forked from OSchip/llvm-project
437 lines
15 KiB
C++
437 lines
15 KiB
C++
//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/MC/MCStreamer.h"
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#include "llvm/MC/MCAsmBackend.h"
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#include "llvm/MC/MCAssembler.h"
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#include "llvm/MC/MCCodeEmitter.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCDwarf.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCInst.h"
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#include "llvm/MC/MCMachOSymbolFlags.h"
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#include "llvm/MC/MCObjectStreamer.h"
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#include "llvm/MC/MCSection.h"
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#include "llvm/MC/MCSectionMachO.h"
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#include "llvm/MC/MCSymbol.h"
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#include "llvm/Support/Dwarf.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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namespace {
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class MCMachOStreamer : public MCObjectStreamer {
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private:
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virtual void EmitInstToData(const MCInst &Inst);
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void EmitDataRegion(DataRegionData::KindTy Kind);
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void EmitDataRegionEnd();
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public:
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MCMachOStreamer(MCContext &Context, MCAsmBackend &MAB, raw_ostream &OS,
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MCCodeEmitter *Emitter)
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: MCObjectStreamer(SK_MachOStreamer, Context, MAB, OS, Emitter) {}
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/// @name MCStreamer Interface
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/// @{
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virtual void InitSections();
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virtual void InitToTextSection();
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virtual void EmitLabel(MCSymbol *Symbol);
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virtual void EmitDebugLabel(MCSymbol *Symbol);
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virtual void EmitEHSymAttributes(const MCSymbol *Symbol,
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MCSymbol *EHSymbol);
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virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
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virtual void EmitLinkerOptions(ArrayRef<std::string> Options);
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virtual void EmitDataRegion(MCDataRegionType Kind);
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virtual void EmitThumbFunc(MCSymbol *Func);
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virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
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virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
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virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
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unsigned ByteAlignment);
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virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {
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llvm_unreachable("macho doesn't support this directive");
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}
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virtual void EmitCOFFSymbolStorageClass(int StorageClass) {
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llvm_unreachable("macho doesn't support this directive");
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}
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virtual void EmitCOFFSymbolType(int Type) {
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llvm_unreachable("macho doesn't support this directive");
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}
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virtual void EndCOFFSymbolDef() {
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llvm_unreachable("macho doesn't support this directive");
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}
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virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
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llvm_unreachable("macho doesn't support this directive");
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}
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virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
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unsigned ByteAlignment);
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virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
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uint64_t Size = 0, unsigned ByteAlignment = 0);
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virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
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uint64_t Size, unsigned ByteAlignment = 0);
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virtual void EmitFileDirective(StringRef Filename) {
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// FIXME: Just ignore the .file; it isn't important enough to fail the
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// entire assembly.
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//report_fatal_error("unsupported directive: '.file'");
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}
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virtual void FinishImpl();
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/// @}
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static bool classof(const MCStreamer *S) {
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return S->getKind() == SK_MachOStreamer;
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}
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};
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} // end anonymous namespace.
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void MCMachOStreamer::InitSections() {
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InitToTextSection();
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}
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void MCMachOStreamer::InitToTextSection() {
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SwitchSection(getContext().getMachOSection(
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"__TEXT", "__text",
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MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 0,
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SectionKind::getText()));
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}
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void MCMachOStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
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MCSymbol *EHSymbol) {
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MCSymbolData &SD =
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getAssembler().getOrCreateSymbolData(*Symbol);
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if (SD.isExternal())
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EmitSymbolAttribute(EHSymbol, MCSA_Global);
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if (SD.getFlags() & SF_WeakDefinition)
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EmitSymbolAttribute(EHSymbol, MCSA_WeakDefinition);
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if (SD.isPrivateExtern())
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EmitSymbolAttribute(EHSymbol, MCSA_PrivateExtern);
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}
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void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
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assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
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// isSymbolLinkerVisible uses the section.
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Symbol->setSection(*getCurrentSection());
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// We have to create a new fragment if this is an atom defining symbol,
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// fragments cannot span atoms.
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if (getAssembler().isSymbolLinkerVisible(*Symbol))
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new MCDataFragment(getCurrentSectionData());
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MCObjectStreamer::EmitLabel(Symbol);
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MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
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// This causes the reference type flag to be cleared. Darwin 'as' was "trying"
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// to clear the weak reference and weak definition bits too, but the
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// implementation was buggy. For now we just try to match 'as', for
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// diffability.
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//
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// FIXME: Cleanup this code, these bits should be emitted based on semantic
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// properties, not on the order of definition, etc.
