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//===- MCStreamer.h - High-level Streaming Machine Code Output --*- C++ -*-===//
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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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// This file declares the MCStreamer class.
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_MC_MCSTREAMER_H
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#define LLVM_MC_MCSTREAMER_H
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#include "llvm/System/DataTypes.h"
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#include "llvm/MC/MCDirectives.h"
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class formatted_raw_ostream;
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/// MCStreamer - Streaming machine code generation interface. This interface
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/// is intended to provide a programatic interface that is very similar to the
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/// level that an assembler .s file provides. It has callbacks to emit bytes,
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/// handle directives, etc. The implementation of this interface retains
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/// state to know what the current section is etc.
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/// There are multiple implementations of this interface: one for writing out
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/// a .s file, and implementations that write out .o files of various formats.
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MCStreamer(const MCStreamer&); // DO NOT IMPLEMENT
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MCStreamer &operator=(const MCStreamer&); // DO NOT IMPLEMENT
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MCStreamer(MCContext &Ctx);
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/// CurSection - This is the current section code is being emitted to, it is
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/// kept up to date by SwitchSection.
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const MCSection *CurSection;
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virtual ~MCStreamer();
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MCContext &getContext() const { return Context; }
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/// @name Assembly File Formatting.
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/// isVerboseAsm - Return true if this streamer supports verbose assembly at
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virtual bool isVerboseAsm() const { return false; }
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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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/// If the comment includes embedded \n's, they will each get the comment
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/// prefix as appropriate. The added comment should not end with a \n.
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virtual void AddComment(const Twine &T) {}
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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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/// 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 Symbol & Section Management
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/// getCurrentSection - Return the current seciton that the streamer is
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const MCSection *getCurrentSection() const { return CurSection; }
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/// SwitchSection - Set the current section where code is being emitted to
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/// @p Section. This is required to update CurSection.
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/// This corresponds to assembler directives like .section, .text, etc.
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virtual void SwitchSection(const MCSection *Section) = 0;
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/// EmitLabel - Emit a label for @p Symbol into the current section.
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/// This corresponds to an assembler statement such as:
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/// @param Symbol - The symbol to emit. A given symbol should only be
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/// emitted as a label once, and symbols emitted as a label should never be
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/// used in an assignment.
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virtual void EmitLabel(MCSymbol *Symbol) = 0;
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/// EmitAssemblerFlag - Note in the output the specified @p Flag
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virtual void EmitAssemblerFlag(MCAssemblerFlag Flag) = 0;
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/// EmitAssignment - Emit an assignment of @p Value to @p Symbol.
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/// This corresponds to an assembler statement such as:
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/// The assignment generates no code, but has the side effect of binding the
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/// value in the current context. For the assembly streamer, this prints the
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/// binding into the .s file.
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/// @param Symbol - The symbol being assigned to.
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/// @param Value - The value for the symbol.
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virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) = 0;
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/// EmitSymbolAttribute - Add the given @p Attribute to @p Symbol.
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virtual void EmitSymbolAttribute(MCSymbol *Symbol,
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MCSymbolAttr Attribute) = 0;
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/// EmitSymbolDesc - Set the @p DescValue for the @p Symbol.
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/// @param Symbol - The symbol to have its n_desc field set.
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/// @param DescValue - The value to set into the n_desc field.
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virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) = 0;
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/// EmitELFSize - Emit an ELF .size directive.
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/// This corresponds to an assembler statement such as:
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/// .size symbol, expression
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virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) = 0;
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/// EmitCommonSymbol - Emit a common 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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/// @param ByteAlignment - The alignment of the symbol if
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/// non-zero. This must be a power of 2.
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virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
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unsigned ByteAlignment) = 0;
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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) = 0;
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/// EmitZerofill - Emit a the zerofill section and an option symbol.
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/// @param Section - The zerofill section to create and or to put the symbol
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/// @param Symbol - The zerofill symbol to emit, if non-NULL.
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/// @param Size - The size of the zerofill symbol.
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/// @param ByteAlignment - The alignment of the zerofill symbol if
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/// non-zero. This must be a power of 2 on some targets.
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virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
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unsigned Size = 0,unsigned ByteAlignment = 0) = 0;
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/// @name Generating Data
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/// EmitBytes - Emit the bytes in \arg Data into the output.
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/// This is used to implement assembler directives such as .byte, .ascii,
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virtual void EmitBytes(StringRef Data, unsigned AddrSpace) = 0;
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/// EmitValue - Emit the expression @p Value into the output as a native
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/// integer of the given @p Size bytes.
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/// This is used to implement assembler directives such as .word, .quad,
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/// @param Value - The value to emit.
