| //===-- Target.cpp ----------------------------------------------*- C++ -*-===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| #include "../Target.h" |
| |
| #include "../Error.h" |
| #include "../ParallelSnippetGenerator.h" |
| #include "../SerialSnippetGenerator.h" |
| #include "../SnippetGenerator.h" |
| #include "MCTargetDesc/X86BaseInfo.h" |
| #include "MCTargetDesc/X86MCTargetDesc.h" |
| #include "X86.h" |
| #include "X86Counter.h" |
| #include "X86RegisterInfo.h" |
| #include "X86Subtarget.h" |
| #include "llvm/ADT/Sequence.h" |
| #include "llvm/MC/MCInstBuilder.h" |
| #include "llvm/Support/Errc.h" |
| #include "llvm/Support/Error.h" |
| #include "llvm/Support/FormatVariadic.h" |
| #include "llvm/Support/Host.h" |
| |
| #include <memory> |
| #include <string> |
| #include <vector> |
| #if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64)) |
| #include <immintrin.h> |
| #include <intrin.h> |
| #endif |
| |
| namespace llvm { |
| namespace exegesis { |
| |
| static cl::OptionCategory |
| BenchmarkOptions("llvm-exegesis benchmark x86-options"); |
| |
| // If a positive value is specified, we are going to use the LBR in |
| // latency-mode. |
| // |
| // Note: |
| // - A small value is preferred, but too low a value could result in |
| // throttling. |
| // - A prime number is preferred to avoid always skipping certain blocks. |
| // |
| static cl::opt<unsigned> LbrSamplingPeriod( |
| "x86-lbr-sample-period", |
| cl::desc("The sample period (nbranches/sample), used for LBR sampling"), |
| cl::cat(BenchmarkOptions), cl::init(0)); |
| |
| // FIXME: Validates that repetition-mode is loop if LBR is requested. |
| |
| // Returns a non-null reason if we cannot handle the memory references in this |
| // instruction. |
| static const char *isInvalidMemoryInstr(const Instruction &Instr) { |
| switch (Instr.Description.TSFlags & X86II::FormMask) { |
| default: |
| return "Unknown FormMask value"; |
| // These have no memory access. |
| case X86II::Pseudo: |
| case X86II::RawFrm: |
| case X86II::AddCCFrm: |
| case X86II::PrefixByte: |
| case X86II::MRMDestReg: |
| case X86II::MRMSrcReg: |
| case X86II::MRMSrcReg4VOp3: |
| case X86II::MRMSrcRegOp4: |
| case X86II::MRMSrcRegCC: |
| case X86II::MRMXrCC: |
| case X86II::MRMr0: |
| case X86II::MRMXr: |
| case X86II::MRM0r: |
| case X86II::MRM1r: |
| case X86II::MRM2r: |
| case X86II::MRM3r: |
| case X86II::MRM4r: |
| case X86II::MRM5r: |
| case X86II::MRM6r: |
| case X86II::MRM7r: |
| case X86II::MRM0X: |
| case X86II::MRM1X: |
| case X86II::MRM2X: |
| case X86II::MRM3X: |
| case X86II::MRM4X: |
| case X86II::MRM5X: |
| case X86II::MRM6X: |
| case X86II::MRM7X: |
| case X86II::MRM_C0: |
| case X86II::MRM_C1: |
| case X86II::MRM_C2: |
| case X86II::MRM_C3: |
| case X86II::MRM_C4: |
| case X86II::MRM_C5: |
| case X86II::MRM_C6: |
| case X86II::MRM_C7: |
| case X86II::MRM_C8: |
| case X86II::MRM_C9: |
| case X86II::MRM_CA: |
| case X86II::MRM_CB: |
| case X86II::MRM_CC: |
| case X86II::MRM_CD: |
| case X86II::MRM_CE: |
| case X86II::MRM_CF: |
| case X86II::MRM_D0: |
| case X86II::MRM_D1: |
| case X86II::MRM_D2: |
| case X86II::MRM_D3: |
| case X86II::MRM_D4: |
| case X86II::MRM_D5: |
| case X86II::MRM_D6: |
| case X86II::MRM_D7: |
| case X86II::MRM_D8: |
| case X86II::MRM_D9: |
| case X86II::MRM_DA: |
| case X86II::MRM_DB: |
| case X86II::MRM_DC: |
| case X86II::MRM_DD: |
| case X86II::MRM_DE: |
| case X86II::MRM_DF: |
| case X86II::MRM_E0: |
| case X86II::MRM_E1: |
| case X86II::MRM_E2: |
| case X86II::MRM_E3: |
| case X86II::MRM_E4: |
| case X86II::MRM_E5: |
| case X86II::MRM_E6: |
| case X86II::MRM_E7: |
| case X86II::MRM_E8: |
| case X86II::MRM_E9: |
| case X86II::MRM_EA: |
| case X86II::MRM_EB: |
| case X86II::MRM_EC: |
| case X86II::MRM_ED: |
| case X86II::MRM_EE: |
| case X86II::MRM_EF: |
| case X86II::MRM_F0: |
| case X86II::MRM_F1: |
| case X86II::MRM_F2: |
| case X86II::MRM_F3: |
| case X86II::MRM_F4: |
| case X86II::MRM_F5: |
| case X86II::MRM_F6: |
| case X86II::MRM_F7: |
| case X86II::MRM_F8: |
| case X86II::MRM_F9: |
| case X86II::MRM_FA: |
