lib/CodeGen/GlobalISel/LegalizerInfo.cpp

   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   LLVM_DEBUG(dbgs() << ".. the first uncovered type index: " << FirstUncovered
 219                     << ", " << (AllCovered ? "OK" : "FAIL") << "\n");
 220   return AllCovered;
 221 #else
 222   return true;
 223 #endif
 224 }
 225
 226 LegalizerInfo::LegalizerInfo() : TablesInitialized(false) {
 227   // Set defaults.
 228   // FIXME: these two (G_ANYEXT and G_TRUNC?) can be legalized to the
 229   // fundamental load/store Jakob proposed. Once loads & stores are supported.
 230   setScalarAction(TargetOpcode::G_ANYEXT, 1, {{1, Legal}});
 231   setScalarAction(TargetOpcode::G_ZEXT, 1, {{1, Legal}});
 232   setScalarAction(TargetOpcode::G_SEXT, 1, {{1, Legal}});
 233   setScalarAction(TargetOpcode::G_TRUNC, 0, {{1, Legal}});
 234   setScalarAction(TargetOpcode::G_TRUNC, 1, {{1, Legal}});
 235
 236   setScalarAction(TargetOpcode::G_INTRINSIC, 0, {{1, Legal}});
 237   setScalarAction(TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS, 0, {{1, Legal}});
 238
 239   setLegalizeScalarToDifferentSizeStrategy(
 240       TargetOpcode::G_IMPLICIT_DEF, 0, narrowToSmallerAndUnsupportedIfTooSmall);
 241   setLegalizeScalarToDifferentSizeStrategy(
 242       TargetOpcode::G_ADD, 0, widenToLargerTypesAndNarrowToLargest);
 243   setLegalizeScalarToDifferentSizeStrategy(
 244       TargetOpcode::G_OR, 0, widenToLargerTypesAndNarrowToLargest);
 245   setLegalizeScalarToDifferentSizeStrategy(
 246       TargetOpcode::G_LOAD, 0, narrowToSmallerAndUnsupportedIfTooSmall);
 247   setLegalizeScalarToDifferentSizeStrategy(
 248       TargetOpcode::G_STORE, 0, narrowToSmallerAndUnsupportedIfTooSmall);
 249
 250   setLegalizeScalarToDifferentSizeStrategy(
 251       TargetOpcode::G_BRCOND, 0, widenToLargerTypesUnsupportedOtherwise);
 252   setLegalizeScalarToDifferentSizeStrategy(
 253       TargetOpcode::G_INSERT, 0, narrowToSmallerAndUnsupportedIfTooSmall);
 254   setLegalizeScalarToDifferentSizeStrategy(
 255       TargetOpcode::G_EXTRACT, 0, narrowToSmallerAndUnsupportedIfTooSmall);
 256   setLegalizeScalarToDifferentSizeStrategy(
 257       TargetOpcode::G_EXTRACT, 1, narrowToSmallerAndUnsupportedIfTooSmall);
 258   setScalarAction(TargetOpcode::G_FNEG, 0, {{1, Lower}});
 259 }
 260
 261 void LegalizerInfo::computeTables() {
 262   assert(TablesInitialized == false);
 263
 264   for (unsigned OpcodeIdx = 0; OpcodeIdx <= LastOp - FirstOp; ++OpcodeIdx) {
 265     const unsigned Opcode = FirstOp + OpcodeIdx;
 266     for (unsigned TypeIdx = 0; TypeIdx != SpecifiedActions[OpcodeIdx].size();
 267          ++TypeIdx) {
 268       // 0. Collect information specified through the setAction API, i.e.
 269       // for specific bit sizes.
