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//===- lib/MC/MCAsmStreamer.cpp - Text Assembly Output --------------------===//
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// The LLVM Compiler Infrastructure
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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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#include "llvm/MC/MCStreamer.h"
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#include "llvm/MC/MCAsmInfo.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/MCExpr.h"
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#include "llvm/MC/MCInst.h"
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#include "llvm/MC/MCInstPrinter.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/ADT/SmallString.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/Support/Format.h"
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#include "llvm/Support/FormattedStream.h"
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class MCAsmStreamer : public MCStreamer {
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formatted_raw_ostream &OS;
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MCInstPrinter *InstPrinter;
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MCCodeEmitter *Emitter;
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SmallString<128> CommentToEmit;
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raw_svector_ostream CommentStream;
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unsigned IsLittleEndian : 1;
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unsigned IsVerboseAsm : 1;
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unsigned ShowInst : 1;
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MCAsmStreamer(MCContext &Context, formatted_raw_ostream &os,
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bool isLittleEndian, bool isVerboseAsm, MCInstPrinter *printer,
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MCCodeEmitter *emitter, bool showInst)
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: MCStreamer(Context), OS(os), MAI(mai), InstPrinter(printer),
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Emitter(emitter), CommentStream(CommentToEmit),
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IsLittleEndian(isLittleEndian), IsVerboseAsm(isVerboseAsm),
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if (InstPrinter && IsVerboseAsm)
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InstPrinter->setCommentStream(CommentStream);
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bool isLittleEndian() const { return IsLittleEndian; }
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inline void EmitEOL() {
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// If we don't have any comments, just emit a \n.
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void EmitCommentsAndEOL();
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/// isVerboseAsm - Return true if this streamer supports verbose assembly at
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virtual bool isVerboseAsm() const { return IsVerboseAsm; }
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/// AddComment - Add a comment that can be emitted to the generated .s
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/// file if applicable as a QoI issue to make the output of the compiler
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/// more readable. This only affects the MCAsmStreamer, and only when
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/// verbose assembly output is enabled.
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virtual void AddComment(const Twine &T);
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/// AddEncodingComment - Add a comment showing the encoding of an instruction.
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virtual void AddEncodingComment(const MCInst &Inst);
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/// GetCommentOS - Return a raw_ostream that comments can be written to.
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/// Unlike AddComment, you are required to terminate comments with \n if you
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virtual raw_ostream &GetCommentOS() {
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return nulls(); // Discard comments unless in verbose asm mode.
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/// AddBlankLine - Emit a blank line to a .s file to pretty it up.
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virtual void AddBlankLine() {
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/// @name MCStreamer Interface
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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 EmitELFSize(MCSymbol *Symbol, const MCExpr *Value);
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virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
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unsigned ByteAlignment);
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/// EmitLocalCommonSymbol - Emit a local common (.lcomm) symbol.
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/// @param Symbol - The common symbol to emit.
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/// @param Size - The size of the common symbol.
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virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size);
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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 EmitIntValue(uint64_t Value, unsigned Size, unsigned AddrSpace);
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virtual void EmitGPRel32Value(const MCExpr *Value);
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virtual void EmitFill(uint64_t NumBytes, uint8_t FillValue,
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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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virtual void EmitDwarfFileDirective(unsigned FileNo, StringRef Filename);
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virtual void EmitInstruction(const MCInst &Inst);
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virtual void Finish();
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} // end anonymous namespace.
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/// AddComment - Add a comment that can be emitted to the generated .s
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/// file if applicable as a QoI issue to make the output of the compiler
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/// more readable. This only affects the MCAsmStreamer, and only when
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/// verbose assembly output is enabled.
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void MCAsmStreamer::AddComment(const Twine &T) {
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if (!IsVerboseAsm) return;
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// Make sure that CommentStream is flushed.
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CommentStream.flush();
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T.toVector(CommentToEmit);
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// Each comment goes on its own line.