| case X86II::MRM_FB: |
| case X86II::MRM_FC: |
| case X86II::MRM_FD: |
| case X86II::MRM_FE: |
| case X86II::MRM_FF: |
| case X86II::RawFrmImm8: |
| return nullptr; |
| case X86II::AddRegFrm: |
| return (Instr.Description.Opcode == X86::POP16r || |
| Instr.Description.Opcode == X86::POP32r || |
| Instr.Description.Opcode == X86::PUSH16r || |
| Instr.Description.Opcode == X86::PUSH32r) |
| ? "unsupported opcode: unsupported memory access" |
| : nullptr; |
| // These access memory and are handled. |
| case X86II::MRMDestMem: |
| case X86II::MRMSrcMem: |
| case X86II::MRMSrcMem4VOp3: |
| case X86II::MRMSrcMemOp4: |
| case X86II::MRMSrcMemCC: |
| case X86II::MRMXmCC: |
| case X86II::MRMXm: |
| case X86II::MRM0m: |
| case X86II::MRM1m: |
| case X86II::MRM2m: |
| case X86II::MRM3m: |
| case X86II::MRM4m: |
| case X86II::MRM5m: |
| case X86II::MRM6m: |
| case X86II::MRM7m: |
| return nullptr; |
| // These access memory and are not handled yet. |
| case X86II::RawFrmImm16: |
| case X86II::RawFrmMemOffs: |
| case X86II::RawFrmSrc: |
| case X86II::RawFrmDst: |
| case X86II::RawFrmDstSrc: |
| return "unsupported opcode: non uniform memory access"; |
| } |
| } |
| |
| // If the opcode is invalid, returns a pointer to a character literal indicating |
| // the reason. nullptr indicates a valid opcode. |
| static const char *isInvalidOpcode(const Instruction &Instr) { |
| const auto OpcodeName = Instr.Name; |
| if ((Instr.Description.TSFlags & X86II::FormMask) == X86II::Pseudo) |
| return "unsupported opcode: pseudo instruction"; |
| if (OpcodeName.startswith("POP") || OpcodeName.startswith("PUSH") || |
| OpcodeName.startswith("ADJCALLSTACK") || OpcodeName.startswith("LEAVE")) |
| return "unsupported opcode: Push/Pop/AdjCallStack/Leave"; |
| if (const auto reason = isInvalidMemoryInstr(Instr)) |
| return reason; |
| // We do not handle instructions with OPERAND_PCREL. |
| for (const Operand &Op : Instr.Operands) |
| if (Op.isExplicit() && |
| Op.getExplicitOperandInfo().OperandType == MCOI::OPERAND_PCREL) |
| return "unsupported opcode: PC relative operand"; |
| // We do not handle second-form X87 instructions. We only handle first-form |
| // ones (_Fp), see comment in X86InstrFPStack.td. |
| for (const Operand &Op : Instr.Operands) |
| if (Op.isReg() && Op.isExplicit() && |
| Op.getExplicitOperandInfo().RegClass == X86::RSTRegClassID) |
| return "unsupported second-form X87 instruction"; |
| return nullptr; |
| } |
| |
| static unsigned getX86FPFlags(const Instruction &Instr) { |
| return Instr.Description.TSFlags & X86II::FPTypeMask; |
| } |
| |
| // Helper to fill a memory operand with a value. |
| static void setMemOp(InstructionTemplate &IT, int OpIdx, |
| const MCOperand &OpVal) { |
| const auto Op = IT.getInstr().Operands[OpIdx]; |
| assert(Op.isExplicit() && "invalid memory pattern"); |
| IT.getValueFor(Op) = OpVal; |
| } |
| |
| // Common (latency, uops) code for LEA templates. `GetDestReg` takes the |
| // addressing base and index registers and returns the LEA destination register. |
| static Expected<std::vector<CodeTemplate>> generateLEATemplatesCommon( |
| const Instruction &Instr, const BitVector &ForbiddenRegisters, |
| const LLVMState &State, const SnippetGenerator::Options &Opts, |
| std::function<void(unsigned, unsigned, BitVector &CandidateDestRegs)> |
| RestrictDestRegs) { |
| assert(Instr.Operands.size() == 6 && "invalid LEA"); |
| assert(X86II::getMemoryOperandNo(Instr.Description.TSFlags) == 1 && |
| "invalid LEA"); |
| |
| constexpr const int kDestOp = 0; |
| constexpr const int kBaseOp = 1; |
| constexpr const int kIndexOp = 3; |
| auto PossibleDestRegs = |
| Instr.Operands[kDestOp].getRegisterAliasing().sourceBits(); |
| remove(PossibleDestRegs, ForbiddenRegisters); |
| auto PossibleBaseRegs = |
| Instr.Operands[kBaseOp].getRegisterAliasing().sourceBits(); |
| remove(PossibleBaseRegs, ForbiddenRegisters); |
| auto PossibleIndexRegs = |
| Instr.Operands[kIndexOp].getRegisterAliasing().sourceBits(); |
| remove(PossibleIndexRegs, ForbiddenRegisters); |
| |
| const auto &RegInfo = State.getRegInfo(); |
