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This enables the linker to match concrete relocation types (absolute or relative) with whatever library or C++ support code is being linked against. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149057 91177308-0d34-0410-b5e6-96231b3b80d8
282 lines
9.1 KiB
C++
282 lines
9.1 KiB
C++
//===-- ARMELFObjectWriter.cpp - ARM 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/ARMFixupKinds.h"
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#include "MCTargetDesc/ARMMCTargetDesc.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/ADT/StringSwitch.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/MCSectionELF.h"
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#include "llvm/MC/MCValue.h"
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using namespace llvm;
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namespace {
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class ARMELFObjectWriter : public MCELFObjectTargetWriter {
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enum { DefaultEABIVersion = 0x05000000U };
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unsigned GetRelocTypeInner(const MCValue &Target,
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const MCFixup &Fixup,
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bool IsPCRel) const;
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public:
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ARMELFObjectWriter(uint8_t OSABI);
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virtual ~ARMELFObjectWriter();
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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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};
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}
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ARMELFObjectWriter::ARMELFObjectWriter(uint8_t OSABI)
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: MCELFObjectTargetWriter(/*Is64Bit*/ false, OSABI,
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ELF::EM_ARM,
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/*HasRelocationAddend*/ false) {}
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ARMELFObjectWriter::~ARMELFObjectWriter() {}
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// FIXME: get the real EABI Version from the Triple.
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unsigned ARMELFObjectWriter::getEFlags() const {
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return ELF::EF_ARM_EABIMASK & DefaultEABIVersion;
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}
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// In ARM, _MergedGlobals and other most symbols get emitted directly.
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// I.e. not as an offset to a section symbol.
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// This code is an approximation of what ARM/gcc does.
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STATISTIC(PCRelCount, "Total number of PIC Relocations");
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STATISTIC(NonPCRelCount, "Total number of non-PIC relocations");
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const MCSymbol *ARMELFObjectWriter::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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const MCSymbol &Symbol = Target.getSymA()->getSymbol();
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bool EmitThisSym = false;
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const MCSectionELF &Section =
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static_cast<const MCSectionELF&>(Symbol.getSection());
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bool InNormalSection = true;
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unsigned RelocType = 0;
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RelocType = GetRelocTypeInner(Target, Fixup, IsPCRel);
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DEBUG(
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const MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind();
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MCSymbolRefExpr::VariantKind Kind2;
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Kind2 = Target.getSymB() ? Target.getSymB()->getKind() :
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MCSymbolRefExpr::VK_None;
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dbgs() << "considering symbol "
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<< Section.getSectionName() << "/"
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<< Symbol.getName() << "/"
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<< " Rel:" << (unsigned)RelocType
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<< " Kind: " << (int)Kind << "/" << (int)Kind2
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<< " Tmp:"
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<< Symbol.isAbsolute() << "/" << Symbol.isDefined() << "/"
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<< Symbol.isVariable() << "/" << Symbol.isTemporary()
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<< " Counts:" << PCRelCount << "/" << NonPCRelCount << "\n");
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if (IsPCRel) { ++PCRelCount;
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switch (RelocType) {
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default:
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// Most relocation types are emitted as explicit symbols
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InNormalSection =
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StringSwitch<bool>(Section.getSectionName())
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.Case(".data.rel.ro.local", false)
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.Case(".data.rel", false)
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.Case(".bss", false)
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.Default(true);
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EmitThisSym = true;
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break;
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case ELF::R_ARM_ABS32:
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// But things get strange with R_ARM_ABS32
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// In this case, most things that go in .rodata show up
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// as section relative relocations
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InNormalSection =
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StringSwitch<bool>(Section.getSectionName())
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.Case(".data.rel.ro.local", false)
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.Case(".data.rel", false)
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.Case(".rodata", false)
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.Case(".bss", false)
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.Default(true);
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EmitThisSym = false;
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break;
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}
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} else {
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NonPCRelCount++;
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InNormalSection =
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StringSwitch<bool>(Section.getSectionName())
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.Case(".data.rel.ro.local", false)
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.Case(".rodata", false)
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.Case(".data.rel", false)
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.Case(".bss", false)
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.Default(true);
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switch (RelocType) {
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default: EmitThisSym = true; break;
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case ELF::R_ARM_ABS32: EmitThisSym = false; break;
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}
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}
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if (EmitThisSym)
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return &Symbol;
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if (! Symbol.isTemporary() && InNormalSection) {
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return &Symbol;
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}
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return NULL;
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}
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// Need to examine the Fixup when determining whether to
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// emit the relocation as an explicit symbol or as a section relative
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// offset
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unsigned ARMELFObjectWriter::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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return GetRelocTypeInner(Target, Fixup, IsPCRel);
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}
