From 3565a06ebf44a193a8b333cbeff2ee154298d450 Mon Sep 17 00:00:00 2001 From: Matt Fleming Date: Mon, 16 Aug 2010 18:57:57 +0000 Subject: [PATCH] Add ELF ObjectWriter and Streamer support. I forgot to add these files in commit 111172. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111174 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/MC/ELFObjectWriter.h | 46 ++ include/llvm/MC/MCELFSymbolFlags.h | 54 ++ lib/MC/ELFObjectWriter.cpp | 1032 ++++++++++++++++++++++++++++ lib/MC/MCELFStreamer.cpp | 401 +++++++++++ 4 files changed, 1533 insertions(+) create mode 100644 include/llvm/MC/ELFObjectWriter.h create mode 100644 include/llvm/MC/MCELFSymbolFlags.h create mode 100644 lib/MC/ELFObjectWriter.cpp create mode 100644 lib/MC/MCELFStreamer.cpp diff --git a/include/llvm/MC/ELFObjectWriter.h b/include/llvm/MC/ELFObjectWriter.h new file mode 100644 index 00000000000..3b9951f4e7a --- /dev/null +++ b/include/llvm/MC/ELFObjectWriter.h @@ -0,0 +1,46 @@ +//===-- llvm/MC/ELFObjectWriter.h - ELF File Writer ---------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_MC_ELFOBJECTWRITER_H +#define LLVM_MC_ELFOBJECTWRITER_H + +#include "llvm/MC/MCObjectWriter.h" +#include "llvm/Support/raw_ostream.h" +#include + +namespace llvm { +class MCAsmFixup; +class MCAssembler; +class MCFragment; +class MCValue; +class raw_ostream; + +class ELFObjectWriter : public MCObjectWriter { + void *Impl; + +public: + ELFObjectWriter(raw_ostream &OS, bool Is64Bit, bool IsLittleEndian = true, + bool HasRelocationAddend = true); + + virtual ~ELFObjectWriter(); + + virtual void ExecutePostLayoutBinding(MCAssembler &Asm); + + virtual void RecordRelocation(const MCAssembler &Asm, + const MCAsmLayout &Layout, + const MCFragment *Fragment, + const MCFixup &Fixup, MCValue Target, + uint64_t &FixedValue); + + virtual void WriteObject(const MCAssembler &Asm, const MCAsmLayout &Layout); +}; + +} // End llvm namespace + +#endif diff --git a/include/llvm/MC/MCELFSymbolFlags.h b/include/llvm/MC/MCELFSymbolFlags.h new file mode 100644 index 00000000000..eb7978b18c5 --- /dev/null +++ b/include/llvm/MC/MCELFSymbolFlags.h @@ -0,0 +1,54 @@ +//===- MCELFSymbolFlags.h - ELF Symbol Flags ----------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file declares the SymbolFlags used for the ELF target. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_MC_MCELFSYMBOLFLAGS_H +#define LLVM_MC_MCELFSYMBOLFLAGS_H + +#include "llvm/Support/ELF.h" + +// Because all the symbol flags need to be stored in the MCSymbolData +// 'flags' variable we need to provide shift constants per flag type. + +namespace llvm { + enum { + ELF_STT_Shift = 0, // Shift value for STT_* flags. + ELF_STB_Shift = 4, // Shift value for STB_* flags. + ELF_STV_Shift = 8 // Shift value ofr STV_* flags. + }; + + enum SymbolFlags { + ELF_STB_Local = (ELF::STB_LOCAL << ELF_STB_Shift), + ELF_STB_Global = (ELF::STB_GLOBAL << ELF_STB_Shift), + ELF_STB_Weak = (ELF::STB_WEAK << ELF_STB_Shift), + ELF_STB_Loproc = (ELF::STB_LOPROC << ELF_STB_Shift), + ELF_STB_Hiproc = (ELF::STB_HIPROC << ELF_STB_Shift), + + ELF_STT_Notype = (ELF::STT_NOTYPE << ELF_STT_Shift), + ELF_STT_Object = (ELF::STT_OBJECT << ELF_STT_Shift), + ELF_STT_Func = (ELF::STT_FUNC << ELF_STT_Shift), + ELF_STT_Section = (ELF::STT_SECTION << ELF_STT_Shift), + ELF_STT_File = (ELF::STT_FILE << ELF_STT_Shift), + ELF_STT_Common = (ELF::STT_COMMON << ELF_STT_Shift), + ELF_STT_Tls = (ELF::STT_TLS << ELF_STT_Shift), + ELF_STT_Loproc = (ELF::STT_LOPROC << ELF_STT_Shift), + ELF_STT_Hiproc = (ELF::STT_HIPROC << ELF_STT_Shift), + + ELF_STV_Default = (ELF::STV_DEFAULT << ELF_STV_Shift), + ELF_STV_Internal = (ELF::STV_INTERNAL << ELF_STV_Shift), + ELF_STV_Hidden = (ELF::STV_HIDDEN << ELF_STV_Shift), + ELF_STV_Protected = (ELF::STV_PROTECTED << ELF_STV_Shift) + }; + +} // end namespace llvm + +#endif diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp new file mode 100644 index 00000000000..84a154c6764 --- /dev/null +++ b/lib/MC/ELFObjectWriter.cpp @@ -0,0 +1,1032 @@ +//===- lib/MC/ELFObjectWriter.cpp - ELF File Writer -------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements ELF object file writer information. +// +//===----------------------------------------------------------------------===// + +#include "llvm/MC/ELFObjectWriter.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/StringMap.h" +#include "llvm/ADT/Twine.h" +#include "llvm/MC/MCAssembler.h" +#include "llvm/MC/MCAsmLayout.h" +#include "llvm/MC/MCContext.h" +#include "llvm/MC/MCELFSymbolFlags.h" +#include "llvm/MC/MCExpr.h" +#include "llvm/MC/MCObjectWriter.h" +#include "llvm/MC/MCSectionELF.h" +#include "llvm/MC/MCSymbol.h" +#include "llvm/MC/MCValue.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/ELF.h" +#include "llvm/Target/TargetAsmBackend.h" + +#include "../Target/X86/X86FixupKinds.h" + +#include +using namespace llvm; + +namespace { + + class ELFObjectWriterImpl { + static bool isFixupKindX86PCRel(unsigned Kind) { + switch (Kind) { + default: + return false; + case X86::reloc_pcrel_1byte: + case X86::reloc_pcrel_4byte: + case X86::reloc_riprel_4byte: + case X86::reloc_riprel_4byte_movq_load: + return true; + } + } + + static bool isFixupKindX86RIPRel(unsigned Kind) { + return Kind == X86::reloc_riprel_4byte || + Kind == X86::reloc_riprel_4byte_movq_load; + } + + + /// ELFSymbolData - Helper struct for containing some precomputed information + /// on symbols. + struct ELFSymbolData { + MCSymbolData *SymbolData; + uint64_t StringIndex; + uint32_t SectionIndex; + + // Support lexicographic sorting. + bool operator<(const ELFSymbolData &RHS) const { + const std::string &Name = SymbolData->getSymbol().getName(); + return Name < RHS.SymbolData->getSymbol().getName(); + } + }; + + /// @name Relocation Data + /// @{ + + struct ELFRelocationEntry { + // Make these big enough for both 