| std::vector<CodeTemplate> Result; |
| for (const unsigned BaseReg : PossibleBaseRegs.set_bits()) { |
| for (const unsigned IndexReg : PossibleIndexRegs.set_bits()) { |
| for (int LogScale = 0; LogScale <= 3; ++LogScale) { |
| // FIXME: Add an option for controlling how we explore immediates. |
| for (const int Disp : {0, 42}) { |
| InstructionTemplate IT(&Instr); |
| const int64_t Scale = 1ull << LogScale; |
| setMemOp(IT, 1, MCOperand::createReg(BaseReg)); |
| setMemOp(IT, 2, MCOperand::createImm(Scale)); |
| setMemOp(IT, 3, MCOperand::createReg(IndexReg)); |
| setMemOp(IT, 4, MCOperand::createImm(Disp)); |
| // SegmentReg must be 0 for LEA. |
| setMemOp(IT, 5, MCOperand::createReg(0)); |
| |
| // Output reg candidates are selected by the caller. |
| auto PossibleDestRegsNow = PossibleDestRegs; |
| RestrictDestRegs(BaseReg, IndexReg, PossibleDestRegsNow); |
| assert(PossibleDestRegsNow.set_bits().begin() != |
| PossibleDestRegsNow.set_bits().end() && |
| "no remaining registers"); |
| setMemOp( |
| IT, 0, |
| MCOperand::createReg(*PossibleDestRegsNow.set_bits().begin())); |
| |
| CodeTemplate CT; |
| CT.Instructions.push_back(std::move(IT)); |
| CT.Config = formatv("{3}(%{0}, %{1}, {2})", RegInfo.getName(BaseReg), |
| RegInfo.getName(IndexReg), Scale, Disp) |
| .str(); |
| Result.push_back(std::move(CT)); |
| if (Result.size() >= Opts.MaxConfigsPerOpcode) |
| return std::move(Result); |
| } |
| } |
| } |
| } |
| |
| return std::move(Result); |
| } |
| |
| namespace { |
| class X86SerialSnippetGenerator : public SerialSnippetGenerator { |
| public: |
| using SerialSnippetGenerator::SerialSnippetGenerator; |
| |
| Expected<std::vector<CodeTemplate>> |
| generateCodeTemplates(InstructionTemplate Variant, |
| const BitVector &ForbiddenRegisters) const override; |
| }; |
| } // namespace |
| |
| Expected<std::vector<CodeTemplate>> |
| X86SerialSnippetGenerator::generateCodeTemplates( |
| InstructionTemplate Variant, const BitVector &ForbiddenRegisters) const { |
| const Instruction &Instr = Variant.getInstr(); |
| |
| if (const auto reason = isInvalidOpcode(Instr)) |
| return make_error<Failure>(reason); |
| |
| // LEA gets special attention. |
| const auto Opcode = Instr.Description.getOpcode(); |
| if (Opcode == X86::LEA64r || Opcode == X86::LEA64_32r) { |
| return generateLEATemplatesCommon( |
| Instr, ForbiddenRegisters, State, Opts, |
| [this](unsigned BaseReg, unsigned IndexReg, |
| BitVector &CandidateDestRegs) { |
| // We just select a destination register that aliases the base |
| // register. |
| CandidateDestRegs &= |
| State.getRATC().getRegister(BaseReg).aliasedBits(); |
| }); |
| } |
| |
| if (Instr.hasMemoryOperands()) |
| return make_error<Failure>( |
| "unsupported memory operand in latency measurements"); |
| |
| switch (getX86FPFlags(Instr)) { |
| case X86II::NotFP: |
| return SerialSnippetGenerator::generateCodeTemplates(Variant, |
| ForbiddenRegisters); |
| case X86II::ZeroArgFP: |
| case X86II::OneArgFP: |
| case X86II::SpecialFP: |
| case X86II::CompareFP: |
| case X86II::CondMovFP: |
| return make_error<Failure>("Unsupported x87 Instruction"); |
| case X86II::OneArgFPRW: |
| case X86II::TwoArgFP: |
| // These are instructions like |
| // - `ST(0) = fsqrt(ST(0))` (OneArgFPRW) |
| // - `ST(0) = ST(0) + ST(i)` (TwoArgFP) |
| // They are intrinsically serial and do not modify the state of the stack. |
| return generateSelfAliasingCodeTemplates(Variant); |
| default: |
| llvm_unreachable("Unknown FP Type!"); |
| } |
| } |
| |
| namespace { |
| class X86ParallelSnippetGenerator : public ParallelSnippetGenerator { |
| public: |
| using ParallelSnippetGenerator::ParallelSnippetGenerator; |
| |
| Expected<std::vector<CodeTemplate>> |
| generateCodeTemplates(InstructionTemplate Variant, |
| const BitVector &ForbiddenRegisters) const override; |
| }; |
| |
| } // namespace |
| |
| Expected<std::vector<CodeTemplate>> |
| X86ParallelSnippetGenerator::generateCodeTemplates( |
| InstructionTemplate Variant, const BitVector &ForbiddenRegisters) const { |
| const Instruction &Instr = Variant.getInstr(); |
| |
