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//===-- ARMELFObjectWriter.cpp - ARM ELF Writer ---------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/ARMMCTargetDesc.h"
#include "MCTargetDesc/ARMFixupKinds.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/MC/MCELFObjectWriter.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm_ks;
namespace {
class ARMELFObjectWriter : public MCELFObjectTargetWriter {
enum { DefaultEABIVersion = 0x05000000U };
unsigned GetRelocTypeInner(const MCValue &Target,
const MCFixup &Fixup,
bool IsPCRel) const;
public:
ARMELFObjectWriter(uint8_t OSABI);
~ARMELFObjectWriter() override;
unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
const MCFixup &Fixup, bool IsPCRel) const override;
bool needsRelocateWithSymbol(const MCSymbol &Sym,
unsigned Type) const override;
};
}
ARMELFObjectWriter::ARMELFObjectWriter(uint8_t OSABI)
: MCELFObjectTargetWriter(/*Is64Bit*/ false, OSABI,
ELF::EM_ARM,
/*HasRelocationAddend*/ false) {}
ARMELFObjectWriter::~ARMELFObjectWriter() {}
bool ARMELFObjectWriter::needsRelocateWithSymbol(const MCSymbol &Sym,
unsigned Type) const {
// FIXME: This is extremely conservative. This really needs to use a
// whitelist with a clear explanation for why each realocation needs to
// point to the symbol, not to the section.
switch (Type) {
default:
return true;
case ELF::R_ARM_PREL31:
case ELF::R_ARM_ABS32:
return false;
}
}
// Need to examine the Fixup when determining whether to
// emit the relocation as an explicit symbol or as a section relative
// offset
unsigned ARMELFObjectWriter::getRelocType(MCContext &Ctx, const MCValue &Target,
const MCFixup &Fixup,
bool IsPCRel) const {
return GetRelocTypeInner(Target, Fixup, IsPCRel);
}
unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
const MCFixup &Fixup,
bool IsPCRel) const {
MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
unsigned Type = 0;
if (IsPCRel) {
switch ((unsigned)Fixup.getKind()) {
default:
report_fatal_error("unsupported relocation on symbol");
return ELF::R_ARM_NONE;
case FK_Data_4:
switch (Modifier) {
default: llvm_unreachable("Unsupported Modifier");
case MCSymbolRefExpr::VK_None:
Type = ELF::R_ARM_REL32;
break;
case MCSymbolRefExpr::VK_TLSGD:
llvm_unreachable("unimplemented");
case MCSymbolRefExpr::VK_GOTTPOFF:
Type = ELF::R_ARM_TLS_IE32;
break;
case MCSymbolRefExpr::VK_ARM_GOT_PREL:
Type = ELF::R_ARM_GOT_PREL;
break;
}
break;
case ARM::fixup_arm_blx:
case ARM::fixup_arm_uncondbl:
switch (Modifier) {
case MCSymbolRefExpr::VK_PLT:
Type = ELF::R_ARM_CALL;
break;
case MCSymbolRefExpr::VK_ARM_TLSCALL:
Type = ELF::R_ARM_TLS_CALL;
break;
default:
Type = ELF::R_ARM_CALL;
break;
}
break;
case ARM::fixup_arm_condbl:
case ARM::fixup_arm_condbranch:
case ARM::fixup_arm_uncondbranch:
Type = ELF::R_ARM_JUMP24;
break;
case ARM::fixup_t2_condbranch:
case ARM::fixup_t2_uncondbranch:
Type = ELF::R_ARM_THM_JUMP24;
break;
case ARM::fixup_arm_movt_hi16:
Type = ELF::R_ARM_MOVT_PREL;
break;