32-bit and 64-bit + uint64_t r_offset; + uint64_t r_info; + uint64_t r_addend; + + // Support lexicographic sorting. + bool operator<(const ELFRelocationEntry &RE) const { + return RE.r_offset < r_offset; + } + }; + + llvm::DenseMap > Relocations; + DenseMap SectionStringTableIndex; + + /// @} + /// @name Symbol Table Data + /// @{ + + SmallString<256> StringTable; + std::vector LocalSymbolData; + std::vector ExternalSymbolData; + std::vector UndefinedSymbolData; + + /// @} + + ELFObjectWriter *Writer; + + raw_ostream &OS; + + // This holds the current offset into the object file. + size_t FileOff; + + unsigned Is64Bit : 1; + + bool HasRelocationAddend; + + // This holds the symbol table index of the last local symbol. + unsigned LastLocalSymbolIndex; + // This holds the .strtab section index. + unsigned StringTableIndex; + + unsigned ShstrtabIndex; + + public: + ELFObjectWriterImpl(ELFObjectWriter *_Writer, bool _Is64Bit, + bool _HasRelAddend) + : Writer(_Writer), OS(Writer->getStream()), FileOff(0), + Is64Bit(_Is64Bit), HasRelocationAddend(_HasRelAddend) { + } + + void Write8(uint8_t Value) { Writer->Write8(Value); } + void Write16(uint16_t Value) { Writer->Write16(Value); } + void Write32(uint32_t Value) { Writer->Write32(Value); } + void Write64(uint64_t Value) { Writer->Write64(Value); } + void WriteZeros(unsigned N) { Writer->WriteZeros(N); } + void WriteBytes(StringRef Str, unsigned ZeroFillSize = 0) { + Writer->WriteBytes(Str, ZeroFillSize); + } + + void WriteWord(uint64_t W) { + if (Is64Bit) { + Writer->Write64(W); + } else { + Writer->Write32(W); + } + } + + void String8(char *buf, uint8_t Value) { + buf[0] = Value; + } + + void StringLE16(char *buf, uint16_t Value) { + buf[0] = char(Value >> 0); + buf[1] = char(Value >> 8); + } + + void StringLE32(char *buf, uint32_t Value) { + buf[0] = char(Value >> 0); + buf[1] = char(Value >> 8); + buf[2] = char(Value >> 16); + buf[3] = char(Value >> 24); + } + + void StringLE64(char *buf, uint64_t Value) { + buf[0] = char(Value >> 0); + buf[1] = char(Value >> 8); + buf[2] = char(Value >> 16); + buf[3] = char(Value >> 24); + buf[4] = char(Value >> 32); + buf[5] = char(Value >> 40); + buf[6] = char(Value >> 48); + buf[7] = char(Value >> 56); + } + + void StringBE16(char *buf ,uint16_t Value) { + buf[0] = char(Value >> 8); + buf[1] = char(Value >> 0); + } + + void StringBE32(char *buf, uint32_t Value) { + buf[0] = char(Value >> 24); + buf[1] = char(Value >> 16); + buf[2] = char(Value >> 8); + buf[3] = char(Value >> 0); + } + + void StringBE64(char *buf, uint64_t Value) { + buf[0] = char(Value >> 56); + buf[1] = char(Value >> 48); + buf[2] = char(Value >> 40); + buf[3] = char(Value >> 32); + buf[4] = char(Value >> 24); + buf[5] = char(Value >> 16); + buf[6] = char(Value >> 8); + buf[7] = char(Value >> 0); + } + + void String16(char *buf, uint16_t Value) { + if (Writer->isLittleEndian()) + StringLE16(buf, Value); + else + StringBE16(buf, Value); + } + + void String32(char *buf, uint32_t Value) { + if (Writer->isLittleEndian()) + StringLE32(buf, Value); + else + StringBE32(buf, Value); + } + + void String64(char *buf, uint64_t Value) { + if (Writer->isLittleEndian()) + StringLE64(buf, Value); + else + StringBE64(buf, Value); + } + + void WriteHeader(uint64_t SectionDataSize, unsigned NumberOfSections); + + void WriteSymbolEntry(MCDataFragment *F, uint64_t name, uint8_t info, + uint64_t value, uint64_t size, + uint8_t other, uint16_t shndx); + + void WriteSymbol(MCDataFragment *F, ELFSymbolData &MSD, + const MCAsmLayout &Layout); + + void WriteSymbolTable(MCDataFragment *F, const MCAssembler &Asm, + const MCAsmLayout &Layout); + + void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout, + const MCFragment *Fragment, const MCFixup &Fixup, + MCValue Target, uint64_t &FixedValue); + + // XXX-PERF: this should be cached + uint64_t getNumOfLocalSymbols(const MCAssembler &Asm) { + std::vector Local; + + uint64_t Index = 0; + for (MCAssembler::const_symbol_iterator it = Asm.symbol_begin(), + ie = Asm.symbol_end(); it != ie; ++it) { + const MCSymbol &Symbol = it->getSymbol(); + + // Ignore non-linker visible symbols. + if (!Asm.isSymbolLinkerVisible(Symbol)) + continue; + + if (it->isExternal() || Symbol.isUndefined()) + continue; + + Index++; + } + + return Index; + } + + uint64_t getSymbolIndexInSymbolTable(MCAssembler &Asm, const MCSymbol *S); + + /// ComputeSymbolTable - Compute the symbol table data + /// + /// \param StringTable [out] - The string table data. + /// \param StringIndexMap [out] - Map from symbol names to offsets in the + /// string table. + void ComputeSymbolTable(MCAssembler &Asm); + + void WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout, + const MCSectionData &SD); + + void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout) { + for (MCAssembler::const_iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + WriteRelocation(Asm, Layout, *it); + } + } + + void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout); + + void ExecutePostLayoutBinding(MCAssembler &Asm) {} + + void WriteSecHdrEntry(uint32_t Name, uint32_t Type, uint64_t Flags, + uint64_t Address, uint64_t Offset, + uint64_t Size, uint32_t Link, uint32_t Info, + uint64_t Alignment, uint64_t EntrySize); + + void WriteRelocationsFragment(const MCAssembler &Asm, MCDataFragment *F, + const MCSectionData *SD); + + void WriteObject(const MCAssembler &Asm, const MCAsmLayout &Layout); + }; + +} + +// Emit the ELF header. +void ELFObjectWriterImpl::WriteHeader(uint64_t SectionDataSize, + unsigned NumberOfSections) { + // ELF Header + // ---------- + // + // Note + // ---- + // emitWord method behaves differently for ELF32 and ELF64, writing + // 4 bytes in the former and 8 in the latter. + + Write8(0x7f); // e_ident[EI_MAG0] + Write8('E'); // e_ident[EI_MAG1] + Write8('L'); // e_ident[EI_MAG2] + Write8('F'); // e_ident[EI_MAG3] + + Write8(Is64Bit ? ELF::ELFCLASS64 : ELF::ELFCLASS32); // e_ident[EI_CLASS] + + // e_ident[EI_DATA] + Write8(Writer->isLittleEndian() ? ELF::ELFDATA2LSB : ELF::ELFDATA2MSB); + + Write8(ELF::EV_CURRENT); // e_ident[EI_VERSION] + Write8(ELF::ELFOSABI_LINUX); // e_ident[EI_OSABI] + Write8(0); // e_ident[EI_ABIVERSION] + + WriteZeros(ELF::EI_NIDENT - ELF::EI_PAD); + + Write16(ELF::ET_REL); // e_type + + // FIXME: Make this configurable + Write16(ELF::EM_X86_64); // e_machine = target + + Write32(ELF::EV_CURRENT); // e_version + WriteWord(0); // e_entry, no entry point in .o file + WriteWord(0); // e_phoff, no program header for .o + WriteWord(SectionDataSize + 64); // e_shoff = sec hdr table off in bytes + + // FIXME: Make this configurable. + Write32(0); // e_flags = whatever the target wants + + // e_ehsize = ELF header size + Write16(Is64Bit ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr)); + + Write16(0); // e_phentsize = prog header entry size + Write16(0); // e_phnum = # prog header entries = 0 + + // e_shentsize = Section header entry size + Write16(Is64Bit ? sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr)); + + // e_shnum = # of section header ents + Write16(NumberOfSections); + + // e_shstrndx = Section # of '.shstrtab' + Write16(ShstrtabIndex); +} + +void ELFObjectWriterImpl::WriteSymbolEntry(MCDataFragment *F, uint64_t name, + uint8_t info, uint64_t value, + uint64_t size, uint8_t other, + uint16_t shndx) { + if (Is64Bit) { + char buf[8]; + + String32(buf, name); + F->getContents() += StringRef(buf, 4); // st_name + + String8(buf, info); + F->getContents() += StringRef(buf, 1); // st_info + String8(buf, other); + F->getContents() += StringRef(buf, 1); // st_other + + String16(buf, shndx); + F->getContents() += StringRef(buf, 2); // st_shndx + + String64(buf, value); + F->getContents() += StringRef(buf, 8); // st_value + + String64(buf, size); + F->getContents() += StringRef(buf, 8); // st_size + } else { + char buf[4]; + + String32(buf, name); + F->getContents() += StringRef(buf, 4); // st_name + + String32(buf, value); + F->getContents() += StringRef(buf, 4); // st_value + + String32(buf, size); + F->getContents() += StringRef(buf, 4); // st_size + + String8(buf, info); + F->getContents() += StringRef(buf, 1); // st_info + + String8(buf, other); + F->getContents() += StringRef(buf, 1); // st_other + + String16(buf, shndx); + F->getContents() += StringRef(buf, 2); // st_shndx + } +} + +void ELFObjectWriterImpl::WriteSymbol(MCDataFragment *F, ELFSymbolData &MSD, + const MCAsmLayout &Layout) { + MCSymbolData &Data = *MSD.SymbolData; + const MCSymbol &Symbol = Data.getSymbol(); + uint8_t Info = (Data.getFlags() & 0xff); + uint8_t Other = ((Data.getFlags() & 0xf00) >> ELF_STV_Shift); + uint64_t Value = 0; + uint64_t Size = 0; + const MCExpr *ESize; + + if (Data.isCommon() && Data.isExternal()) + Value = Data.getCommonAlignment(); + + ESize = Data.getSize(); + if (Data.getSize()) { + MCValue Res; + if (ESize->getKind() == MCExpr::Binary) { + const MCBinaryExpr *BE = static_cast(ESize); + + if (BE->EvaluateAsRelocatable(Res, &Layout)) { + MCSymbolData &A = + Layout.getAssembler().getSymbolData(Res.getSymA()->getSymbol()); + MCSymbolData &B = + Layout.getAssembler().getSymbolData(Res.getSymB()->getSymbol()); + + Size = Layout.getSymbolAddress(&A) - Layout.getSymbolAddress(&B); + Value = Layout.getSymbolAddress(&Data); + } + } else if (ESize->getKind() == MCExpr::Constant) { + const MCConstantExpr *CE; + CE = static_cast(ESize); + Size = CE->getValue(); + } else { + assert(0 && "Unsupported size expression"); + } + } + + // Write out the symbol table entry + WriteSymbolEntry(F, MSD.StringIndex, Info, Value, + Size, Other, MSD.SectionIndex); +} + +void ELFObjectWriterImpl::WriteSymbolTable(MCDataFragment *F, + const MCAssembler &Asm, + const MCAsmLayout &Layout) { + // The string table must be emitted first because we need the index + // into the string table for all the symbol names. + assert(StringTable.size() && "Missing string table"); + + // FIXME: Make sure the start of the symbol table is aligned. + + // The first entry is the undefined symbol entry. + unsigned EntrySize = Is64Bit ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32; + for (unsigned i = 0; i < EntrySize; ++i) + F->getContents() += '\x00'; + + // Write the symbol table entries. + LastLocalSymbolIndex = LocalSymbolData.size() + 1; + for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) { + ELFSymbolData &MSD = LocalSymbolData[i]; + WriteSymbol(F, MSD, Layout); + } + + // Write out a symbol table entry for each section. + for (unsigned Index = 1; Index < Asm.size(); ++Index) + WriteSymbolEntry(F, 0, ELF::STT_SECTION, 0, 0, ELF::STV_DEFAULT, Index); + LastLocalSymbolIndex += Asm.size() - 1; + + for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) { + ELFSymbolData &MSD = ExternalSymbolData[i]; + MCSymbolData &Data = *MSD.SymbolData; + assert((Data.getFlags() & ELF_STB_Global) && + "External symbol requires STB_GLOBAL flag"); + WriteSymbol(F, MSD, Layout); + if (Data.getFlags() & ELF_STB_Local) + LastLocalSymbolIndex++; + } + + for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) { + ELFSymbolData &MSD = UndefinedSymbolData[i]; + MCSymbolData &Data = *MSD.SymbolData; + Data.setFlags(Data.getFlags() | ELF_STB_Global); + WriteSymbol(F, MSD, Layout); + if (Data.getFlags() & ELF_STB_Local) + LastLocalSymbolIndex++; + } +} + +// FIXME: this is currently X86_64 only +void ELFObjectWriterImpl::RecordRelocation(const MCAssembler &Asm, + const MCAsmLayout &Layout, + const MCFragment *Fragment, + const MCFixup &Fixup, + MCValue Target, + uint64_t &FixedValue) { + unsigned IsPCRel = isFixupKindX86PCRel(Fixup.getKind()); + ELFRelocationEntry ERE; + struct ELF::Elf64_Rela ERE64; + + uint64_t FixupOffset = + Layout.getFragmentOffset(Fragment) + Fixup.getOffset(); + int64_t Value; + int64_t Addend = 0; + unsigned Index = 0; + unsigned Type; + + Value = Target.getConstant(); + + if (Target.isAbsolute()) { + Type = ELF::R_X86_64_NONE; + Index = 0; + } else { + const MCSymbol *Symbol = &Target.getSymA()->getSymbol(); + MCSymbolData &SD = Asm.getSymbolData(*Symbol); + const MCSymbolData *Base = Asm.getAtom(Layout, &SD); + + if (Base) { + Index = getSymbolIndexInSymbolTable(const_cast(Asm), &Base->getSymbol()); + if (Base != &SD) + Value += Layout.getSymbolAddress(&SD) - Layout.getSymbolAddress(Base); + Addend = Value; + Value = 0; + } else { + MCFragment *F = SD.getFragment(); + if (F) { + // Index of the section in .symtab against this symbol + // is being relocated + 2 (empty section + abs. symbols). + Index = SD.getFragment()->getParent()->getOrdinal() + + getNumOfLocalSymbols(Asm) + 1; + + MCSectionData *FSD = F->getParent(); + // Offset of the symbol in the section + Addend = Layout.getSymbolAddress(&SD) - Layout.getSectionAddress(FSD); + } else { + FixedValue = Value; + return; + } + } + } + + // determine the type of the relocation + if (IsPCRel) { + Type = ELF::R_X86_64_PC32; + } else { + switch (Fixup.getKind()) { + case FK_Data_8: Type = ELF::R_X86_64_64; break; + case X86::reloc_pcrel_4byte: + case FK_Data_4: + long Offset; + Offset = Target.getConstant(); + // check that the offset fits within a signed long + if (!(((long) -1 << 31) & Offset) || (((long) -1 << 31) & Offset) == ((long) -1 << 31)) + Type = ELF::R_X86_64_32S; + else + Type = ELF::R_X86_64_32; + break; + case FK_Data_2: Type = ELF::R_X86_64_16; break; + case X86::reloc_pcrel_1byte: + case FK_Data_1: + Type = ELF::R_X86_64_8; + break; + } + } + + FixedValue = Value; + + ERE64.setSymbolAndType(Index, Type); + + ERE.r_offset = FixupOffset; + ERE.r_info = ERE64.r_info; + if (HasRelocationAddend) + ERE.r_addend = Addend; + + Relocations[Fragment->getParent()].push_back(ERE); +} + +// XXX-PERF: this should be cached +uint64_t ELFObjectWriterImpl::getSymbolIndexInSymbolTable(MCAssembler &Asm, + const MCSymbol *S) { + std::vector Local; + std::vector External; + std::vector Undefined; + + for (MCAssembler::symbol_iterator it = Asm.symbol_begin(), + ie = Asm.symbol_end(); it != ie; ++it) { + const MCSymbol &Symbol = it->getSymbol(); + + // Ignore non-linker visible symbols. + if (!Asm.isSymbolLinkerVisible(Symbol)) + continue; + + if (it->isExternal() || Symbol.isUndefined()) + continue; + + ELFSymbolData MSD; + MSD.SymbolData = it; + + Local.push_back(MSD); + } + for (MCAssembler::symbol_iterator it = Asm.symbol_begin(), + ie = Asm.symbol_end(); it != ie; ++it) { + const MCSymbol &Symbol = it->getSymbol(); + + // Ignore non-linker visible symbols. + if (!Asm.isSymbolLinkerVisible(Symbol)) + continue; + + if (!it->isExternal() && !Symbol.isUndefined()) + continue; + + ELFSymbolData MSD; + MSD.SymbolData = it; + + if (Symbol.isUndefined()) { + Undefined.push_back(MSD); + } else if (Symbol.isAbsolute()) { + External.push_back(MSD); + } else if (it->isCommon()) { + External.push_back(MSD); + } else { + External.push_back(MSD); + } + } + + array_pod_sort(Local.begin(), Local.end()); + array_pod_sort(External.begin(), External.end()); + array_pod_sort(Undefined.begin(), Undefined.end()); + + for (unsigned i = 0, e = Local.size(); i != e; ++i) + if (&Local[i].SymbolData->getSymbol() == S) + return i + /* empty symbol */ 1; + for (unsigned i = 0, e = External.size(); i != e; ++i) + if (&External[i].SymbolData->getSymbol() == S) + return i + Local.size() + Asm.size() + /* empty symbol */ 1 + + /* .rela.text + .rela.eh_frame */ + 2; + for (unsigned i = 0, e = Undefined.size(); i != e; ++i) + if (&Undefined[i].SymbolData->getSymbol() == S) + return i + Local.size() + External.size() + Asm.size() + /* empty symbol */ 1 + + /* .rela.text + .rela.eh_frame */ + 2; +} + +void ELFObjectWriterImpl::ComputeSymbolTable(MCAssembler &Asm) { + // Build section lookup table. + DenseMap SectionIndexMap; + unsigned Index = 1; + for (MCAssembler::iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it, ++Index) + SectionIndexMap[&it->getSection()] = Index; + + // Index 0 is always the empty string. + StringMap StringIndexMap; + StringTable += '\x00'; + + // Add the data for local symbols. + for (MCAssembler::symbol_iterator it = Asm.symbol_begin(), + ie = Asm.symbol_end(); it != ie; ++it) { + const MCSymbol &Symbol = it->getSymbol(); + + // Ignore non-linker visible symbols. + if (!Asm.isSymbolLinkerVisible(Symbol)) + continue; + + if (it->isExternal() || Symbol.isUndefined()) + continue; + + uint64_t &Entry = StringIndexMap[Symbol.getName()]; + if (!Entry) { + Entry = StringTable.size(); + StringTable += Symbol.getName(); + StringTable += '\x00'; + } + + ELFSymbolData MSD; + MSD.SymbolData = it; + MSD.StringIndex = Entry; + + if (Symbol.isAbsolute()) { + MSD.SectionIndex = ELF::SHN_ABS; + LocalSymbolData.push_back(MSD); + } else { + MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection()); + assert(MSD.SectionIndex && "Invalid section index!"); + LocalSymbolData.push_back(MSD); + } + } + + // Now add non-local symbols. + for (MCAssembler::symbol_iterator it = Asm.symbol_begin(), + ie = Asm.symbol_end(); it != ie; ++it) { + const MCSymbol &Symbol = it->getSymbol(); + + // Ignore non-linker visible symbols. + if (!Asm.isSymbolLinkerVisible(Symbol)) + continue; + + if (!it->isExternal() && !Symbol.isUndefined()) + continue; + + uint64_t &Entry = StringIndexMap[Symbol.getName()]; + if (!Entry) { + Entry = StringTable.size(); + StringTable += Symbol.getName(); + StringTable += '\x00'; + } + + ELFSymbolData MSD; + MSD.SymbolData = it; + MSD.StringIndex = Entry; + + if (Symbol.isUndefined()) { + MSD.SectionIndex = ELF::SHN_UNDEF; + // XXX: for some reason we dont Emit* this + it->setFlags(it->getFlags() | ELF_STB_Global); + UndefinedSymbolData.push_back(MSD); + } else if (Symbol.isAbsolute()) { + MSD.SectionIndex = ELF::SHN_ABS; + ExternalSymbolData.push_back(MSD); + } else if (it->isCommon()) { + MSD.SectionIndex = ELF::SHN_COMMON; + ExternalSymbolData.push_back(MSD); + } else { + MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection()); + assert(MSD.SectionIndex && "Invalid section index!"); + ExternalSymbolData.push_back(MSD); + } + } + + // Symbols are required to be in lexicographic order. + array_pod_sort(LocalSymbolData.begin(), LocalSymbolData.end()); + array_pod_sort(ExternalSymbolData.begin(), ExternalSymbolData.end()); + array_pod_sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end()); + + // Set the symbol indices. Local symbols must come before all other + // symbols with non-local bindings. + Index = 0; + for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) + LocalSymbolData[i].SymbolData->setIndex(Index++); + for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) + ExternalSymbolData[i].SymbolData->setIndex(Index++); + for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) + UndefinedSymbolData[i].SymbolData->setIndex(Index++); +} + +void ELFObjectWriterImpl::WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout, + const MCSectionData &SD) { + if (!Relocations[&SD].empty()) { + MCContext &Ctx = Asm.getContext(); + const MCSection *RelaSection; + const MCSectionELF &Section = + static_cast(SD.getSection()); + + const StringRef SectionName = Section.getSectionName(); + std::string RelaSectionName = ".rela"; + + RelaSectionName += SectionName; + unsigned EntrySize = Is64Bit ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32; + + RelaSection = Ctx.getELFSection(RelaSectionName, ELF::SHT_RELA, 0, + SectionKind::getReadOnly(), + false, EntrySize); + + MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection); + RelaSD.setAlignment(1); + + MCDataFragment *F = new MCDataFragment(&RelaSD); + + WriteRelocationsFragment(Asm, F, &SD); + + Asm.AddSectionToTheEnd(RelaSD, Layout); + } +} + +void ELFObjectWriterImpl::WriteSecHdrEntry(uint32_t Name, uint32_t Type, + uint64_t Flags, uint64_t Address, + uint64_t Offset, uint64_t Size, + uint32_t Link, uint32_t Info, + uint64_t Alignment, + uint64_t EntrySize) { + Write32(Name); // sh_name: index into string table + Write32(Type); // sh_type + WriteWord(Flags); // sh_flags + WriteWord(Address); // sh_addr + WriteWord(Offset); // sh_offset + WriteWord(Size); // sh_size + Write32(Link); // sh_link + Write32(Info); // sh_info + WriteWord(Alignment); // sh_addralign + WriteWord(EntrySize); // sh_entsize +} + +void ELFObjectWriterImpl::WriteRelocationsFragment(const MCAssembler &Asm, + MCDataFragment *F, + const MCSectionData *SD) { + std::vector &Relocs = Relocations[SD]; + // sort by the r_offset just like gnu as does + array_pod_sort(Relocs.begin(), Relocs.end()); + + for (unsigned i = 0, e = Relocs.size(); i != e; ++i) { + ELFRelocationEntry entry = Relocs[e - i - 1]; + + if (Is64Bit) { + F->getContents() += StringRef((const char *)&entry.r_offset, 8); + F->getContents() += StringRef((const char *)&entry.r_info, 8); + + if (HasRelocationAddend) + F->getContents() += StringRef((const char *)&entry.r_addend, 8); + } else { + F->getContents() += StringRef((const char *)&entry.r_offset, 4); + F->getContents() += StringRef((const char *)&entry.r_info, 4); + + if (HasRelocationAddend) + F->getContents() += StringRef((const char *)&entry.r_addend, 4); + } + } +} + +void ELFObjectWriterImpl::CreateMetadataSections(MCAssembler &Asm, + MCAsmLayout &Layout) { + MCContext &Ctx = Asm.getContext(); + MCDataFragment *F; + + WriteRelocations(Asm, Layout); + + const MCSection *SymtabSection; + unsigned EntrySize = Is64Bit ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32; + + SymtabSection = Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0, + SectionKind::getReadOnly(), + false, EntrySize); + + MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection); + + SymtabSD.setAlignment(Is64Bit ? 8 : 4); + + F = new MCDataFragment(&SymtabSD); + + // Symbol table + WriteSymbolTable(F, Asm, Layout); + Asm.AddSectionToTheEnd(SymtabSD, Layout); + + const MCSection *StrtabSection; + StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0, + SectionKind::getReadOnly(), false); + + MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection); + StrtabSD.setAlignment(1); + + // FIXME: This isn't right. If the sections get rearranged this will + // be wrong. We need a proper lookup. + StringTableIndex = Asm.size(); + + F = new MCDataFragment(&StrtabSD); + F->getContents().append(StringTable.begin(), StringTable.end()); + Asm.AddSectionToTheEnd(StrtabSD, Layout); + + const MCSection *ShstrtabSection; + ShstrtabSection = Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0, + SectionKind::getReadOnly(), false); + + MCSectionData &ShstrtabSD = Asm.getOrCreateSectionData(*ShstrtabSection); + ShstrtabSD.setAlignment(1); + + F = new MCDataFragment(&ShstrtabSD); + + // FIXME: This isn't right. If the sections get rearranged this will + // be wrong. We need a proper lookup. + ShstrtabIndex = Asm.size(); + + // Section header string table. + // + // The first entry of a string table holds a null character so skip + // section 0. + uint64_t Index = 1; + F->getContents() += '\x00'; + + for (MCAssembler::const_iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + const MCSectionData &SD = *it; + const MCSectionELF &Section = + static_cast(SD.getSection()); + + + // Remember the index into the string table so we can write it + // into the sh_name field of the section header table. + SectionStringTableIndex[&it->getSection()] = Index; + + Index += Section.getSectionName().size() + 1; + F->getContents() += Section.getSectionName(); + F->getContents() += '\x00'; + } + + Asm.AddSectionToTheEnd(ShstrtabSD, Layout); +} + +void