| if (const auto reason = isInvalidOpcode(Instr)) |
| return make_error<Failure>(reason); |
| |
| // LEA gets special attention. |
| const auto Opcode = Instr.Description.getOpcode(); |
| if (Opcode == X86::LEA64r || Opcode == X86::LEA64_32r) { |
| return generateLEATemplatesCommon( |
| Instr, ForbiddenRegisters, State, Opts, |
| [this](unsigned BaseReg, unsigned IndexReg, |
| BitVector &CandidateDestRegs) { |
| // Any destination register that is not used for addressing is fine. |
| remove(CandidateDestRegs, |
| State.getRATC().getRegister(BaseReg).aliasedBits()); |
| remove(CandidateDestRegs, |
| State.getRATC().getRegister(IndexReg).aliasedBits()); |
| }); |
| } |
| |
| switch (getX86FPFlags(Instr)) { |
| case X86II::NotFP: |
| return ParallelSnippetGenerator::generateCodeTemplates(Variant, |
| ForbiddenRegisters); |
| case X86II::ZeroArgFP: |
| case X86II::OneArgFP: |
| case X86II::SpecialFP: |
| return make_error<Failure>("Unsupported x87 Instruction"); |
| case X86II::OneArgFPRW: |
| case X86II::TwoArgFP: |
| // These are instructions like |
| // - `ST(0) = fsqrt(ST(0))` (OneArgFPRW) |
| // - `ST(0) = ST(0) + ST(i)` (TwoArgFP) |
| // They are intrinsically serial and do not modify the state of the stack. |
| // We generate the same code for latency and uops. |
| return generateSelfAliasingCodeTemplates(Variant); |
| case X86II::CompareFP: |
| case X86II::CondMovFP: |
| // We can compute uops for any FP instruction that does not grow or shrink |
| // the stack (either do not touch the stack or push as much as they pop). |
| return generateUnconstrainedCodeTemplates( |
| Variant, "instruction does not grow/shrink the FP stack"); |
| default: |
| llvm_unreachable("Unknown FP Type!"); |
| } |
| } |
| |
| static unsigned getLoadImmediateOpcode(unsigned RegBitWidth) { |
| switch (RegBitWidth) { |
| case 8: |
| return X86::MOV8ri; |
| case 16: |
| return X86::MOV16ri; |
| case 32: |
| return X86::MOV32ri; |
| case 64: |
| return X86::MOV64ri; |
| } |
| llvm_unreachable("Invalid Value Width"); |
| } |
| |
| // Generates instruction to load an immediate value into a register. |
| static MCInst loadImmediate(unsigned Reg, unsigned RegBitWidth, |
| const APInt &Value) { |
| if (Value.getBitWidth() > RegBitWidth) |
| llvm_unreachable("Value must fit in the Register"); |
| return MCInstBuilder(getLoadImmediateOpcode(RegBitWidth)) |
| .addReg(Reg) |
| .addImm(Value.getZExtValue()); |
| } |
| |
| // Allocates scratch memory on the stack. |
| static MCInst allocateStackSpace(unsigned Bytes) { |
| return MCInstBuilder(X86::SUB64ri8) |
| .addReg(X86::RSP) |
| .addReg(X86::RSP) |
| .addImm(Bytes); |
| } |
| |
| // Fills scratch memory at offset `OffsetBytes` with value `Imm`. |
| static MCInst fillStackSpace(unsigned MovOpcode, unsigned OffsetBytes, |
| uint64_t Imm) { |
| return MCInstBuilder(MovOpcode) |
| // Address = ESP |
| .addReg(X86::RSP) // BaseReg |
| .addImm(1) // ScaleAmt |
| .addReg(0) // IndexReg |
| .addImm(OffsetBytes) // Disp |
| .addReg(0) // Segment |
| // Immediate. |
| .addImm(Imm); |
| } |
| |
| // Loads scratch memory into register `Reg` using opcode `RMOpcode`. |
| static MCInst loadToReg(unsigned Reg, unsigned RMOpcode) { |
| return MCInstBuilder(RMOpcode) |
| .addReg(Reg) |
| // Address = ESP |
| .addReg(X86::RSP) // BaseReg |
| .addImm(1) // ScaleAmt |
| .addReg(0) // IndexReg |
| .addImm(0) // Disp |
| .addReg(0); // Segment |
| } |
| |
| // Releases scratch memory. |
| static MCInst releaseStackSpace(unsigned Bytes) { |
| return MCInstBuilder(X86::ADD64ri8) |
| .addReg(X86::RSP) |
| .addReg(X86::RSP) |
| .addImm(Bytes); |
| } |
| |
| // Reserves some space on the stack, fills it with the content of the provided |
| // constant and provide methods to load the stack value into a register. |
| namespace { |
| struct ConstantInliner { |
| explicit ConstantInliner(const APInt &Constant) : Constant_(Constant) {} |
| |
| std::vector<MCInst> loadAndFinalize(unsigned Reg, unsigned RegBitWidth, |
| unsigned Opcode); |
| |
| std::vector<MCInst> loadX87STAndFinalize(unsigned Reg); |
| |
| std::vector<MCInst> loadX87FPAndFinalize(unsigned Reg); |