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CommentToEmit.push_back('\n');
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// Tell the comment stream that the vector changed underneath it.
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CommentStream.resync();
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void MCAsmStreamer::EmitCommentsAndEOL() {
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if (CommentToEmit.empty() && CommentStream.GetNumBytesInBuffer() == 0) {
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CommentStream.flush();
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StringRef Comments = CommentToEmit.str();
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assert(Comments.back() == '\n' &&
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"Comment array not newline terminated");
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// Emit a line of comments.
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OS.PadToColumn(MAI.getCommentColumn());
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size_t Position = Comments.find('\n');
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OS << MAI.getCommentString() << ' ' << Comments.substr(0, Position) << '\n';
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Comments = Comments.substr(Position+1);
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} while (!Comments.empty());
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CommentToEmit.clear();
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// Tell the comment stream that the vector changed underneath it.
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CommentStream.resync();
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static inline int64_t truncateToSize(int64_t Value, unsigned Bytes) {
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assert(Bytes && "Invalid size!");
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return Value & ((uint64_t) (int64_t) -1 >> (64 - Bytes * 8));
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void MCAsmStreamer::SwitchSection(const MCSection *Section) {
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assert(Section && "Cannot switch to a null section!");
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if (Section != CurSection) {
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CurSection = Section;
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Section->PrintSwitchToSection(MAI, OS);
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void MCAsmStreamer::EmitLabel(MCSymbol *Symbol) {
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assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
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assert(CurSection && "Cannot emit before setting section!");
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OS << *Symbol << ":";
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Symbol->setSection(*CurSection);
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void MCAsmStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
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default: assert(0 && "Invalid flag!");
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case MCAF_SubsectionsViaSymbols: OS << ".subsections_via_symbols"; break;
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void MCAsmStreamer::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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OS << *Symbol << " = " << *Value;
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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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void MCAsmStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
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MCSymbolAttr Attribute) {
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case MCSA_Invalid: assert(0 && "Invalid symbol attribute");
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case MCSA_ELF_TypeFunction: /// .type _foo, STT_FUNC # aka @function
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case MCSA_ELF_TypeIndFunction: /// .type _foo, STT_GNU_IFUNC
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case MCSA_ELF_TypeObject: /// .type _foo, STT_OBJECT # aka @object
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case MCSA_ELF_TypeTLS: /// .type _foo, STT_TLS # aka @tls_object
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case MCSA_ELF_TypeCommon: /// .type _foo, STT_COMMON # aka @common
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case MCSA_ELF_TypeNoType: /// .type _foo, STT_NOTYPE # aka @notype
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assert(MAI.hasDotTypeDotSizeDirective() && "Symbol Attr not supported");
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OS << "\t.type\t" << *Symbol << ','
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<< ((MAI.getCommentString()[0] != '@') ? '@' : '%');
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default: assert(0 && "Unknown ELF .type");
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case MCSA_ELF_TypeFunction: OS << "function"; break;
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case MCSA_ELF_TypeIndFunction: OS << "gnu_indirect_function"; break;
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case MCSA_ELF_TypeObject: OS << "object"; break;
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case MCSA_ELF_TypeTLS: OS << "tls_object"; break;
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case MCSA_ELF_TypeCommon: OS << "common"; break;
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case MCSA_ELF_TypeNoType: OS << "no_type"; break;
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case MCSA_Global: // .globl/.global
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OS << MAI.getGlobalDirective();
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case MCSA_Hidden: OS << ".hidden "; break;
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case MCSA_IndirectSymbol: OS << ".indirect_symbol "; break;
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case MCSA_Internal: OS << ".internal "; break;
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case MCSA_LazyReference: OS << ".lazy_reference "; break;
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case MCSA_Local: OS << ".local "; break;
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case MCSA_NoDeadStrip: OS << ".no_dead_strip "; break;
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case MCSA_PrivateExtern: OS << ".private_extern "; break;
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case MCSA_Protected: OS << ".protected "; break;
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case MCSA_Reference: OS << ".reference "; break;
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case MCSA_Weak: OS << ".weak "; break;
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case MCSA_WeakDefinition: OS << ".weak_definition "; break;
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case MCSA_WeakReference: OS << MAI.getWeakRefDirective(); break;
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void MCAsmStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
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OS << ".desc" << ' ' << *Symbol << ',' << DescValue;
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void MCAsmStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
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assert(MAI.hasDotTypeDotSizeDirective());
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OS << "\t.size\t" << *Symbol << ", " << *Value << '\n';
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void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
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unsigned ByteAlignment) {
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OS << "\t.comm\t" << *Symbol << ',' << Size;
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if (ByteAlignment != 0) {
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if (MAI.getCOMMDirectiveAlignmentIsInBytes())
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OS << ',' << ByteAlignment;
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OS << ',' << Log2_32(ByteAlignment);
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/// EmitLocalCommonSymbol - Emit a local common (.lcomm) symbol.
