1 //===- MCStreamer.h - High-level Streaming Machine Code Output --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file declares the MCStreamer class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_MC_MCSTREAMER_H
15 #define LLVM_MC_MCSTREAMER_H
17 #include "llvm/System/DataTypes.h"
18 #include "llvm/MC/MCDirectives.h"
32 class formatted_raw_ostream;
34 /// MCStreamer - Streaming machine code generation interface. This interface
35 /// is intended to provide a programatic interface that is very similar to the
36 /// level that an assembler .s file provides. It has callbacks to emit bytes,
37 /// handle directives, etc. The implementation of this interface retains
38 /// state to know what the current section is etc.
40 /// There are multiple implementations of this interface: one for writing out
41 /// a .s file, and implementations that write out .o files of various formats.
46 MCStreamer(const MCStreamer&); // DO NOT IMPLEMENT
47 MCStreamer &operator=(const MCStreamer&); // DO NOT IMPLEMENT
50 MCStreamer(MCContext &Ctx);
52 /// CurSection - This is the current section code is being emitted to, it is
53 /// kept up to date by SwitchSection.
54 const MCSection *CurSection;
57 virtual ~MCStreamer();
59 MCContext &getContext() const { return Context; }
61 /// @name Assembly File Formatting.
64 /// isVerboseAsm - Return true if this streamer supports verbose assembly at
66 virtual bool isVerboseAsm() const { return false; }
68 /// AddComment - Add a comment that can be emitted to the generated .s
69 /// file if applicable as a QoI issue to make the output of the compiler
70 /// more readable. This only affects the MCAsmStreamer, and only when
71 /// verbose assembly output is enabled.
73 /// If the comment includes embedded \n's, they will each get the comment
74 /// prefix as appropriate. The added comment should not end with a \n.
75 virtual void AddComment(const Twine &T) {}
77 /// GetCommentOS - Return a raw_ostream that comments can be written to.
78 /// Unlike AddComment, you are required to terminate comments with \n if you
80 virtual raw_ostream &GetCommentOS();
82 /// AddBlankLine - Emit a blank line to a .s file to pretty it up.
83 virtual void AddBlankLine() {}
87 /// @name Symbol & Section Management
90 /// getCurrentSection - Return the current seciton that the streamer is
92 const MCSection *getCurrentSection() const { return CurSection; }
94 /// SwitchSection - Set the current section where code is being emitted to
95 /// @p Section. This is required to update CurSection.
97 /// This corresponds to assembler directives like .section, .text, etc.
98 virtual void SwitchSection(const MCSection *Section) = 0;
100 /// EmitLabel - Emit a label for @p Symbol into the current section.
102 /// This corresponds to an assembler statement such as:
105 /// @param Symbol - The symbol to emit. A given symbol should only be
106 /// emitted as a label once, and symbols emitted as a label should never be
107 /// used in an assignment.
108 virtual void EmitLabel(MCSymbol *Symbol) = 0;
110 /// EmitAssemblerFlag - Note in the output the specified @p Flag
111 virtual void EmitAssemblerFlag(MCAssemblerFlag Flag) = 0;
113 /// EmitAssignment - Emit an assignment of @p Value to @p Symbol.
115 /// This corresponds to an assembler statement such as:
118 /// The assignment generates no code, but has the side effect of binding the
119 /// value in the current context. For the assembly streamer, this prints the
120 /// binding into the .s file.
122 /// @param Symbol - The symbol being assigned to.
123 /// @param Value - The value for the symbol.
124 virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) = 0;
126 /// EmitSymbolAttribute - Add the given @p Attribute to @p Symbol.
127 virtual void EmitSymbolAttribute(MCSymbol *Symbol,
128 MCSymbolAttr Attribute) = 0;
130 /// EmitSymbolDesc - Set the @p DescValue for the @p Symbol.
132 /// @param Symbol - The symbol to have its n_desc field set.
133 /// @param DescValue - The value to set into the n_desc field.
134 virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) = 0;
137 /// EmitELFSize - Emit an ELF .size directive.
139 /// This corresponds to an assembler statement such as:
140 /// .size symbol, expression
142 virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) = 0;
144 /// EmitCommonSymbol - Emit a common symbol.
146 /// @param Symbol - The common symbol to emit.
147 /// @param Size - The size of the common symbol.
148 /// @param ByteAlignment - The alignment of the symbol if
149 /// non-zero. This must be a power of 2.
150 virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
151 unsigned ByteAlignment) = 0;
153 /// EmitLocalCommonSymbol - Emit a local common (.lcomm) symbol.
155 /// @param Symbol - The common symbol to emit.
156 /// @param Size - The size of the common symbol.
157 virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) = 0;
159 /// EmitZerofill - Emit a the zerofill section and an option symbol.
161 /// @param Section - The zerofill section to create and or to put the symbol
162 /// @param Symbol - The zerofill symbol to emit, if non-NULL.
163 /// @param Size - The size of the zerofill symbol.
164 /// @param ByteAlignment - The alignment of the zerofill symbol if
165 /// non-zero. This must be a power of 2 on some targets.
