| //===- lib/CodeGen/GlobalISel/LegalizerInfo.cpp - Legalizer ---------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // Implement an interface to specify and query how an illegal operation on a |
| // given type should be expanded. |
| // |
| // Issues to be resolved: |
| // + Make it fast. |
| // + Support weird types like i3, <7 x i3>, ... |
| // + Operations with more than one type (ICMP, CMPXCHG, intrinsics, ...) |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/CodeGen/GlobalISel/LegalizerInfo.h" |
| #include "llvm/ADT/SmallBitVector.h" |
| #include "llvm/CodeGen/MachineInstr.h" |
| #include "llvm/CodeGen/MachineOperand.h" |
| #include "llvm/CodeGen/MachineRegisterInfo.h" |
| #include "llvm/MC/MCInstrDesc.h" |
| #include "llvm/Support/ErrorHandling.h" |
| #include "llvm/Support/LowLevelTypeImpl.h" |
| #include "llvm/Support/MathExtras.h" |
| #include "llvm/Target/TargetOpcodes.h" |
| #include <algorithm> |
| #include <map> |
| using namespace llvm; |
| |
| LegalizerInfo::LegalizerInfo() : TablesInitialized(false) { |
| // Set defaults. |
| // FIXME: these two (G_ANYEXT and G_TRUNC?) can be legalized to the |
| // fundamental load/store Jakob proposed. Once loads & stores are supported. |
| setScalarAction(TargetOpcode::G_ANYEXT, 1, {{1, Legal}}); |
| setScalarAction(TargetOpcode::G_ZEXT, 1, {{1, Legal}}); |
| setScalarAction(TargetOpcode::G_SEXT, 1, {{1, Legal}}); |
| setScalarAction(TargetOpcode::G_TRUNC, 0, {{1, Legal}}); |
| setScalarAction(TargetOpcode::G_TRUNC, 1, {{1, Legal}}); |
| |
| setScalarAction(TargetOpcode::G_INTRINSIC, 0, {{1, Legal}}); |
| setScalarAction(TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS, 0, {{1, Legal}}); |
| |
| setLegalizeScalarToDifferentSizeStrategy( |
| TargetOpcode::G_IMPLICIT_DEF, 0, narrowToSmallerAndUnsupportedIfTooSmall); |
| setLegalizeScalarToDifferentSizeStrategy( |
| TargetOpcode::G_ADD, 0, widenToLargerTypesAndNarrowToLargest); |
| setLegalizeScalarToDifferentSizeStrategy( |
| TargetOpcode::G_OR, 0, widenToLargerTypesAndNarrowToLargest); |
| setLegalizeScalarToDifferentSizeStrategy( |
| TargetOpcode::G_LOAD, 0, narrowToSmallerAndUnsupportedIfTooSmall); |
| setLegalizeScalarToDifferentSizeStrategy( |
| TargetOpcode::G_STORE, 0, narrowToSmallerAndUnsupportedIfTooSmall); |
| |
| setLegalizeScalarToDifferentSizeStrategy( |
| TargetOpcode::G_BRCOND, 0, widenToLargerTypesUnsupportedOtherwise); |
| setLegalizeScalarToDifferentSizeStrategy( |
| TargetOpcode::G_INSERT, 0, narrowToSmallerAndUnsupportedIfTooSmall); |
| setLegalizeScalarToDifferentSizeStrategy( |
| TargetOpcode::G_EXTRACT, 0, narrowToSmallerAndUnsupportedIfTooSmall); |
| setLegalizeScalarToDifferentSizeStrategy( |
| TargetOpcode::G_EXTRACT, 1, narrowToSmallerAndUnsupportedIfTooSmall); |
| setScalarAction(TargetOpcode::G_FNEG, 0, {{1, Lower}}); |
| } |
| |
| void LegalizerInfo::computeTables() { |
| assert(TablesInitialized == false); |
| |
| for (unsigned OpcodeIdx = 0; OpcodeIdx <= LastOp - FirstOp; ++OpcodeIdx) { |
| const unsigned Opcode = FirstOp + OpcodeIdx; |
| for (unsigned TypeIdx = 0; TypeIdx != SpecifiedActions[OpcodeIdx].size(); |
