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//===-- ELFWriter.h - Target-independent ELF writer support -----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the ELFWriter class.
//
//===----------------------------------------------------------------------===//
#ifndef ELFWRITER_H
#define ELFWRITER_H
#include "llvm/ADT/SetVector.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/Support/OutputBuffer.h"
#include "llvm/Target/TargetAsmInfo.h"
#include "llvm/Target/TargetELFWriterInfo.h"
#include "ELF.h"
#include <list>
#include <map>
namespace llvm {
class ConstantStruct;
class ELFCodeEmitter;
class GlobalVariable;
class Mangler;
class MachineCodeEmitter;
class raw_ostream;
/// ELFWriter - This class implements the common target-independent code for
/// writing ELF files. Targets should derive a class from this to
/// parameterize the output format.
///
class ELFWriter : public MachineFunctionPass {
friend class ELFCodeEmitter;
public:
static char ID;
MachineCodeEmitter &getMachineCodeEmitter() const {
return *(MachineCodeEmitter*)MCE;
}
ELFWriter(raw_ostream &O, TargetMachine &TM);
~ELFWriter();
typedef std::vector<unsigned char> DataBuffer;
protected:
/// Output stream to send the resultant object file to.
raw_ostream &O;
/// Target machine description.
TargetMachine &TM;
/// Mang - The object used to perform name mangling for this module.
Mangler *Mang;
/// MCE - The MachineCodeEmitter object that we are exposing to emit machine
/// code for functions to the .o file.
ELFCodeEmitter *MCE;
/// TAI - Target Asm Info, provide information about section names for
/// globals and other target specific stuff.
const TargetAsmInfo *TAI;
//===------------------------------------------------------------------===//
// Properties inferred automatically from the target machine.
//===------------------------------------------------------------------===//
/// is64Bit/isLittleEndian - This information is inferred from the target
/// machine directly, indicating whether to emit a 32- or 64-bit ELF file.
bool is64Bit, isLittleEndian;
/// doInitialization - Emit the file header and all of the global variables
/// for the module to the ELF file.
bool doInitialization(Module &M);
bool runOnMachineFunction(MachineFunction &MF);
/// doFinalization - Now that the module has been completely processed, emit
/// the ELF file to 'O'.
bool doFinalization(Module &M);
private:
// The buffer we accumulate the file header into. Note that this should be
// changed into something much more efficient later (and the bitcode writer
// as well!).
DataBuffer FileHeader;
/// ElfHdr - Hold information about the ELF Header
ELFHeader *ElfHdr;
/// SectionList - This is the list of sections that we have emitted to the
/// file. Once the file has been completely built, the section header table
/// is constructed from this info.
std::list<ELFSection> SectionList;
unsigned NumSections; // Always = SectionList.size()
/// SectionLookup - This is a mapping from section name to section number in
/// the SectionList.
std::map<std::string, ELFSection*> SectionLookup;
/// getSection - Return the section with the specified name, creating a new
/// section if one does not already exist.
ELFSection &getSection(const std::string &Name, unsigned Type,
unsigned Flags = 0, unsigned Align = 0) {
ELFSection *&SN = SectionLookup[Name];
if (SN) return *SN;
SectionList.push_back(Name);
SN = &SectionList.back();
SN->SectionIdx = NumSections++;
SN->Type = Type;
SN->Flags = Flags;
SN->Link = ELFSection::SHN_UNDEF;
SN->Align = Align;
return *SN;
}
ELFSection &getTextSection() {
return getSection(".text", ELFSection::SHT_PROGBITS,
ELFSection::SHF_EXECINSTR | ELFSection::SHF_ALLOC);
}
ELFSection &getSymbolTableSection() {
return getSection(".symtab", ELFSection::SHT_SYMTAB, 0);
}
ELFSection &getStringTableSection() {
return getSection(".strtab", ELFSection::SHT_STRTAB, 0, 1);
}
ELFSection &getDataSection() {
return getSection(".data", ELFSection::SHT_PROGBITS,
ELFSection::SHF_WRITE | ELFSection::SHF_ALLOC);
}
ELFSection &getBSSSection() {
return getSection(".bss", ELFSection::SHT_NOBITS,
ELFSection::SHF_WRITE | ELFSection::SHF_ALLOC);
}
/// SymbolTable - This is the list of symbols we have emitted to the file.
/// This actually gets rearranged before emission to the file (to put the
/// local symbols first in the list).
std::vector<ELFSym> SymbolTable;
/// PendingSyms - This is a list of externally defined symbols that we have
/// been asked to emit, but have not seen a reference to. When a reference
/// is seen, the symbol will move from this list to the SymbolTable.
SetVector<GlobalValue*> PendingGlobals;
// As we complete the ELF file, we need to update fields in the ELF header
// (e.g. the location of the section table). These members keep track of
// the offset in ELFHeader of these various pieces to update and other
// locations in the file.
unsigned ELFHdr_e_shoff_Offset; // e_shoff in ELF header.
unsigned ELFHdr_e_shstrndx_Offset; // e_shstrndx in ELF header.
unsigned ELFHdr_e_shnum_Offset; // e_shnum in ELF header.
private:
void EmitGlobal(GlobalVariable *GV);
void EmitGlobalConstant(const Constant *C, OutputBuffer &GblCstTab);
void EmitGlobalConstantStruct(const ConstantStruct *CVS,
OutputBuffer &GblCstTab);
void EmitRelocations();
void EmitSectionHeader(OutputBuffer &TableOut, const ELFSection &Section);
void EmitSectionTableStringTable();
void EmitSymbol(OutputBuffer &SymTabOut, ELFSym &Sym);
void EmitSymbolTable();
void OutputSectionsAndSectionTable();
};
}
#endif
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