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			325 lines
		
	
	
		
			11 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			325 lines
		
	
	
		
			11 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
//===-- MipsELFObjectWriter.cpp - Mips ELF Writer -------------------------===//
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//
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//                     The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "MCTargetDesc/MipsBaseInfo.h"
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#include "MCTargetDesc/MipsFixupKinds.h"
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#include "MCTargetDesc/MipsMCTargetDesc.h"
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#include "llvm/MC/MCAssembler.h"
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#include "llvm/MC/MCELFObjectWriter.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCSection.h"
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#include "llvm/MC/MCValue.h"
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#include "llvm/Support/ErrorHandling.h"
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#include <list>
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using namespace llvm;
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namespace {
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  struct RelEntry {
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    RelEntry(const ELFRelocationEntry &R, const MCSymbol *S, int64_t O) :
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      Reloc(R), Sym(S), Offset(O) {}
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    ELFRelocationEntry Reloc;
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    const MCSymbol *Sym;
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    int64_t Offset;
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  };
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  typedef std::list<RelEntry> RelLs;
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  typedef RelLs::iterator RelLsIter;
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  class MipsELFObjectWriter : public MCELFObjectTargetWriter {
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  public:
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    MipsELFObjectWriter(bool _is64Bit, uint8_t OSABI,
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                        bool _isN64, bool IsLittleEndian);
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    virtual ~MipsELFObjectWriter();
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    virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
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                                  bool IsPCRel, bool IsRelocWithSymbol,
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                                  int64_t Addend) const;
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    virtual const MCSymbol *ExplicitRelSym(const MCAssembler &Asm,
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                                           const MCValue &Target,
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                                           const MCFragment &F,
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                                           const MCFixup &Fixup,
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                                           bool IsPCRel) const;
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    virtual void sortRelocs(const MCAssembler &Asm,
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                            std::vector<ELFRelocationEntry> &Relocs);
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  };
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}
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MipsELFObjectWriter::MipsELFObjectWriter(bool _is64Bit, uint8_t OSABI,
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                                         bool _isN64, bool IsLittleEndian)
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  : MCELFObjectTargetWriter(_is64Bit, OSABI, ELF::EM_MIPS,
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                            /*HasRelocationAddend*/ (_isN64) ? true : false,
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                            /*IsN64*/ _isN64) {}
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MipsELFObjectWriter::~MipsELFObjectWriter() {}
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const MCSymbol *MipsELFObjectWriter::ExplicitRelSym(const MCAssembler &Asm,
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                                                    const MCValue &Target,
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                                                    const MCFragment &F,
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                                                    const MCFixup &Fixup,
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                                                    bool IsPCRel) const {
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  assert(Target.getSymA() && "SymA cannot be 0.");
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  const MCSymbol &Sym = Target.getSymA()->getSymbol().AliasedSymbol();
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  if (Sym.getSection().getKind().isMergeableCString() ||
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      Sym.getSection().getKind().isMergeableConst())
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    return &Sym;
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  return NULL;
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}
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unsigned MipsELFObjectWriter::GetRelocType(const MCValue &Target,
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                                           const MCFixup &Fixup,
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                                           bool IsPCRel,
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                                           bool IsRelocWithSymbol,
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                                           int64_t Addend) const {
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  // determine the type of the relocation
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  unsigned Type = (unsigned)ELF::R_MIPS_NONE;
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  unsigned Kind = (unsigned)Fixup.getKind();
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  switch (Kind) {
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  default:
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    llvm_unreachable("invalid fixup kind!");
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  case FK_Data_4:
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    Type = ELF::R_MIPS_32;
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    break;
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  case FK_Data_8:
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    Type = ELF::R_MIPS_64;
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    break;
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  case FK_GPRel_4:
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    if (isN64()) {
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      Type = setRType((unsigned)ELF::R_MIPS_GPREL32, Type);
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      Type = setRType2((unsigned)ELF::R_MIPS_64, Type);
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      Type = setRType3((unsigned)ELF::R_MIPS_NONE, Type);
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    }
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    else
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      Type = ELF::R_MIPS_GPREL32;
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    break;
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  case Mips::fixup_Mips_GPREL16:
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    Type = ELF::R_MIPS_GPREL16;
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    break;
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  case Mips::fixup_Mips_26:
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    Type = ELF::R_MIPS_26;
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    break;
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  case Mips::fixup_Mips_CALL16:
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    Type = ELF::R_MIPS_CALL16;
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    break;
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  case Mips::fixup_Mips_GOT_Global:
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  case Mips::fixup_Mips_GOT_Local:
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    Type = ELF::R_MIPS_GOT16;
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    break;
