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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 <map>
namespace llvm {
class BinaryObject;
class Constant;
class ConstantInt;
class ConstantStruct;
class ELFCodeEmitter;
class ELFRelocation;
class ELFSection;
struct ELFSym;
class GlobalVariable;
class JITDebugRegisterer;
class Mangler;
class MachineCodeEmitter;
class MachineConstantPoolEntry;
class ObjectCodeEmitter;
class MCAsmInfo;
class TargetELFWriterInfo;
class TargetLoweringObjectFile;
class raw_ostream;
class SectionKind;
class MCContext;
class TargetMachine;
typedef std::vector<ELFSym*>::iterator ELFSymIter;
typedef std::vector<ELFSection*>::iterator ELFSectionIter;
typedef SetVector<const GlobalValue*>::const_iterator PendingGblsIter;
typedef SetVector<const char *>::const_iterator PendingExtsIter;
typedef std::pair<const Constant *, int64_t> CstExprResTy;
/// 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;
friend class JITDebugRegisterer;
public:
static char ID;
/// Return the ELFCodeEmitter as an instance of ObjectCodeEmitter
ObjectCodeEmitter *getObjectCodeEmitter() {
return reinterpret_cast<ObjectCodeEmitter*>(ElfCE);
}
ELFWriter(raw_ostream &O, TargetMachine &TM);
~ELFWriter();
protected:
/// Output stream to send the resultant object file to.
raw_ostream &O;
/// Target machine description.
TargetMachine &TM;
/// Context object for machine code objects.
MCContext &OutContext;
/// Target Elf Writer description.
const TargetELFWriterInfo *TEW;
/// 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 *ElfCE;
/// TLOF - Target Lowering Object File, provide section names for globals
/// and other object file specific stuff
const TargetLoweringObjectFile &TLOF;
/// MAI - Target Asm Info, provide information about section names for
/// globals and other target specific stuff.
const MCAsmInfo *MAI;
//===------------------------------------------------------------------===//
// 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:
/// Blob containing the Elf header
BinaryObject 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::vector<ELFSection*> SectionList;
unsigned NumSections; // Always = SectionList.size()
/// SectionLookup - This is a mapping from section name to section number in
/// the SectionList. Used to quickly gather the Section Index from MAI names
std::map<std::string, ELFSection*> SectionLookup;
/// PendingGlobals - Globals not processed as symbols yet.
SetVector<const GlobalValue*> PendingGlobals;
/// GblSymLookup - This is a mapping from global value to a symbol index
/// in the symbol table or private symbols list. This is useful since reloc
/// symbol references must be quickly mapped to their indices on the lists.
std::map<const GlobalValue*, uint32_t> GblSymLookup;
/// PendingExternals - Externals not processed as symbols yet.
SetVector<const char *> PendingExternals;
/// ExtSymLookup - This is a mapping from externals to a symbol index
/// in the symbol table list. This is useful since reloc symbol references
/// must be quickly mapped to their symbol table indices.
std::map<const char *, uint32_t> ExtSymLookup;
/// SymbolList - This is the list of symbols emitted to the symbol table.
/// When the SymbolList is finally built, local symbols must be placed in
/// the beginning while non-locals at the end.
std::vector<ELFSym*> SymbolList;
/// PrivateSyms - Record private symbols, every symbol here must never be
/// present in the SymbolList.
std::vector<ELFSym*> PrivateSyms;
/// 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(new ELFSection(Name, isLittleEndian, is64Bit));
SN = SectionList.back();
SN->SectionIdx = NumSections++;
SN->Type = Type;
SN->Flags = Flags;
SN->Link = ELF::SHN_UNDEF;
SN->Align = Align;
return *SN;
}
ELFSection &getNonExecStackSection() {
return getSection(".note.GNU-stack", ELF::SHT_PROGBITS, 0, 1);
}
ELFSection &getSymbolTableSection() {
return getSection(".symtab", ELF::SHT_SYMTAB, 0);
}
ELFSection &getStringTableSection() {
return getSection(".strtab", ELF::SHT_STRTAB, 0, 1);
}
ELFSection &getSectionHeaderStringTableSection() {
return getSection(".shstrtab", ELF::SHT_STRTAB, 0, 1);
}
ELFSection &getNullSection() {
return getSection("", ELF::SHT_NULL, 0);
}
ELFSection &getDataSection();
ELFSection &getBSSSection();
ELFSection &getCtorSection();
ELFSection &getDtorSection();
ELFSection &getJumpTableSection();
ELFSection &getConstantPoolSection(MachineConstantPoolEntry &CPE);
ELFSection &getTextSection(const Function *F);
ELFSection &getRelocSection(ELFSection &S);
// Helpers for obtaining ELF specific info.
unsigned getGlobalELFBinding(const GlobalValue *GV);
unsigned getGlobalELFType(const GlobalValue *GV);
unsigned getGlobalELFVisibility(const GlobalValue *GV);
// AddPendingGlobalSymbol - Add a global to be processed and to
// the global symbol lookup, use a zero index because the table
// index will be determined later.
void AddPendingGlobalSymbol(const GlobalValue *GV,
bool AddToLookup = false);
// AddPendingExternalSymbol - Add the external to be processed
// and to the external symbol lookup, use a zero index because
// the symbol table index will be determined later.
void AddPendingExternalSymbol(const char *External);
// AddToSymbolList - Update the symbol lookup and If the symbol is
// private add it to PrivateSyms list, otherwise to SymbolList.
void AddToSymbolList(ELFSym *GblSym);
// 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(const GlobalValue *GV);
void EmitGlobalConstant(const Constant *C, ELFSection &GblS);
void EmitGlobalConstantStruct(const ConstantStruct *CVS,
ELFSection &GblS);
void EmitGlobalConstantLargeInt(const ConstantInt *CI, ELFSection &S);
void EmitGlobalDataRelocation(const GlobalValue *GV, unsigned Size,
ELFSection &GblS, int64_t Offset = 0);
bool EmitSpecialLLVMGlobal(const GlobalVariable *GV);
void EmitXXStructorList(Constant *List, ELFSection &Xtor);
void EmitRelocations();
void EmitRelocation(BinaryObject &RelSec, ELFRelocation &Rel, bool HasRelA);
void EmitSectionHeader(BinaryObject &SHdrTab, const ELFSection &SHdr);
void EmitSectionTableStringTable();
void EmitSymbol(BinaryObject &SymbolTable, ELFSym &Sym);
void EmitSymbolTable();
void EmitStringTable(const std::string &ModuleName);
void OutputSectionsAndSectionTable();
void RelocateField(BinaryObject &BO, uint32_t Offset, int64_t Value,
unsigned Size);
unsigned SortSymbols();
CstExprResTy ResolveConstantExpr(const Constant *CV);
};
}
#endif