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/// @param Size - The size of the integer (in bytes) to emit. This must
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/// match a native machine width.
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virtual void EmitValue(const MCExpr *Value, unsigned Size,
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unsigned AddrSpace) = 0;
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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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virtual void EmitIntValue(uint64_t Value, unsigned Size,unsigned AddrSpace);
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/// EmitGPRel32Value - Emit the expression @p Value into the output as a
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/// gprel32 (32-bit GP relative) value.
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/// This is used to implement assembler directives such as .gprel32 on
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/// targets that support them.
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virtual void EmitGPRel32Value(const MCExpr *Value) = 0;
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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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virtual void EmitFill(uint64_t NumBytes, uint8_t FillValue,
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/// EmitZeros - Emit NumBytes worth of zeros. This is a convenience
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/// function that just wraps EmitFill.
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void EmitZeros(uint64_t NumBytes, unsigned AddrSpace) {
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EmitFill(NumBytes, 0, AddrSpace);
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/// EmitValueToAlignment - Emit some number of copies of @p Value until
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/// the byte alignment @p ByteAlignment is reached.
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/// If the number of bytes need to emit for the alignment is not a multiple
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/// of @p ValueSize, then the contents of the emitted fill bytes is
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/// This used to implement the .align assembler directive.
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/// @param ByteAlignment - The alignment to reach. This must be a power of
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/// two on some targets.
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/// @param Value - The value to use when filling bytes.
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/// @param ValueSize - The size of the integer (in bytes) to emit for
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/// @p Value. This must match a native machine width.
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/// @param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If
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/// the alignment cannot be reached in this many bytes, no bytes are
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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) = 0;
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/// EmitCodeAlignment - Emit nops until the byte alignment @p ByteAlignment
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/// This used to align code where the alignment bytes may be executed. This
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/// can emit different bytes for different sizes to optimize execution.
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/// @param ByteAlignment - The alignment to reach. This must be a power of
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/// two on some targets.
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/// @param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If
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/// the alignment cannot be reached in this many bytes, no bytes are
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virtual void EmitCodeAlignment(unsigned ByteAlignment,
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unsigned MaxBytesToEmit = 0) = 0;
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/// EmitValueToOffset - Emit some number of copies of @p Value until the
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/// byte offset @p Offset is reached.
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/// This is used to implement assembler directives such as .org.
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/// @param Offset - The offset to reach. This may be an expression, but the
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/// expression must be associated with the current section.
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/// @param Value - The value to use when filling bytes.
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virtual void EmitValueToOffset(const MCExpr *Offset,
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unsigned char Value = 0) = 0;
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/// EmitFileDirective - Switch to a new logical file. This is used to
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/// implement the '.file "foo.c"' assembler directive.
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virtual void EmitFileDirective(StringRef Filename) = 0;
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/// EmitDwarfFileDirective - Associate a filename with a specified logical
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/// file number. This implements the DWARF2 '.file 4 "foo.c"' assembler
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virtual void EmitDwarfFileDirective(unsigned FileNo,StringRef Filename) = 0;
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/// EmitInstruction - Emit the given @p Instruction into the current
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virtual void EmitInstruction(const MCInst &Inst) = 0;
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/// Finish - Finish emission of machine code and flush any output.
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virtual void Finish() = 0;
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/// createNullStreamer - Create a dummy machine code streamer, which does
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/// nothing. This is useful for timing the assembler front end.
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MCStreamer *createNullStreamer(MCContext &Ctx);
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/// createAsmStreamer - Create a machine code streamer which will print out
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/// assembly for the native target, suitable for compiling with a native
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/// \param InstPrint - If given, the instruction printer to use. If not given
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/// the MCInst representation will be printed.
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/// \param CE - If given, a code emitter to use to show the instruction
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/// encoding inline with the assembly.
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/// \param ShowInst - Whether to show the MCInst representation inline with
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MCStreamer *createAsmStreamer(MCContext &Ctx, formatted_raw_ostream &OS,
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const MCAsmInfo &MAI, bool isLittleEndian,
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MCInstPrinter *InstPrint = 0,
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MCCodeEmitter *CE = 0,
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bool ShowInst = false);
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// FIXME: These two may end up getting rolled into a single
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// createObjectStreamer interface, which implements the assembler backend, and
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// is parameterized on an output object file writer.
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/// createMachOStream - Create a machine code streamer which will generative
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/// Mach-O format object files.
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MCStreamer *createMachOStreamer(MCContext &Ctx, raw_ostream &OS,
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/// createELFStreamer - Create a machine code streamer which will generative
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/// ELF format object files.
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MCStreamer *createELFStreamer(MCContext &Ctx, raw_ostream &OS);
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} // end namespace llvm