From fe183150a442da27c9f2982812dfc11f5be523e2 Mon Sep 17 00:00:00 2001 From: Kristof Beyls Date: Fri, 30 Jun 2017 08:26:20 +0000 Subject: [PATCH] [GlobalISel] Make multi-step legalization work. In r301116, a custom lowering needed to be introduced to be able to legalize 8 and 16-bit divisions on ARM targets without a division instruction, since 2-step legalization (WidenScalar from 8 bit to 32 bit, then Libcall the 32-bit division) doesn't work. This fixes this and makes this kind of multi-step legalization, where first the size of the type needs to be changed and then some action is needed that doesn't require changing the size of the type, straighforward to specify. Differential Revision: https://reviews.llvm.org/D32529 llvm-svn: 306806 --- .../llvm/CodeGen/GlobalISel/LegalizerInfo.h | 22 ++++++++--- lib/CodeGen/GlobalISel/LegalizerInfo.cpp | 26 +++++++------ lib/Target/ARM/ARMLegalizerInfo.cpp | 39 +------------------ .../CodeGen/GlobalISel/LegalizerInfoTest.cpp | 19 +++++++++ 4 files changed, 52 insertions(+), 54 deletions(-) diff --git a/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h b/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h index 6694d09c05a..c259e93fdd3 100644 --- a/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h +++ b/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h @@ -107,6 +107,19 @@ public: /// before any query is made or incorrect results may be returned. void computeTables(); + static bool needsLegalizingToDifferentSize(const LegalizeAction Action) { + switch (Action) { + case NarrowScalar: + case WidenScalar: + case FewerElements: + case MoreElements: + case Unsupported: + return true; + default: + return false; + } + } + /// More friendly way to set an action for common types that have an LLT /// representation. void setAction(const InstrAspect &Aspect, LegalizeAction Action) { @@ -147,8 +160,8 @@ public: /// Iterate the given function (typically something like doubling the width) /// on Ty until we find a legal type for this operation. - Optional findLegalType(const InstrAspect &Aspect, - function_ref NextType) const { + Optional findLegalizableSize(const InstrAspect &Aspect, + function_ref NextType) const { LegalizeAction Action; const TypeMap &Map = Actions[Aspect.Opcode - FirstOp][Aspect.Idx]; LLT Ty = Aspect.Type; @@ -160,10 +173,9 @@ public: if (DefaultIt == DefaultActions.end()) return None; Action = DefaultIt->second; - } - else + } else Action = ActionIt->second; - } while(Action != Legal); + } while (needsLegalizingToDifferentSize(Action)); return Ty; } diff --git a/lib/CodeGen/GlobalISel/LegalizerInfo.cpp b/lib/CodeGen/GlobalISel/LegalizerInfo.cpp index b8b820341a2..7e957590ede 100644 --- a/lib/CodeGen/GlobalISel/LegalizerInfo.cpp +++ b/lib/CodeGen/GlobalISel/LegalizerInfo.cpp @@ -178,19 +178,23 @@ Optional LegalizerInfo::findLegalType(const InstrAspect &Aspect, case Libcall: case Custom: return Aspect.Type; - case NarrowScalar: - return findLegalType(Aspect, - [](LLT Ty) -> LLT { return Ty.halfScalarSize(); }); - case WidenScalar: - return findLegalType(Aspect, [](LLT Ty) -> LLT { + case NarrowScalar: { + return findLegalizableSize( + Aspect, [&](LLT Ty) -> LLT { return Ty.halfScalarSize(); }); + } + case WidenScalar: { + return findLegalizableSize(Aspect, [&](LLT Ty) -> LLT { return Ty.getSizeInBits() < 8 ? LLT::scalar(8) : Ty.doubleScalarSize(); }); - case FewerElements: - return findLegalType(Aspect, - [](LLT Ty) -> LLT { return