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
diff --git a/lib/MC/MCELFStreamer.cpp b/lib/MC/MCELFStreamer.cpp
new file mode 100644
index 0000000..fa48f95
--- /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<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;
+}