ELFObjectWriterImpl::WriteObject(const MCAssembler &Asm, + const MCAsmLayout &Layout) { + // Compute symbol table information. + ComputeSymbolTable(const_cast(Asm)); + + CreateMetadataSections(const_cast(Asm), + const_cast(Layout)); + + // Add 1 for the null section. + unsigned NumSections = Asm.size() + 1; + + uint64_t SectionDataSize = 0; + + for (MCAssembler::const_iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + const MCSectionData &SD = *it; + const MCSectionELF &Section = + static_cast(SD.getSection()); + + // Get the size of the section in the output file (including padding). + uint64_t Size = Layout.getSectionFileSize(&SD); + SectionDataSize += Size; + } + + // Write out the ELF header ... + WriteHeader(SectionDataSize, NumSections); + FileOff = Is64Bit ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr); + + // ... then all of the sections ... + DenseMap SectionOffsetMap; + + for (MCAssembler::const_iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + // Remember the offset into the file for this section. + SectionOffsetMap[&it->getSection()] = FileOff; + + const MCSectionData &SD = *it; + FileOff += Layout.getSectionFileSize(&SD); + + Asm.WriteSectionData(it, Layout, Writer); + } + + // ... and then the section header table. + // Should we align the section header table? + // + // Null section first. + WriteSecHdrEntry(0, 0, 0, 0, 0, 0, 0, 0, 0, 0); + + for (MCAssembler::const_iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + const MCSectionData &SD = *it; + const MCSectionELF &Section = + static_cast(SD.getSection()); + + uint64_t sh_link = 0; + uint64_t sh_info = 0; + + switch(Section.getType()) { + case ELF::SHT_DYNAMIC: + sh_link = SectionStringTableIndex[&it->getSection()]; + sh_info = 0; + break; + + case ELF::SHT_REL: + case ELF::SHT_RELA: + const MCSection *SymtabSection; + const MCSection *InfoSection; + const StringRef *SectionName; + const MCSectionData *SymtabSD; + const MCSectionData *InfoSD; + + SymtabSection = Asm.getContext().getELFSection(".symtab", ELF::SHT_SYMTAB, 0, + SectionKind::getReadOnly(), + false); + SymtabSD = &Asm.getSectionData(*SymtabSection); + // we have to count the empty section in too + sh_link = SymtabSD->getLayoutOrder() + 1; + + SectionName = &Section.getSectionName(); + SectionName = &SectionName->slice(5, SectionName->size()); + InfoSection = Asm.getContext().getELFSection(*SectionName, + ELF::SHT_PROGBITS, 0, + SectionKind::getReadOnly(), + false); + InfoSD = &Asm.getSectionData(*InfoSection); + sh_info = InfoSD->getLayoutOrder() + 1; + break; + + case ELF::SHT_SYMTAB: + case ELF::SHT_DYNSYM: + sh_link = StringTableIndex; + sh_info = LastLocalSymbolIndex; + break; + + case ELF::SHT_PROGBITS: + case ELF::SHT_STRTAB: + case ELF::SHT_NOBITS: + // Nothing to do. + break; + + case ELF::SHT_HASH: + case ELF::SHT_GROUP: + case ELF::SHT_SYMTAB_SHNDX: + default: + assert(0 && "FIXME: sh_type value not supported!"); + break; + } + + WriteSecHdrEntry(SectionStringTableIndex[&it->getSection()], + Section.getType(), Section.getFlags(), + Layout.getSectionAddress(&SD), + SectionOffsetMap.lookup(&SD.getSection()), + Layout.getSectionSize(&SD), sh_link, + sh_info, SD.getAlignment(), + Section.getEntrySize()); + } +} + +ELFObjectWriter::ELFObjectWriter(raw_ostream &OS, + bool Is64Bit, + bool IsLittleEndian, + bool HasRelocationAddend) + : MCObjectWriter(OS, IsLittleEndian) +{ + Impl = new ELFObjectWriterImpl(this, Is64Bit, HasRelocationAddend); +} + +ELFObjectWriter::~ELFObjectWriter() { + delete (ELFObjectWriterImpl*) Impl; +} + +void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm) { + ((ELFObjectWriterImpl*) Impl)->ExecutePostLayoutBinding(Asm); +} + +void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm, + const MCAsmLayout &Layout, + const MCFragment *Fragment, + const MCFixup &Fixup, MCValue Target, + uint64_t &FixedValue) { + ((ELFObjectWriterImpl*) Impl)->RecordRelocation(Asm, Layout, Fragment, Fixup, + Target, FixedValue); +} + +void ELFObjectWriter::WriteObject(const MCAssembler &Asm, + const MCAsmLayout &Layout) { + ((ELFObjectWriterImpl*) Impl)->WriteObject(Asm, Layout); +} diff --git a/lib/MC/MCELFStreamer.cpp b/lib/MC/MCELFStreamer.cpp new file mode 100644 index 00000000000..fa48f951780 --- /dev/null +++ b/lib/MC/MCELFStreamer.cpp @@ -0,0 +1,401 @@ +//===- lib/MC/MCELFStreamer.cpp - ELF Object Output ------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file assembles .s files and emits ELF .o object files. +// +//===----------------------------------------------------------------------===// + +#include "llvm/MC/MCStreamer.h" + +#include "llvm/MC/MCAssembler.h" +#include "llvm/MC/MCContext.h" +#include "llvm/MC/MCCodeEmitter.h" +#include "llvm/MC/MCELFSymbolFlags.h" +#include "llvm/MC/MCExpr.h" +#include "llvm/MC/MCInst.h" +#include "llvm/MC/MCObjectStreamer.h" +#include "llvm/MC/MCSection.h" +#include "llvm/MC/MCSectionELF.h" +#include "llvm/MC/MCSymbol.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/ELF.