| ++TypeIdx) { |
| // 0. Collect information specified through the setAction API, i.e. |
| // for specific bit sizes. |
| // For scalar types: |
| SizeAndActionsVec ScalarSpecifiedActions; |
| // For pointer types: |
| std::map<uint16_t, SizeAndActionsVec> AddressSpace2SpecifiedActions; |
| // For vector types: |
| std::map<uint16_t, SizeAndActionsVec> ElemSize2SpecifiedActions; |
| for (auto LLT2Action : SpecifiedActions[OpcodeIdx][TypeIdx]) { |
| const LLT Type = LLT2Action.first; |
| const LegalizeAction Action = LLT2Action.second; |
| |
| auto SizeAction = std::make_pair(Type.getSizeInBits(), Action); |
| if (Type.isPointer()) |
| AddressSpace2SpecifiedActions[Type.getAddressSpace()].push_back( |
| SizeAction); |
| else if (Type.isVector()) |
| ElemSize2SpecifiedActions[Type.getElementType().getSizeInBits()] |
| .push_back(SizeAction); |
| else |
| ScalarSpecifiedActions.push_back(SizeAction); |
| } |
| |
| // 1. Handle scalar types |
| { |
| // Decide how to handle bit sizes for which no explicit specification |
| // was given. |
| SizeChangeStrategy S = &unsupportedForDifferentSizes; |
| if (TypeIdx < ScalarSizeChangeStrategies[OpcodeIdx].size() && |
| ScalarSizeChangeStrategies[OpcodeIdx][TypeIdx] != nullptr) |
| S = ScalarSizeChangeStrategies[OpcodeIdx][TypeIdx]; |
| std::sort(ScalarSpecifiedActions.begin(), ScalarSpecifiedActions.end()); |
| checkPartialSizeAndActionsVector(ScalarSpecifiedActions); |
| setScalarAction(Opcode, TypeIdx, S(ScalarSpecifiedActions)); |
| } |
| |
| // 2. Handle pointer types |
| for (auto PointerSpecifiedActions : AddressSpace2SpecifiedActions) { |
| std::sort(PointerSpecifiedActions.second.begin(), |
| PointerSpecifiedActions.second.end()); |
| checkPartialSizeAndActionsVector(PointerSpecifiedActions.second); |
| // For pointer types, we assume that there isn't a meaningfull way |
| // to change the number of bits used in the pointer. |
| setPointerAction( |
| Opcode, TypeIdx, PointerSpecifiedActions.first, |
| unsupportedForDifferentSizes(PointerSpecifiedActions.second)); |
| } |
| |
| // 3. Handle vector types |
| SizeAndActionsVec ElementSizesSeen; |
| for (auto VectorSpecifiedActions : ElemSize2SpecifiedActions) { |
| std::sort(VectorSpecifiedActions.second.begin(), |
| VectorSpecifiedActions.second.end()); |
| const uint16_t ElementSize = VectorSpecifiedActions.first; |
| ElementSizesSeen.push_back({ElementSize, Legal}); |
| checkPartialSizeAndActionsVector(VectorSpecifiedActions.second); |
| // For vector types, we assume that the best way to adapt the number |
| // of elements is to the next larger number of elements type for which |
| // the vector type is legal, unless there is no such type. In that case, |
| // legalize towards a vector type with a smaller number of elements. |
| SizeAndActionsVec NumElementsActions; |
| for (SizeAndAction BitsizeAndAction : VectorSpecifiedActions.second) { |
| assert(BitsizeAndAction.first % ElementSize == 0); |
| const uint16_t NumElements = BitsizeAndAction.first / ElementSize; |
| NumElementsActions.push_back({NumElements, BitsizeAndAction.second}); |