 270       // For scalar types:
 271       SizeAndActionsVec ScalarSpecifiedActions;
 272       // For pointer types:
 273       std::map<uint16_t, SizeAndActionsVec> AddressSpace2SpecifiedActions;
 274       // For vector types:
 275       std::map<uint16_t, SizeAndActionsVec> ElemSize2SpecifiedActions;
 276       for (auto LLT2Action : SpecifiedActions[OpcodeIdx][TypeIdx]) {
 277         const LLT Type = LLT2Action.first;
 278         const LegalizeAction Action = LLT2Action.second;
 279
 280         auto SizeAction = std::make_pair(Type.getSizeInBits(), Action);
 281         if (Type.isPointer())
 282           AddressSpace2SpecifiedActions[Type.getAddressSpace()].push_back(
 283               SizeAction);
 284         else if (Type.isVector())
 285           ElemSize2SpecifiedActions[Type.getElementType().getSizeInBits()]
 286               .push_back(SizeAction);
 287         else
 288           ScalarSpecifiedActions.push_back(SizeAction);
 289       }
 290
 291       // 1. Handle scalar types
 292       {
 293         // Decide how to handle bit sizes for which no explicit specification
 294         // was given.
 295         SizeChangeStrategy S = &unsupportedForDifferentSizes;
 296         if (TypeIdx < ScalarSizeChangeStrategies[OpcodeIdx].size() &&
 297             ScalarSizeChangeStrategies[OpcodeIdx][TypeIdx] != nullptr)
 298           S = ScalarSizeChangeStrategies[OpcodeIdx][TypeIdx];
 299         llvm::sort(ScalarSpecifiedActions);
 300         checkPartialSizeAndActionsVector(ScalarSpecifiedActions);
 301         setScalarAction(Opcode, TypeIdx, S(ScalarSpecifiedActions));
 302       }
 303
 304       // 2. Handle pointer types
 305       for (auto PointerSpecifiedActions : AddressSpace2SpecifiedActions) {
 306         llvm::sort(PointerSpecifiedActions.second);
 307         checkPartialSizeAndActionsVector(PointerSpecifiedActions.second);
 308         // For pointer types, we assume that there isn't a meaningfull way
 309         // to change the number of bits used in the pointer.
 310         setPointerAction(
 311             Opcode, TypeIdx, PointerSpecifiedActions.first,
 312             unsupportedForDifferentSizes(PointerSpecifiedActions.second));
 313       }
 314
 315       // 3. Handle vector types
 316       SizeAndActionsVec ElementSizesSeen;
 317       for (auto VectorSpecifiedActions : ElemSize2SpecifiedActions) {
 318         llvm::sort(VectorSpecifiedActions.second);
 319         const uint16_t ElementSize = VectorSpecifiedActions.first;
 320         ElementSizesSeen.push_back({ElementSize, Legal});
 321         checkPartialSizeAndActionsVector(VectorSpecifiedActions.second);
 322         // For vector types, we assume that the best way to adapt the number
 323         // of elements is to the next larger number of elements type for which
 324         // the vector type is legal, unless there is no such type. In that case,
 325         // legalize towards a vector type with a smaller number of elements.
 326         SizeAndActionsVec NumElementsActions;
 327         for (SizeAndAction BitsizeAndAction : VectorSpecifiedActions.second) {
 328           assert(BitsizeAndAction.first % ElementSize == 0);
 329           const uint16_t NumElements = BitsizeAndAction.first / ElementSize;
 330           NumElementsActions.push_back({NumElements, BitsizeAndAction.second});
 331         }
 332         setVectorNumElementAction(
 333             Opcode, TypeIdx, ElementSize,
 334             moreToWiderTypesAndLessToWidest(NumElementsActions));
 335       }
 336       llvm::sort(ElementSizesSeen);
 337       SizeChangeStrategy VectorElementSizeChangeStrategy =
 338           &unsupportedForDifferentSizes;
 339       if (TypeIdx < VectorElementSizeChangeStrategies[OpcodeIdx].size() &&
 340           VectorElementSizeChangeStrategies[OpcodeIdx][TypeIdx] != nullptr)
 341         VectorElementSizeChangeStrategy =
 342             VectorElementSizeChangeStrategies[OpcodeIdx][TypeIdx];
 343       setScalarInVectorAction(
 344           Opcode, TypeIdx, VectorElementSizeChangeStrategy(ElementSizesSeen));
 345     }
 346   }
 347
 348   TablesInitialized = true;
 349 }
 350
 351 // FIXME: inefficient implementation for now. Without ComputeValueVTs we're
 352 // probably going to need specialized lookup structures for various types before
 353 // we have any hope of doing well with something like <13 x i3>. Even the common
 354 // cases should do better than what we have now.