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Target/TargetAsmBackend.h" + +using namespace llvm; + +namespace { + +class MCELFStreamer : public MCObjectStreamer { +public: + MCELFStreamer(MCContext &Context, TargetAsmBackend &TAB, + raw_ostream &OS, MCCodeEmitter *Emitter) + : MCObjectStreamer(Context, TAB, OS, Emitter) {} + + ~MCELFStreamer() {} + + /// @name MCStreamer Interface + /// @{ + + virtual void EmitLabel(MCSymbol *Symbol); + virtual void EmitAssemblerFlag(MCAssemblerFlag Flag); + virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value); + virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute); + virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) { + assert(0 && "ELF doesn't support this directive"); + } + virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size, + unsigned ByteAlignment); + virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) { + assert(0 && "ELF doesn't support this directive"); + } + + virtual void EmitCOFFSymbolStorageClass(int StorageClass) { + assert(0 && "ELF doesn't support this directive"); + } + + virtual void EmitCOFFSymbolType(int Type) { + assert(0 && "ELF doesn't support this directive"); + } + + virtual void EndCOFFSymbolDef() { + assert(0 && "ELF doesn't support this directive"); + } + + virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) { + MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol); + SD.setSize(Value); + } + + virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) { + assert(0 && "ELF doesn't support this directive"); + } + virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0, + unsigned Size = 0, unsigned ByteAlignment = 0) { + assert(0 && "ELF doesn't support this directive"); + } + virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol, + uint64_t Size, unsigned ByteAlignment = 0) { + assert(0 && "ELF doesn't support this directive"); + } + virtual void EmitBytes(StringRef Data, unsigned AddrSpace); + virtual void EmitValue(const MCExpr *Value, unsigned Size,unsigned AddrSpace); + virtual void EmitGPRel32Value(const MCExpr *Value) { + assert(0 && "ELF doesn't support this directive"); + } + virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0, + unsigned ValueSize = 1, + unsigned MaxBytesToEmit = 0); + virtual void EmitCodeAlignment(unsigned ByteAlignment, + unsigned MaxBytesToEmit = 0); + virtual void EmitValueToOffset(const MCExpr *Offset, + unsigned char Value = 0); + + virtual void EmitFileDirective(StringRef Filename); + virtual void EmitDwarfFileDirective(unsigned FileNo, StringRef Filename) { + DEBUG(dbgs() << "FIXME: MCELFStreamer:EmitDwarfFileDirective not implemented\n"); + } + + virtual void EmitInstruction(const MCInst &Inst); + virtual void Finish(); + + /// @} +}; + +} // end anonymous namespace. + +void MCELFStreamer::EmitLabel(MCSymbol *Symbol) { + assert(Symbol->isUndefined() && "Cannot define a symbol twice!"); + + // FIXME: This is wasteful, we don't necessarily need to create a data + // fragment. Instead, we should mark the symbol as pointing into the data + // fragment if it exists, otherwise we should just queue the label and set its + // fragment pointer when we emit the next fragment. + MCDataFragment *F = getOrCreateDataFragment(); + MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol); + assert(!SD.getFragment() && "Unexpected fragment on symbol data!"); + SD.setFragment(F); + SD.setOffset(F->getContents().size()); + + Symbol->setSection(*CurSection); +} + +void MCELFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) { + switch (Flag) { + case MCAF_SubsectionsViaSymbols: + getAssembler().setSubsectionsViaSymbols(true); + return; + } + + assert(0 && "invalid assembler flag!"); +} + +void MCELFStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) { + // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into + // MCObjectStreamer. + // FIXME: Lift context changes into super class. + getAssembler().getOrCreateSymbolData(*Symbol); + Symbol->setVariableValue(AddValueSymbols(Value)); +} + +void MCELFStreamer::EmitSymbolAttribute(MCSymbol *Symbol, + MCSymbolAttr Attribute) { + // Indirect symbols are handled differently, to match how 'as' handles + // them. This makes writing matching .o files easier. + if (Attribute == MCSA_IndirectSymbol) { + // Note that we intentionally cannot use the symbol data here; this is + // important for matching the string table that 'as' generates. + IndirectSymbolData ISD; + ISD.Symbol = Symbol; + ISD.SectionData = getCurrentSectionData(); + getAssembler().getIndirectSymbols().push_back(ISD); + return; + } + + // Adding a symbol attribute always introduces the symbol, note that an + // important side effect of calling getOrCreateSymbolData here is to register + // the symbol with the assembler. + MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol); + + // The implementation of symbol attributes is designed to match 'as', but it + // leaves much to desired. It doesn't really make sense to arbitrarily add and + // remove flags, but 'as' allows this (in particular, see .desc). + // + // In the future it might be worth trying to make these operations more well + // defined. + switch (Attribute) { + case MCSA_LazyReference: + case MCSA_Reference: + case MCSA_NoDeadStrip: + case MCSA_PrivateExtern: + case MCSA_WeakReference: + case MCSA_WeakDefinition: + case MCSA_Invalid: + case MCSA_ELF_TypeIndFunction: + case MCSA_IndirectSymbol: + assert(0 && "Invalid symbol attribute for ELF!"); + break; + + case MCSA_Global: + SD.setFlags(SD.getFlags() | ELF_STB_Global); + SD.setExternal(true); + break; + + case MCSA_Weak: + SD.setFlags(SD.getFlags() | ELF_STB_Weak); + break; + + case MCSA_Local: + SD.setFlags(SD.getFlags() | ELF_STB_Local); + break; + + case MCSA_ELF_TypeFunction: + SD.setFlags(SD.getFlags() | ELF_STT_Func); + break; + + case MCSA_ELF_TypeObject: + SD.setFlags(SD.getFlags() | ELF_STT_Object); + break; + + case MCSA_ELF_TypeTLS: + SD.setFlags(SD.getFlags() | ELF_STT_Tls); + break; + + case MCSA_ELF_TypeCommon: + SD.setFlags(SD.getFlags() | ELF_STT_Common); + break; + + case MCSA_ELF_TypeNoType: + SD.setFlags(SD.getFlags() | ELF_STT_Notype); + break; + + case MCSA_Protected: + SD.setFlags(SD.getFlags() | ELF_STV_Protected); + break; + + case MCSA_Hidden: + SD.setFlags(SD.getFlags() | ELF_STV_Hidden); + break; + + case MCSA_Internal: + SD.setFlags(SD.getFlags() | ELF_STV_Internal); + break; + } +} + +void MCELFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size, + unsigned ByteAlignment) { + MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol); + + if ((SD.getFlags() & (0xf << ELF_STB_Shift)) == ELF_STB_Local) { + const