << "\n"); 469 return {Action.first, i, Action.second}; 470 } else 471 LLVM_DEBUG(dbgs() << ".. (legacy) Type " << i << " Legal\n"); 472 } 473 LLVM_DEBUG(dbgs() << ".. (legacy) Legal\n"); 474 return {Legal, 0, LLT{}}; 475 } 476 477 LegalizeActionStep 478 LegalizerInfo::getAction(const MachineInstr &MI, 479 const MachineRegisterInfo &MRI) const { 480 SmallVector<LLT, 2> Types; 481 SmallBitVector SeenTypes(8); 482 const MCOperandInfo *OpInfo = MI.getDesc().OpInfo; 483 // FIXME: probably we'll need to cache the results here somehow? 484 for (unsigned i = 0; i < MI.getDesc().getNumOperands(); ++i) { 485 if (!OpInfo[i].isGenericType()) 486 continue; 487 488 // We must only record actions once for each TypeIdx; otherwise we'd 489 // try to legalize operands multiple times down the line. 490 unsigned TypeIdx = OpInfo[i].getGenericTypeIndex(); 491 if (SeenTypes[TypeIdx]) 492 continue; 493 494 SeenTypes.set(TypeIdx); 495 496 LLT Ty = getTypeFromTypeIdx(MI, MRI, i, TypeIdx); 497 Types.push_back(Ty); 498 } 499 500 SmallVector<LegalityQuery::MemDesc, 2> MemDescrs; 501 for (const auto &MMO : MI.memoperands()) 502 MemDescrs.push_back({8 * MMO->getSize() /* in bits */, 503 8 * MMO->getAlignment(), 504 MMO->getOrdering()}); 505 506 return getAction({MI.getOpcode(), Types, MemDescrs}); 507 } 508 509 bool LegalizerInfo::isLegal(const MachineInstr &MI, 510 const MachineRegisterInfo &MRI) const { 511 return getAction(MI, MRI).Action == Legal; 512 } 513 514 bool LegalizerInfo::isLegalOrCustom(const MachineInstr &MI, 515 const MachineRegisterInfo &MRI) const { 516 auto Action = getAction(MI, MRI).Action; 517 // If the action is custom, it may not necessarily modify the instruction, 518 // so we have to assume it's legal. 519 return Action == Legal || Action == Custom; 520 } 521 522 bool LegalizerInfo::legalizeCustom(MachineInstr &MI, MachineRegisterInfo &MRI, 523 MachineIRBuilder &MIRBuilder, 524 GISelChangeObserver &Observer) const { 525 return false; 526 } 527 528 LegalizerInfo::SizeAndActionsVec 529 LegalizerInfo::increaseToLargerTypesAndDecreaseToLargest( 530 const SizeAndActionsVec &v, LegalizeAction IncreaseAction, 531 LegalizeAction DecreaseAction) { 532 SizeAndActionsVec result; 533 unsigned LargestSizeSoFar = 0; 534 if (v.size() >= 1 && v[0].first != 1) 535 result.push_back({1, IncreaseAction}); 536 for (size_t i = 0; i < v.size(); ++i) { 537 result.push_back(v[i]); 538 LargestSizeSoFar = v[i].first; 539 if (i + 1 < v.size() && v[i + 1].first != v[i].first + 1) { 540 result.push_back({LargestSizeSoFar + 1, IncreaseAction}); 541 LargestSizeSoFar = v[i].first + 1; 542 } 543 } 544 result.push_back({LargestSizeSoFar + 1, DecreaseAction}); 545 return result; 546 } 547 548 LegalizerInfo::SizeAndActionsVec 549 LegalizerInfo::decreaseToSmallerTypesAndIncreaseToSmallest( 550 const SizeAndActionsVec &v, LegalizeAction DecreaseAction, 551 LegalizeAction IncreaseAction) { 552 SizeAndActionsVec result; 553 if (v.size() == 0 || v[0].first != 1) 554 result.push_back({1, IncreaseAction}); 555 for (size_t i = 0; i < v.size(); ++i) { 556 result.push_back(v[i]); 557 if (i + 1 == v.size() || v[i + 1].first != v[i].first + 1) { 558 result.push_back({v[i].first + 1, DecreaseAction}); 559 } 560 } 561 return result; 562 } 563 564 LegalizerInfo::SizeAndAction 565 LegalizerInfo::findAction(const SizeAndActionsVec &Vec, const uint32_t Size) { 566 assert(Size >= 1); 567 // Find the last element in Vec that has a bitsize equal to or smaller than 568 // the requested bit size. 569 // That is the element just before the first element that is bigger than Size. 570 auto It = partition_point( 571 Vec, [=](const SizeAndAction &A) { return A.first <= Size; }); 572 assert(It != Vec.begin() && "Does Vec not start with size 1?"); 573 int VecIdx = It - Vec.begin() - 1; 574 575 LegalizeAction Action = Vec[VecIdx].second; 576 switch (Action) { 577 case Legal: 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 bool LegalizerInfo::legalizeIntrinsic(MachineInstr &MI, 685 MachineRegisterInfo &MRI, 686 MachineIRBuilder &MIRBuilder) const { 687 return true; 688 } 689 690 unsigned LegalizerInfo::getExtOpcodeForWideningConstant(LLT SmallTy) const { 691 return SmallTy.isByteSized() ? TargetOpcode::G_SEXT : TargetOpcode::G_ZEXT; 692 } 693 694 /// \pre Type indices of every opcode form a dense set starting from 0. 695 void LegalizerInfo::verify(const MCInstrInfo &MII) const { 696 #ifndef NDEBUG 697 std::vector<unsigned> FailedOpcodes; 698 for (unsigned Opcode = FirstOp; Opcode <= LastOp; ++Opcode) { 699 const MCInstrDesc &MCID = MII.get(Opcode); 700 const unsigned NumTypeIdxs = std::accumulate( 701 MCID.opInfo_begin(), MCID.opInfo_end(), 0U, 702 [](unsigned Acc, const MCOperandInfo &OpInfo) { 703 return OpInfo.isGenericType() 704 ? std::max(OpInfo.getGenericTypeIndex() + 1U, Acc) 705 : Acc; 706 }); 707 const unsigned NumImmIdxs = std::accumulate( 708 MCID.opInfo_begin(), MCID.opInfo_end(), 0U, 709 [](unsigned Acc, const MCOperandInfo &OpInfo) { 710 return OpInfo.isGenericImm() 711 ? std::max(OpInfo.getGenericImmIndex() + 1U, Acc) 712 : Acc; 713 }); 714 LLVM_DEBUG(dbgs() << MII.getName(Opcode) << " (opcode " << Opcode 715 << "): " << NumTypeIdxs << " type ind" 716 << (NumTypeIdxs == 1 ? "ex" : "ices") << ", " 717 << NumImmIdxs << " imm ind" 718 << (NumImmIdxs == 1 ? "ex" : "ices") << "\n"); 719 const LegalizeRuleSet &RuleSet = getActionDefinitions(Opcode); 720 if (!RuleSet.verifyTypeIdxsCoverage(NumTypeIdxs)) 721 FailedOpcodes.push_back(Opcode); 722 else if (!RuleSet.verifyImmIdxsCoverage(NumImmIdxs)) 723 FailedOpcodes.push_back(Opcode); 724 } 725 if (!FailedOpcodes.empty()) { 726 errs() << "The following opcodes have ill-defined legalization rules:"; 727 for (unsigned Opcode : FailedOpcodes) 728 errs() << " " << MII.getName(Opcode); 729 errs() << "\n"; 730 731 report_fatal_error("ill-defined LegalizerInfo" 732 ", try -debug-only=legalizer-info for details"); 733 } 734 #endif 735 } 736 737 #ifndef NDEBUG 738 // FIXME: This should be in the MachineVerifier, but it can't use the 739 // LegalizerInfo as it's currently in the separate GlobalISel library. 740 // Note that RegBankSelected property already checked in the verifier 741 // has the same layering problem, but we only use inline methods so 742 // end up not needing to link against the GlobalISel library. 743 const MachineInstr *llvm::machineFunctionIsIllegal(const MachineFunction &MF) { 744 if (const LegalizerInfo *MLI = MF.getSubtarget().getLegalizerInfo()) { 745 const MachineRegisterInfo &MRI = MF.getRegInfo(); 746 for (const MachineBasicBlock &MBB : MF) 747 for (const MachineInstr &MI : MBB) 748 if (isPreISelGenericOpcode(MI.getOpcode()) && 749 !MLI->isLegalOrCustom(MI, MRI)) 750 return &MI; 751 } 752 return nullptr; 753 } 754 #endif 755