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//===- MCStreamer.h - High-level Streaming Machine Code Output --*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares the MCStreamer class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_MC_MCSTREAMER_H
#define LLVM_MC_MCSTREAMER_H
#include "llvm/System/DataTypes.h"
namespace llvm {
class MCAsmInfo;
class MCCodeEmitter;
class MCContext;
class MCExpr;
class MCInst;
class MCInstPrinter;
class MCSection;
class MCSymbol;
class StringRef;
class Twine;
class raw_ostream;
class formatted_raw_ostream;
/// MCStreamer - Streaming machine code generation interface. This interface
/// is intended to provide a programatic interface that is very similar to the
/// level that an assembler .s file provides. It has callbacks to emit bytes,
/// handle directives, etc. The implementation of this interface retains
/// state to know what the current section is etc.
///
/// There are multiple implementations of this interface: one for writing out
/// a .s file, and implementations that write out .o files of various formats.
///
class MCStreamer {
public:
enum SymbolAttr {
Global, /// .globl
Hidden, /// .hidden (ELF)
IndirectSymbol, /// .indirect_symbol (Apple)
Internal, /// .internal (ELF)
LazyReference, /// .lazy_reference (Apple)
NoDeadStrip, /// .no_dead_strip (Apple)
PrivateExtern, /// .private_extern (Apple)
Protected, /// .protected (ELF)
Reference, /// .reference (Apple)
Weak, /// .weak
WeakDefinition, /// .weak_definition (Apple)
WeakReference, /// .weak_reference (Apple)
SymbolAttrFirst = Global,
SymbolAttrLast = WeakReference
};
enum AssemblerFlag {
SubsectionsViaSymbols /// .subsections_via_symbols (Apple)
};
private:
MCContext &Context;
MCStreamer(const MCStreamer&); // DO NOT IMPLEMENT
MCStreamer &operator=(const MCStreamer&); // DO NOT IMPLEMENT
protected:
MCStreamer(MCContext &Ctx);
/// CurSection - This is the current section code is being emitted to, it is
/// kept up to date by SwitchSection.
const MCSection *CurSection;
public:
virtual ~MCStreamer();
MCContext &getContext() const { return Context; }
/// addComment - Add a comment that can be emitted to the generated .s
/// file if applicable as a QoI issue to make the output of the compiler
/// more readable. This only affects the MCAsmStreamer, and only when
/// verbose assembly output is enabled.
///
/// If the comment includes embedded \n's, they will each get the comment
/// prefix as appropriate. The added comment should not end with a \n.
virtual void addComment(const Twine &T) {}
/// @name Symbol & Section Management
/// @{
/// getCurrentSection - Return the current seciton that the streamer is
/// emitting code to.
const MCSection *getCurrentSection() const { return CurSection; }
/// SwitchSection - Set the current section where code is being emitted to
/// @param Section. This is required to update CurSection.
///
/// This corresponds to assembler directives like .section, .text, etc.
virtual void SwitchSection(const MCSection *Section) = 0;
/// EmitLabel - Emit a label for @param Symbol into the current section.
///
/// This corresponds to an assembler statement such as:
/// foo:
///
/// @param Symbol - The symbol to emit. A given symbol should only be
/// emitted as a label once, and symbols emitted as a label should never be
/// used in an assignment.
virtual void EmitLabel(MCSymbol *Symbol) = 0;
/// EmitAssemblerFlag - Note in the output the specified @param Flag
virtual void EmitAssemblerFlag(AssemblerFlag Flag) = 0;
/// EmitAssignment - Emit an assignment of @param Value to @param Symbol.
///
/// This corresponds to an assembler statement such as:
/// symbol = value
///
/// The assignment generates no code, but has the side effect of binding the
/// value in the current context. For the assembly streamer, this prints the
/// binding into the .s file.
///
/// @param Symbol - The symbol being assigned to.
/// @param Value - The value for the symbol.
virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) = 0;
/// EmitSymbolAttribute - Add the given @param Attribute to @param Symbol.
virtual void EmitSymbolAttribute(MCSymbol *Symbol,
SymbolAttr Attribute) = 0;
/// EmitSymbolDesc - Set the @param DescValue for the @param Symbol.
///
/// @param Symbol - The symbol to have its n_desc field set.
/// @param DescValue - The value to set into the n_desc field.
virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) = 0;
/// EmitCommonSymbol - Emit a common or local common symbol.
///
/// @param Symbol - The common symbol to emit.
/// @param Size - The size of the common symbol.