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/// @param Symbol - The common symbol to emit.
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/// @param Size - The size of the common symbol.
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void MCAsmStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
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assert(MAI.hasLCOMMDirective() && "Doesn't have .lcomm, can't emit it!");
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OS << "\t.lcomm\t" << *Symbol << ',' << Size;
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void MCAsmStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
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unsigned Size, unsigned ByteAlignment) {
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// Note: a .zerofill directive does not switch sections.
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// This is a mach-o specific directive.
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const MCSectionMachO *MOSection = ((const MCSectionMachO*)Section);
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OS << MOSection->getSegmentName() << "," << MOSection->getSectionName();
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if (Symbol != NULL) {
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OS << ',' << *Symbol << ',' << Size;
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if (ByteAlignment != 0)
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OS << ',' << Log2_32(ByteAlignment);
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static inline char toOctal(int X) { return (X&7)+'0'; }
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static void PrintQuotedString(StringRef Data, raw_ostream &OS) {
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for (unsigned i = 0, e = Data.size(); i != e; ++i) {
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unsigned char C = Data[i];
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if (C == '"' || C == '\\') {
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OS << '\\' << (char)C;
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if (isprint((unsigned char)C)) {
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case '\b': OS << "\\b"; break;
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case '\f': OS << "\\f"; break;
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case '\n': OS << "\\n"; break;
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case '\r': OS << "\\r"; break;
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case '\t': OS << "\\t"; break;
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OS << toOctal(C >> 6);
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OS << toOctal(C >> 3);
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OS << toOctal(C >> 0);
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void MCAsmStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
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assert(CurSection && "Cannot emit contents before setting section!");
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if (Data.empty()) return;
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if (Data.size() == 1) {
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OS << MAI.getData8bitsDirective(AddrSpace);
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OS << (unsigned)(unsigned char)Data[0];
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// If the data ends with 0 and the target supports .asciz, use it, otherwise
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if (MAI.getAscizDirective() && Data.back() == 0) {
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OS << MAI.getAscizDirective();
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Data = Data.substr(0, Data.size()-1);
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OS << MAI.getAsciiDirective();
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PrintQuotedString(Data, OS);
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/// EmitIntValue - Special case of EmitValue that avoids the client having
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/// to pass in a MCExpr for constant integers.
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void MCAsmStreamer::EmitIntValue(uint64_t Value, unsigned Size,
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unsigned AddrSpace) {
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assert(CurSection && "Cannot emit contents before setting section!");
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const char *Directive = 0;
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case 1: Directive = MAI.getData8bitsDirective(AddrSpace); break;
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case 2: Directive = MAI.getData16bitsDirective(AddrSpace); break;
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case 4: Directive = MAI.getData32bitsDirective(AddrSpace); break;
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Directive = MAI.getData64bitsDirective(AddrSpace);
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// If the target doesn't support 64-bit data, emit as two 32-bit halves.
