diff options
Diffstat (limited to 'contrib/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp')
| -rw-r--r-- | contrib/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp | 458 |
1 files changed, 458 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp b/contrib/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp new file mode 100644 index 000000000000..69ad7d7b6b32 --- /dev/null +++ b/contrib/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp @@ -0,0 +1,458 @@ +//===-- X86AsmBackend.cpp - X86 Assembler Backend -------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#include "llvm/MC/MCAsmBackend.h" +#include "MCTargetDesc/X86BaseInfo.h" +#include "MCTargetDesc/X86FixupKinds.h" +#include "llvm/ADT/Twine.h" +#include "llvm/MC/MCAssembler.h" +#include "llvm/MC/MCELFObjectWriter.h" +#include "llvm/MC/MCExpr.h" +#include "llvm/MC/MCFixupKindInfo.h" +#include "llvm/MC/MCMachObjectWriter.h" +#include "llvm/MC/MCObjectWriter.h" +#include "llvm/MC/MCSectionCOFF.h" +#include "llvm/MC/MCSectionELF.h" +#include "llvm/MC/MCSectionMachO.h" +#include "llvm/Object/MachOFormat.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/ELF.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/TargetRegistry.h" +#include "llvm/Support/raw_ostream.h" +using namespace llvm; + +// Option to allow disabling arithmetic relaxation to workaround PR9807, which +// is useful when running bitwise comparison experiments on Darwin. We should be +// able to remove this once PR9807 is resolved. +static cl::opt<bool> +MCDisableArithRelaxation("mc-x86-disable-arith-relaxation", + cl::desc("Disable relaxation of arithmetic instruction for X86")); + +static unsigned getFixupKindLog2Size(unsigned Kind) { + switch (Kind) { + default: assert(0 && "invalid fixup kind!"); + case FK_PCRel_1: + case FK_Data_1: return 0; + case FK_PCRel_2: + case FK_Data_2: return 1; + case FK_PCRel_4: + case X86::reloc_riprel_4byte: + case X86::reloc_riprel_4byte_movq_load: + case X86::reloc_signed_4byte: + case X86::reloc_global_offset_table: + case FK_Data_4: return 2; + case FK_PCRel_8: + case FK_Data_8: return 3; + } +} + +namespace { + +class X86ELFObjectWriter : public MCELFObjectTargetWriter { +public: + X86ELFObjectWriter(bool is64Bit, Triple::OSType OSType, uint16_t EMachine, + bool HasRelocationAddend) + : MCELFObjectTargetWriter(is64Bit, OSType, EMachine, HasRelocationAddend) {} +}; + +class X86AsmBackend : public MCAsmBackend { +public: + X86AsmBackend(const Target &T) + : MCAsmBackend() {} + + unsigned getNumFixupKinds() const { + return X86::NumTargetFixupKinds; + } + + const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const { + const static MCFixupKindInfo Infos[X86::NumTargetFixupKinds] = { + { "reloc_riprel_4byte", 0, 4 * 8, MCFixupKindInfo::FKF_IsPCRel }, + { "reloc_riprel_4byte_movq_load", 0, 4 * 8, MCFixupKindInfo::FKF_IsPCRel}, + { "reloc_signed_4byte", 0, 4 * 8, 0}, + { "reloc_global_offset_table", 0, 4 * 8, 0} + }; + + if (Kind < FirstTargetFixupKind) + return MCAsmBackend::getFixupKindInfo(Kind); + + assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() && + "Invalid kind!"); + return Infos[Kind - FirstTargetFixupKind]; + } + + void ApplyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize, + uint64_t Value) const { + unsigned Size = 1 << getFixupKindLog2Size(Fixup.getKind()); + + assert(Fixup.getOffset() + Size <= DataSize && + "Invalid fixup offset!"); + + // Check that uppper bits are either all zeros or all ones. + // Specifically ignore overflow/underflow as long as the leakage is + // limited to the lower bits. This is to remain compatible with + // other assemblers. + assert(isIntN(Size * 8 + 1, Value) && + "Value does not fit