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"
27 /// MCStreamer - Streaming machine code generation interface. This interface
28 /// is intended to provide a programatic interface that is very similar to the
29 /// level that an assembler .s file provides. It has callbacks to emit bytes,
30 /// "emit directives", etc. The implementation of this interface retains
31 /// state to know what the current section is etc.
33 /// There are multiple implementations of this interface: one for writing out
34 /// a .s file, and implementations that write out .o files of various formats.
40 Hidden, /// .hidden (ELF)
41 IndirectSymbol, /// .indirect_symbol (Apple)
42 Internal, /// .internal (ELF)
43 LazyReference, /// .lazy_reference (Apple)
44 NoDeadStrip, /// .no_dead_strip (Apple)
45 PrivateExtern, /// .private_extern (Apple)
46 Protected, /// .protected (ELF)
47 Reference, /// .reference (Apple)
49 WeakDefinition, /// .weak_definition (Apple)
50 WeakReference, /// .weak_reference (Apple)
52 SymbolAttrFirst = Global,
53 SymbolAttrLast = WeakReference
59 MCStreamer(const MCStreamer&); // DO NOT IMPLEMENT
60 MCStreamer &operator=(const MCStreamer&); // DO NOT IMPLEMENT
63 MCStreamer(MCContext &Ctx);
66 virtual ~MCStreamer();
68 MCContext &getContext() const { return Context; }
70 /// @name Symbol & Section Management
73 /// SwitchSection - Set the current section where code is being emitted to
76 /// This corresponds to assembler directives like .section, .text, etc.
77 virtual void SwitchSection(MCSection *Section) = 0;
79 /// EmitLabel - Emit a label for @param Symbol into the current section.
81 /// This corresponds to an assembler statement such as:
84 /// @param Symbol - The symbol to emit. A given symbol should only be
85 /// emitted as a label once, and symbols emitted as a label should never be
86 /// used in an assignment.
88 // FIXME: What to do about the current section? Should we get rid of the
89 // symbol section in the constructor and initialize it here?
90 virtual void EmitLabel(MCSymbol *Symbol) = 0;
92 /// SubsectionsViaSymbols - Note in the output that the conventions used in
93 /// in the assembly file allows the bytes of a section to be divided up at
94 /// the boundaries of the symbols by a link editor for processing as atoms.
95 virtual void SubsectionsViaSymbols(void) = 0;
97 /// EmitAssignment - Emit an assignment of @param Value to @param Symbol.
99 /// This corresponds to an assembler statement such as:
102 /// The assignment generates no code, but has the side effect of binding the
103 /// value in the current context. For the assembly streamer, this prints the
104 /// binding into the .s file.
106 /// @param Symbol - The symbol being assigned to.
107 /// @param Value - The value for the symbol.
108 /// @param MakeAbsolute - If true, then the symbol should be given the
109 /// absolute value of @param Value, even if @param Value would be
110 /// relocatable expression. This corresponds to the ".set" directive.
111 virtual void EmitAssignment(MCSymbol *Symbol, const MCValue &Value,
112 bool MakeAbsolute = false) = 0;
114 /// EmitSymbolAttribute - Add the given @param Attribute to @param Symbol.
116 // FIXME: This doesn't make much sense, could we just have attributes be on
117 // the symbol and make the printer smart enough to add the right symbols?
118 // This should work as long as the order of attributes in the file doesn't
120 virtual void EmitSymbolAttribute(MCSymbol *Symbol,
121 SymbolAttr Attribute) = 0;
123 /// EmitCommonSymbol - Emit a common or local common symbol of @param Size
124 /// with the @param Pow2Alignment if non-zero.
126 /// @param Symbol - The common symbol to emit.
127 /// @param Size - The size of the common symbol.
128 /// @param Pow2Alignment - The alignment of the common symbol if non-zero.