166 virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
167 unsigned Size = 0,unsigned ByteAlignment = 0) = 0;
170 /// @name Generating Data
173 /// EmitBytes - Emit the bytes in \arg Data into the output.
175 /// This is used to implement assembler directives such as .byte, .ascii,
177 virtual void EmitBytes(StringRef Data, unsigned AddrSpace) = 0;
179 /// EmitValue - Emit the expression @p Value into the output as a native
180 /// integer of the given @p Size bytes.
182 /// This is used to implement assembler directives such as .word, .quad,
185 /// @param Value - The value to emit.
186 /// @param Size - The size of the integer (in bytes) to emit. This must
187 /// match a native machine width.
188 virtual void EmitValue(const MCExpr *Value, unsigned Size,
189 unsigned AddrSpace) = 0;
191 /// EmitIntValue - Special case of EmitValue that avoids the client having
192 /// to pass in a MCExpr for constant integers.
193 virtual void EmitIntValue(uint64_t Value, unsigned Size,unsigned AddrSpace);
195 /// EmitGPRel32Value - Emit the expression @p Value into the output as a
196 /// gprel32 (32-bit GP relative) value.
198 /// This is used to implement assembler directives such as .gprel32 on
199 /// targets that support them.
200 virtual void EmitGPRel32Value(const MCExpr *Value) = 0;
202 /// EmitFill - Emit NumBytes bytes worth of the value specified by
203 /// FillValue. This implements directives such as '.space'.
204 virtual void EmitFill(uint64_t NumBytes, uint8_t FillValue,
207 /// EmitZeros - Emit NumBytes worth of zeros. This is a convenience
208 /// function that just wraps EmitFill.
209 void EmitZeros(uint64_t NumBytes, unsigned AddrSpace) {
210 EmitFill(NumBytes, 0, AddrSpace);
214 /// EmitValueToAlignment - Emit some number of copies of @p Value until
215 /// the byte alignment @p ByteAlignment is reached.
217 /// If the number of bytes need to emit for the alignment is not a multiple
218 /// of @p ValueSize, then the contents of the emitted fill bytes is
221 /// This used to implement the .align assembler directive.
223 /// @param ByteAlignment - The alignment to reach. This must be a power of
224 /// two on some targets.
225 /// @param Value - The value to use when filling bytes.
226 /// @param ValueSize - The size of the integer (in bytes) to emit for
227 /// @p Value. This must match a native machine width.
228 /// @param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If
229 /// the alignment cannot be reached in this many bytes, no bytes are
231 virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
232 unsigned ValueSize = 1,
233 unsigned MaxBytesToEmit = 0) = 0;
235 /// EmitValueToOffset - Emit some number of copies of @p Value until the
236 /// byte offset @p Offset is reached.
238 /// This is used to implement assembler directives such as .org.
240 /// @param Offset - The offset to reach. This may be an expression, but the
241 /// expression must be associated with the current section.
242 /// @param Value - The value to use when filling bytes.
243 virtual void EmitValueToOffset(const MCExpr *Offset,
244 unsigned char Value = 0) = 0;
248 /// EmitFileDirective - Switch to a new logical file. This is used to
249 /// implement the '.file "foo.c"' assembler directive.
250 virtual void EmitFileDirective(StringRef Filename) = 0;
252 /// EmitDwarfFileDirective - Associate a filename with a specified logical
253 /// file number. This implements the DWARF2 '.file 4 "foo.c"' assembler
255 virtual void EmitDwarfFileDirective(unsigned FileNo,StringRef Filename) = 0;
257 /// EmitInstruction - Emit the given @p Instruction into the current
259 virtual void EmitInstruction(const MCInst &Inst) = 0;
261 /// Finish - Finish emission of machine code and flush any output.
262 virtual void Finish() = 0;
265 /// createNullStreamer - Create a dummy machine code streamer, which does
266 /// nothing. This is useful for timing the assembler front end.
267 MCStreamer *createNullStreamer(MCContext &Ctx);
269 /// createAsmStreamer - Create a machine code streamer which will print out
270 /// assembly for the native target, suitable for compiling with a native
273 /// \param InstPrint - If given, the instruction printer to use. If not given
274 /// the MCInst representation will be printed.
276 /// \param CE - If given, a code emitter to use to show the instruction
277 /// encoding inline with the assembly.
279 /// \param ShowInst - Whether to show the MCInst representation inline with
281 MCStreamer *createAsmStreamer(MCContext &Ctx, formatted_raw_ostream &OS,
282 const MCAsmInfo &MAI, bool isLittleEndian,
284 MCInstPrinter *InstPrint = 0,
285 MCCodeEmitter *CE = 0,
286 bool ShowInst = false);
288 // FIXME: These two may end up getting rolled into a single
289 // createObjectStreamer interface, which implements the assembler backend, and
290 // is parameterized on an output object file writer.
292 /// createMachOStream - Create a machine code streamer which will generative
293 /// Mach-O format object files.
294 MCStreamer *createMachOStreamer(MCContext &Ctx, raw_ostream &OS,
297 /// createELFStreamer - Create a machine code streamer which will generative
298 /// ELF format object files.
299 MCStreamer *createELFStreamer(MCContext &Ctx, raw_ostream &OS);
301 } // end namespace llvm