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https://github.com/c64scene-ar/llvm-6502.git
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6e72048add
to be aligned with optimal nops. This patch does not change any functionality and when the compiler is changed to use EmitCodeAlignment() it should also not change the resulting output. Once the compiler change is made and everything looks good the next patch with the table of optimal X86 nops will be added to WriteNopData() changing the output. There are many FIXMEs in this patch which will be removed when we have better target hooks (coming soon I hear). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96963 91177308-0d34-0410-b5e6-96231b3b80d8
425 lines
14 KiB
C++
425 lines
14 KiB
C++
//===- lib/MC/MCMachOStreamer.cpp - Mach-O Object Output ------------===//
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//
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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/MCAssembler.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCCodeEmitter.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/MCSection.h"
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#include "llvm/MC/MCSymbol.h"
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#include "llvm/MC/MCValue.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 MCStreamer {
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/// SymbolFlags - We store the value for the 'desc' symbol field in the lowest
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/// 16 bits of the implementation defined flags.
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enum SymbolFlags { // See <mach-o/nlist.h>.
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SF_DescFlagsMask = 0xFFFF,
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// Reference type flags.
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SF_ReferenceTypeMask = 0x0007,
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SF_ReferenceTypeUndefinedNonLazy = 0x0000,
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SF_ReferenceTypeUndefinedLazy = 0x0001,
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SF_ReferenceTypeDefined = 0x0002,
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SF_ReferenceTypePrivateDefined = 0x0003,
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SF_ReferenceTypePrivateUndefinedNonLazy = 0x0004,
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SF_ReferenceTypePrivateUndefinedLazy = 0x0005,
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// Other 'desc' flags.
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SF_NoDeadStrip = 0x0020,
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SF_WeakReference = 0x0040,
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SF_WeakDefinition = 0x0080
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};
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private:
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MCAssembler Assembler;
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MCCodeEmitter *Emitter;
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MCSectionData *CurSectionData;
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DenseMap<const MCSection*, MCSectionData*> SectionMap;
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DenseMap<const MCSymbol*, MCSymbolData*> SymbolMap;
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private:
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MCFragment *getCurrentFragment() const {
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assert(CurSectionData && "No current section!");
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if (!CurSectionData->empty())
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return &CurSectionData->getFragmentList().back();
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return 0;
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}
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MCSectionData &getSectionData(const MCSection &Section) {
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MCSectionData *&Entry = SectionMap[&Section];
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if (!Entry)
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Entry = new MCSectionData(Section, &Assembler);
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return *Entry;
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}
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MCSymbolData &getSymbolData(const MCSymbol &Symbol) {
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MCSymbolData *&Entry = SymbolMap[&Symbol];
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if (!Entry)
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Entry = new MCSymbolData(Symbol, 0, 0, &Assembler);
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return *Entry;
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}
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public:
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MCMachOStreamer(MCContext &Context, raw_ostream &_OS, MCCodeEmitter *_Emitter)
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: MCStreamer(Context), Assembler(Context, _OS), Emitter(_Emitter),
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CurSectionData(0) {}
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~MCMachOStreamer() {}
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const MCExpr *AddValueSymbols(const MCExpr *Value) {
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switch (Value->getKind()) {
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case MCExpr::Target: assert(0 && "Can't handle target exprs yet!");
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case MCExpr::Constant:
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break;
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case MCExpr::Binary: {
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const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
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AddValueSymbols(BE->getLHS());
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AddValueSymbols(BE->getRHS());
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break;
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}
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case MCExpr::SymbolRef:
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getSymbolData(cast<MCSymbolRefExpr>(Value)->getSymbol());
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break;
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case MCExpr::Unary:
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AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
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break;
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}
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return Value;
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}
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/// @name MCStreamer Interface
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/// @{
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virtual void SwitchSection(const MCSection *Section);
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virtual void EmitLabel(MCSymbol *Symbol);
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virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
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virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
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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 EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
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assert(0 && "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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assert(0 && "macho doesn't support this directive");
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}
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virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
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unsigned Size = 0, unsigned ByteAlignment = 0);
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virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
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virtual void EmitValue(const MCExpr *Value, unsigned Size,unsigned AddrSpace);
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virtual void EmitGPRel32Value(const MCExpr *Value) {
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assert(0 && "macho doesn't support this directive");
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}
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virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
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unsigned ValueSize = 1,
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unsigned MaxBytesToEmit = 0);
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virtual void EmitCodeAlignment(unsigned ByteAlignment,
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unsigned MaxBytesToEmit = 0);
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virtual void EmitValueToOffset(const MCExpr *Offset,
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unsigned char Value = 0);
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virtual void EmitFileDirective(StringRef Filename) {
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errs() << "FIXME: MCMachoStreamer:EmitFileDirective not implemented\n";
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}
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virtual void EmitDwarfFileDirective(unsigned FileNo, StringRef Filename) {
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errs() << "FIXME: MCMachoStreamer:EmitDwarfFileDirective not implemented\n";
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}
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virtual void EmitInstruction(const MCInst &Inst);
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virtual void Finish();
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/// @}
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};
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} // end anonymous namespace.