| |
| std::vector<MCInst> popFlagAndFinalize(); |
| |
| std::vector<MCInst> loadImplicitRegAndFinalize(unsigned Opcode, |
| unsigned Value); |
| |
| private: |
| ConstantInliner &add(const MCInst &Inst) { |
| Instructions.push_back(Inst); |
| return *this; |
| } |
| |
| void initStack(unsigned Bytes); |
| |
| static constexpr const unsigned kF80Bytes = 10; // 80 bits. |
| |
| APInt Constant_; |
| std::vector<MCInst> Instructions; |
| }; |
| } // namespace |
| |
| std::vector<MCInst> ConstantInliner::loadAndFinalize(unsigned Reg, |
| unsigned RegBitWidth, |
| unsigned Opcode) { |
| assert((RegBitWidth & 7) == 0 && "RegBitWidth must be a multiple of 8 bits"); |
| initStack(RegBitWidth / 8); |
| add(loadToReg(Reg, Opcode)); |
| add(releaseStackSpace(RegBitWidth / 8)); |
| return std::move(Instructions); |
| } |
| |
| std::vector<MCInst> ConstantInliner::loadX87STAndFinalize(unsigned Reg) { |
| initStack(kF80Bytes); |
| add(MCInstBuilder(X86::LD_F80m) |
| // Address = ESP |
| .addReg(X86::RSP) // BaseReg |
| .addImm(1) // ScaleAmt |
| .addReg(0) // IndexReg |
| .addImm(0) // Disp |
| .addReg(0)); // Segment |
| if (Reg != X86::ST0) |
| add(MCInstBuilder(X86::ST_Frr).addReg(Reg)); |
| add(releaseStackSpace(kF80Bytes)); |
| return std::move(Instructions); |
| } |
| |
| std::vector<MCInst> ConstantInliner::loadX87FPAndFinalize(unsigned Reg) { |
| initStack(kF80Bytes); |
| add(MCInstBuilder(X86::LD_Fp80m) |
| .addReg(Reg) |
| // Address = ESP |
| .addReg(X86::RSP) // BaseReg |
| .addImm(1) // ScaleAmt |
| .addReg(0) // IndexReg |
| .addImm(0) // Disp |
| .addReg(0)); // Segment |
| add(releaseStackSpace(kF80Bytes)); |
| return std::move(Instructions); |
| } |
| |
| std::vector<MCInst> ConstantInliner::popFlagAndFinalize() { |
| initStack(8); |
| add(MCInstBuilder(X86::POPF64)); |
| return std::move(Instructions); |
| } |
| |
| std::vector<MCInst> |
| ConstantInliner::loadImplicitRegAndFinalize(unsigned Opcode, unsigned Value) { |
| add(allocateStackSpace(4)); |
| add(fillStackSpace(X86::MOV32mi, 0, Value)); // Mask all FP exceptions |
| add(MCInstBuilder(Opcode) |
| // Address = ESP |
| .addReg(X86::RSP) // BaseReg |
| .addImm(1) // ScaleAmt |
| .addReg(0) // IndexReg |
| .addImm(0) // Disp |
| .addReg(0)); // Segment |
| add(releaseStackSpace(4)); |
| return std::move(Instructions); |
| } |
| |
| void ConstantInliner::initStack(unsigned Bytes) { |
| assert(Constant_.getBitWidth() <= Bytes * 8 && |
| "Value does not have the correct size"); |
| const APInt WideConstant = Constant_.getBitWidth() < Bytes * 8 |
| ? Constant_.sext(Bytes * 8) |
| : Constant_; |
| add(allocateStackSpace(Bytes)); |
| size_t ByteOffset = 0; |
| for (; Bytes - ByteOffset >= 4; ByteOffset += 4) |
| add(fillStackSpace( |
| X86::MOV32mi, ByteOffset, |
| WideConstant.extractBits(32, ByteOffset * 8).getZExtValue())); |
| if (Bytes - ByteOffset >= 2) { |
| add(fillStackSpace( |
| X86::MOV16mi, ByteOffset, |
| WideConstant.extractBits(16, ByteOffset * 8).getZExtValue())); |
| ByteOffset += 2; |
| } |
| if (Bytes - ByteOffset >= 1) |
| add(fillStackSpace( |
| X86::MOV8mi, ByteOffset, |
| WideConstant.extractBits(8, ByteOffset * 8).getZExtValue())); |
| } |
| |
| #include "X86GenExegesis.inc" |
| |
| namespace { |
| |
| class X86SavedState : public ExegesisTarget::SavedState { |
| public: |
| X86SavedState() { |
| #ifdef __x86_64__ |
| # if defined(_MSC_VER) |
| _fxsave64(FPState); |
| Eflags = __readeflags(); |
| # elif defined(__GNUC__) |
| __builtin_ia32_fxsave64(FPState); |
| Eflags = __builtin_ia32_readeflags_u64(); |
| # endif |
| #else |
| llvm_unreachable("X86 exegesis running on non-X86 target"); |
| #endif |
| } |
| |
| ~X86SavedState() { |
| // Restoring the X87 state does not flush pending exceptions, make sure |
| // these exceptions are flushed now. |
| #ifdef __x86_64__ |
| # if defined(_MSC_VER) |
| _clearfp(); |
| _fxrstor64(FPState); |
| __writeeflags(Eflags); |
| # elif defined(__GNUC__) |
| asm volatile("fwait"); |
| __builtin_ia32_fxrstor64(FPState); |
| __builtin_ia32_writeeflags_u64(Eflags); |
| # endif |
| #else |
