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/Support/DataTypes.h"
30 /// MCStreamer - Streaming machine code generation interface. This interface
31 /// is intended to provide a programatic interface that is very similar to the
32 /// level that an assembler .s file provides. It has callbacks to emit bytes,
33 /// "emit directives", etc. The implementation of this interface retains
34 /// state to know what the current section is etc.
36 /// There are multiple implementations of this interface: one for writing out
37 /// a .s file, and implementations that write out .o files of various formats.
43 Hidden, /// .hidden (ELF)
44 IndirectSymbol, /// .indirect_symbol (Apple)
45 Internal, /// .internal (ELF)
46 LazyReference, /// .lazy_reference (Apple)
47 NoDeadStrip, /// .no_dead_strip (Apple)
48 PrivateExtern, /// .private_extern (Apple)
49 Protected, /// .protected (ELF)
50 Reference, /// .reference (Apple)
52 WeakDefinition, /// .weak_definition (Apple)
53 WeakReference, /// .weak_reference (Apple)
55 SymbolAttrFirst = Global,
56 SymbolAttrLast = WeakReference
60 SubsectionsViaSymbols /// .subsections_via_symbols (Apple)
66 MCStreamer(const MCStreamer&); // DO NOT IMPLEMENT
67 MCStreamer &operator=(const MCStreamer&); // DO NOT IMPLEMENT
70 MCStreamer(MCContext &Ctx);
73 virtual ~MCStreamer();
75 MCContext &getContext() const { return Context; }
77 /// @name Symbol & Section Management
80 /// SwitchSection - Set the current section where code is being emitted to
83 /// This corresponds to assembler directives like .section, .text, etc.
84 virtual void SwitchSection(const MCSection *Section) = 0;
86 /// EmitLabel - Emit a label for @param Symbol into the current section.
88 /// This corresponds to an assembler statement such as:
91 /// @param Symbol - The symbol to emit. A given symbol should only be
92 /// emitted as a label once, and symbols emitted as a label should never be
93 /// used in an assignment.
95 // FIXME: What to do about the current section? Should we get rid of the
96 // symbol section in the constructor and initialize it here?
97 virtual void EmitLabel(MCSymbol *Symbol) = 0;
99 /// EmitAssemblerFlag - Note in the output the specified @param Flag
100 virtual void EmitAssemblerFlag(AssemblerFlag Flag) = 0;
102 /// EmitAssignment - Emit an assignment of @param Value to @param Symbol.
104 /// This corresponds to an assembler statement such as:
107 /// The assignment generates no code, but has the side effect of binding the
108 /// value in the current context. For the assembly streamer, this prints the
109 /// binding into the .s file.
111 /// @param Symbol - The symbol being assigned to.
112 /// @param Value - The value for the symbol.
113 /// @param MakeAbsolute - If true, then the symbol should be given the
114 /// absolute value of @param Value, even if @param Value would be
115 /// relocatable expression. This corresponds to the ".set" directive.
116 virtual void EmitAssignment(MCSymbol *Symbol, const MCValue &Value,
117 bool MakeAbsolute = false) = 0;
119 /// EmitSymbolAttribute - Add the given @param Attribute to @param Symbol.
121 // FIXME: This doesn't make much sense, could we just have attributes be on
122 // the symbol and make the printer smart enough to add the right symbols?
123 // This should work as long as the order of attributes in the file doesn't
125 virtual void EmitSymbolAttribute(MCSymbol *Symbol,
126 SymbolAttr Attribute) = 0;
128 /// EmitSymbolDesc - Set the @param DescValue for the @param Symbol.
130 /// @param Symbol - The symbol to have its n_desc field set.
131 /// @param DescValue - The value to set into the n_desc field.
132 virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) = 0;
134 /// EmitLocalSymbol - Emit a local symbol of @param Value to @param Symbol.
136 /// @param Symbol - The local symbol being created.
137 /// @param Value - The value for the symbol.
138 virtual void EmitLocalSymbol(MCSymbol *Symbol, const MCValue &Value) = 0;
140 /// EmitCommonSymbol - Emit a common or local common symbol of @param Size
141 /// with the @param Pow2Alignment if non-zero.
143 /// @param Symbol - The common symbol to emit.
144 /// @param Size - The size of the common symbol.