129 /// @param IsLocal - If true, then the symbol is to be a local common
130 virtual void EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
131 unsigned Pow2Alignment, bool IsLocal) = 0;
133 /// EmitZerofill - Emit a the zerofill section and possiblity a symbol, if
134 /// @param Symbol is non-NULL, for @param Size and with the @param
135 /// Pow2Alignment if non-zero.
137 /// @param Section - The zerofill section to create and or to put the symbol
138 /// @param Symbol - The zerofill symbol to emit, if non-NULL.
139 /// @param Size - The size of the zerofill symbol.
140 /// @param Pow2Alignment - The alignment of the zerofill symbol if non-zero.
141 virtual void EmitZerofill(MCSection *Section, MCSymbol *Symbol = 0,
142 unsigned Size = 0,unsigned Pow2Alignment = 0) = 0;
144 /// AbortAssembly - Stop and don't produce output, printing @param
145 /// AbortReason if non-NULL to indicate the reason the assembly is
148 /// @param AbortReason - The reason assembly is terminated, if non-NULL.
149 virtual void AbortAssembly(const char *AbortReason) = 0;
152 /// @name Generating Data
155 /// EmitBytes - Emit @param Length bytes starting at @param Data into the
158 /// This is used to implement assembler directives such as .byte, .ascii,
160 virtual void EmitBytes(const char *Data, unsigned Length) = 0;
162 /// EmitValue - Emit the expression @param Value into the output as a native
163 /// integer of the given @param Size bytes.
165 /// This is used to implement assembler directives such as .word, .quad,
168 /// @param Value - The value to emit.
169 /// @param Size - The size of the integer (in bytes) to emit. This must
170 /// match a native machine width.
171 virtual void EmitValue(const MCValue &Value, unsigned Size) = 0;
173 /// EmitValueToAlignment - Emit some number of copies of @param Value until
174 /// the byte alignment @param ByteAlignment is reached.
176 /// If the number of bytes need to emit for the alignment is not a multiple
177 /// of @param ValueSize, then the contents of the emitted fill bytes is
180 /// This used to implement the .align assembler directive.
182 /// @param ByteAlignment - The alignment to reach. This must be a power of
183 /// two on some targets.
184 /// @param Value - The value to use when filling bytes.
185 /// @param Size - The size of the integer (in bytes) to emit for @param
186 /// Value. This must match a native machine width.
187 /// @param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If
188 /// the alignment cannot be reached in this many bytes, no bytes are
190 virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
191 unsigned ValueSize = 1,
192 unsigned MaxBytesToEmit = 0) = 0;
194 /// EmitValueToOffset - Emit some number of copies of @param Value until the
195 /// byte offset @param Offset is reached.
197 /// This is used to implement assembler directives such as .org.
199 /// @param Offset - The offset to reach.This may be an expression, but the
200 /// expression must be associated with the current section.
201 /// @param Value - The value to use when filling bytes.
203 // FIXME: How are we going to signal failures out of this?
204 virtual void EmitValueToOffset(const MCValue &Offset,
205 unsigned char Value = 0) = 0;
209 /// EmitInstruction - Emit the given @param Instruction into the current
211 virtual void EmitInstruction(const MCInst &Inst) = 0;
213 /// Finish - Finish emission of machine code and flush any output.
214 virtual void Finish() = 0;
217 /// createAsmStreamer - Create a machine code streamer which will print out
218 /// assembly for the native target, suitable for compiling with a native
220 MCStreamer *createAsmStreamer(MCContext &Ctx, raw_ostream &OS);
222 // FIXME: These two may end up getting rolled into a single
223 // createObjectStreamer interface, which implements the assembler backend, and
224 // is parameterized on an output object file writer.
226 /// createMachOStream - Create a machine code streamer which will generative
227 /// Mach-O format object files.
228 MCStreamer *createMachOStreamer(MCContext &Ctx, raw_ostream &OS);
230 /// createELFStreamer - Create a machine code streamer which will generative
231 /// ELF format object files.
232 MCStreamer *createELFStreamer(MCContext &Ctx, raw_ostream &OS);
234 } // end namespace llvm