| llvm_unreachable("X86 exegesis running on non-X86 target"); |
| #endif |
| } |
| |
| private: |
| #ifdef __x86_64__ |
| alignas(16) char FPState[512]; |
| uint64_t Eflags; |
| #endif |
| }; |
| |
| class ExegesisX86Target : public ExegesisTarget { |
| public: |
| ExegesisX86Target() : ExegesisTarget(X86CpuPfmCounters) {} |
| |
| Expected<std::unique_ptr<pfm::Counter>> |
| createCounter(StringRef CounterName, const LLVMState &State) const override { |
| // If LbrSamplingPeriod was provided, then ignore the |
| // CounterName because we only have one for LBR. |
| if (LbrSamplingPeriod > 0) { |
| // Can't use LBR without HAVE_LIBPFM, LIBPFM_HAS_FIELD_CYCLES, or without |
| // __linux__ (for now) |
| #if defined(HAVE_LIBPFM) && defined(LIBPFM_HAS_FIELD_CYCLES) && \ |
| defined(__linux__) |
| return std::make_unique<X86LbrCounter>( |
| X86LbrPerfEvent(LbrSamplingPeriod)); |
| #else |
| return llvm::make_error<llvm::StringError>( |
| "LBR counter requested without HAVE_LIBPFM, LIBPFM_HAS_FIELD_CYCLES, " |
| "or running on Linux.", |
| llvm::errc::invalid_argument); |
| #endif |
| } |
| return ExegesisTarget::createCounter(CounterName, State); |
| } |
| |
| private: |
| void addTargetSpecificPasses(PassManagerBase &PM) const override; |
| |
| unsigned getScratchMemoryRegister(const Triple &TT) const override; |
| |
| unsigned getLoopCounterRegister(const Triple &) const override; |
| |
| unsigned getMaxMemoryAccessSize() const override { return 64; } |
| |
| Error randomizeTargetMCOperand(const Instruction &Instr, const Variable &Var, |
| MCOperand &AssignedValue, |
| const BitVector &ForbiddenRegs) const override; |
| |
| void fillMemoryOperands(InstructionTemplate &IT, unsigned Reg, |
| unsigned Offset) const override; |
| |
| void decrementLoopCounterAndJump(MachineBasicBlock &MBB, |
| MachineBasicBlock &TargetMBB, |
| const MCInstrInfo &MII) const override; |
| |
| std::vector<MCInst> setRegTo(const MCSubtargetInfo &STI, unsigned Reg, |
| const APInt &Value) const override; |
| |
| ArrayRef<unsigned> getUnavailableRegisters() const override { |
| return makeArrayRef(kUnavailableRegisters, |
| sizeof(kUnavailableRegisters) / |
| sizeof(kUnavailableRegisters[0])); |
| } |
| |
| bool allowAsBackToBack(const Instruction &Instr) const override { |
| const unsigned Opcode = Instr.Description.Opcode; |
| return !isInvalidOpcode(Instr) && Opcode != X86::LEA64r && |
| Opcode != X86::LEA64_32r && Opcode != X86::LEA16r; |
| } |
| |
| std::vector<InstructionTemplate> |
| generateInstructionVariants(const Instruction &Instr, |
| unsigned MaxConfigsPerOpcode) const override; |
| |
| std::unique_ptr<SnippetGenerator> createSerialSnippetGenerator( |
| const LLVMState &State, |
| const SnippetGenerator::Options &Opts) const override { |
| return std::make_unique<X86SerialSnippetGenerator>(State, Opts); |
| } |
| |
| std::unique_ptr<SnippetGenerator> createParallelSnippetGenerator( |
| const LLVMState &State, |
| const SnippetGenerator::Options &Opts) const override { |
| return std::make_unique<X86ParallelSnippetGenerator>(State, Opts); |
| } |
| |
| bool matchesArch(Triple::ArchType Arch) const override { |
| return Arch == Triple::x86_64 || Arch == Triple::x86; |
| } |
| |
| Error checkFeatureSupport() const override { |
| // LBR is the only feature we conditionally support now. |
| // So if LBR is not requested, then we should be able to run the benchmarks. |
| if (LbrSamplingPeriod == 0) |
| return Error::success(); |
| |
| #if defined(__linux__) && defined(HAVE_LIBPFM) && \ |
| defined(LIBPFM_HAS_FIELD_CYCLES) |
| // FIXME: Fix this. |
| // https://bugs.llvm.org/show_bug.cgi?id=48918 |
| // For now, only do the check if we see an Intel machine because |
| // the counter uses some intel-specific magic and it could |
| // be confuse and think an AMD machine actually has LBR support. |
| #if defined(__i386__) || defined(_M_IX86) || defined(__x86_64__) || \ |
| defined(_M_X64) |
| using namespace sys::detail::x86; |
| |
| if (getVendorSignature() == VendorSignatures::GENUINE_INTEL) |
| // If the kernel supports it, the hardware still may not have it. |
