1 //===-- ELFWriter.h - Target-independent ELF writer support -----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the ELFWriter class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CODEGEN_ELFWRITER_H
15 #define LLVM_CODEGEN_ELFWRITER_H
17 #include "llvm/CodeGen/MachineFunctionPass.h"
23 /// ELFWriter - This class implements the common target-independent code for
24 /// writing ELF files. Targets should derive a class from this to
25 /// parameterize the output format.
27 class ELFWriter : public MachineFunctionPass {
29 ELFWriter(std::ostream &O, TargetMachine &TM);
31 /// Output stream to send the resultant object file to.
35 /// Target machine description.
39 /// Mang - The object used to perform name mangling for this module.
43 //===------------------------------------------------------------------===//
44 // Properties to be set by the derived class ctor, used to configure the
47 // e_machine - This field is the target specific value to emit as the
48 // e_machine member of the ELF header.
49 unsigned short e_machine;
51 // e_flags - The machine flags for the target. This defaults to zero.
54 //===------------------------------------------------------------------===//
55 // Properties inferred automatically from the target machine.
58 /// is64Bit/isLittleEndian - This information is inferred from the target
59 /// machine directly, indicating whether to emit a 32- or 64-bit ELF file.
60 bool is64Bit, isLittleEndian;
62 /// doInitialization - Emit the file header and all of the global variables
63 /// for the module to the ELF file.
64 bool doInitialization(Module &M);
66 bool runOnMachineFunction(MachineFunction &MF);
69 /// doFinalization - Now that the module has been completely processed, emit
70 /// the ELF file to 'O'.
71 bool doFinalization(Module &M);
74 // The buffer we are accumulating the file into. Note that this should be
75 // changed into something much more efficient later (and the bytecode writer
77 std::vector<unsigned char> OutputBuffer;
79 /// ELFSection - This struct contains information about each section that is
80 /// emitted to the OutputBuffer. This is eventually turned into the section
81 /// header table at the end of the file.
83 std::string Name; // Name of the section.
84 unsigned NameIdx; // Index in .shstrtab of name, once emitted.
95 enum { SHT_NULL = 0, SHT_PROGBITS = 1, SHT_SYMTAB = 2, SHT_STRTAB = 3,
96 SHT_RELA = 4, SHT_HASH = 5, SHT_DYNAMIC = 6, SHT_NOTE = 7,
97 SHT_NOBITS = 8, SHT_REL = 9, SHT_SHLIB = 10, SHT_DYNSYM = 11 };
98 enum { SHN_UNDEF = 0, SHN_ABS = 0xFFF1, SHN_COMMON = 0xFFF2 };
99 enum { SHF_WRITE = 1, SHF_ALLOC = 2, SHF_EXECINSTR = 4 };
101 ELFSection(const char *name = "", unsigned offset = 0)
102 : Name(name), Type(0), Flags(0), Addr(0), Offset(offset), Size(0),
103 Link(0), Info(0), Align(0), EntSize(0) {
107 /// SectionList - This is the list of sections that we have emitted to the
108 /// file. Once the file has been completely built, the section header table
109 /// is constructed from this info.
110 std::vector<ELFSection> SectionList;
112 /// ELFSym - This struct contains information about each symbol that is
113 /// added to logical symbol table for the module. This is eventually
114 /// turned into a real symbol table in the file.
116 GlobalValue *GV; // The global value this corresponds to.
117 //std::string Name; // Name of the symbol.
118 unsigned NameIdx; // Index in .strtab of name, once emitted.
123 unsigned short SectionIdx;
125 enum { STB_LOCAL = 0, STB_GLOBAL = 1, STB_WEAK = 2 };
126 enum { STT_NOTYPE = 0, STT_OBJECT = 1, STT_FUNC = 2, STT_SECTION = 3,
128 ELFSym(GlobalValue *gv) : GV(gv), Value(0), Size(0), Info(0),
129 Other(0), SectionIdx(0) {}
131 void SetBind(unsigned X) {
132 assert(X == (X & 0xF) && "Bind value out of range!");
133 Info = (Info & 0x0F) | (X << 4);
135 void SetType(unsigned X) {
136 assert(X == (X & 0xF) && "Type value out of range!");
137 Info = (Info & 0xF0) | X;
141 /// SymbolTable - This is the list of symbols we have emitted to the file.
142 /// This actually gets rearranged before emission to OutputBuffer (to put
143 /// the local symbols first in the list).
144 std::vector<ELFSym> SymbolTable;
147 // As we accumulate the ELF file into OutputBuffer, we occasionally need to
148 // keep track of locations to update later (e.g. the location of the section
149 // table in the ELF header. These members keep track of the offset in
150 // OffsetBuffer of these various pieces to update and other locations in the
152 unsigned ELFHeader_e_shoff_Offset; // e_shoff in ELF header.
153 unsigned ELFHeader_e_shstrndx_Offset; // e_shstrndx in ELF header.
154 unsigned ELFHeader_e_shnum_Offset; // e_shnum in ELF header.
156 // align - Emit padding into the file until the current output position is
157 // aligned to the specified power of two boundary.
158 void align(unsigned Boundary) {
159 assert(Boundary && (Boundary & (Boundary-1)) == 0 &&
160 "Must align to 2^k boundary");
161 while (OutputBuffer.size() & (Boundary-1))
165 void outbyte(unsigned char X) { OutputBuffer.push_back(X); }
166 void outhalf(unsigned short X) {
167 if (isLittleEndian) {
168 OutputBuffer.push_back(X&255);
169 OutputBuffer.push_back(X >> 8);
171 OutputBuffer.push_back(X >> 8);
172 OutputBuffer.push_back(X&255);
175 void outword(unsigned X) {
176 if (isLittleEndian) {
177 OutputBuffer.push_back((X >> 0) & 255);
178 OutputBuffer.push_back((X >> 8) & 255);
179 OutputBuffer.push_back((X >> 16) & 255);
180 OutputBuffer.push_back((X >> 24) & 255);
182 OutputBuffer.push_back((X >> 24) & 255);
183 OutputBuffer.push_back((X >> 16) & 255);
184 OutputBuffer.push_back((X >> 8) & 255);
185 OutputBuffer.push_back((X >> 0) & 255);
188 void outaddr(uint64_t X) {
190 outword((unsigned)X);
192 assert(0 && "Emission of 64-bit data not implemented yet!");
195 // fix functions - Replace an existing entry at an offset.
196 void fixhalf(unsigned short X, unsigned Offset) {
197 unsigned char *P = &OutputBuffer[Offset];
198 P[0] = (X >> (isLittleEndian ? 0 : 8)) & 255;
199 P[1] = (X >> (isLittleEndian ? 8 : 0)) & 255;
202 void fixword(unsigned X, unsigned Offset) {
203 unsigned char *P = &OutputBuffer[Offset];
204 P[0] = (X >> (isLittleEndian ? 0 : 24)) & 255;
205 P[1] = (X >> (isLittleEndian ? 8 : 16)) & 255;
206 P[2] = (X >> (isLittleEndian ? 16 : 8)) & 255;
207 P[3] = (X >> (isLittleEndian ? 24 : 0)) & 255;
210 void fixaddr(uint64_t X, unsigned Offset) {
212 fixword((unsigned)X, Offset);
214 assert(0 && "Emission of 64-bit data not implemented yet!");
218 void EmitGlobal(GlobalVariable *GV, ELFSection &DataSection,
219 ELFSection &BSSSection);
221 void EmitSymbolTable();
223 void EmitSectionTableStringTable();
224 void EmitSectionTable();