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Simple ELF32/64 binary files can now be emitted for x86 and x86_64 without

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relocation sections.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73038 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bruno Cardoso Lopes
2009-06-07 21:22:38 +00:00
parent faeedf1254
commit a029a27fae
6 changed files with 174 additions and 60 deletions
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lib/CodeGen/ELFWriter.cpp
+55 -35
View File
@@ -31,6 +31,8 @@
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "elfwriter"
#include "ELFWriter.h"
#include "ELFCodeEmitter.h"
#include "ELF.h"
@@ -48,6 +50,7 @@
#include "llvm/Support/OutputBuffer.h"
#include "llvm/Support/Streams.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Debug.h"
#include <list>
using namespace llvm;
@@ -67,13 +70,13 @@ MachineCodeEmitter *llvm::AddELFWriter(PassManagerBase &PM,
//===----------------------------------------------------------------------===//
ELFWriter::ELFWriter(raw_ostream &o, TargetMachine &tm)
: MachineFunctionPass(&ID), O(o), TM(tm) {
e_flags = 0; // e_flags defaults to 0, no flags.
e_machine = TM.getELFWriterInfo()->getEMachine();
: MachineFunctionPass(&ID), O(o), TM(tm), ElfHdr() {
is64Bit = TM.getTargetData()->getPointerSizeInBits() == 64;
isLittleEndian = TM.getTargetData()->isLittleEndian();
ElfHdr = new ELFHeader(TM.getELFWriterInfo()->getEMachine(), 0,
is64Bit, isLittleEndian);
// Create the machine code emitter object for this target.
MCE = new ELFCodeEmitter(*this);
NumSections = 0;
@@ -81,6 +84,7 @@ ELFWriter::ELFWriter(raw_ostream &o, TargetMachine &tm)
ELFWriter::~ELFWriter() {
delete MCE;
delete ElfHdr;
}
// doInitialization - Emit the file header and all of the global variables for
@@ -92,9 +96,6 @@ bool ELFWriter::doInitialization(Module &M) {
std::vector<unsigned char> &FH = FileHeader;
OutputBuffer FHOut(FH, is64Bit, isLittleEndian);
unsigned ElfClass = is64Bit ? ELFCLASS64 : ELFCLASS32;
unsigned ElfEndian = isLittleEndian ? ELFDATA2LSB : ELFDATA2MSB;
// ELF Header
// ----------
// Fields e_shnum e_shstrndx are only known after all section have
@@ -111,26 +112,26 @@ bool ELFWriter::doInitialization(Module &M) {
FHOut.outbyte('L'); // e_ident[EI_MAG2]
FHOut.outbyte('F'); // e_ident[EI_MAG3]
FHOut.outbyte(ElfClass); // e_ident[EI_CLASS]
FHOut.outbyte(ElfEndian); // e_ident[EI_DATA]
FHOut.outbyte(EV_CURRENT); // e_ident[EI_VERSION]
FHOut.outbyte(ElfHdr->getElfClass()); // e_ident[EI_CLASS]
FHOut.outbyte(ElfHdr->getByteOrder()); // e_ident[EI_DATA]
FHOut.outbyte(EV_CURRENT); // e_ident[EI_VERSION]
FH.resize(16); // e_ident[EI_NIDENT-EI_PAD]
FHOut.outhalf(ET_REL); // e_type
FHOut.outhalf(e_machine); // e_machine = target
FHOut.outword(EV_CURRENT); // e_version
FHOut.outaddr(0); // e_entry = 0 -> no entry point in .o file
FHOut.outaddr(0); // e_phoff = 0 -> no program header for .o
FHOut.outhalf(ET_REL); // e_type
FHOut.outhalf(ElfHdr->getMachine()); // e_machine = target
FHOut.outword(EV_CURRENT); // e_version
FHOut.outaddr(0); // e_entry = 0, no entry point in .o file
FHOut.outaddr(0); // e_phoff = 0, no program header for .o
ELFHdr_e_shoff_Offset = FH.size();
FHOut.outaddr(0); // e_shoff = sec hdr table off in bytes
FHOut.outword(e_flags); // e_flags = whatever the target wants
FHOut.outaddr(0); // e_shoff = sec hdr table off in bytes
FHOut.outword(ElfHdr->getFlags()); // e_flags = whatever the target wants
FHOut.outhalf(ElfHdr->getSize()); // e_ehsize = ELF header size
FHOut.outhalf(0); // e_phentsize = prog header entry size
FHOut.outhalf(0); // e_phnum = # prog header entries = 0
FHOut.outhalf(is64Bit ? 64 : 52); // e_ehsize = ELF header size
FHOut.outhalf(0); // e_phentsize = prog header entry size
FHOut.outhalf(0); // e_phnum = # prog header entries = 0
FHOut.outhalf(is64Bit ? 64 : 40); // e_shentsize = sect hdr entry size
// e_shentsize = Section header entry size
FHOut.outhalf(ELFSection::getSectionHdrSize(is64Bit));
// e_shnum = # of section header ents
ELFHdr_e_shnum_Offset = FH.size();
@@ -251,9 +252,10 @@ bool ELFWriter::doFinalization(Module &M) {
// Emit the symbol table now, if non-empty.