| return X86LbrCounter::checkLbrSupport(); |
| #else |
| llvm_unreachable("Running X86 exegesis on non-X86 target"); |
| #endif |
| #endif |
| return llvm::make_error<llvm::StringError>( |
| "LBR not supported on this kernel and/or platform", |
| llvm::errc::not_supported); |
| } |
| |
| std::unique_ptr<SavedState> withSavedState() const override { |
| return std::make_unique<X86SavedState>(); |
| } |
| |
| static const unsigned kUnavailableRegisters[4]; |
| }; |
| |
| // We disable a few registers that cannot be encoded on instructions with a REX |
| // prefix. |
| const unsigned ExegesisX86Target::kUnavailableRegisters[4] = {X86::AH, X86::BH, |
| X86::CH, X86::DH}; |
| |
| // We're using one of R8-R15 because these registers are never hardcoded in |
| // instructions (e.g. MOVS writes to EDI, ESI, EDX), so they have less |
| // conflicts. |
| constexpr const unsigned kLoopCounterReg = X86::R8; |
| |
| } // namespace |
| |
| void ExegesisX86Target::addTargetSpecificPasses(PassManagerBase &PM) const { |
| // Lowers FP pseudo-instructions, e.g. ABS_Fp32 -> ABS_F. |
| PM.add(createX86FloatingPointStackifierPass()); |
| } |
| |
| unsigned ExegesisX86Target::getScratchMemoryRegister(const Triple &TT) const { |
| if (!TT.isArch64Bit()) { |
| // FIXME: This would require popping from the stack, so we would have to |
| // add some additional setup code. |
| return 0; |
| } |
| return TT.isOSWindows() ? X86::RCX : X86::RDI; |
| } |
| |
| unsigned ExegesisX86Target::getLoopCounterRegister(const Triple &TT) const { |
| if (!TT.isArch64Bit()) { |
| return 0; |
| } |
| return kLoopCounterReg; |
| } |
| |
| Error ExegesisX86Target::randomizeTargetMCOperand( |
| const Instruction &Instr, const Variable &Var, MCOperand &AssignedValue, |
| const BitVector &ForbiddenRegs) const { |
| const Operand &Op = Instr.getPrimaryOperand(Var); |
| switch (Op.getExplicitOperandInfo().OperandType) { |
| case X86::OperandType::OPERAND_ROUNDING_CONTROL: |
| AssignedValue = |
| MCOperand::createImm(randomIndex(X86::STATIC_ROUNDING::TO_ZERO)); |
| return Error::success(); |
| default: |
| break; |
| } |
| return make_error<Failure>( |
| Twine("unimplemented operand type ") |
| .concat(Twine(Op.getExplicitOperandInfo().OperandType))); |
| } |
| |
| void ExegesisX86Target::fillMemoryOperands(InstructionTemplate &IT, |
| unsigned Reg, |
| unsigned Offset) const { |
| assert(!isInvalidMemoryInstr(IT.getInstr()) && |
| "fillMemoryOperands requires a valid memory instruction"); |
| int MemOpIdx = X86II::getMemoryOperandNo(IT.getInstr().Description.TSFlags); |
| assert(MemOpIdx >= 0 && "invalid memory operand index"); |
| // getMemoryOperandNo() ignores tied operands, so we have to add them back. |
| MemOpIdx += X86II::getOperandBias(IT.getInstr().Description); |
| setMemOp(IT, MemOpIdx + 0, MCOperand::createReg(Reg)); // BaseReg |
| setMemOp(IT, MemOpIdx + 1, MCOperand::createImm(1)); // ScaleAmt |
| setMemOp(IT, MemOpIdx + 2, MCOperand::createReg(0)); // IndexReg |
| setMemOp(IT, MemOpIdx + 3, MCOperand::createImm(Offset)); // Disp |
| setMemOp(IT, MemOpIdx + 4, MCOperand::createReg(0)); // Segment |
| } |
| |
| void ExegesisX86Target::decrementLoopCounterAndJump( |
| MachineBasicBlock &MBB, MachineBasicBlock &TargetMBB, |
| const MCInstrInfo &MII) const { |
| BuildMI(&MBB, DebugLoc(), MII.get(X86::ADD64ri8)) |
| .addDef(kLoopCounterReg) |
| .addUse(kLoopCounterReg) |
| .addImm(-1); |
| BuildMI(&MBB, DebugLoc(), MII.get(X86::JCC_1)) |
| .addMBB(&TargetMBB) |
| .addImm(X86::COND_NE); |
| } |
| |
| std::vector<MCInst> ExegesisX86Target::setRegTo(const MCSubtargetInfo &STI, |
| unsigned Reg, |
| const APInt &Value) const { |
| if (X86::GR8RegClass.contains(Reg)) |
| return {loadImmediate(Reg, 8, Value)}; |
| if (X86::GR16RegClass.contains(Reg)) |
| return {loadImmediate(Reg, 16, Value)}; |
| if (X86::GR32RegClass.contains(Reg)) |
| return {loadImmediate(Reg, 32, Value)}; |
| if (X86::GR64RegClass.contains(Reg)) |
| return {loadImmediate(Reg, 64, Value)}; |
| ConstantInliner CI(Value); |
| if (X86::VR64RegClass.contains(Reg)) |