 355 std::pair<LegalizeAction, LLT>
 356 LegalizerInfo::getAspectAction(const InstrAspect &Aspect) const {
 357   assert(TablesInitialized && "backend forgot to call computeTables");
 358   // These *have* to be implemented for now, they're the fundamental basis of
 359   // how everything else is transformed.
 360   if (Aspect.Type.isScalar() || Aspect.Type.isPointer())
 361     return findScalarLegalAction(Aspect);
 362   assert(Aspect.Type.isVector());
 363   return findVectorLegalAction(Aspect);
 364 }
 365
 366 /// Helper function to get LLT for the given type index.
 367 static LLT getTypeFromTypeIdx(const MachineInstr &MI,
 368                               const MachineRegisterInfo &MRI, unsigned OpIdx,
 369                               unsigned TypeIdx) {
 370   assert(TypeIdx < MI.getNumOperands() && "Unexpected TypeIdx");
 371   // G_UNMERGE_VALUES has variable number of operands, but there is only
 372   // one source type and one destination type as all destinations must be the
 373   // same type. So, get the last operand if TypeIdx == 1.
 374   if (MI.getOpcode() == TargetOpcode::G_UNMERGE_VALUES && TypeIdx == 1)
 375     return MRI.getType(MI.getOperand(MI.getNumOperands() - 1).getReg());
 376   return MRI.getType(MI.getOperand(OpIdx).getReg());
 377 }
 378
 379 unsigned LegalizerInfo::getOpcodeIdxForOpcode(unsigned Opcode) const {
 380   assert(Opcode >= FirstOp && Opcode <= LastOp && "Unsupported opcode");
 381   return Opcode - FirstOp;
 382 }
 383
 384 unsigned LegalizerInfo::getActionDefinitionsIdx(unsigned Opcode) const {
 385   unsigned OpcodeIdx = getOpcodeIdxForOpcode(Opcode);
 386   if (unsigned Alias = RulesForOpcode[OpcodeIdx].getAlias()) {
 387     LLVM_DEBUG(dbgs() << ".. opcode " << Opcode << " is aliased to " << Alias
 388                       << "\n");
 389     OpcodeIdx = getOpcodeIdxForOpcode(Alias);
 390     LLVM_DEBUG(dbgs() << ".. opcode " << Alias << " is aliased to "
 391                       << RulesForOpcode[OpcodeIdx].getAlias() << "\n");
 392     assert(RulesForOpcode[OpcodeIdx].getAlias() == 0 && "Cannot chain aliases");
 393   }
 394
 395   return OpcodeIdx;
 396 }
 397
 398 const LegalizeRuleSet &
 399 LegalizerInfo::getActionDefinitions(unsigned Opcode) const {
 400   unsigned OpcodeIdx = getActionDefinitionsIdx(Opcode);
 401   return RulesForOpcode[OpcodeIdx];
 402 }
 403
 404 LegalizeRuleSet &LegalizerInfo::getActionDefinitionsBuilder(unsigned Opcode) {
 405   unsigned OpcodeIdx = getActionDefinitionsIdx(Opcode);
 406   auto &Result = RulesForOpcode[OpcodeIdx];
 407   assert(!Result.isAliasedByAnother() && "Modifying this opcode will modify aliases");
 408   return Result;
 409 }
 410
 411 LegalizeRuleSet &LegalizerInfo::getActionDefinitionsBuilder(
 412     std::initializer_list<unsigned> Opcodes) {
 413   unsigned Representative = *Opcodes.begin();
 414
 415   assert(!empty(Opcodes) && Opcodes.begin() + 1 != Opcodes.end() &&
 416          "Initializer list must have at least two opcodes");
 417
 418   for (auto I = Opcodes.begin() + 1, E = Opcodes.end(); I != E; ++I)
 419     aliasActionDefinitions(Representative, *I);
 420