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if (Directive) break;
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if (isLittleEndian()) {
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EmitIntValue((uint32_t)(Value >> 0 ), 4, AddrSpace);
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EmitIntValue((uint32_t)(Value >> 32), 4, AddrSpace);
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EmitIntValue((uint32_t)(Value >> 32), 4, AddrSpace);
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EmitIntValue((uint32_t)(Value >> 0 ), 4, AddrSpace);
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assert(Directive && "Invalid size for machine code value!");
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OS << Directive << truncateToSize(Value, Size);
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void MCAsmStreamer::EmitValue(const MCExpr *Value, unsigned Size,
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unsigned AddrSpace) {
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assert(CurSection && "Cannot emit contents before setting section!");
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const char *Directive = 0;
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case 1: Directive = MAI.getData8bitsDirective(AddrSpace); break;
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case 2: Directive = MAI.getData16bitsDirective(AddrSpace); break;
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case 4: Directive = MAI.getData32bitsDirective(AddrSpace); break;
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case 8: Directive = MAI.getData64bitsDirective(AddrSpace); break;
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assert(Directive && "Invalid size for machine code value!");
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OS << Directive << *Value;
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void MCAsmStreamer::EmitGPRel32Value(const MCExpr *Value) {
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assert(MAI.getGPRel32Directive() != 0);
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OS << MAI.getGPRel32Directive() << *Value;
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/// EmitFill - Emit NumBytes bytes worth of the value specified by
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/// FillValue. This implements directives such as '.space'.
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void MCAsmStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue,
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unsigned AddrSpace) {
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if (NumBytes == 0) return;
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if (const char *ZeroDirective = MAI.getZeroDirective()) {
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OS << ZeroDirective << NumBytes;
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OS << ',' << (int)FillValue;
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// Emit a byte at a time.
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MCStreamer::EmitFill(NumBytes, FillValue, AddrSpace);
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void MCAsmStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
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unsigned MaxBytesToEmit) {
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// Some assemblers don't support non-power of two alignments, so we always
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// emit alignments as a power of two if possible.
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if (isPowerOf2_32(ByteAlignment)) {
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default: llvm_unreachable("Invalid size for machine code value!");
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case 1: OS << MAI.getAlignDirective(); break;
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// FIXME: use MAI for this!
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case 2: OS << ".p2alignw "; break;
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case 4: OS << ".p2alignl "; break;
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case 8: llvm_unreachable("Unsupported alignment size!");
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if (MAI.getAlignmentIsInBytes())
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OS << Log2_32(ByteAlignment);
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if (Value || MaxBytesToEmit) {
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OS.write_hex(truncateToSize(Value, ValueSize));
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OS << ", " << MaxBytesToEmit;
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// Non-power of two alignment. This is not widely supported by assemblers.
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// FIXME: Parameterize this based on MAI.
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default: llvm_unreachable("Invalid size for machine code value!");
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case 1: OS << ".balign"; break;
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case 2: OS << ".balignw"; break;
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case 4: OS << ".balignl"; break;
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case 8: llvm_unreachable("Unsupported alignment size!");
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OS << ' ' << ByteAlignment;
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OS << ", " << truncateToSize(Value, ValueSize);
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OS << ", " << MaxBytesToEmit;
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void MCAsmStreamer::EmitCodeAlignment(unsigned ByteAlignment,
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unsigned MaxBytesToEmit) {
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// Emit with a text fill value.
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EmitValueToAlignment(ByteAlignment, MAI.getTextAlignFillValue(),
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void MCAsmStreamer::EmitValueToOffset(const MCExpr *Offset,
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unsigned char Value) {
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// FIXME: Verify that Offset is associated with the current section.