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unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
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const MCFixup &Fixup,
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bool IsPCRel) const {
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MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
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MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
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unsigned Type = 0;
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if (IsPCRel) {
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switch ((unsigned)Fixup.getKind()) {
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default: assert(0 && "Unimplemented");
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case FK_Data_4:
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switch (Modifier) {
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default: llvm_unreachable("Unsupported Modifier");
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case MCSymbolRefExpr::VK_None:
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Type = ELF::R_ARM_REL32;
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break;
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case MCSymbolRefExpr::VK_ARM_TLSGD:
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assert(0 && "unimplemented");
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break;
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case MCSymbolRefExpr::VK_ARM_GOTTPOFF:
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Type = ELF::R_ARM_TLS_IE32;
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break;
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}
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break;
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case ARM::fixup_arm_uncondbranch:
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switch (Modifier) {
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case MCSymbolRefExpr::VK_ARM_PLT:
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Type = ELF::R_ARM_PLT32;
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break;
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default:
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Type = ELF::R_ARM_CALL;
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break;
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}
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break;
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case ARM::fixup_arm_condbranch:
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Type = ELF::R_ARM_JUMP24;
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break;
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case ARM::fixup_arm_movt_hi16:
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case ARM::fixup_arm_movt_hi16_pcrel:
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Type = ELF::R_ARM_MOVT_PREL;
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break;
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case ARM::fixup_arm_movw_lo16:
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case ARM::fixup_arm_movw_lo16_pcrel:
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Type = ELF::R_ARM_MOVW_PREL_NC;
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break;
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case ARM::fixup_t2_movt_hi16:
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case ARM::fixup_t2_movt_hi16_pcrel:
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Type = ELF::R_ARM_THM_MOVT_PREL;
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break;
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case ARM::fixup_t2_movw_lo16:
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case ARM::fixup_t2_movw_lo16_pcrel:
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Type = ELF::R_ARM_THM_MOVW_PREL_NC;
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break;
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case ARM::fixup_arm_thumb_bl:
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case ARM::fixup_arm_thumb_blx:
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Type = ELF::R_ARM_THM_CALL;
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break;
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}
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} else {
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switch ((unsigned)Fixup.getKind()) {
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default: llvm_unreachable("invalid fixup kind!");
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case FK_Data_4:
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switch (Modifier) {
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default: llvm_unreachable("Unsupported Modifier");
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case MCSymbolRefExpr::VK_ARM_GOT:
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Type = ELF::R_ARM_GOT_BREL;
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break;
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case MCSymbolRefExpr::VK_ARM_TLSGD:
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Type = ELF::R_ARM_TLS_GD32;
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break;
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case MCSymbolRefExpr::VK_ARM_TPOFF:
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Type = ELF::R_ARM_TLS_LE32;
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break;
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case MCSymbolRefExpr::VK_ARM_GOTTPOFF:
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Type = ELF::R_ARM_TLS_IE32;
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break;
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case MCSymbolRefExpr::VK_None:
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Type = ELF::R_ARM_ABS32;
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break;
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case MCSymbolRefExpr::VK_ARM_GOTOFF:
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Type = ELF::R_ARM_GOTOFF32;
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break;
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case MCSymbolRefExpr::VK_ARM_TARGET1:
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Type = ELF::R_ARM_TARGET1;
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break;
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}
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break;
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case ARM::fixup_arm_ldst_pcrel_12:
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case ARM::fixup_arm_pcrel_10:
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case ARM::fixup_arm_adr_pcrel_12:
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case ARM::fixup_arm_thumb_bl:
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case ARM::fixup_arm_thumb_cb:
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case ARM::fixup_arm_thumb_cp:
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case ARM::fixup_arm_thumb_br:
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assert(0 && "Unimplemented");
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break;
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case ARM::fixup_arm_uncondbranch:
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Type = ELF::R_ARM_CALL;
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break;
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case ARM::fixup_arm_condbranch:
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Type = ELF::R_ARM_JUMP24;
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break;
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case ARM::fixup_arm_movt_hi16:
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Type = ELF::R_ARM_MOVT_ABS;
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break;
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case ARM::fixup_arm_movw_lo16:
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Type = ELF::R_ARM_MOVW_ABS_NC;
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break;
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case ARM::fixup_t2_movt_hi16:
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Type = ELF::R_ARM_THM_MOVT_ABS;
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break;
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case ARM::fixup_t2_movw_lo16:
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Type = ELF::R_ARM_THM_MOVW_ABS_NC;
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break;
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}
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}
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return Type;
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}
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MCObjectWriter *llvm::createARMELFObjectWriter(raw_ostream &OS,
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uint8_t OSABI) {
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MCELFObjectTargetWriter *MOTW = new ARMELFObjectWriter(OSABI);
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return createELFObjectWriter(MOTW, OS, /*IsLittleEndian=*/true);
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}
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