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  case Mips::fixup_Mips_HI16:
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    Type = ELF::R_MIPS_HI16;
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    break;
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  case Mips::fixup_Mips_LO16:
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    Type = ELF::R_MIPS_LO16;
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    break;
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  case Mips::fixup_Mips_TLSGD:
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    Type = ELF::R_MIPS_TLS_GD;
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    break;
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  case Mips::fixup_Mips_GOTTPREL:
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    Type = ELF::R_MIPS_TLS_GOTTPREL;
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    break;
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  case Mips::fixup_Mips_TPREL_HI:
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    Type = ELF::R_MIPS_TLS_TPREL_HI16;
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    break;
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  case Mips::fixup_Mips_TPREL_LO:
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    Type = ELF::R_MIPS_TLS_TPREL_LO16;
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    break;
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  case Mips::fixup_Mips_TLSLDM:
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    Type = ELF::R_MIPS_TLS_LDM;
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    break;
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  case Mips::fixup_Mips_DTPREL_HI:
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    Type = ELF::R_MIPS_TLS_DTPREL_HI16;
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    break;
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  case Mips::fixup_Mips_DTPREL_LO:
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    Type = ELF::R_MIPS_TLS_DTPREL_LO16;
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    break;
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  case Mips::fixup_Mips_Branch_PCRel:
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  case Mips::fixup_Mips_PC16:
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    Type = ELF::R_MIPS_PC16;
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    break;
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  case Mips::fixup_Mips_GOT_PAGE:
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    Type = ELF::R_MIPS_GOT_PAGE;
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    break;
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  case Mips::fixup_Mips_GOT_OFST:
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    Type = ELF::R_MIPS_GOT_OFST;
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    break;
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  case Mips::fixup_Mips_GOT_DISP:
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    Type = ELF::R_MIPS_GOT_DISP;
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    break;
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  case Mips::fixup_Mips_GPOFF_HI:
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    Type = setRType((unsigned)ELF::R_MIPS_GPREL16, Type);
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    Type = setRType2((unsigned)ELF::R_MIPS_SUB, Type);
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    Type = setRType3((unsigned)ELF::R_MIPS_HI16, Type);
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    break;
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  case Mips::fixup_Mips_GPOFF_LO:
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    Type = setRType((unsigned)ELF::R_MIPS_GPREL16, Type);
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    Type = setRType2((unsigned)ELF::R_MIPS_SUB, Type);
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    Type = setRType3((unsigned)ELF::R_MIPS_LO16, Type);
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    break;
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  case Mips::fixup_Mips_HIGHER:
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    Type = ELF::R_MIPS_HIGHER;
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    break;
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  case Mips::fixup_Mips_HIGHEST:
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    Type = ELF::R_MIPS_HIGHEST;
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    break;
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  case Mips::fixup_Mips_GOT_HI16:
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    Type = ELF::R_MIPS_GOT_HI16;
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    break;
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  case Mips::fixup_Mips_GOT_LO16:
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    Type = ELF::R_MIPS_GOT_LO16;
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    break;
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  case Mips::fixup_Mips_CALL_HI16:
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    Type = ELF::R_MIPS_CALL_HI16;
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    break;
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  case Mips::fixup_Mips_CALL_LO16:
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    Type = ELF::R_MIPS_CALL_LO16;
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    break;
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  case Mips::fixup_MICROMIPS_26_S1:
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    Type = ELF::R_MICROMIPS_26_S1;
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    break;
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  case Mips::fixup_MICROMIPS_HI16:
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    Type = ELF::R_MICROMIPS_HI16;
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    break;
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  case Mips::fixup_MICROMIPS_LO16:
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    Type = ELF::R_MICROMIPS_LO16;
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    break;
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  case Mips::fixup_MICROMIPS_GOT16:
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    Type = ELF::R_MICROMIPS_GOT16;
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    break;
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  case Mips::fixup_MICROMIPS_PC16_S1:
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    Type = ELF::R_MICROMIPS_PC16_S1;
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    break;
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  case Mips::fixup_MICROMIPS_CALL16:
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    Type = ELF::R_MICROMIPS_CALL16;
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    break;
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  case Mips::fixup_MICROMIPS_GOT_DISP:
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    Type = ELF::R_MICROMIPS_GOT_DISP;
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    break;
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  case Mips::fixup_MICROMIPS_GOT_PAGE:
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    Type = ELF::R_MICROMIPS_GOT_PAGE;
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    break;
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  case Mips::fixup_MICROMIPS_GOT_OFST:
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    Type = ELF::R_MICROMIPS_GOT_OFST;
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    break;
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  case Mips::fixup_MICROMIPS_TLS_DTPREL_HI16:
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    Type = ELF::R_MICROMIPS_TLS_DTPREL_HI16;
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    break;
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  case Mips::fixup_MICROMIPS_TLS_DTPREL_LO16:
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    Type = ELF::R_MICROMIPS_TLS_DTPREL_LO16;
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    break;
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  case Mips::fixup_MICROMIPS_TLS_TPREL_HI16:
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    Type = ELF::R_MICROMIPS_TLS_TPREL_HI16;
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    break;
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  case Mips::fixup_MICROMIPS_TLS_TPREL_LO16:
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    Type = ELF::R_MICROMIPS_TLS_TPREL_LO16;
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    break;
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  }
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  return Type;
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}
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// Return true if R is either a GOT16 against a local symbol or HI16.