 421   auto &Return = getActionDefinitionsBuilder(Representative);
 422   Return.setIsAliasedByAnother();
 423   return Return;
 424 }
 425
 426 void LegalizerInfo::aliasActionDefinitions(unsigned OpcodeTo,
 427                                            unsigned OpcodeFrom) {
 428   assert(OpcodeTo != OpcodeFrom && "Cannot alias to self");
 429   assert(OpcodeTo >= FirstOp && OpcodeTo <= LastOp && "Unsupported opcode");
 430   const unsigned OpcodeFromIdx = getOpcodeIdxForOpcode(OpcodeFrom);
 431   RulesForOpcode[OpcodeFromIdx].aliasTo(OpcodeTo);
 432 }
 433
 434 LegalizeActionStep
 435 LegalizerInfo::getAction(const LegalityQuery &Query) const {
 436   LegalizeActionStep Step = getActionDefinitions(Query.Opcode).apply(Query);
 437   if (Step.Action != LegalizeAction::UseLegacyRules) {
 438     return Step;
 439   }
 440
 441   for (unsigned i = 0; i < Query.Types.size(); ++i) {
 442     auto Action = getAspectAction({Query.Opcode, i, Query.Types[i]});
 443     if (Action.first != Legal) {
 444       LLVM_DEBUG(dbgs() << ".. (legacy) Type " << i << " Action="
 445                         << Action.first << ", " << Action.second << "\n");
 446       return {Action.first, i, Action.second};
 447     } else
 448       LLVM_DEBUG(dbgs() << ".. (legacy) Type " << i << " Legal\n");
 449   }
 450   LLVM_DEBUG(dbgs() << ".. (legacy) Legal\n");
 451   return {Legal, 0, LLT{}};
 452 }
 453
 454 LegalizeActionStep
 455 LegalizerInfo::getAction(const MachineInstr &MI,
 456                          const MachineRegisterInfo &MRI) const {
 457   SmallVector<LLT, 2> Types;
 458   SmallBitVector SeenTypes(8);
 459   const MCOperandInfo *OpInfo = MI.getDesc().OpInfo;
 460   // FIXME: probably we'll need to cache the results here somehow?
 461   for (unsigned i = 0; i < MI.getDesc().getNumOperands(); ++i) {
 462     if (!OpInfo[i].isGenericType())
 463       continue;
 464
 465     // We must only record actions once for each TypeIdx; otherwise we'd
 466     // try to legalize operands multiple times down the line.
 467     unsigned TypeIdx = OpInfo[i].getGenericTypeIndex();
 468     if (SeenTypes[TypeIdx])
 469       continue;
 470
 471     SeenTypes.set(TypeIdx);
 472
 473     LLT Ty = getTypeFromTypeIdx(MI, MRI, i, TypeIdx);
 474     Types.push_back(Ty);
 475   }
 476
 477   SmallVector<LegalityQuery::MemDesc, 2> MemDescrs;
 478   for (const auto &MMO : MI.memoperands())
 479     MemDescrs.push_back({8 * MMO->getSize() /* in bits */,
 480                          8 * MMO->getAlignment(),
 481                          MMO->getOrdering()});
 482
 483   return getAction({MI.getOpcode(), Types, MemDescrs});
 484 }
 485
 486 bool LegalizerInfo::isLegal(const MachineInstr &MI,
 487                             const MachineRegisterInfo &MRI) const {
 488   return getAction(MI, MRI).Action == Legal;
 489 }
 490
 491 bool LegalizerInfo::isLegalOrCustom(const MachineInstr &MI,
 492                                     const MachineRegisterInfo &MRI) const {
 493   auto Action = getAction(MI, MRI).Action;
 494   // If the action is custom, it may not necessarily modify the instruction,
 495   // so we have to assume it's legal.