MCSection *Section = getAssembler().getContext().getELFSection(".bss", + MCSectionELF::SHT_NOBITS, + MCSectionELF::SHF_WRITE | + MCSectionELF::SHF_ALLOC, + SectionKind::getBSS()); + + MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section); + MCFragment *F = new MCFillFragment(0, 0, Size, &SectData); + SD.setFragment(F); + Symbol->setSection(*Section); + SD.setSize(MCConstantExpr::Create(Size, getContext())); + } else { + SD.setExternal(true); + } + + SD.setCommon(Size, ByteAlignment); +} + +void MCELFStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) { + // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into + // MCObjectStreamer. + getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end()); +} + +void MCELFStreamer::EmitValue(const MCExpr *Value, unsigned Size, + unsigned AddrSpace) { + // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into + // MCObjectStreamer. + MCDataFragment *DF = getOrCreateDataFragment(); + + // Avoid fixups when possible. + int64_t AbsValue; + if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue)) { + // FIXME: Endianness assumption. + for (unsigned i = 0; i != Size; ++i) + DF->getContents().push_back(uint8_t(AbsValue >> (i * 8))); + } else { + DF->addFixup(MCFixup::Create(DF->getContents().size(), AddValueSymbols(Value), + MCFixup::getKindForSize(Size))); + DF->getContents().resize(DF->getContents().size() + Size, 0); + } +} + +void MCELFStreamer::EmitValueToAlignment(unsigned ByteAlignment, + int64_t Value, unsigned ValueSize, + unsigned MaxBytesToEmit) { + // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into + // MCObjectStreamer. + if (MaxBytesToEmit == 0) + MaxBytesToEmit = ByteAlignment; + new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit, + getCurrentSectionData()); + + // Update the maximum alignment on the current section if necessary. + if (ByteAlignment > getCurrentSectionData()->getAlignment()) + getCurrentSectionData()->setAlignment(ByteAlignment); +} + +void MCELFStreamer::EmitCodeAlignment(unsigned ByteAlignment, + unsigned MaxBytesToEmit) { + // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into + // MCObjectStreamer. + if (MaxBytesToEmit == 0) + MaxBytesToEmit = ByteAlignment; + MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit, + getCurrentSectionData()); + F->setEmitNops(true); + + // Update the maximum alignment on the current section if necessary. + if (ByteAlignment > getCurrentSectionData()->getAlignment()) + getCurrentSectionData()->setAlignment(ByteAlignment); +} + +void MCELFStreamer::EmitValueToOffset(const MCExpr *Offset, + unsigned char Value) { + // TODO: This is exactly the same as MCMachOStreamer. Consider merging into + // MCObjectStreamer. + new MCOrgFragment(*Offset, Value, getCurrentSectionData()); +} + +// Add a symbol for the file name of this module. This is the second +// entry in the module's symbol table (the first being the null symbol). +void MCELFStreamer::EmitFileDirective(StringRef Filename) { + MCSymbol *Symbol = getAssembler().getContext().GetOrCreateSymbol(Filename); + Symbol->setSection(*CurSection); + Symbol->setAbsolute(); + + MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol); + + SD.setFlags(ELF_STT_File | ELF_STB_Local | ELF_STV_Default); +} + +void MCELFStreamer::EmitInstruction(const MCInst &Inst) { + // Scan for values. + for (unsigned i = 0; i != Inst.getNumOperands(); ++i) + if (Inst.getOperand(i).isExpr()) + AddValueSymbols(Inst.getOperand(i).getExpr()); + + getCurrentSectionData()->setHasInstructions(true); + + // FIXME-PERF: Common case is that we don't need to relax, encode directly + // onto the data fragments buffers. + + SmallVector Fixups; + SmallString<256> Code; + raw_svector_ostream VecOS(Code); + getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups); + VecOS.flush(); + + // FIXME: Eliminate this copy. + SmallVector AsmFixups; + for (unsigned i = 0, e = Fixups.size(); i != e; ++i) { + MCFixup &F = Fixups[i]; + AsmFixups.push_back(MCFixup::Create(F.getOffset(), F.getValue(), + F.getKind())); + } + + // See if we might need to relax this instruction, if so it needs its own + // fragment. + // + // FIXME-PERF: Support target hook to do a fast path that avoids the encoder, + // when we can immediately tell that we will get something which might need + // relaxation (and compute its size). + // + // FIXME-PERF: We should also be smart about immediately relaxing instructions + // which we can already show will never possibly fit (we can also do a very + // good job of this before we do the first relaxation pass, because we have + // total knowledge about undefined symbols at that point). Even now, though, + // we can do a decent job, especially on Darwin where scattering means that we + // are going to often know that we can never fully resolve a fixup. + if (getAssembler().getBackend().MayNeedRelaxation(Inst)) { + MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData()); + + // Add the fixups and data. + // + // FIXME: Revisit this design decision when relaxation is done, we may be + // able to get away with not storing any extra data in the MCInst. + IF->getCode() = Code; + IF->getFixups() = AsmFixups; + + return; + } + + // Add the fixups and data. + MCDataFragment *DF = getOrCreateDataFragment(); + for (unsigned i = 0, e = AsmFixups.size(); i != e; ++i) { + AsmFixups[i].setOffset(AsmFixups[i].getOffset() + DF->getContents().size()); + DF->addFixup(AsmFixups[i]); + } + DF->getContents().append(Code.begin(), Code.end()); +} + +void MCELFStreamer::Finish() { + getAssembler().Finish(); +} + +MCStreamer *llvm::createELFStreamer(MCContext &Context, TargetAsmBackend &TAB, + raw_ostream &OS, MCCodeEmitter *CE, + bool RelaxAll) { + MCELFStreamer *S = new MCELFStreamer(Context, TAB, OS, CE); + if (RelaxAll) + S->getAssembler().setRelaxAll(true); + return S; +}