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static bool NeedsMatchingLo(const MCAssembler &Asm, const RelEntry &R) {
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  if (!R.Sym)
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    return false;
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  MCSymbolData &SD = Asm.getSymbolData(R.Sym->AliasedSymbol());
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  return ((R.Reloc.Type == ELF::R_MIPS_GOT16) && !SD.isExternal()) ||
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    (R.Reloc.Type == ELF::R_MIPS_HI16);
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}
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static bool HasMatchingLo(const MCAssembler &Asm, RelLsIter I, RelLsIter Last) {
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  if (I == Last)
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    return false;
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  RelLsIter Hi = I++;
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  return (I->Reloc.Type == ELF::R_MIPS_LO16) && (Hi->Sym == I->Sym) &&
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    (Hi->Offset == I->Offset);
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}
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static bool HasSameSymbol(const RelEntry &R0, const RelEntry &R1) {
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  return R0.Sym == R1.Sym;
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}
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static int CompareOffset(const RelEntry &R0, const RelEntry &R1) {
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  return (R0.Offset > R1.Offset) ? 1 : ((R0.Offset == R1.Offset) ? 0 : -1);
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}
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void MipsELFObjectWriter::sortRelocs(const MCAssembler &Asm,
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                                     std::vector<ELFRelocationEntry> &Relocs) {
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  // Call the default function first. Relocations are sorted in descending
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  // order of r_offset.
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  MCELFObjectTargetWriter::sortRelocs(Asm, Relocs);
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  RelLs RelocLs;
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  std::vector<RelLsIter> Unmatched;
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  // Fill RelocLs. Traverse Relocs backwards so that relocations in RelocLs
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  // are in ascending order of r_offset.
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  for (std::vector<ELFRelocationEntry>::reverse_iterator R = Relocs.rbegin();
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       R != Relocs.rend(); ++R) {
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     std::pair<const MCSymbolRefExpr*, int64_t> P =
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       MipsGetSymAndOffset(*R->Fixup);
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     RelocLs.push_back(RelEntry(*R, P.first ? &P.first->getSymbol() : 0,
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                                P.second));
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  }
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  // Get list of unmatched HI16 and GOT16.
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  for (RelLsIter R = RelocLs.begin(); R != RelocLs.end(); ++R)
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    if (NeedsMatchingLo(Asm, *R) && !HasMatchingLo(Asm, R, --RelocLs.end()))
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      Unmatched.push_back(R);
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  // Insert unmatched HI16 and GOT16 immediately before their matching LO16.
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  for (std::vector<RelLsIter>::iterator U = Unmatched.begin();
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       U != Unmatched.end(); ++U) {
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    RelLsIter LoPos = RelocLs.end(), HiPos = *U;
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    bool MatchedLo = false;
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    for (RelLsIter R = RelocLs.begin(); R != RelocLs.end(); ++R) {
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      if ((R->Reloc.Type == ELF::R_MIPS_LO16) && HasSameSymbol(*HiPos, *R) &&
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          (CompareOffset(*R, *HiPos) >= 0) &&
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          ((LoPos == RelocLs.end()) || ((CompareOffset(*R, *LoPos) < 0)) ||
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           (!MatchedLo && !CompareOffset(*R, *LoPos))))
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        LoPos = R;
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      MatchedLo = NeedsMatchingLo(Asm, *R) &&
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        HasMatchingLo(Asm, R, --RelocLs.end());
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    }
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    // If a matching LoPos was found, move HiPos and insert it before LoPos.
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    // Make the offsets of HiPos and LoPos match.
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    if (LoPos != RelocLs.end()) {
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      HiPos->Offset = LoPos->Offset;
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      RelocLs.insert(LoPos, *HiPos);
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      RelocLs.erase(HiPos);
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    }
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  }
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  // Put the sorted list back in reverse order.
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  assert(Relocs.size() == RelocLs.size());
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  unsigned I = RelocLs.size();
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  for (RelLsIter R = RelocLs.begin(); R != RelocLs.end(); ++R)
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    Relocs[--I] = R->Reloc;
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}
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MCObjectWriter *llvm::createMipsELFObjectWriter(raw_ostream &OS,
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                                                uint8_t OSABI,
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                                                bool IsLittleEndian,
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                                                bool Is64Bit) {
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  MCELFObjectTargetWriter *MOTW = new MipsELFObjectWriter(Is64Bit, OSABI,
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                                                (Is64Bit) ? true : false,
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                                                IsLittleEndian);
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  return createELFObjectWriter(MOTW, OS, IsLittleEndian);
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}
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