case ARM::fixup_arm_movw_lo16:
Type = ELF::R_ARM_MOVW_PREL_NC;
break;
case ARM::fixup_t2_movt_hi16:
Type = ELF::R_ARM_THM_MOVT_PREL;
break;
case ARM::fixup_t2_movw_lo16:
Type = ELF::R_ARM_THM_MOVW_PREL_NC;
break;
case ARM::fixup_arm_thumb_bl:
case ARM::fixup_arm_thumb_blx:
switch (Modifier) {
case MCSymbolRefExpr::VK_ARM_TLSCALL:
Type = ELF::R_ARM_THM_TLS_CALL;
break;
default:
Type = ELF::R_ARM_THM_CALL;
break;
}
break;
}
} else {
switch ((unsigned)Fixup.getKind()) {
default:
report_fatal_error("unsupported relocation on symbol");
return ELF::R_ARM_NONE;
case FK_Data_1:
switch (Modifier) {
default: llvm_unreachable("unsupported Modifier");
case MCSymbolRefExpr::VK_None:
Type = ELF::R_ARM_ABS8;
break;
}
break;
case FK_Data_2:
switch (Modifier) {
default: llvm_unreachable("unsupported modifier");
case MCSymbolRefExpr::VK_None:
Type = ELF::R_ARM_ABS16;
break;
}
break;
case FK_Data_4:
switch (Modifier) {
default: llvm_unreachable("Unsupported Modifier");
case MCSymbolRefExpr::VK_ARM_NONE:
Type = ELF::R_ARM_NONE;
break;
case MCSymbolRefExpr::VK_GOT:
Type = ELF::R_ARM_GOT_BREL;
break;
case MCSymbolRefExpr::VK_TLSGD:
Type = ELF::R_ARM_TLS_GD32;
break;
case MCSymbolRefExpr::VK_TPOFF:
Type = ELF::R_ARM_TLS_LE32;
break;
case MCSymbolRefExpr::VK_GOTTPOFF:
Type = ELF::R_ARM_TLS_IE32;
break;
case MCSymbolRefExpr::VK_None:
Type = ELF::R_ARM_ABS32;
break;
case MCSymbolRefExpr::VK_GOTOFF:
Type = ELF::R_ARM_GOTOFF32;
break;
case MCSymbolRefExpr::VK_ARM_GOT_PREL:
Type = ELF::R_ARM_GOT_PREL;
break;
case MCSymbolRefExpr::VK_ARM_TARGET1:
Type = ELF::R_ARM_TARGET1;
break;
case MCSymbolRefExpr::VK_ARM_TARGET2:
Type = ELF::R_ARM_TARGET2;
break;
case MCSymbolRefExpr::VK_ARM_PREL31:
Type = ELF::R_ARM_PREL31;
break;
case MCSymbolRefExpr::VK_ARM_SBREL:
Type = ELF::R_ARM_SBREL32;
break;
case MCSymbolRefExpr::VK_ARM_TLSLDO:
Type = ELF::R_ARM_TLS_LDO32;
break;
case MCSymbolRefExpr::VK_ARM_TLSCALL:
Type = ELF::R_ARM_TLS_CALL;
break;
case MCSymbolRefExpr::VK_ARM_TLSDESC:
Type = ELF::R_ARM_TLS_GOTDESC;
break;
case MCSymbolRefExpr::VK_ARM_TLSDESCSEQ:
Type = ELF::R_ARM_TLS_DESCSEQ;
break;
}
break;
case ARM::fixup_arm_ldst_pcrel_12:
case ARM::fixup_arm_pcrel_10:
case ARM::fixup_arm_adr_pcrel_12:
case ARM::fixup_arm_thumb_bl:
case ARM::fixup_arm_thumb_cb:
case ARM::fixup_arm_thumb_cp:
case ARM::fixup_arm_thumb_br:
llvm_unreachable("Unimplemented");
case ARM::fixup_arm_condbranch:
case ARM::fixup_arm_uncondbranch:
Type = ELF::R_ARM_JUMP24;
break;
case ARM::fixup_arm_movt_hi16:
Type = ELF::R_ARM_MOVT_ABS;
break;
case ARM::fixup_arm_movw_lo16:
Type = ELF::R_ARM_MOVW_ABS_NC;
break;
case ARM::fixup_t2_movt_hi16:
Type = ELF::R_ARM_THM_MOVT_ABS;
break;
case ARM::fixup_t2_movw_lo16:
Type = ELF::R_ARM_THM_MOVW_ABS_NC;
break;
}
}
return Type;
}
MCObjectWriter *llvm_ks::createARMELFObjectWriter(raw_pwrite_stream &OS,
uint8_t OSABI,
bool IsLittleEndian) {
MCELFObjectTargetWriter *MOTW = new ARMELFObjectWriter(OSABI);
return createELFObjectWriter(MOTW, OS, IsLittleEndian);
}