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Diffstat (limited to 'contrib/llvm/lib/Target/X86/X86AsmBackend.cpp')
| -rw-r--r-- | contrib/llvm/lib/Target/X86/X86AsmBackend.cpp | 304 |
1 files changed, 304 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Target/X86/X86AsmBackend.cpp b/contrib/llvm/lib/Target/X86/X86AsmBackend.cpp new file mode 100644 index 0000000..151087f --- /dev/null +++ b/contrib/llvm/lib/Target/X86/X86AsmBackend.cpp @@ -0,0 +1,304 @@ +//===-- 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/Target/TargetAsmBackend.h" +#include "X86.h" +#include "X86FixupKinds.h" +#include "llvm/ADT/Twine.h" +#include "llvm/MC/MCAssembler.h" +#include "llvm/MC/MCExpr.h" +#include "llvm/MC/MCObjectWriter.h" +#include "llvm/MC/MCSectionELF.h" +#include "llvm/MC/MCSectionMachO.h" +#include "llvm/MC/MachObjectWriter.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Target/TargetRegistry.h" +#include "llvm/Target/TargetAsmBackend.h" +using namespace llvm; + +namespace { + +static unsigned getFixupKindLog2Size(unsigned Kind) { + switch (Kind) { + default: assert(0 && "invalid fixup kind!"); + case X86::reloc_pcrel_1byte: + case FK_Data_1: return 0; + case FK_Data_2: return 1; + case X86::reloc_pcrel_4byte: + case X86::reloc_riprel_4byte: + case X86::reloc_riprel_4byte_movq_load: + case FK_Data_4: return 2; + case FK_Data_8: return 3; + } +} + +class X86AsmBackend : public TargetAsmBackend { +public: + X86AsmBackend(const Target &T) + : TargetAsmBackend(T) {} + + void ApplyFixup(const MCFixup &Fixup, MCDataFragment &DF, + uint64_t Value) const { + unsigned Size = 1 << getFixupKindLog2Size(Fixup.getKind()); + + assert(Fixup.getOffset() + Size <= DF.getContents().size() && + "Invalid fixup offset!"); + for (unsigned i = 0; i != Size; ++i) + DF.getContents()[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; +}; + +static unsigned getRelaxedOpcode(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::TAILJMP_1: + 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; + } +} + +bool X86AsmBackend::MayNeedRelaxation(const MCInst &Inst) const { + // Check if this instruction is ever relaxable. + if (getRelaxedOpcode(Inst.getOpcode()) == Inst.getOpcode()) + return false; + + // If so, just assume it can be relaxed. Once we support relaxing more complex + // instructions we should check that the instruction actually has symbolic + // operands before doing this, but we need to be careful about things like + // PCrel. + return true; +} + +// 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. +/// +/// FIXME this is X86 32-bit specific and should move to a better place. +bool X86AsmBackend::WriteNopData(uint64_t Count, MCObjectWriter *OW) const { + static const uint8_t Nops[16][16] = { + // 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}, + // nopl 0(%[re]ax,%[re]ax,1) + // nopw 0(%[re]ax,%[re]ax,1) + {0x0f, 0x1f, 0x44, 0x00, 0x00, + 0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00}, + // nopw 0(%[re]ax,%[re]ax,1) + // nopw 0(%[re]ax,%[re]ax,1) + {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00, + 0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00}, + // nopw 0(%[re]ax,%[re]ax,1) + // nopl 0L(%[re]ax) */ + {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00, + 0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00}, + // nopl 0L(%[re]ax) + // nopl 0L(%[re]ax) + {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00, + 0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00}, + // nopl 0L(%[re]ax) + // nopl 0L(%[re]ax,%[re]ax,1) + {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00, + 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00} + }; + + // Write an optimal sequence for the first 15 bytes. + uint64_t OptimalCount = (Count < 16) ? Count : 15; + for (uint64_t i = 0, e = OptimalCount; i != e; i++) + OW->Write8(Nops[OptimalCount - 1][i]); + + // Finish with single byte nops. + for (uint64_t i = OptimalCount, e = Count; i != e; ++i) + OW->Write8(0x90); + + return true; +} + +/* *** */ + +class ELFX86AsmBackend : public X86AsmBackend { +public: + ELFX86AsmBackend(const Target &T) + : X86AsmBackend(T) { + HasAbsolutizedSet = true; + HasScatteredSymbols = true; + } + + MCObjectWriter *createObjectWriter(raw_ostream &OS) const { + return 0; + } + + bool isVirtualSection(const MCSection &Section) const { + const MCSectionELF &SE = static_cast<const MCSectionELF&>(Section); + return SE.getType() == MCSectionELF::SHT_NOBITS;; + } +}; + +class ELFX86_32AsmBackend : public ELFX86AsmBackend { +public: + ELFX86_32AsmBackend(const Target &T) + : ELFX86AsmBackend(T) {} +}; + +class ELFX86_64AsmBackend : public ELFX86AsmBackend { +public: + ELFX86_64AsmBackend(const Target &T) + : ELFX86AsmBackend(T) {} +}; + +class DarwinX86AsmBackend : public X86AsmBackend { +public: + DarwinX86AsmBackend(const Target &T) + : X86AsmBackend(T) { + HasAbsolutizedSet = true; + HasScatteredSymbols = true; + } + + bool isVirtualSection(const MCSection &Section) const { + const MCSectionMachO &SMO = static_cast<const MCSectionMachO&>(Section); + return (SMO.getType() == MCSectionMachO::S_ZEROFILL || + SMO.getType() == MCSectionMachO::S_GB_ZEROFILL || + SMO.getType() == MCSectionMachO::S_THREAD_LOCAL_ZEROFILL); + } +}; + +class DarwinX86_32AsmBackend : public DarwinX86AsmBackend { +public: + DarwinX86_32AsmBackend(const Target &T) + : DarwinX86AsmBackend(T) {} + + MCObjectWriter *createObjectWriter(raw_ostream &OS) const { + return new MachObjectWriter(OS, /*Is64Bit=*/false); + } +}; + +class DarwinX86_64AsmBackend : public DarwinX86AsmBackend { +public: + DarwinX86_64AsmBackend(const Target &T) + : DarwinX86AsmBackend(T) { + HasReliableSymbolDifference = true; + } + + MCObjectWriter *createObjectWriter(raw_ostream &OS) const { + return new MachObjectWriter(OS, /*Is64Bit=*/true); + } + + 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; + } + } +}; + +} + +TargetAsmBackend *llvm::createX86_32AsmBackend(const Target &T, + const std::string &TT) { + switch (Triple(TT).getOS()) { + case Triple::Darwin: + return new DarwinX86_32AsmBackend(T); + default: + return new ELFX86_32AsmBackend(T); + } +} + +TargetAsmBackend *llvm::createX86_64AsmBackend(const Target &T, + const std::string &TT) { + switch (Triple(TT).getOS()) { + case Triple::Darwin: + return new DarwinX86_64AsmBackend(T); + default: + return new ELFX86_64AsmBackend(T); + } +} |