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void MCMachOStreamer::SwitchSection(const MCSection *Section) {
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assert(Section && "Cannot switch to a null section!");
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// If already in this section, then this is a noop.
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if (Section == CurSection) return;
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CurSection = Section;
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CurSectionData = &getSectionData(*Section);
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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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// FIXME: We should also use offsets into Fill fragments.
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MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
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if (!F)
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F = new MCDataFragment(CurSectionData);
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MCSymbolData &SD = getSymbolData(*Symbol);
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assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
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SD.setFragment(F);
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SD.setOffset(F->getContents().size());
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// This causes the reference type and weak reference flags to be cleared.
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SD.setFlags(SD.getFlags() & ~(SF_WeakReference | SF_ReferenceTypeMask));
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Symbol->setSection(*CurSection);
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}
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void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
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switch (Flag) {
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case MCAF_SubsectionsViaSymbols:
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Assembler.setSubsectionsViaSymbols(true);
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return;
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}
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assert(0 && "invalid assembler flag!");
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}
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void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
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// Only absolute symbols can be redefined.
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assert((Symbol->isUndefined() || Symbol->isAbsolute()) &&
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"Cannot define a symbol twice!");
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// FIXME: Lift context changes into super class.
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// FIXME: Set associated section.
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Symbol->setValue(Value);
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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 = CurSectionData;
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Assembler.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 getSymbolData here is to register the
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// symbol with the assembler.
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MCSymbolData &SD = getSymbolData(*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_IndirectSymbol:
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case MCSA_Hidden:
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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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assert(0 && "Invalid symbol attribute for Mach-O!");
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break;
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case MCSA_Global:
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SD.setExternal(true);
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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_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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}
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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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getSymbolData(*Symbol).setFlags(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 = getSymbolData(*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::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
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unsigned Size, unsigned ByteAlignment) {
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MCSectionData &SectData = getSectionData(*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 = getSymbolData(*Symbol);
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MCFragment *F = new MCZeroFillFragment(Size, ByteAlignment, &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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void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
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MCDataFragment *DF = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
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if (!DF)
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DF = new MCDataFragment(CurSectionData);
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DF->getContents().append(Data.begin(), Data.end());
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}
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void MCMachOStreamer::EmitValue(const MCExpr *Value, unsigned Size,
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unsigned AddrSpace) {
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MCDataFragment *DF = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
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if (!DF)
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DF = new MCDataFragment(CurSectionData);
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// Avoid fixups when possible.
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int64_t AbsValue;
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if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue)) {
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// FIXME: Endianness assumption.
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for (unsigned i = 0; i != Size; ++i)
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DF->getContents().push_back(uint8_t(AbsValue >> (i * 8)));
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} else {
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DF->getFixups().push_back(MCAsmFixup(DF->getContents().size(),
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*AddValueSymbols(Value),
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MCFixup::getKindForSize(Size)));
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DF->getContents().resize(DF->getContents().size() + Size, 0);
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}
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}
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void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
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int64_t Value, unsigned ValueSize,
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unsigned MaxBytesToEmit) {
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if (MaxBytesToEmit == 0)
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MaxBytesToEmit = ByteAlignment;
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new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
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false /* EmitNops */, CurSectionData);
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// Update the maximum alignment on the current section if necessary.
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if (ByteAlignment > CurSectionData->getAlignment())
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CurSectionData->setAlignment(ByteAlignment);
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}
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void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
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unsigned MaxBytesToEmit) {
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if (MaxBytesToEmit == 0)
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MaxBytesToEmit = ByteAlignment;
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// FIXME the 0x90 is the default x86 1 byte nop opcode.
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new MCAlignFragment(ByteAlignment, 0x90, 1, MaxBytesToEmit,
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true /* EmitNops */, CurSectionData);
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// Update the maximum alignment on the current section if necessary.
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if (ByteAlignment > CurSectionData->getAlignment())
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CurSectionData->setAlignment(ByteAlignment);
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}
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void MCMachOStreamer::EmitValueToOffset(const MCExpr *Offset,
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unsigned char Value) {
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new MCOrgFragment(*Offset, Value, CurSectionData);
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}
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void MCMachOStreamer::EmitInstruction(const MCInst &Inst) {
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// Scan for values.
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for (unsigned i = 0; i != Inst.getNumOperands(); ++i)
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if (Inst.getOperand(i).isExpr())
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AddValueSymbols(Inst.getOperand(i).getExpr());
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if (!Emitter)
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llvm_unreachable("no code emitter available!");
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CurSectionData->setHasInstructions(true);
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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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Emitter->EncodeInstruction(Inst, VecOS, Fixups);
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VecOS.flush();
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// Add the fixups and data.
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MCDataFragment *DF = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
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if (!DF)
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DF = new MCDataFragment(CurSectionData);
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for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
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MCFixup &F = Fixups[i];
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DF->getFixups().push_back(MCAsmFixup(DF->getContents().size()+F.getOffset(),
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*F.getValue(),
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F.getKind()));
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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::Finish() {
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Assembler.Finish();
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}
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MCStreamer *llvm::createMachOStreamer(MCContext &Context, raw_ostream &OS,
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MCCodeEmitter *CE) {
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return new MCMachOStreamer(Context, OS, CE);
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}
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