in the Fixup field"); + + for (unsigned i = 0; i != Size; ++i) + Data[Fixup.getOffset() + i] = uint8_t(Value >> (i * 8)); + } + + bool MayNeedRelaxation(const MCInst &Inst) const; + + void RelaxInstruction(const MCInst &Inst, MCInst &Res) const; + + bool WriteNopData(uint64_t Count, MCObjectWriter *OW) const; +}; +} // end anonymous namespace + +static unsigned getRelaxedOpcodeBranch(unsigned Op) { + switch (Op) { + default: + return Op; + + case X86::JAE_1: return X86::JAE_4; + case X86::JA_1: return X86::JA_4; + case X86::JBE_1: return X86::JBE_4; + case X86::JB_1: return X86::JB_4; + case X86::JE_1: return X86::JE_4; + case X86::JGE_1: return X86::JGE_4; + case X86::JG_1: return X86::JG_4; + case X86::JLE_1: return X86::JLE_4; + case X86::JL_1: return X86::JL_4; + case X86::JMP_1: return X86::JMP_4; + case X86::JNE_1: return X86::JNE_4; + case X86::JNO_1: return X86::JNO_4; + case X86::JNP_1: return X86::JNP_4; + case X86::JNS_1: return X86::JNS_4; + case X86::JO_1: return X86::JO_4; + case X86::JP_1: return X86::JP_4; + case X86::JS_1: return X86::JS_4; + } +} + +static unsigned getRelaxedOpcodeArith(unsigned Op) { + switch (Op) { + default: + return Op; + + // IMUL + case X86::IMUL16rri8: return X86::IMUL16rri; + case X86::IMUL16rmi8: return X86::IMUL16rmi; + case X86::IMUL32rri8: return X86::IMUL32rri; + case X86::IMUL32rmi8: return X86::IMUL32rmi; + case X86::IMUL64rri8: return X86::IMUL64rri32; + case X86::IMUL64rmi8: return X86::IMUL64rmi32; + + // AND + case X86::AND16ri8: return X86::AND16ri; + case X86::AND16mi8: return X86::AND16mi; + case X86::AND32ri8: return X86::AND32ri; + case X86::AND32mi8: return X86::AND32mi; + case X86::AND64ri8: return X86::AND64ri32; + case X86::AND64mi8: return X86::AND64mi32; + + // OR + case X86::OR16ri8: return X86::OR16ri; + case X86::OR16mi8: return X86::OR16mi; + case X86::OR32ri8: return X86::OR32ri; + case X86::OR32mi8: return X86::OR32mi; + case X86::OR64ri8: return X86::OR64ri32; + case X86::OR64mi8: return X86::OR64mi32; + + // XOR + case X86::XOR16ri8: return X86::XOR16ri; + case X86::XOR16mi8: return X86::XOR16mi; + case X86::XOR32ri8: return X86::XOR32ri; + case X86::XOR32mi8: return X86::XOR32mi; + case X86::XOR64ri8: return X86::XOR64ri32; + case X86::XOR64mi8: return X86::XOR64mi32; + + // ADD + case X86::ADD16ri8: return X86::ADD16ri; + case X86::ADD16mi8: return X86::ADD16mi; + case X86::ADD32ri8: return X86::ADD32ri; + case X86::ADD32mi8: return X86::ADD32mi; + case X86::ADD64ri8: return X86::ADD64ri32; + case X86::ADD64mi8: return X86::ADD64mi32; + + // SUB + case X86::SUB16ri8: return X86::SUB16ri; + case X86::SUB16mi8: return X86::SUB16mi; + case X86::SUB32ri8: return X86::SUB32ri; + case X86::SUB32mi8: return X86::SUB32mi; + case X86::SUB64ri8: return X86::SUB64ri32; + case X86::SUB64mi8: return X86::SUB64mi32; + + // CMP + case X86::CMP16ri8: return X86::CMP16ri; + case X86::CMP16mi8: return X86::CMP16mi; + case X86::CMP32ri8: return X86::CMP32ri; + case X86::CMP32mi8: return X86::CMP32mi; + case X86::CMP64ri8: return X86::CMP64ri32; + case X86::CMP64mi8: return X86::CMP64mi32; + + // PUSH + case X86::PUSHi8: return X86::PUSHi32; + case X86::PUSHi16: return X86::PUSHi32; + case X86::PUSH64i8: return X86::PUSH64i32; + case X86::PUSH64i16: return X86::PUSH64i32; + } +} + +static unsigned getRelaxedOpcode(unsigned Op) { + unsigned R = getRelaxedOpcodeArith(Op); + if (R != Op) + return R; + return getRelaxedOpcodeBranch(Op); +} + +bool X86AsmBackend::MayNeedRelaxation(const MCInst &Inst) const { + // Branches can always be relaxed. + if (getRelaxedOpcodeBranch(Inst.getOpcode()) != Inst.getOpcode()) + return true; + + if (MCDisableArithRelaxation) + return false; + + // Check