| return CI.loadAndFinalize(Reg, 64, X86::MMX_MOVQ64rm); |
| if (X86::VR128XRegClass.contains(Reg)) { |
| if (STI.getFeatureBits()[X86::FeatureAVX512]) |
| return CI.loadAndFinalize(Reg, 128, X86::VMOVDQU32Z128rm); |
| if (STI.getFeatureBits()[X86::FeatureAVX]) |
| return CI.loadAndFinalize(Reg, 128, X86::VMOVDQUrm); |
| return CI.loadAndFinalize(Reg, 128, X86::MOVDQUrm); |
| } |
| if (X86::VR256XRegClass.contains(Reg)) { |
| if (STI.getFeatureBits()[X86::FeatureAVX512]) |
| return CI.loadAndFinalize(Reg, 256, X86::VMOVDQU32Z256rm); |
| if (STI.getFeatureBits()[X86::FeatureAVX]) |
| return CI.loadAndFinalize(Reg, 256, X86::VMOVDQUYrm); |
| } |
| if (X86::VR512RegClass.contains(Reg)) |
| if (STI.getFeatureBits()[X86::FeatureAVX512]) |
| return CI.loadAndFinalize(Reg, 512, X86::VMOVDQU32Zrm); |
| if (X86::RSTRegClass.contains(Reg)) { |
| return CI.loadX87STAndFinalize(Reg); |
| } |
| if (X86::RFP32RegClass.contains(Reg) || X86::RFP64RegClass.contains(Reg) || |
| X86::RFP80RegClass.contains(Reg)) { |
| return CI.loadX87FPAndFinalize(Reg); |
| } |
| if (Reg == X86::EFLAGS) |
| return CI.popFlagAndFinalize(); |
| if (Reg == X86::MXCSR) |
| return CI.loadImplicitRegAndFinalize( |
| STI.getFeatureBits()[X86::FeatureAVX] ? X86::VLDMXCSR : X86::LDMXCSR, |
| 0x1f80); |
| if (Reg == X86::FPCW) |
| return CI.loadImplicitRegAndFinalize(X86::FLDCW16m, 0x37f); |
| return {}; // Not yet implemented. |
| } |
| |
| // Instruction can have some variable operands, and we may want to see how |
| // different operands affect performance. So for each operand position, |
| // precompute all the possible choices we might care about, |
| // and greedily generate all the possible combinations of choices. |
| std::vector<InstructionTemplate> ExegesisX86Target::generateInstructionVariants( |
| const Instruction &Instr, unsigned MaxConfigsPerOpcode) const { |
| bool Exploration = false; |
| SmallVector<SmallVector<MCOperand, 1>, 4> VariableChoices; |
| VariableChoices.resize(Instr.Variables.size()); |
| for (auto I : llvm::zip(Instr.Variables, VariableChoices)) { |
| const Variable &Var = std::get<0>(I); |
| SmallVectorImpl<MCOperand> &Choices = std::get<1>(I); |
| |
| switch (Instr.getPrimaryOperand(Var).getExplicitOperandInfo().OperandType) { |
| default: |
| // We don't wish to explicitly explore this variable. |
| Choices.emplace_back(); // But add invalid MCOperand to simplify logic. |
| continue; |
| case X86::OperandType::OPERAND_COND_CODE: { |
| Exploration = true; |
| auto CondCodes = seq((int)X86::CondCode::COND_O, |
| 1 + (int)X86::CondCode::LAST_VALID_COND); |
| Choices.reserve(std::distance(CondCodes.begin(), CondCodes.end())); |
| for (int CondCode : CondCodes) |
| Choices.emplace_back(MCOperand::createImm(CondCode)); |
| break; |
| } |
| } |
| } |
| |
| // If we don't wish to explore any variables, defer to the baseline method. |
| if (!Exploration) |
| return ExegesisTarget::generateInstructionVariants(Instr, |
| MaxConfigsPerOpcode); |
| |
| std::vector<InstructionTemplate> Variants; |
| size_t NumVariants; |
| CombinationGenerator<MCOperand, decltype(VariableChoices)::value_type, 4> G( |
| VariableChoices); |
| |
| // How many operand combinations can we produce, within the limit? |
| NumVariants = std::min(G.numCombinations(), (size_t)MaxConfigsPerOpcode); |
| // And actually produce all the wanted operand combinations. |
| Variants.reserve(NumVariants); |
| G.generate([&](ArrayRef<MCOperand> State) -> bool { |
| Variants.emplace_back(&Instr); |
| Variants.back().setVariableValues(State); |
| // Did we run out of space for variants? |
| return Variants.size() >= NumVariants; |
| }); |
| |
| assert(Variants.size() == NumVariants && |
| Variants.size() <= MaxConfigsPerOpcode && |
| "Should not produce too many variants"); |
| return Variants; |
| } |
| |
| static ExegesisTarget *getTheExegesisX86Target() { |
| static ExegesisX86Target Target; |
| return &Target; |
| } |
| |
| void InitializeX86ExegesisTarget() { |
| ExegesisTarget::registerTarget(getTheExegesisX86Target()); |
| } |
| |
| } // namespace exegesis |
| } // namespace llvm |
