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259 lines
7.8 KiB
259 lines
7.8 KiB
4 years ago
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//===-- 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/ARMMCTargetDesc.h"
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#include "MCTargetDesc/ARMFixupKinds.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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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm_ks;
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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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~ARMELFObjectWriter() override;
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unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
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const MCFixup &Fixup, bool IsPCRel) const override;
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bool needsRelocateWithSymbol(const MCSymbol &Sym,
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unsigned Type) const override;
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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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bool ARMELFObjectWriter::needsRelocateWithSymbol(const MCSymbol &Sym,
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unsigned Type) const {
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// FIXME: This is extremely conservative. This really needs to use a
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// whitelist with a clear explanation for why each realocation needs to
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// point to the symbol, not to the section.
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switch (Type) {
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default:
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return true;
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case ELF::R_ARM_PREL31:
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case ELF::R_ARM_ABS32:
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return false;
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}
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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(MCContext &Ctx, const MCValue &Target,
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const MCFixup &Fixup,
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bool IsPCRel) 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.getAccessVariant();
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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:
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report_fatal_error("unsupported relocation on symbol");
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return ELF::R_ARM_NONE;
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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_TLSGD:
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llvm_unreachable("unimplemented");
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case MCSymbolRefExpr::VK_GOTTPOFF:
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Type = ELF::R_ARM_TLS_IE32;
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break;
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case MCSymbolRefExpr::VK_ARM_GOT_PREL:
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Type = ELF::R_ARM_GOT_PREL;
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break;
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}
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break;
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case ARM::fixup_arm_blx:
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case ARM::fixup_arm_uncondbl:
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switch (Modifier) {
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case MCSymbolRefExpr::VK_PLT:
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Type = ELF::R_ARM_CALL;
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break;
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case MCSymbolRefExpr::VK_ARM_TLSCALL:
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Type = ELF::R_ARM_TLS_CALL;
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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_condbl:
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case ARM::fixup_arm_condbranch:
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case ARM::fixup_arm_uncondbranch:
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Type = ELF::R_ARM_JUMP24;
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break;
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case ARM::fixup_t2_condbranch:
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case ARM::fixup_t2_uncondbranch:
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Type = ELF::R_ARM_THM_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_PREL;
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break;
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case ARM::fixup_arm_movw_lo16:
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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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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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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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switch (Modifier) {
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case MCSymbolRefExpr::VK_ARM_TLSCALL:
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Type = ELF::R_ARM_THM_TLS_CALL;
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break;
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default:
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Type = ELF::R_ARM_THM_CALL;
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break;
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}
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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:
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report_fatal_error("unsupported relocation on symbol");
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return ELF::R_ARM_NONE;
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case FK_Data_1:
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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_ABS8;
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break;
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}
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break;
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case FK_Data_2:
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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_ABS16;
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break;
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}
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break;
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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_NONE:
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Type = ELF::R_ARM_NONE;
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break;
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case MCSymbolRefExpr::VK_GOT:
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Type = ELF::R_ARM_GOT_BREL;
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break;
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case MCSymbolRefExpr::VK_TLSGD:
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Type = ELF::R_ARM_TLS_GD32;
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break;
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case MCSymbolRefExpr::VK_TPOFF:
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Type = ELF::R_ARM_TLS_LE32;
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break;
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case MCSymbolRefExpr::VK_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_GOTOFF:
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Type = ELF::R_ARM_GOTOFF32;
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break;
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case MCSymbolRefExpr::VK_ARM_GOT_PREL:
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Type = ELF::R_ARM_GOT_PREL;
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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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case MCSymbolRefExpr::VK_ARM_TARGET2:
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Type = ELF::R_ARM_TARGET2;
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break;
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case MCSymbolRefExpr::VK_ARM_PREL31:
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Type = ELF::R_ARM_PREL31;
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break;
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case MCSymbolRefExpr::VK_ARM_SBREL:
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Type = ELF::R_ARM_SBREL32;
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break;
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case MCSymbolRefExpr::VK_ARM_TLSLDO:
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Type = ELF::R_ARM_TLS_LDO32;
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break;
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case MCSymbolRefExpr::VK_ARM_TLSCALL:
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Type = ELF::R_ARM_TLS_CALL;
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break;
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case MCSymbolRefExpr::VK_ARM_TLSDESC:
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Type = ELF::R_ARM_TLS_GOTDESC;
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break;
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case MCSymbolRefExpr::VK_ARM_TLSDESCSEQ:
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Type = ELF::R_ARM_TLS_DESCSEQ;
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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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llvm_unreachable("Unimplemented");
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case ARM::fixup_arm_condbranch:
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case ARM::fixup_arm_uncondbranch:
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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_ks::createARMELFObjectWriter(raw_pwrite_stream &OS,
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uint8_t OSABI,
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bool IsLittleEndian) {
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MCELFObjectTargetWriter *MOTW = new ARMELFObjectWriter(OSABI);
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return createELFObjectWriter(MOTW, OS, IsLittleEndian);
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}
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