if this instruction is ever relaxable. + if (getRelaxedOpcodeArith(Inst.getOpcode()) == Inst.getOpcode()) + return false; + + + // Check if it has an expression and is not RIP relative. + bool hasExp = false; + bool hasRIP = false; + for (unsigned i = 0; i < Inst.getNumOperands(); ++i) { + const MCOperand &Op = Inst.getOperand(i); + if (Op.isExpr()) + hasExp = true; + + if (Op.isReg() && Op.getReg() == X86::RIP) + hasRIP = true; + } + + // FIXME: Why exactly do we need the !hasRIP? Is it just a limitation on + // how we do relaxations? + return hasExp && !hasRIP; +} + +// FIXME: Can tblgen help at all here to verify there aren't other instructions +// we can relax? +void X86AsmBackend::RelaxInstruction(const MCInst &Inst, MCInst &Res) const { + // The only relaxations X86 does is from a 1byte pcrel to a 4byte pcrel. + unsigned RelaxedOp = getRelaxedOpcode(Inst.getOpcode()); + + if (RelaxedOp == Inst.getOpcode()) { + SmallString<256> Tmp; + raw_svector_ostream OS(Tmp); + Inst.dump_pretty(OS); + OS << "\n"; + report_fatal_error("unexpected instruction to relax: " + OS.str()); + } + + Res = Inst; + Res.setOpcode(RelaxedOp); +} + +/// WriteNopData - Write optimal nops to the output file for the \arg Count +/// bytes. This returns the number of bytes written. It may return 0 if +/// the \arg Count is more than the maximum optimal nops. +bool X86AsmBackend::WriteNopData(uint64_t Count, MCObjectWriter *OW) const { + static const uint8_t Nops[10][10] = { + // nop + {0x90}, + // xchg %ax,%ax + {0x66, 0x90}, + // nopl (%[re]ax) + {0x0f, 0x1f, 0x00}, + // nopl 0(%[re]ax) + {0x0f, 0x1f, 0x40, 0x00}, + // nopl 0(%[re]ax,%[re]ax,1) + {0x0f, 0x1f, 0x44, 0x00, 0x00}, + // nopw 0(%[re]ax,%[re]ax,1) + {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00}, + // nopl 0L(%[re]ax) + {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00}, + // nopl 0L(%[re]ax,%[re]ax,1) + {0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00}, + // nopw 0L(%[re]ax,%[re]ax,1) + {0x66, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00}, + // nopw %cs:0L(%[re]ax,%[re]ax,1) + {0x66, 0x2e, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00}, + }; + + // Write an optimal sequence for the first 15 bytes. + const uint64_t OptimalCount = (Count < 16) ? Count : 15; + const uint64_t Prefixes = OptimalCount <= 10 ? 0 : OptimalCount - 10; + for (uint64_t i = 0, e = Prefixes; i != e; i++) + OW->Write8(0x66); + const uint64_t Rest = OptimalCount - Prefixes; + for (uint64_t i = 0, e = Rest; i != e; i++) + OW->Write8(Nops[Rest - 1][i]); + + // Finish with single byte nops. + for (uint64_t i = OptimalCount, e = Count; i != e; ++i) + OW->Write8(0x90); + + return true; +} + +/* *** */ + +namespace { +class ELFX86AsmBackend : public X86AsmBackend { +public: + Triple::OSType OSType; + ELFX86AsmBackend(const Target &T, Triple::OSType _OSType) + : X86AsmBackend(T), OSType(_OSType) { + HasReliableSymbolDifference = true; + } + + virtual bool doesSectionRequireSymbols(const MCSection &Section) const { + const MCSectionELF &ES = static_cast<const MCSectionELF&>(Section); + return ES.getFlags() & ELF::SHF_MERGE; + } +}; + +class ELFX86_32AsmBackend : public ELFX86AsmBackend { +public: + ELFX86_32AsmBackend(const Target &T, Triple::OSType OSType) + : ELFX86AsmBackend(T, OSType) {} + + MCObjectWriter *createObjectWriter(raw_ostream &OS) const { + return createELFObjectWriter(createELFObjectTargetWriter(), + OS, /*IsLittleEndian*/ true); + } + + MCELFObjectTargetWriter *createELFObjectTargetWriter() const { + return new X86ELFObjectWriter(false, OSType, ELF::EM_386, false); + } +}; + +class ELFX86_64AsmBackend : public ELFX86AsmBackend { +public: + ELFX86_64AsmBackend(const