 496   return Action == Legal || Action == Custom;
 497 }
 498
 499 bool LegalizerInfo::legalizeCustom(MachineInstr &MI, MachineRegisterInfo &MRI,
 500                                    MachineIRBuilder &MIRBuilder,
 501                                    GISelChangeObserver &Observer) const {
 502   return false;
 503 }
 504
 505 LegalizerInfo::SizeAndActionsVec
 506 LegalizerInfo::increaseToLargerTypesAndDecreaseToLargest(
 507     const SizeAndActionsVec &v, LegalizeAction IncreaseAction,
 508     LegalizeAction DecreaseAction) {
 509   SizeAndActionsVec result;
 510   unsigned LargestSizeSoFar = 0;
 511   if (v.size() >= 1 && v[0].first != 1)
 512     result.push_back({1, IncreaseAction});
 513   for (size_t i = 0; i < v.size(); ++i) {
 514     result.push_back(v[i]);
 515     LargestSizeSoFar = v[i].first;
 516     if (i + 1 < v.size() && v[i + 1].first != v[i].first + 1) {
 517       result.push_back({LargestSizeSoFar + 1, IncreaseAction});
 518       LargestSizeSoFar = v[i].first + 1;
 519     }
 520   }
 521   result.push_back({LargestSizeSoFar + 1, DecreaseAction});
 522   return result;
 523 }
 524
 525 LegalizerInfo::SizeAndActionsVec
 526 LegalizerInfo::decreaseToSmallerTypesAndIncreaseToSmallest(
 527     const SizeAndActionsVec &v, LegalizeAction DecreaseAction,
 528     LegalizeAction IncreaseAction) {
 529   SizeAndActionsVec result;
 530   if (v.size() == 0 || v[0].first != 1)
 531     result.push_back({1, IncreaseAction});
 532   for (size_t i = 0; i < v.size(); ++i) {
 533     result.push_back(v[i]);
 534     if (i + 1 == v.size() || v[i + 1].first != v[i].first + 1) {
 535       result.push_back({v[i].first + 1, DecreaseAction});
 536     }
 537   }
 538   return result;
 539 }
 540
 541 LegalizerInfo::SizeAndAction
 542 LegalizerInfo::findAction(const SizeAndActionsVec &Vec, const uint32_t Size) {
 543   assert(Size >= 1);
 544   // Find the last element in Vec that has a bitsize equal to or smaller than
 545   // the requested bit size.
 546   // That is the element just before the first element that is bigger than Size.
 547   auto It = partition_point(
 548       Vec, [=](const SizeAndAction &A) { return A.first <= Size; });
 549   assert(It != Vec.begin() && "Does Vec not start with size 1?");
 550   int VecIdx = It - Vec.begin() - 1;
 551
 552   LegalizeAction Action = Vec[VecIdx].second;
 553   switch (Action) {
 554   case Legal:
 555   case Lower:
 556   case Libcall:
 557   case Custom:
 558     return {Size, Action};
 559   case FewerElements:
 560     // FIXME: is this special case still needed and correct?
 561     // Special case for scalarization:
 562     if (Vec == SizeAndActionsVec({{1, FewerElements}}))
 563       return {1, FewerElements};
 564     LLVM_FALLTHROUGH;
 565   case NarrowScalar: {
 566     // The following needs to be a loop, as for now, we do allow needing to
 567     // go over "Unsupported" bit sizes before finding a legalizable bit size.
 568     // e.g. (s8, WidenScalar), (s9, Unsupported), (s32, Legal). if Size==8,
 569     // we need to iterate over s9, and then to s32 to return (s32, Legal).