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SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
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}
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void MCMachOStreamer::EmitDebugLabel(MCSymbol *Symbol) {
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EmitLabel(Symbol);
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}
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void MCMachOStreamer::EmitDataRegion(DataRegionData::KindTy Kind) {
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if (!getAssembler().getBackend().hasDataInCodeSupport())
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return;
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// Create a temporary label to mark the start of the data region.
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MCSymbol *Start = getContext().CreateTempSymbol();
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EmitLabel(Start);
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// Record the region for the object writer to use.
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DataRegionData Data = { Kind, Start, NULL };
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std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
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Regions.push_back(Data);
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}
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void MCMachOStreamer::EmitDataRegionEnd() {
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if (!getAssembler().getBackend().hasDataInCodeSupport())
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return;
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std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
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assert(Regions.size() && "Mismatched .end_data_region!");
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DataRegionData &Data = Regions.back();
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assert(Data.End == NULL && "Mismatched .end_data_region!");
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// Create a temporary label to mark the end of the data region.
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Data.End = getContext().CreateTempSymbol();
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EmitLabel(Data.End);
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}
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void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
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// Let the target do whatever target specific stuff it needs to do.
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getAssembler().getBackend().handleAssemblerFlag(Flag);
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// Do any generic stuff we need to do.
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switch (Flag) {
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case MCAF_SyntaxUnified: return; // no-op here.
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case MCAF_Code16: return; // Change parsing mode; no-op here.
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case MCAF_Code32: return; // Change parsing mode; no-op here.
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case MCAF_Code64: return; // Change parsing mode; no-op here.
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case MCAF_SubsectionsViaSymbols:
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getAssembler().setSubsectionsViaSymbols(true);
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return;
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}
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}
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void MCMachOStreamer::EmitLinkerOptions(ArrayRef<std::string> Options) {
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getAssembler().getLinkerOptions().push_back(Options);
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}
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void MCMachOStreamer::EmitDataRegion(MCDataRegionType Kind) {
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switch (Kind) {
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case MCDR_DataRegion:
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EmitDataRegion(DataRegionData::Data);
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return;
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case MCDR_DataRegionJT8:
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EmitDataRegion(DataRegionData::JumpTable8);
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return;
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case MCDR_DataRegionJT16:
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EmitDataRegion(DataRegionData::JumpTable16);
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return;
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case MCDR_DataRegionJT32:
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EmitDataRegion(DataRegionData::JumpTable32);
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return;
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case MCDR_DataRegionEnd:
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EmitDataRegionEnd();
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return;
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}
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}
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void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
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// Remember that the function is a thumb function. Fixup and relocation
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// values will need adjusted.
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getAssembler().setIsThumbFunc(Symbol);
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// Mark the thumb bit on the symbol.
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MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
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SD.setFlags(SD.getFlags() | SF_ThumbFunc);
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}
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void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
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MCSymbolAttr Attribute) {
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// Indirect symbols are handled differently, to match how 'as' handles
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// them. This makes writing matching .o files easier.
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if (Attribute == MCSA_IndirectSymbol) {
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// Note that we intentionally cannot use the symbol data here; this is
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// important for matching the string table that 'as' generates.
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IndirectSymbolData ISD;
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ISD.Symbol = Symbol;
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ISD.SectionData = getCurrentSectionData();
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getAssembler().getIndirectSymbols().push_back(ISD);
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return;
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}
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// Adding a symbol attribute always introduces the symbol, note that an
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// important side effect of calling getOrCreateSymbolData here is to register
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// the symbol with the assembler.
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MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
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// The implementation of symbol attributes is designed to match 'as', but it
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// leaves much to desired. It doesn't really make sense to arbitrarily add and
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// remove flags, but 'as' allows this (in particular, see .desc).
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//
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// In the future it might be worth trying to make these operations more well
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// defined.
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switch (Attribute) {
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case MCSA_Invalid:
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case MCSA_ELF_TypeFunction:
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case MCSA_ELF_TypeIndFunction:
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case MCSA_ELF_TypeObject:
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case MCSA_ELF_TypeTLS:
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case MCSA_ELF_TypeCommon:
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case MCSA_ELF_TypeNoType:
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case MCSA_ELF_TypeGnuUniqueObject:
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case MCSA_Hidden:
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case MCSA_IndirectSymbol:
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case MCSA_Internal:
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case MCSA_Protected:
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case MCSA_Weak:
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case MCSA_Local:
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llvm_unreachable("Invalid symbol attribute for Mach-O!");
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case MCSA_Global:
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SD.setExternal(true);
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// This effectively clears the undefined lazy bit, in Darwin 'as', although
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// it isn't very consistent because it implements this as part of symbol
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// lookup.
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//
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// FIXME: Cleanup this code, these bits should be emitted based on semantic
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// properties, not on the order of definition, etc.