EmitSymbolTable();
// FIXME: Emit the relocations now.
// Emit the relocation sections.
EmitRelocations();
// Emit the string table for the sections in the ELF file we have.
// Emit the string table for the sections in the ELF file.
EmitSectionTableStringTable();
// Emit the sections to the .o file, and emit the section table for the file.
@@ -268,6 +270,10 @@ bool ELFWriter::doFinalization(Module &M) {
return false;
}
/// EmitRelocations - Emit relocations
void ELFWriter::EmitRelocations() {
}
/// EmitSymbolTable - If the current symbol table is non-empty, emit the string
/// table for it and then the symbol table itself.
void ELFWriter::EmitSymbolTable() {
@@ -284,7 +290,7 @@ void ELFWriter::EmitSymbolTable() {
// Set the zero'th symbol to a null byte, as required.
StrTabOut.outbyte(0);
SymbolTable[0].NameIdx = 0;
//SymbolTable[0].NameIdx = 0;
unsigned Index = 1;
for (unsigned i = 1, e = SymbolTable.size(); i != e; ++i) {
// Use the name mangler to uniquify the LLVM symbol.
@@ -312,9 +318,9 @@ void ELFWriter::EmitSymbolTable() {
// string table of each symbol, emit the symbol table itself.
ELFSection &SymTab = getSection(".symtab", ELFSection::SHT_SYMTAB, 0);
SymTab.Align = is64Bit ? 8 : 4;
SymTab.Link = SymTab.SectionIdx; // Section Index of .strtab.
SymTab.Info = FirstNonLocalSymbol; // First non-STB_LOCAL symbol.
SymTab.EntSize = 16; // Size of each symtab entry. FIXME: wrong for ELF64
SymTab.Link = StrTab.SectionIdx; // Section Index of .strtab.
SymTab.Info = FirstNonLocalSymbol; // First non-STB_LOCAL symbol.
SymTab.EntSize = is64Bit ? 24 : 16; // Size of each symtab entry.
DataBuffer &SymTabBuf = SymTab.SectionData;
OutputBuffer SymTabOut(SymTabBuf, is64Bit, isLittleEndian);
@@ -391,11 +397,21 @@ void ELFWriter::OutputSectionsAndSectionTable() {
// Emit all of the section data in order.
for (std::list<ELFSection>::iterator I = SectionList.begin(),
E = SectionList.end(); I != E; ++I) {
// Section idx 0 has 0 offset
if (!I->SectionIdx)
continue;
// Update Section size
if (!I->Size)
I->Size = I->SectionData.size();
// Align FileOff to whatever the alignment restrictions of the section are.
if (I->Align)
FileOff = (FileOff+I->Align-1) & ~(I->Align-1);
I->Offset = FileOff;
FileOff += I->SectionData.size();
FileOff += I->Size;
}
// Align Section Header.
@@ -429,19 +445,23 @@ void ELFWriter::OutputSectionsAndSectionTable() {
for (size_t NewFileOff = (FileOff+S.Align-1) & ~(S.Align-1);
FileOff != NewFileOff; ++FileOff)
O << (char)0xAB;
O.write((char*)&S.SectionData[0], S.SectionData.size());
FileOff += S.SectionData.size();
O.write((char*)&S.SectionData[0], S.Size);
DOUT << "SectionIdx: " << S.SectionIdx << ", Name: " << S.Name
<< ", Size: " << S.Size << ", Offset: " << S.Offset << "\n";
FileOff += S.Size;
TableOut.outword(S.NameIdx); // sh_name - Symbol table name idx
TableOut.outword(S.Type); // sh_type - Section contents & semantics
TableOut.outword(S.Flags); // sh_flags - Section flags.
TableOut.outaddr(S.Flags); // sh_flags - Section flags.
TableOut.outaddr(S.Addr); // sh_addr - The mem addr this section is in.
TableOut.outaddr(S.Offset); // sh_offset - Offset from the file start.
TableOut.outword(S.Size); // sh_size - The section size.
TableOut.outaddr(S.Size); // sh_size - The section size.
TableOut.outword(S.Link); // sh_link - Section header table index link.
TableOut.outword(S.Info); // sh_info - Auxillary information.
TableOut.outword(S.Align); // sh_addralign - Alignment of section.
TableOut.outword(S.EntSize); // sh_entsize - Size of entries in the section
TableOut.outaddr(S.Align); // sh_addralign - Alignment of section.
TableOut.outaddr(S.EntSize); // sh_entsize - Size of entries in the section
SectionList.pop_front();
}