 570     // If we want to get rid of the below loop, we should have stronger asserts
 571     // when building the SizeAndActionsVecs, probably not allowing
 572     // "Unsupported" unless at the ends of the vector.
 573     for (int i = VecIdx - 1; i >= 0; --i)
 574       if (!needsLegalizingToDifferentSize(Vec[i].second) &&
 575           Vec[i].second != Unsupported)
 576         return {Vec[i].first, Action};
 577     llvm_unreachable("");
 578   }
 579   case WidenScalar:
 580   case MoreElements: {
 581     // See above, the following needs to be a loop, at least for now.
 582     for (std::size_t i = VecIdx + 1; i < Vec.size(); ++i)
 583       if (!needsLegalizingToDifferentSize(Vec[i].second) &&
 584           Vec[i].second != Unsupported)
 585         return {Vec[i].first, Action};
 586     llvm_unreachable("");
 587   }
 588   case Unsupported:
 589     return {Size, Unsupported};
 590   case NotFound:
 591   case UseLegacyRules:
 592     llvm_unreachable("NotFound");
 593   }
 594   llvm_unreachable("Action has an unknown enum value");
 595 }
 596
 597 std::pair<LegalizeAction, LLT>
 598 LegalizerInfo::findScalarLegalAction(const InstrAspect &Aspect) const {
 599   assert(Aspect.Type.isScalar() || Aspect.Type.isPointer());
 600   if (Aspect.Opcode < FirstOp || Aspect.Opcode > LastOp)
 601     return {NotFound, LLT()};
 602   const unsigned OpcodeIdx = getOpcodeIdxForOpcode(Aspect.Opcode);
 603   if (Aspect.Type.isPointer() &&
 604       AddrSpace2PointerActions[OpcodeIdx].find(Aspect.Type.getAddressSpace()) ==
 605           AddrSpace2PointerActions[OpcodeIdx].end()) {
 606     return {NotFound, LLT()};
 607   }
 608   const SmallVector<SizeAndActionsVec, 1> &Actions =
 609       Aspect.Type.isPointer()
 610           ? AddrSpace2PointerActions[OpcodeIdx]
 611                 .find(Aspect.Type.getAddressSpace())
 612                 ->second
 613           : ScalarActions[OpcodeIdx];
 614   if (Aspect.Idx >= Actions.size())
 615     return {NotFound, LLT()};
 616   const SizeAndActionsVec &Vec = Actions[Aspect.Idx];
 617   // FIXME: speed up this search, e.g. by using a results cache for repeated
 618   // queries?
 619   auto SizeAndAction = findAction(Vec, Aspect.Type.getSizeInBits());
 620   return {SizeAndAction.second,
 621           Aspect.Type.isScalar() ? LLT::scalar(SizeAndAction.first)
 622                                  : LLT::pointer(Aspect.Type.getAddressSpace(),
 623                                                 SizeAndAction.first)};
 624 }
 625
 626 std::pair<LegalizeAction, LLT>
 627 LegalizerInfo::findVectorLegalAction(const InstrAspect &Aspect) const {
 628   assert(Aspect.Type.isVector());
 629   // First legalize the vector element size, then legalize the number of
 630   // lanes in the vector.