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SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
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break;
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case MCSA_LazyReference:
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// FIXME: This requires -dynamic.
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SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
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if (Symbol->isUndefined())
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SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
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break;
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// Since .reference sets the no dead strip bit, it is equivalent to
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// .no_dead_strip in practice.
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case MCSA_Reference:
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case MCSA_NoDeadStrip:
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SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
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break;
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case MCSA_SymbolResolver:
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SD.setFlags(SD.getFlags() | SF_SymbolResolver);
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break;
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case MCSA_PrivateExtern:
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SD.setExternal(true);
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SD.setPrivateExtern(true);
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break;
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case MCSA_WeakReference:
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// FIXME: This requires -dynamic.
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if (Symbol->isUndefined())
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SD.setFlags(SD.getFlags() | SF_WeakReference);
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break;
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case MCSA_WeakDefinition:
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// FIXME: 'as' enforces that this is defined and global. The manual claims
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// it has to be in a coalesced section, but this isn't enforced.
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SD.setFlags(SD.getFlags() | SF_WeakDefinition);
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break;
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case MCSA_WeakDefAutoPrivate:
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SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
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break;
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}
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}
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void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
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// Encode the 'desc' value into the lowest implementation defined bits.
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assert(DescValue == (DescValue & SF_DescFlagsMask) &&
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"Invalid .desc value!");
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getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
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DescValue & SF_DescFlagsMask);
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}
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void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
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unsigned ByteAlignment) {
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// FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
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assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
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MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
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SD.setExternal(true);
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SD.setCommon(Size, ByteAlignment);
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}
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void MCMachOStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
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unsigned ByteAlignment) {
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// '.lcomm' is equivalent to '.zerofill'.
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return EmitZerofill(getContext().getMachOSection("__DATA", "__bss",
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MCSectionMachO::S_ZEROFILL,
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0, SectionKind::getBSS()),
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Symbol, Size, ByteAlignment);
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}
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void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
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uint64_t Size, unsigned ByteAlignment) {
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MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
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// The symbol may not be present, which only creates the section.
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if (!Symbol)
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return;
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// FIXME: Assert that this section has the zerofill type.
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assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
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MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
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// Emit an align fragment if necessary.
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if (ByteAlignment != 1)
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new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
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MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
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SD.setFragment(F);
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Symbol->setSection(*Section);
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// Update the maximum alignment on the zero fill section if necessary.
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if (ByteAlignment > SectData.getAlignment())
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SectData.setAlignment(ByteAlignment);
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}
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// This should always be called with the thread local bss section. Like the
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// .zerofill directive this doesn't actually switch sections on us.
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void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
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uint64_t Size, unsigned ByteAlignment) {
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EmitZerofill(Section, Symbol, Size, ByteAlignment);
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return;
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}
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void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
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MCDataFragment *DF = getOrCreateDataFragment();
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SmallVector<MCFixup, 4> Fixups;
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SmallString<256> Code;
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raw_svector_ostream VecOS(Code);
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getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
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VecOS.flush();
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// Add the fixups and data.
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for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
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Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
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DF->getFixups().push_back(Fixups[i]);
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}
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DF->getContents().append(Code.begin(), Code.end());
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}
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void MCMachOStreamer::FinishImpl() {
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EmitFrames(true);
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// We have to set the fragment atom associations so we can relax properly for
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// Mach-O.
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// First, scan the symbol table to build a lookup table from fragments to
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// defining symbols.
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DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
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for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
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ie = getAssembler().symbol_end(); it != ie; ++it) {
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if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
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it->getFragment()) {
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// An atom defining symbol should never be internal to a fragment.
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assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
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DefiningSymbolMap[it->getFragment()] = it;
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}
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}
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// Set the fragment atom associations by tracking the last seen atom defining
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// symbol.
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for (MCAssembler::iterator it = getAssembler().begin(),
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ie = getAssembler().end(); it != ie; ++it) {
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MCSymbolData *CurrentAtom = 0;
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for (MCSectionData::iterator it2 = it->begin(),
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ie2 = it->end(); it2 != ie2; ++it2) {
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if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
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CurrentAtom = SD;
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it2->setAtom(CurrentAtom);
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}
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}
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this->MCObjectStreamer::FinishImpl();
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}
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MCStreamer *llvm::createMachOStreamer(MCContext &Context, MCAsmBackend &MAB,
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raw_ostream &OS, MCCodeEmitter *CE,
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bool RelaxAll) {
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MCMachOStreamer *S = new MCMachOStreamer(Context, MAB, OS, CE);
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if (RelaxAll)
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S->getAssembler().setRelaxAll(true);
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return S;
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}
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