lib/Target/Mips/MipsELFWriterInfo.cpp

//===-- MipsELFWriterInfo.cpp - ELF Writer Info for the Mips backend --------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements ELF writer information for the Mips backend.
//
//===----------------------------------------------------------------------===//

#include "MipsELFWriterInfo.h"
#include "MipsRelocations.h"
#include "llvm/Function.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/ELF.h"

using namespace llvm;

//===----------------------------------------------------------------------===//
//  Implementation of the MipsELFWriterInfo class
//===----------------------------------------------------------------------===//

MipsELFWriterInfo::MipsELFWriterInfo(bool is64Bit_, bool isLittleEndian_)
  : TargetELFWriterInfo(is64Bit_, isLittleEndian_) {
    EMachine = EM_MIPS;
  }

MipsELFWriterInfo::~MipsELFWriterInfo() {}

unsigned MipsELFWriterInfo::getRelocationType(unsigned MachineRelTy) const {
    switch(MachineRelTy) {
    case Mips::reloc_mips_pc16:
      return ELF::R_MIPS_GOT16;
    case Mips::reloc_mips_hi:
      return ELF::R_MIPS_HI16;
    case Mips::reloc_mips_lo:
      return ELF::R_MIPS_LO16;
    case Mips::reloc_mips_26:
      return ELF::R_MIPS_26;
    default:
      llvm_unreachable("unknown Mips machine relocation type");
    }
}

long int MipsELFWriterInfo::getDefaultAddendForRelTy(unsigned RelTy,
                                                    long int Modifier) const {
    switch(RelTy) {
    case ELF::R_MIPS_26: return Modifier;
    default:
      llvm_unreachable("unknown Mips relocation type");
    }
}

unsigned MipsELFWriterInfo::getRelocationTySize(unsigned RelTy) const {
    switch(RelTy) {
    case ELF::R_MIPS_GOT16:
    case ELF::R_MIPS_26:
        return 32;
    default:
      llvm_unreachable("unknown Mips relocation type");
    }
}

bool MipsELFWriterInfo::isPCRelativeRel(unsigned RelTy) const {
    switch(RelTy) {
    case ELF::R_MIPS_GOT16:
        return true;
    case ELF::R_MIPS_26:
        return false;
    default:
      llvm_unreachable("unknown Mips relocation type");
    }
}

unsigned MipsELFWriterInfo::getAbsoluteLabelMachineRelTy() const {
  return Mips::reloc_mips_26;
}

long int MipsELFWriterInfo::computeRelocation(unsigned SymOffset,
                                             unsigned RelOffset,
                                             unsigned RelTy) const {

  if (RelTy == ELF::R_MIPS_GOT16)
    return SymOffset - (RelOffset + 4);

  llvm_unreachable("computeRelocation unknown for this relocation type");
}