 631   if (Aspect.Opcode < FirstOp || Aspect.Opcode > LastOp)
 632     return {NotFound, Aspect.Type};
 633   const unsigned OpcodeIdx = getOpcodeIdxForOpcode(Aspect.Opcode);
 634   const unsigned TypeIdx = Aspect.Idx;
 635   if (TypeIdx >= ScalarInVectorActions[OpcodeIdx].size())
 636     return {NotFound, Aspect.Type};
 637   const SizeAndActionsVec &ElemSizeVec =
 638       ScalarInVectorActions[OpcodeIdx][TypeIdx];
 639
 640   LLT IntermediateType;
 641   auto ElementSizeAndAction =
 642       findAction(ElemSizeVec, Aspect.Type.getScalarSizeInBits());
 643   IntermediateType =
 644       LLT::vector(Aspect.Type.getNumElements(), ElementSizeAndAction.first);
 645   if (ElementSizeAndAction.second != Legal)
 646     return {ElementSizeAndAction.second, IntermediateType};
 647
 648   auto i = NumElements2Actions[OpcodeIdx].find(
 649       IntermediateType.getScalarSizeInBits());
 650   if (i == NumElements2Actions[OpcodeIdx].end()) {
 651     return {NotFound, IntermediateType};
 652   }
 653   const SizeAndActionsVec &NumElementsVec = (*i).second[TypeIdx];
 654   auto NumElementsAndAction =
 655       findAction(NumElementsVec, IntermediateType.getNumElements());
 656   return {NumElementsAndAction.second,
 657           LLT::vector(NumElementsAndAction.first,
 658                       IntermediateType.getScalarSizeInBits())};
 659 }
 660
 661 bool LegalizerInfo::legalizeIntrinsic(MachineInstr &MI,
 662                                       MachineRegisterInfo &MRI,
 663                                       MachineIRBuilder &MIRBuilder) const {
 664   return true;
 665 }
 666
 667 /// \pre Type indices of every opcode form a dense set starting from 0.
 668 void LegalizerInfo::verify(const MCInstrInfo &MII) const {
 669 #ifndef NDEBUG
 670   std::vector<unsigned> FailedOpcodes;
 671   for (unsigned Opcode = FirstOp; Opcode <= LastOp; ++Opcode) {
 672     const MCInstrDesc &MCID = MII.get(Opcode);
 673     const unsigned NumTypeIdxs = std::accumulate(
 674         MCID.opInfo_begin(), MCID.opInfo_end(), 0U,
 675         [](unsigned Acc, const MCOperandInfo &OpInfo) {
 676           return OpInfo.isGenericType()
 677                      ? std::max(OpInfo.getGenericTypeIndex() + 1U, Acc)
 678                      : Acc;
 679         });
 680     LLVM_DEBUG(dbgs() << MII.getName(Opcode) << " (opcode " << Opcode
 681                       << "): " << NumTypeIdxs << " type ind"
 682                       << (NumTypeIdxs == 1 ? "ex" : "ices") << "\n");
 683     const LegalizeRuleSet &RuleSet = getActionDefinitions(Opcode);
 684     if (!RuleSet.verifyTypeIdxsCoverage(NumTypeIdxs))
 685       FailedOpcodes.push_back(Opcode);
 686   }
 687   if (!FailedOpcodes.empty()) {
 688     errs() << "The following opcodes have ill-defined legalization rules:";
 689     for (unsigned Opcode : FailedOpcodes)
 690       errs() << " " << MII.getName(Opcode);
 691     errs() << "\n";
 692
 693     report_fatal_error("ill-defined LegalizerInfo"
 694                        ", try -debug-only=legalizer-info for details");
 695   }
 696 #endif
 697 }
 698
 699 #ifndef NDEBUG
 700 // FIXME: This should be in the MachineVerifier, but it can't use the
 701 // LegalizerInfo as it's currently in the separate GlobalISel library.
 702 // Note that RegBankSelected property already checked in the verifier
 703 // has the same layering problem, but we only use inline methods so
 704 // end up not needing to link against the GlobalISel library.
 705 const MachineInstr *llvm::machineFunctionIsIllegal(const MachineFunction &MF) {
 706   if (const LegalizerInfo *MLI = MF.getSubtarget().getLegalizerInfo()) {
 707     const MachineRegisterInfo &MRI = MF.getRegInfo();
 708     for (const MachineBasicBlock &MBB : MF)
 709       for (const MachineInstr &MI : MBB)
 710         if (isPreISelGenericOpcode(MI.getOpcode()) &&
 711             !MLI->isLegalOrCustom(MI, MRI))
 712           return &MI;
 713   }
 714   return nullptr;
 715 }
 716 #endif