diff options
Diffstat (limited to 'lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp')
| -rw-r--r-- | lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp | 283 |
1 files changed, 283 insertions, 0 deletions
diff --git a/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp b/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp new file mode 100644 index 000000000000..aa649badaf82 --- /dev/null +++ b/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp @@ -0,0 +1,283 @@ +//===-- 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/ARMFixupKinds.h" +#include "MCTargetDesc/ARMMCTargetDesc.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/ADT/Statistic.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" + +using namespace llvm; + +namespace { + class ARMELFObjectWriter : public MCELFObjectTargetWriter { + enum { DefaultEABIVersion = 0x05000000U }; + unsigned GetRelocTypeInner(const MCValue &Target, + const MCFixup &Fixup, + bool IsPCRel) const; + + + public: + ARMELFObjectWriter(uint8_t OSABI); + + virtual ~ARMELFObjectWriter(); + + virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup, + bool IsPCRel, bool IsRelocWithSymbol, + int64_t Addend) const; + virtual unsigned getEFlags() const; + virtual const MCSymbol *ExplicitRelSym(const MCAssembler &Asm, + const MCValue &Target, + const MCFragment &F, + const MCFixup &Fixup, + bool IsPCRel) const; + }; +} + +ARMELFObjectWriter::ARMELFObjectWriter(uint8_t OSABI) + : MCELFObjectTargetWriter(/*Is64Bit*/ false, OSABI, + ELF::EM_ARM, + /*HasRelocationAddend*/ false) {} + +ARMELFObjectWriter::~ARMELFObjectWriter() {} + +// FIXME: get the real EABI Version from the Triple. +unsigned ARMELFObjectWriter::getEFlags() const { + return ELF::EF_ARM_EABIMASK & DefaultEABIVersion; +} + +// In ARM, _MergedGlobals and other most symbols get emitted directly. +// I.e. not as an offset to a section symbol. +// This code is an approximation of what ARM/gcc does. + +STATISTIC(PCRelCount, "Total number of PIC Relocations"); +STATISTIC(NonPCRelCount, "Total number of non-PIC relocations"); + +const MCSymbol *ARMELFObjectWriter::ExplicitRelSym(const MCAssembler &Asm, + const MCValue &Target, + const MCFragment &F, + const MCFixup &Fixup, + bool IsPCRel) const { + const MCSymbol &Symbol = Target.getSymA()->getSymbol().AliasedSymbol(); + bool EmitThisSym = false; + + const MCSectionELF &Section = + static_cast<const MCSectionELF&>(Symbol.getSection()); + bool InNormalSection = true; + unsigned RelocType = 0; + RelocType = GetRelocTypeInner(Target, Fixup, IsPCRel); + + DEBUG( + const MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind(); + MCSymbolRefExpr::VariantKind Kind2; + Kind2 = Target.getSymB() ? Target.getSymB()->getKind() : + MCSymbolRefExpr::VK_None; + dbgs() << "considering symbol " + << Section.getSectionName() << "/" + << Symbol.getName() << "/" + << " Rel:" << (unsigned)RelocType + << " Kind: " << (int)Kind << "/" << (int)Kind2 + << " Tmp:" + << Symbol.isAbsolute() << "/" << Symbol.isDefined() << "/" + << Symbol.isVariable() << "/" << Symbol.isTemporary() + << " Counts:" << PCRelCount << "/" << NonPCRelCount << "\n"); + + if (IsPCRel) { ++PCRelCount; + switch (RelocType) { + default: + // Most relocation types are emitted as explicit symbols + InNormalSection = + StringSwitch<bool>(Section.getSectionName()) + .Case(".data.rel.ro.local", false) + .Case(".data.rel", false) + .Case(".bss", false) + .Default(true); + EmitThisSym = true; + break; + case ELF::R_ARM_ABS32: + // But things get strange with R_ARM_ABS32 + // In this case, most things that go in .rodata show up + // as section relative relocations + InNormalSection = + StringSwitch<bool>(Section.getSectionName()) + .Case(".data.rel.ro.local", false) + .Case(".data.rel", false) + .Case(".rodata", false) + .Case(".bss", false) + .Default(true); + EmitThisSym = false; + break; + } + } else { + NonPCRelCount++; + InNormalSection = + StringSwitch<bool>(Section.getSectionName()) + .Case(".data.rel.ro.local", false) + .Case(".rodata", false) + .Case(".data.rel", false) + .Case(".bss", false) + .Default(true); + + switch (RelocType) { + default: EmitThisSym = true; break; + case ELF::R_ARM_ABS32: EmitThisSym = false; break; + } + } + + if (EmitThisSym) + return &Symbol; + if (! Symbol.isTemporary() && InNormalSection) { + return &Symbol; + } + return NULL; +} + +// 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(const MCValue &Target, + const MCFixup &Fixup, + bool IsPCRel, + bool IsRelocWithSymbol, + int64_t Addend) const { + return GetRelocTypeInner(Target, Fixup, IsPCRel); +} + +unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target, + const MCFixup &Fixup, + bool IsPCRel) const { + MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ? + MCSymbolRefExpr::VK_None : Target.getSymA()->getKind(); + + unsigned Type = 0; + if (IsPCRel) { + switch ((unsigned)Fixup.getKind()) { + default: llvm_unreachable("Unimplemented"); + case FK_Data_4: + switch (Modifier) { + default: llvm_unreachable("Unsupported Modifier"); + case MCSymbolRefExpr::VK_None: + Type = ELF::R_ARM_REL32; + break; + case MCSymbolRefExpr::VK_ARM_TLSGD: + llvm_unreachable("unimplemented"); + case MCSymbolRefExpr::VK_ARM_GOTTPOFF: + Type = ELF::R_ARM_TLS_IE32; + break; + } + break; + case ARM::fixup_arm_uncondbl: + case ARM::fixup_arm_blx: + case ARM::fixup_arm_uncondbranch: + switch (Modifier) { + case MCSymbolRefExpr::VK_ARM_PLT: + Type = ELF::R_ARM_PLT32; + break; + default: + Type = ELF::R_ARM_CALL; + break; + } + break; + case ARM::fixup_arm_condbl: + case ARM::fixup_arm_condbranch: + Type = ELF::R_ARM_JUMP24; + break; + case ARM::fixup_arm_movt_hi16: + case ARM::fixup_arm_movt_hi16_pcrel: + Type = ELF::R_ARM_MOVT_PREL; + break; + case ARM::fixup_arm_movw_lo16: + case ARM::fixup_arm_movw_lo16_pcrel: + Type = ELF::R_ARM_MOVW_PREL_NC; + break; + case ARM::fixup_t2_movt_hi16: + case ARM::fixup_t2_movt_hi16_pcrel: + Type = ELF::R_ARM_THM_MOVT_PREL; + break; + case ARM::fixup_t2_movw_lo16: + case ARM::fixup_t2_movw_lo16_pcrel: + Type = ELF::R_ARM_THM_MOVW_PREL_NC; + break; + case ARM::fixup_arm_thumb_bl: + case ARM::fixup_arm_thumb_blx: + Type = ELF::R_ARM_THM_CALL; + break; + } + } else { + switch ((unsigned)Fixup.getKind()) { + default: llvm_unreachable("invalid fixup kind!"); + case FK_Data_4: + switch (Modifier) { + default: llvm_unreachable("Unsupported Modifier"); + case MCSymbolRefExpr::VK_ARM_GOT: + Type = ELF::R_ARM_GOT_BREL; + break; + case MCSymbolRefExpr::VK_ARM_TLSGD: + Type = ELF::R_ARM_TLS_GD32; + break; + case MCSymbolRefExpr::VK_ARM_TPOFF: + Type = ELF::R_ARM_TLS_LE32; + break; + case MCSymbolRefExpr::VK_ARM_GOTTPOFF: + Type = ELF::R_ARM_TLS_IE32; + break; + case MCSymbolRefExpr::VK_None: + Type = ELF::R_ARM_ABS32; + break; + case MCSymbolRefExpr::VK_ARM_GOTOFF: + Type = ELF::R_ARM_GOTOFF32; + break; + case MCSymbolRefExpr::VK_ARM_TARGET1: + Type = ELF::R_ARM_TARGET1; + 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_uncondbranch: + Type = ELF::R_ARM_CALL; + break; + case ARM::fixup_arm_condbranch: + 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::createARMELFObjectWriter(raw_ostream &OS, + uint8_t OSABI) { + MCELFObjectTargetWriter *MOTW = new ARMELFObjectWriter(OSABI); + return createELFObjectWriter(MOTW, OS, /*IsLittleEndian=*/true); +} |