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OS << ".org " << *Offset << ", " << (unsigned) Value;
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void MCAsmStreamer::EmitFileDirective(StringRef Filename) {
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assert(MAI.hasSingleParameterDotFile());
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PrintQuotedString(Filename, OS);
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void MCAsmStreamer::EmitDwarfFileDirective(unsigned FileNo, StringRef Filename){
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OS << "\t.file\t" << FileNo << ' ';
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PrintQuotedString(Filename, OS);
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void MCAsmStreamer::AddEncodingComment(const MCInst &Inst) {
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raw_ostream &OS = GetCommentOS();
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SmallString<256> Code;
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SmallVector<MCFixup, 4> Fixups;
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raw_svector_ostream VecOS(Code);
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Emitter->EncodeInstruction(Inst, VecOS, Fixups);
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// If we are showing fixups, create symbolic markers in the encoded
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// representation. We do this by making a per-bit map to the fixup item index,
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// then trying to display it as nicely as possible.
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SmallVector<uint8_t, 64> FixupMap;
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FixupMap.resize(Code.size() * 8);
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for (unsigned i = 0, e = Code.size() * 8; i != e; ++i)
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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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const MCFixupKindInfo &Info = Emitter->getFixupKindInfo(F.getKind());
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for (unsigned j = 0; j != Info.TargetSize; ++j) {
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unsigned Index = F.getOffset() * 8 + Info.TargetOffset + j;
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assert(Index < Code.size() * 8 && "Invalid offset in fixup!");
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FixupMap[Index] = 1 + i;
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for (unsigned i = 0, e = Code.size(); i != e; ++i) {
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// See if all bits are the same map entry.
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uint8_t MapEntry = FixupMap[i * 8 + 0];
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for (unsigned j = 1; j != 8; ++j) {
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if (FixupMap[i * 8 + j] == MapEntry)
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MapEntry = uint8_t(~0U);
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if (MapEntry != uint8_t(~0U)) {
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OS << format("0x%02x", uint8_t(Code[i]));
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assert(Code[i] == 0 && "Encoder wrote into fixed up bit!");
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OS << char('A' + MapEntry - 1);
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// Otherwise, write out in binary.
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for (unsigned j = 8; j--;) {
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unsigned Bit = (Code[i] >> j) & 1;
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if (uint8_t MapEntry = FixupMap[i * 8 + j]) {
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assert(Bit == 0 && "Encoder wrote into fixed up bit!");
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OS << char('A' + MapEntry - 1);
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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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const MCFixupKindInfo &Info = Emitter->getFixupKindInfo(F.getKind());
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OS << " fixup " << char('A' + i) << " - " << "offset: " << F.getOffset()
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<< ", value: " << *F.getValue() << ", kind: " << Info.Name << "\n";
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void MCAsmStreamer::EmitInstruction(const MCInst &Inst) {
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assert(CurSection && "Cannot emit contents before setting section!");
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// Show the encoding in a comment if we have a code emitter.
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AddEncodingComment(Inst);
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// Show the MCInst if enabled.
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raw_ostream &OS = GetCommentOS();
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OS << "<MCInst #" << Inst.getOpcode();
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InstName = InstPrinter->getOpcodeName(Inst.getOpcode());
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if (!InstName.empty())
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OS << ' ' << InstName;
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for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i) {
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Inst.getOperand(i).print(OS, &MAI);
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// If we have an AsmPrinter, use that to print, otherwise dump the MCInst.
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InstPrinter->printInst(&Inst);
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Inst.print(OS, &MAI);
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void MCAsmStreamer::Finish() {
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MCStreamer *llvm::createAsmStreamer(MCContext &Context,
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formatted_raw_ostream &OS,
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const MCAsmInfo &MAI, bool isLittleEndian,
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bool isVerboseAsm, MCInstPrinter *IP,
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MCCodeEmitter *CE, bool ShowInst) {
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return new MCAsmStreamer(Context, OS, MAI, isLittleEndian, isVerboseAsm,