Add ELF ObjectWriter and Streamer support.

I forgot to add these files in commit 111172.

llvm-svn: 111174

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 <cassert>
+
+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

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

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<MCFixup, 4> Fixups;
+  SmallString<256> Code;
+  raw_svector_ostream VecOS(Code);
+  getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
+  VecOS.flush();
+
+  // FIXME: Eliminate this copy.
+  SmallVector<MCFixup, 4> 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;
+}