| } |
| setVectorNumElementAction( |
| Opcode, TypeIdx, ElementSize, |
| moreToWiderTypesAndLessToWidest(NumElementsActions)); |
| } |
| std::sort(ElementSizesSeen.begin(), ElementSizesSeen.end()); |
| SizeChangeStrategy VectorElementSizeChangeStrategy = |
| &unsupportedForDifferentSizes; |
| if (TypeIdx < VectorElementSizeChangeStrategies[OpcodeIdx].size() && |
| VectorElementSizeChangeStrategies[OpcodeIdx][TypeIdx] != nullptr) |
| VectorElementSizeChangeStrategy = |
| VectorElementSizeChangeStrategies[OpcodeIdx][TypeIdx]; |
| setScalarInVectorAction( |
| Opcode, TypeIdx, VectorElementSizeChangeStrategy(ElementSizesSeen)); |
| } |
| } |
| |
| TablesInitialized = true; |
| } |
| |
| // FIXME: inefficient implementation for now. Without ComputeValueVTs we're |
| // probably going to need specialized lookup structures for various types before |
| // we have any hope of doing well with something like <13 x i3>. Even the common |
| // cases should do better than what we have now. |
| std::pair<LegalizerInfo::LegalizeAction, LLT> |
| LegalizerInfo::getAction(const InstrAspect &Aspect) const { |
| assert(TablesInitialized && "backend forgot to call computeTables"); |
| // These *have* to be implemented for now, they're the fundamental basis of |
| // how everything else is transformed. |
| |
| // FIXME: the long-term plan calls for expansion in terms of load/store (if |
| // they're not legal). |
| if (Aspect.Opcode == TargetOpcode::G_MERGE_VALUES || |
| Aspect.Opcode == TargetOpcode::G_UNMERGE_VALUES) |
| return std::make_pair(Legal, Aspect.Type); |
| |
| if (Aspect.Type.isScalar() || Aspect.Type.isPointer()) |
| return findScalarLegalAction(Aspect); |
| assert(Aspect.Type.isVector()); |
| return findVectorLegalAction(Aspect); |
| } |
| |
| std::tuple<LegalizerInfo::LegalizeAction, unsigned, LLT> |
| LegalizerInfo::getAction(const MachineInstr &MI, |
| const MachineRegisterInfo &MRI) const { |
| SmallBitVector SeenTypes(8); |
| const MCOperandInfo *OpInfo = MI.getDesc().OpInfo; |
| // FIXME: probably we'll need to cache the results here somehow? |
| for (unsigned i = 0; i < MI.getDesc().getNumOperands(); ++i) { |
| if (!OpInfo[i].isGenericType()) |
| continue; |
| |
| // We must only record actions once for each TypeIdx; otherwise we'd |
| // try to legalize operands multiple times down the line. |
| unsigned TypeIdx = OpInfo[i].getGenericTypeIndex(); |
| if (SeenTypes[TypeIdx]) |
| continue; |
| |
| SeenTypes.set(TypeIdx); |
| |
| LLT Ty = MRI.getType(MI.getOperand(i).getReg()); |
| auto Action = getAction({MI.getOpcode(), TypeIdx, Ty}); |
| if (Action.first != Legal) |
| return std::make_tuple(Action.first, TypeIdx, Action.second); |
| } |
| return std::make_tuple(Legal, 0, LLT{}); |
| } |
| |
| bool LegalizerInfo::isLegal(const MachineInstr &MI, |
| const MachineRegisterInfo &MRI) const { |
| return std::get<0>(getAction(MI, MRI)) == Legal; |
| } |
| |
| bool LegalizerInfo::legalizeCustom(MachineInstr &MI, MachineRegisterInfo &MRI, |
| MachineIRBuilder &MIRBuilder) const { |
| return false; |
| } |
| |
| LegalizerInfo::SizeAndActionsVec |
