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"
22 /// ELFWriter - This class implements the common target-independent code for
23 /// writing ELF files. Targets should derive a class from this to
24 /// parameterize the output format.
26 class ELFWriter : public MachineFunctionPass {
28 ELFWriter(std::ostream &O, TargetMachine &TM);
30 /// Output stream to send the resultant object file to.
34 /// Target machine description.
38 //===------------------------------------------------------------------===//
39 // Properties to be set by the derived class ctor, used to configure the
42 // e_machine - This field is the target specific value to emit as the
43 // e_machine member of the ELF header.
44 unsigned short e_machine;
46 // e_flags - The machine flags for the target. This defaults to zero.
49 //===------------------------------------------------------------------===//
50 // Properties inferred automatically from the target machine.
53 /// is64Bit/isLittleEndian - This information is inferred from the target
54 /// machine directly, indicating whether to emit a 32- or 64-bit ELF file.
55 bool is64Bit, isLittleEndian;
57 /// doInitialization - Emit the file header and all of the global variables
58 /// for the module to the ELF file.
59 bool doInitialization(Module &M);
61 bool runOnMachineFunction(MachineFunction &MF);
64 /// doFinalization - Now that the module has been completely processed, emit
65 /// the ELF file to 'O'.
66 bool doFinalization(Module &M);
69 // The buffer we are accumulating the file into. Note that this should be
70 // changed into something much more efficient later (and the bytecode writer
72 std::vector<unsigned char> OutputBuffer;
74 /// ELFSection - This struct contains information about each section that is
75 /// emitted to the OutputBuffer. This is eventually turned into the section
76 /// header table at the end of the file.
78 std::string Name; // Name of the section.
79 unsigned NameIdx; // Index in .shstrtab of name, once emitted.
90 enum { SHT_NULL = 0, SHT_PROGBITS = 1, SHT_SYMTAB = 2, SHT_STRTAB = 3,
91 SHT_RELA = 4, SHT_HASH = 5, SHT_DYNAMIC = 6, SHT_NOTE = 7,
92 SHT_NOBITS = 8, SHT_REL = 9, SHT_SHLIB = 10, SHT_DYNSYM = 11 };
93 enum { SHN_UNDEF = 0, SHN_ABS = 0xFFF1, SHN_COMMON = 0xFFF2 };
94 enum { SHF_WRITE = 1, SHF_ALLOC = 2, SHF_EXECINSTR = 4 };
96 ELFSection(const char *name = "", unsigned offset = 0)
97 : Name(name), Type(0), Flags(0), Addr(0), Offset(offset), Size(0),
98 Link(0), Info(0), Align(0), EntSize(0) {
102 /// SectionList - This is the list of sections that we have emitted to the
103 /// file. Once the file has been completely built, the section header table
104 /// is constructed from this info.
105 std::vector<ELFSection> SectionList;
107 /// ELFSym - This struct contains information about each symbol that is
108 /// added to logical symbol table for the module. This is eventually
109 /// turned into a real symbol table in the file.
111 GlobalValue *GV; // The global value this corresponds to.
112 //std::string Name; // Name of the symbol.
113 unsigned NameIdx; // Index in .strtab of name, once emitted.
118 unsigned short SectionIdx;
120 enum { STB_LOCAL = 0, STB_GLOBAL = 1, STB_WEAK = 2 };
121 enum { STT_NOTYPE = 0, STT_OBJECT = 1, STT_FUNC = 2, STT_SECTION = 3,
123 ELFSym(GlobalValue *gv) : GV(gv), Value(0), Size(0), Info(0),
124 Other(0), SectionIdx(0) {}
126 void SetBind(unsigned X) {
127 assert(X == (X & 0xF) && "Bind value out of range!");
128 Info = (Info & 0x0F) | (X << 4);
130 void SetType(unsigned X) {
131 assert(X == (X & 0xF) && "Type value out of range!");
132 Info = (Info & 0xF0) | X;
136 /// SymbolTable - This is the list of symbols we have emitted to the file.
137 /// This actually gets rearranged before emission to OutputBuffer (to put
138 /// the local symbols first in the list).
139 std::vector<ELFSym> SymbolTable;
142 // As we accumulate the ELF file into OutputBuffer, we occasionally need to
143 // keep track of locations to update later (e.g. the location of the section
144 // table in the ELF header. These members keep track of the offset in
145 // OffsetBuffer of these various pieces to update and other locations in the
147 unsigned ELFHeader_e_shoff_Offset; // e_shoff in ELF header.
148 unsigned ELFHeader_e_shstrndx_Offset; // e_shstrndx in ELF header.
149 unsigned ELFHeader_e_shnum_Offset; // e_shnum in ELF header.
151 // align - Emit padding into the file until the current output position is
152 // aligned to the specified power of two boundary.
153 void align(unsigned Boundary) {
154 assert(Boundary && (Boundary & (Boundary-1)) == 0 &&
155 "Must align to 2^k boundary");
156 while (OutputBuffer.size() & (Boundary-1))
160 void outbyte(unsigned char X) { OutputBuffer.push_back(X); }
161 void outhalf(unsigned short X) {
162 if (isLittleEndian) {
163 OutputBuffer.push_back(X&255);
164 OutputBuffer.push_back(X >> 8);
166 OutputBuffer.push_back(X >> 8);
167 OutputBuffer.push_back(X&255);
170 void outword(unsigned X) {
171 if (isLittleEndian) {
172 OutputBuffer.push_back((X >> 0) & 255);
173 OutputBuffer.push_back((X >> 8) & 255);
174 OutputBuffer.push_back((X >> 16) & 255);
175 OutputBuffer.push_back((X >> 24) & 255);
177 OutputBuffer.push_back((X >> 24) & 255);
178 OutputBuffer.push_back((X >> 16) & 255);
179 OutputBuffer.push_back((X >> 8) & 255);
180 OutputBuffer.push_back((X >> 0) & 255);
183 void outaddr(uint64_t X) {
185 outword((unsigned)X);
187 assert(0 && "Emission of 64-bit data not implemented yet!");
190 // fix functions - Replace an existing entry at an offset.
191 void fixhalf(unsigned short X, unsigned Offset) {
192 unsigned char *P = &OutputBuffer[Offset];
193 P[0] = (X >> (isLittleEndian ? 0 : 8)) & 255;
194 P[1] = (X >> (isLittleEndian ? 8 : 0)) & 255;
197 void fixword(unsigned X, unsigned Offset) {
198 unsigned char *P = &OutputBuffer[Offset];
199 P[0] = (X >> (isLittleEndian ? 0 : 24)) & 255;
200 P[1] = (X >> (isLittleEndian ? 8 : 16)) & 255;
201 P[2] = (X >> (isLittleEndian ? 16 : 8)) & 255;
202 P[3] = (X >> (isLittleEndian ? 24 : 0)) & 255;
205 void fixaddr(uint64_t X, unsigned Offset) {
207 fixword((unsigned)X, Offset);
209 assert(0 && "Emission of 64-bit data not implemented yet!");
213 void EmitGlobal(GlobalVariable *GV, ELFSection &DataSection,
214 ELFSection &BSSSection);
216 void EmitSymbolTable();
218 void EmitSectionTableStringTable();
219 void EmitSectionTable();