Target &T, Triple::OSType OSType) + : ELFX86AsmBackend(T, OSType) {} + + MCObjectWriter *createObjectWriter(raw_ostream &OS) const { + return createELFObjectWriter(createELFObjectTargetWriter(), + OS, /*IsLittleEndian*/ true); + } + + MCELFObjectTargetWriter *createELFObjectTargetWriter() const { + return new X86ELFObjectWriter(true, OSType, ELF::EM_X86_64, true); + } +}; + +class WindowsX86AsmBackend : public X86AsmBackend { + bool Is64Bit; + +public: + WindowsX86AsmBackend(const Target &T, bool is64Bit) + : X86AsmBackend(T) + , Is64Bit(is64Bit) { + } + + MCObjectWriter *createObjectWriter(raw_ostream &OS) const { + return createWinCOFFObjectWriter(OS, Is64Bit); + } +}; + +class DarwinX86AsmBackend : public X86AsmBackend { +public: + DarwinX86AsmBackend(const Target &T) + : X86AsmBackend(T) { } +}; + +class DarwinX86_32AsmBackend : public DarwinX86AsmBackend { +public: + DarwinX86_32AsmBackend(const Target &T) + : DarwinX86AsmBackend(T) {} + + MCObjectWriter *createObjectWriter(raw_ostream &OS) const { + return createX86MachObjectWriter(OS, /*Is64Bit=*/false, + object::mach::CTM_i386, + object::mach::CSX86_ALL); + } +}; + +class DarwinX86_64AsmBackend : public DarwinX86AsmBackend { +public: + DarwinX86_64AsmBackend(const Target &T) + : DarwinX86AsmBackend(T) { + HasReliableSymbolDifference = true; + } + + MCObjectWriter *createObjectWriter(raw_ostream &OS) const { + return createX86MachObjectWriter(OS, /*Is64Bit=*/true, + object::mach::CTM_x86_64, + object::mach::CSX86_ALL); + } + + virtual bool doesSectionRequireSymbols(const MCSection &Section) const { + // Temporary labels in the string literals sections require symbols. The + // issue is that the x86_64 relocation format does not allow symbol + + // offset, and so the linker does not have enough information to resolve the + // access to the appropriate atom unless an external relocation is used. For + // non-cstring sections, we expect the compiler to use a non-temporary label + // for anything that could have an addend pointing outside the symbol. + // + // See <rdar://problem/4765733>. + const MCSectionMachO &SMO = static_cast<const MCSectionMachO&>(Section); + return SMO.getType() == MCSectionMachO::S_CSTRING_LITERALS; + } + + virtual bool isSectionAtomizable(const MCSection &Section) const { + const MCSectionMachO &SMO = static_cast<const MCSectionMachO&>(Section); + // Fixed sized data sections are uniqued, they cannot be diced into atoms. + switch (SMO.getType()) { + default: + return true; + + case MCSectionMachO::S_4BYTE_LITERALS: + case MCSectionMachO::S_8BYTE_LITERALS: + case MCSectionMachO::S_16BYTE_LITERALS: + case MCSectionMachO::S_LITERAL_POINTERS: + case MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS: + case MCSectionMachO::S_LAZY_SYMBOL_POINTERS: + case MCSectionMachO::S_MOD_INIT_FUNC_POINTERS: + case MCSectionMachO::S_MOD_TERM_FUNC_POINTERS: + case MCSectionMachO::S_INTERPOSING: + return false; + } + } +}; + +} // end anonymous namespace + +MCAsmBackend *llvm::createX86_32AsmBackend(const Target &T, StringRef TT) { + Triple TheTriple(TT); + + if (TheTriple.isOSDarwin() || TheTriple.getEnvironment() == Triple::MachO) + return new DarwinX86_32AsmBackend(T); + + if (TheTriple.isOSWindows()) + return new WindowsX86AsmBackend(T, false); + + return new ELFX86_32AsmBackend(T, TheTriple.getOS()); +} + +MCAsmBackend *llvm::createX86_64AsmBackend(const Target &T, StringRef TT) { + Triple TheTriple(TT); + + if (TheTriple.isOSDarwin() || TheTriple.getEnvironment() == Triple::MachO) + return new DarwinX86_64AsmBackend(T); + + if (TheTriple.isOSWindows()) + return new WindowsX86AsmBackend(T, true); + + return new ELFX86_64AsmBackend(T, TheTriple.getOS()); +} |