| LegalizerInfo::increaseToLargerTypesAndDecreaseToLargest( |
| const SizeAndActionsVec &v, LegalizeAction IncreaseAction, |
| LegalizeAction DecreaseAction) { |
| SizeAndActionsVec result; |
| unsigned LargestSizeSoFar = 0; |
| if (v.size() >= 1 && v[0].first != 1) |
| result.push_back({1, IncreaseAction}); |
| for (size_t i = 0; i < v.size(); ++i) { |
| result.push_back(v[i]); |
| LargestSizeSoFar = v[i].first; |
| if (i + 1 < v.size() && v[i + 1].first != v[i].first + 1) { |
| result.push_back({LargestSizeSoFar + 1, IncreaseAction}); |
| LargestSizeSoFar = v[i].first + 1; |
| } |
| } |
| result.push_back({LargestSizeSoFar + 1, DecreaseAction}); |
| return result; |
| } |
| |
| LegalizerInfo::SizeAndActionsVec |
| LegalizerInfo::decreaseToSmallerTypesAndIncreaseToSmallest( |
| const SizeAndActionsVec &v, LegalizeAction DecreaseAction, |
| LegalizeAction IncreaseAction) { |
| SizeAndActionsVec result; |
| if (v.size() == 0 || v[0].first != 1) |
| result.push_back({1, IncreaseAction}); |
| for (size_t i = 0; i < v.size(); ++i) { |
| result.push_back(v[i]); |
| if (i + 1 == v.size() || v[i + 1].first != v[i].first + 1) { |
| result.push_back({v[i].first + 1, DecreaseAction}); |
| } |
| } |
| return result; |
| } |
| |
| LegalizerInfo::SizeAndAction |
| LegalizerInfo::findAction(const SizeAndActionsVec &Vec, const uint32_t Size) { |
| assert(Size >= 1); |
| // Find the last element in Vec that has a bitsize equal to or smaller than |
| // the requested bit size. |
| // That is the element just before the first element that is bigger than Size. |
| auto VecIt = std::upper_bound( |
| Vec.begin(), Vec.end(), Size, |
| [](const uint32_t Size, const SizeAndAction lhs) -> bool { |
| return Size < lhs.first; |
| }); |
| assert(VecIt != Vec.begin() && "Does Vec not start with size 1?"); |
| --VecIt; |
| int VecIdx = VecIt - Vec.begin(); |
| |
| LegalizeAction Action = Vec[VecIdx].second; |
| switch (Action) { |
| case Legal: |
| case Lower: |
| case Libcall: |
| case Custom: |
| return {Size, Action}; |
| case FewerElements: |
| // FIXME: is this special case still needed and correct? |
| // Special case for scalarization: |
| if (Vec == SizeAndActionsVec({{1, FewerElements}})) |
| return {1, FewerElements}; |
| LLVM_FALLTHROUGH; |
| case NarrowScalar: { |
| // The following needs to be a loop, as for now, we do allow needing to |
| // go over "Unsupported" bit sizes before finding a legalizable bit size. |
| // e.g. (s8, WidenScalar), (s9, Unsupported), (s32, Legal). if Size==8, |
| // we need to iterate over s9, and then to s32 to return (s32, Legal). |
| // If we want to get rid of the below loop, we should have stronger asserts |
| // when building the SizeAndActionsVecs, probably not allowing |
| // "Unsupported" unless at the ends of the vector. |
| for (int i = VecIdx - 1; i >= 0; --i) |
| if (!needsLegalizingToDifferentSize(Vec[i].second) && |
| Vec[i].second != Unsupported) |
| return {Vec[i].first, Action}; |
| llvm_unreachable(""); |
| } |
| case WidenScalar: |
| case MoreElements: { |
| // See above, the following needs to be a loop, at least for now. |