Ty.halfElements(); }); - case MoreElements: - return findLegalType(Aspect, - [](LLT Ty) -> LLT { return Ty.doubleElements(); }); + } + case FewerElements: { + return findLegalizableSize( + Aspect, [&](LLT Ty) -> LLT { return Ty.halfElements(); }); + } + case MoreElements: { + return findLegalizableSize( + Aspect, [&](LLT Ty) -> LLT { return Ty.doubleElements(); }); + } } } diff --git a/lib/Target/ARM/ARMLegalizerInfo.cpp b/lib/Target/ARM/ARMLegalizerInfo.cpp index 0b6738c2f63..f3e62d09cc3 100644 --- a/lib/Target/ARM/ARMLegalizerInfo.cpp +++ b/lib/Target/ARM/ARMLegalizerInfo.cpp @@ -55,10 +55,7 @@ ARMLegalizerInfo::ARMLegalizerInfo(const ARMSubtarget &ST) { for (unsigned Op : {G_SDIV, G_UDIV}) { for (auto Ty : {s8, s16}) - // FIXME: We need WidenScalar here, but in the case of targets with - // software division we'll also need Libcall afterwards. Treat as Custom - // until we have better support for chaining legalization actions. - setAction({Op, Ty}, Custom); + setAction({Op, Ty}, WidenScalar); if (ST.hasDivideInARMMode()) setAction({Op, s32}, Legal); else @@ -122,40 +119,6 @@ bool ARMLegalizerInfo::legalizeCustom(MachineInstr &MI, switch (MI.getOpcode()) { default: return false; - case G_SDIV: - case G_UDIV: { - LLT Ty = MRI.getType(MI.getOperand(0).getReg()); - if (Ty != LLT::scalar(16) && Ty != LLT::scalar(8)) - return false; - - // We need to widen to 32 bits and then maybe, if the target requires, - // transform into a libcall. - LegalizerHelper Helper(MIRBuilder.getMF()); - - MachineInstr *NewMI = nullptr; - Helper.MIRBuilder.recordInsertions([&](MachineInstr *MI) { - // Store the new, 32-bit div instruction. - if (MI->getOpcode() == G_SDIV || MI->getOpcode() == G_UDIV) - NewMI = MI; - }); - - auto Result = Helper.widenScalar(MI, 0, LLT::scalar(32)); - Helper.MIRBuilder.stopRecordingInsertions(); - if (Result == LegalizerHelper::UnableToLegalize) { - return false; - } - assert(NewMI && "Couldn't find widened instruction"); - assert((NewMI->getOpcode() == G_SDIV || NewMI->getOpcode() == G_UDIV) && - "Unexpected widened instruction"); - assert(MRI.getType(NewMI->getOperand(0).getReg()).getSizeInBits() == 32 && - "Unexpected type for the widened instruction"); - - Result = Helper.legalizeInstrStep(*NewMI); - if (Result == LegalizerHelper::UnableToLegalize) { - return false; - } - return true; - } case G_SREM: case G_UREM: { unsigned OriginalResult = MI.getOperand(0).getReg(); diff --git a/unittests/CodeGen/GlobalISel/LegalizerInfoTest.cpp b/unittests/CodeGen/GlobalISel/LegalizerInfoTest.cpp index 882df5f2521..0e881759656 100644 --- a/unittests/CodeGen/GlobalISel/LegalizerInfoTest.cpp +++ b/unittests/CodeGen/GlobalISel/LegalizerInfoTest.cpp @@ -117,4 +117,23 @@ TEST(LegalizerInfoTest, MultipleTypes) { ASSERT_EQ(L.getAction({G_PTRTOINT, 1, p0}), std::make_pair(LegalizerInfo::Legal, p0)); } + +TEST(LegalizerInfoTest, MultipleSteps) { + using namespace TargetOpcode; + LegalizerInfo L; + LLT s16 = LLT::scalar(16); + LLT s32 = LLT::scalar(32); + LLT s64 = LLT::scalar(64); + + L.setAction({G_UREM, 0, s16}, LegalizerInfo::WidenScalar); + L.setAction({G_UREM, 0, s32}, LegalizerInfo::Lower); + L.setAction({G_UREM, 0, s64}, LegalizerInfo::Lower); + + L.computeTables(); + + ASSERT_EQ(L.getAction({G_UREM, LLT::scalar(16)}), + std::make_pair(LegalizerInfo::WidenScalar, LLT::scalar(32))); + ASSERT_EQ(L.getAction({G_UREM, LLT::scalar(32)}), + std::make_pair(LegalizerInfo::Lower, LLT::scalar(32))); +} }