145 /// @param Pow2Alignment - The alignment of the common symbol if non-zero.
146 /// @param IsLocal - If true, then the symbol is to be a local common
147 virtual void EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
148 unsigned Pow2Alignment, bool IsLocal) = 0;
150 /// EmitZerofill - Emit a the zerofill section and possiblity a symbol, if
151 /// @param Symbol is non-NULL, for @param Size and with the @param
152 /// Pow2Alignment if non-zero.
154 /// @param Section - The zerofill section to create and or to put the symbol
155 /// @param Symbol - The zerofill symbol to emit, if non-NULL.
156 /// @param Size - The size of the zerofill symbol.
157 /// @param Pow2Alignment - The alignment of the zerofill symbol if non-zero.
158 virtual void EmitZerofill(MCSection *Section, MCSymbol *Symbol = 0,
159 unsigned Size = 0,unsigned Pow2Alignment = 0) = 0;
162 /// @name Generating Data
165 /// EmitBytes - Emit the bytes in @param Data into the output.
167 /// This is used to implement assembler directives such as .byte, .ascii,
169 virtual void EmitBytes(const StringRef &Data) = 0;
171 /// EmitValue - Emit the expression @param Value into the output as a native
172 /// integer of the given @param Size bytes.
174 /// This is used to implement assembler directives such as .word, .quad,
177 /// @param Value - The value to emit.
178 /// @param Size - The size of the integer (in bytes) to emit. This must
179 /// match a native machine width.
180 virtual void EmitValue(const MCValue &Value, unsigned Size) = 0;
182 /// EmitValueToAlignment - Emit some number of copies of @param Value until
183 /// the byte alignment @param ByteAlignment is reached.
185 /// If the number of bytes need to emit for the alignment is not a multiple
186 /// of @param ValueSize, then the contents of the emitted fill bytes is
189 /// This used to implement the .align assembler directive.
191 /// @param ByteAlignment - The alignment to reach. This must be a power of
192 /// two on some targets.
193 /// @param Value - The value to use when filling bytes.
194 /// @param Size - The size of the integer (in bytes) to emit for @param
195 /// Value. This must match a native machine width.
196 /// @param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If
197 /// the alignment cannot be reached in this many bytes, no bytes are
199 virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
200 unsigned ValueSize = 1,
201 unsigned MaxBytesToEmit = 0) = 0;
203 /// EmitValueToOffset - Emit some number of copies of @param Value until the
204 /// byte offset @param Offset is reached.
206 /// This is used to implement assembler directives such as .org.
208 /// @param Offset - The offset to reach.This may be an expression, but the
209 /// expression must be associated with the current section.
210 /// @param Value - The value to use when filling bytes.
212 // FIXME: How are we going to signal failures out of this?
213 virtual void EmitValueToOffset(const MCValue &Offset,
214 unsigned char Value = 0) = 0;
218 /// EmitInstruction - Emit the given @param Instruction into the current
220 virtual void EmitInstruction(const MCInst &Inst) = 0;
222 /// Finish - Finish emission of machine code and flush any output.
223 virtual void Finish() = 0;
226 /// createNullStreamer - Create a dummy machine code streamer, which does
227 /// nothing. This is useful for timing the assembler front end.
228 MCStreamer *createNullStreamer(MCContext &Ctx);
230 /// createAsmStreamer - Create a machine code streamer which will print out
231 /// assembly for the native target, suitable for compiling with a native
234 /// \arg AP - If given, an AsmPrinter to use for printing instructions.
235 MCStreamer *createAsmStreamer(MCContext &Ctx, raw_ostream &OS,
236 const TargetAsmInfo &TAI, AsmPrinter *AP = 0);
238 // FIXME: These two may end up getting rolled into a single
239 // createObjectStreamer interface, which implements the assembler backend, and
240 // is parameterized on an output object file writer.
242 /// createMachOStream - Create a machine code streamer which will generative
243 /// Mach-O format object files.
244 MCStreamer *createMachOStreamer(MCContext &Ctx, raw_ostream &OS);
246 /// createELFStreamer - Create a machine code streamer which will generative
247 /// ELF format object files.
248 MCStreamer *createELFStreamer(MCContext &Ctx, raw_ostream &OS);
250 } // end namespace llvm