/// @param ByteAlignment - The alignment of the symbol if
/// non-zero. This must be a power of 2 on some targets.
virtual void EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
unsigned ByteAlignment) = 0;
/// EmitZerofill - Emit a the zerofill section and an option symbol.
///
/// @param Section - The zerofill section to create and or to put the symbol
/// @param Symbol - The zerofill symbol to emit, if non-NULL.
/// @param Size - The size of the zerofill symbol.
/// @param ByteAlignment - The alignment of the zerofill symbol if
/// non-zero. This must be a power of 2 on some targets.
virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
unsigned Size = 0,unsigned ByteAlignment = 0) = 0;
/// @}
/// @name Generating Data
/// @{
/// EmitBytes - Emit the bytes in \arg Data into the output.
///
/// This is used to implement assembler directives such as .byte, .ascii,
/// etc.
virtual void EmitBytes(StringRef Data, unsigned AddrSpace) = 0;
/// EmitValue - Emit the expression @param Value into the output as a native
/// integer of the given @param Size bytes.
///
/// This is used to implement assembler directives such as .word, .quad,
/// etc.
///
/// @param Value - The value to emit.
/// @param Size - The size of the integer (in bytes) to emit. This must
/// match a native machine width.
virtual void EmitValue(const MCExpr *Value, unsigned Size,
unsigned AddrSpace) = 0;
/// EmitIntValue - Special case of EmitValue that avoids the client having
/// to pass in a MCExpr for constant integers.
virtual void EmitIntValue(uint64_t Value, unsigned Size,unsigned AddrSpace);
/// EmitFill - Emit NumBytes bytes worth of the value specified by
/// FillValue. This implements directives such as '.space'.
virtual void EmitFill(uint64_t NumBytes, uint8_t FillValue,
unsigned AddrSpace);
/// EmitZeros - Emit NumBytes worth of zeros. This is a convenience
/// function that just wraps EmitFill.
void EmitZeros(uint64_t NumBytes, unsigned AddrSpace) {
EmitFill(NumBytes, 0, AddrSpace);
}
/// EmitValueToAlignment - Emit some number of copies of @param Value until
/// the byte alignment @param ByteAlignment is reached.
///
/// If the number of bytes need to emit for the alignment is not a multiple
/// of @param ValueSize, then the contents of the emitted fill bytes is
/// undefined.
///
/// This used to implement the .align assembler directive.
///
/// @param ByteAlignment - The alignment to reach. This must be a power of
/// two on some targets.
/// @param Value - The value to use when filling bytes.
/// @param Size - The size of the integer (in bytes) to emit for @param
/// Value. This must match a native machine width.
/// @param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If
/// the alignment cannot be reached in this many bytes, no bytes are
/// emitted.
virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
unsigned ValueSize = 1,
unsigned MaxBytesToEmit = 0) = 0;
/// EmitValueToOffset - Emit some number of copies of @param Value until the
/// byte offset @param Offset is reached.
///
/// This is used to implement assembler directives such as .org.
///
/// @param Offset - The offset to reach. This may be an expression, but the
/// expression must be associated with the current section.
/// @param Value - The value to use when filling bytes.
virtual void EmitValueToOffset(const MCExpr *Offset,
unsigned char Value = 0) = 0;
/// @}
/// EmitInstruction - Emit the given @param Instruction into the current
/// section.
virtual void EmitInstruction(const MCInst &Inst) = 0;
/// Finish - Finish emission of machine code and flush any output.
virtual void Finish() = 0;
};
/// createNullStreamer - Create a dummy machine code streamer, which does
/// nothing. This is useful for timing the assembler front end.
MCStreamer *createNullStreamer(MCContext &Ctx);
/// createAsmStreamer - Create a machine code streamer which will print out
/// assembly for the native target, suitable for compiling with a native
/// assembler.
MCStreamer *createAsmStreamer(MCContext &Ctx, formatted_raw_ostream &OS,
const MCAsmInfo &MAI, bool isLittleEndian,
bool isVerboseAsm,
MCInstPrinter *InstPrint = 0,
MCCodeEmitter *CE = 0);
// FIXME: These two may end up getting rolled into a single
// createObjectStreamer interface, which implements the assembler backend, and
// is parameterized on an output object file writer.
/// createMachOStream - Create a machine code streamer which will generative
/// Mach-O format object files.
MCStreamer *createMachOStreamer(MCContext &Ctx, raw_ostream &OS,
MCCodeEmitter *CE = 0);
/// createELFStreamer - Create a machine code streamer which will generative
/// ELF format object files.
MCStreamer *createELFStreamer(MCContext &Ctx, raw_ostream &OS);
} // end namespace llvm
#endif
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