| for (std::size_t i = VecIdx + 1; i < Vec.size(); ++i) |
| if (!needsLegalizingToDifferentSize(Vec[i].second) && |
| Vec[i].second != Unsupported) |
| return {Vec[i].first, Action}; |
| llvm_unreachable(""); |
| } |
| case Unsupported: |
| return {Size, Unsupported}; |
| case NotFound: |
| llvm_unreachable("NotFound"); |
| } |
| llvm_unreachable("Action has an unknown enum value"); |
| } |
| |
| std::pair<LegalizerInfo::LegalizeAction, LLT> |
| LegalizerInfo::findScalarLegalAction(const InstrAspect &Aspect) const { |
| assert(Aspect.Type.isScalar() || Aspect.Type.isPointer()); |
| if (Aspect.Opcode < FirstOp || Aspect.Opcode > LastOp) |
| return {NotFound, LLT()}; |
| const unsigned OpcodeIdx = Aspect.Opcode - FirstOp; |
| if (Aspect.Type.isPointer() && |
| AddrSpace2PointerActions[OpcodeIdx].find(Aspect.Type.getAddressSpace()) == |
| AddrSpace2PointerActions[OpcodeIdx].end()) { |
| return {NotFound, LLT()}; |
| } |
| const SmallVector<SizeAndActionsVec, 1> &Actions = |
| Aspect.Type.isPointer() |
| ? AddrSpace2PointerActions[OpcodeIdx] |
| .find(Aspect.Type.getAddressSpace()) |
| ->second |
| : ScalarActions[OpcodeIdx]; |
| if (Aspect.Idx >= Actions.size()) |
| return {NotFound, LLT()}; |
| const SizeAndActionsVec &Vec = Actions[Aspect.Idx]; |
| // FIXME: speed up this search, e.g. by using a results cache for repeated |
| // queries? |
| auto SizeAndAction = findAction(Vec, Aspect.Type.getSizeInBits()); |
| return {SizeAndAction.second, |
| Aspect.Type.isScalar() ? LLT::scalar(SizeAndAction.first) |
| : LLT::pointer(Aspect.Type.getAddressSpace(), |
| SizeAndAction.first)}; |
| } |
| |
| std::pair<LegalizerInfo::LegalizeAction, LLT> |
| LegalizerInfo::findVectorLegalAction(const InstrAspect &Aspect) const { |
| assert(Aspect.Type.isVector()); |
| // First legalize the vector element size, then legalize the number of |
| // lanes in the vector. |
| if (Aspect.Opcode < FirstOp || Aspect.Opcode > LastOp) |
| return {NotFound, Aspect.Type}; |
| const unsigned OpcodeIdx = Aspect.Opcode - FirstOp; |
| const unsigned TypeIdx = Aspect.Idx; |
| if (TypeIdx >= ScalarInVectorActions[OpcodeIdx].size()) |
| return {NotFound, Aspect.Type}; |
| const SizeAndActionsVec &ElemSizeVec = |
| ScalarInVectorActions[OpcodeIdx][TypeIdx]; |
| |
| LLT IntermediateType; |
| auto ElementSizeAndAction = |
| findAction(ElemSizeVec, Aspect.Type.getScalarSizeInBits()); |
| IntermediateType = |
| LLT::vector(Aspect.Type.getNumElements(), ElementSizeAndAction.first); |
| if (ElementSizeAndAction.second != Legal) |
| return {ElementSizeAndAction.second, IntermediateType}; |
| |
| auto i = NumElements2Actions[OpcodeIdx].find( |
| IntermediateType.getScalarSizeInBits()); |
| if (i == NumElements2Actions[OpcodeIdx].end()) { |
| return {NotFound, IntermediateType}; |
| } |
| const SizeAndActionsVec &NumElementsVec = (*i).second[TypeIdx]; |
| auto NumElementsAndAction = |
| findAction(NumElementsVec, IntermediateType.getNumElements()); |
| return {NumElementsAndAction.second, |
| LLT::vector(NumElementsAndAction.first, |
| IntermediateType.getScalarSizeInBits())}; |
| } |