250 lines
8.1 KiB
C++
250 lines
8.1 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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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 unsigned getEFlags() 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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: MCELFObjectTargetWriter(_is64Bit, OSABI, ELF::EM_MIPS,
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/*HasRelocationAddend*/ false) {}
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MipsELFObjectWriter::~MipsELFObjectWriter() {}
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// FIXME: get the real EABI Version from the Subtarget class.
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unsigned MipsELFObjectWriter::getEFlags() const {
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// FIXME: We can't tell if we are PIC (dynamic) or CPIC (static)
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unsigned Flag = ELF::EF_MIPS_NOREORDER;
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if (is64Bit())
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Flag |= ELF::EF_MIPS_ARCH_64R2;
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else
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Flag |= ELF::EF_MIPS_ARCH_32R2;
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return Flag;
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}
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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_GPRel_4:
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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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}
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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 defualt 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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return createELFObjectWriter(MOTW, OS, IsLittleEndian);
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}
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