397 lines
11 KiB
C++
397 lines
11 KiB
C++
//===- ELFObjectFile.cpp - ELF object file implementation -----------------===//
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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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//
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// Part of the ELFObjectFile class implementation.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Object/ELFObjectFile.h"
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#include "llvm/ADT/Triple.h"
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#include "llvm/BinaryFormat/ELF.h"
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#include "llvm/MC/MCInstrAnalysis.h"
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#include "llvm/MC/SubtargetFeature.h"
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#include "llvm/Object/ELF.h"
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#include "llvm/Object/ELFTypes.h"
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#include "llvm/Object/Error.h"
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#include "llvm/Support/ARMAttributeParser.h"
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#include "llvm/Support/ARMBuildAttributes.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/Support/TargetRegistry.h"
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#include <algorithm>
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#include <cstddef>
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#include <cstdint>
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#include <memory>
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#include <string>
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#include <system_error>
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#include <utility>
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using namespace llvm;
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using namespace object;
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ELFObjectFileBase::ELFObjectFileBase(unsigned int Type, MemoryBufferRef Source)
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: ObjectFile(Type, Source) {}
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template <class ELFT>
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static Expected<std::unique_ptr<ELFObjectFile<ELFT>>>
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createPtr(MemoryBufferRef Object) {
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auto Ret = ELFObjectFile<ELFT>::create(Object);
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if (Error E = Ret.takeError())
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return std::move(E);
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return make_unique<ELFObjectFile<ELFT>>(std::move(*Ret));
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}
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Expected<std::unique_ptr<ObjectFile>>
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ObjectFile::createELFObjectFile(MemoryBufferRef Obj) {
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std::pair<unsigned char, unsigned char> Ident =
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getElfArchType(Obj.getBuffer());
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std::size_t MaxAlignment =
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1ULL << countTrailingZeros(uintptr_t(Obj.getBufferStart()));
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if (MaxAlignment < 2)
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return createError("Insufficient alignment");
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if (Ident.first == ELF::ELFCLASS32) {
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if (Ident.second == ELF::ELFDATA2LSB)
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return createPtr<ELF32LE>(Obj);
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else if (Ident.second == ELF::ELFDATA2MSB)
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return createPtr<ELF32BE>(Obj);
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else
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return createError("Invalid ELF data");
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} else if (Ident.first == ELF::ELFCLASS64) {
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if (Ident.second == ELF::ELFDATA2LSB)
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return createPtr<ELF64LE>(Obj);
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else if (Ident.second == ELF::ELFDATA2MSB)
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return createPtr<ELF64BE>(Obj);
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else
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return createError("Invalid ELF data");
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}
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return createError("Invalid ELF class");
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}
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SubtargetFeatures ELFObjectFileBase::getMIPSFeatures() const {
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SubtargetFeatures Features;
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unsigned PlatformFlags = getPlatformFlags();
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switch (PlatformFlags & ELF::EF_MIPS_ARCH) {
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case ELF::EF_MIPS_ARCH_1:
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break;
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case ELF::EF_MIPS_ARCH_2:
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Features.AddFeature("mips2");
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break;
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case ELF::EF_MIPS_ARCH_3:
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Features.AddFeature("mips3");
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break;
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case ELF::EF_MIPS_ARCH_4:
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Features.AddFeature("mips4");
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break;
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case ELF::EF_MIPS_ARCH_5:
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Features.AddFeature("mips5");
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break;
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case ELF::EF_MIPS_ARCH_32:
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Features.AddFeature("mips32");
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break;
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case ELF::EF_MIPS_ARCH_64:
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Features.AddFeature("mips64");
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break;
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case ELF::EF_MIPS_ARCH_32R2:
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Features.AddFeature("mips32r2");
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break;
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case ELF::EF_MIPS_ARCH_64R2:
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Features.AddFeature("mips64r2");
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break;
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case ELF::EF_MIPS_ARCH_32R6:
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Features.AddFeature("mips32r6");
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break;
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case ELF::EF_MIPS_ARCH_64R6:
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Features.AddFeature("mips64r6");
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break;
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default:
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llvm_unreachable("Unknown EF_MIPS_ARCH value");
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}
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switch (PlatformFlags & ELF::EF_MIPS_MACH) {
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case ELF::EF_MIPS_MACH_NONE:
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// No feature associated with this value.
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break;
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case ELF::EF_MIPS_MACH_OCTEON:
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Features.AddFeature("cnmips");
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break;
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default:
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llvm_unreachable("Unknown EF_MIPS_ARCH value");
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}
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if (PlatformFlags & ELF::EF_MIPS_ARCH_ASE_M16)
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Features.AddFeature("mips16");
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if (PlatformFlags & ELF::EF_MIPS_MICROMIPS)
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Features.AddFeature("micromips");
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return Features;
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}
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SubtargetFeatures ELFObjectFileBase::getARMFeatures() const {
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SubtargetFeatures Features;
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ARMAttributeParser Attributes;
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std::error_code EC = getBuildAttributes(Attributes);
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if (EC)
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return SubtargetFeatures();
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// both ARMv7-M and R have to support thumb hardware div
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bool isV7 = false;
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if (Attributes.hasAttribute(ARMBuildAttrs::CPU_arch))
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isV7 = Attributes.getAttributeValue(ARMBuildAttrs::CPU_arch)
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== ARMBuildAttrs::v7;
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if (Attributes.hasAttribute(ARMBuildAttrs::CPU_arch_profile)) {
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switch(Attributes.getAttributeValue(ARMBuildAttrs::CPU_arch_profile)) {
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case ARMBuildAttrs::ApplicationProfile:
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Features.AddFeature("aclass");
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break;
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case ARMBuildAttrs::RealTimeProfile:
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Features.AddFeature("rclass");
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if (isV7)
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Features.AddFeature("hwdiv");
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break;
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case ARMBuildAttrs::MicroControllerProfile:
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Features.AddFeature("mclass");
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if (isV7)
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Features.AddFeature("hwdiv");
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break;
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}
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}
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if (Attributes.hasAttribute(ARMBuildAttrs::THUMB_ISA_use)) {
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switch(Attributes.getAttributeValue(ARMBuildAttrs::THUMB_ISA_use)) {
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default:
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break;
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case ARMBuildAttrs::Not_Allowed:
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Features.AddFeature("thumb", false);
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Features.AddFeature("thumb2", false);
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break;
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case ARMBuildAttrs::AllowThumb32:
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Features.AddFeature("thumb2");
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break;
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}
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}
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if (Attributes.hasAttribute(ARMBuildAttrs::FP_arch)) {
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switch(Attributes.getAttributeValue(ARMBuildAttrs::FP_arch)) {
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default:
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break;
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case ARMBuildAttrs::Not_Allowed:
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Features.AddFeature("vfp2", false);
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Features.AddFeature("vfp3", false);
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Features.AddFeature("vfp4", false);
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break;
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case ARMBuildAttrs::AllowFPv2:
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Features.AddFeature("vfp2");
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break;
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case ARMBuildAttrs::AllowFPv3A:
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case ARMBuildAttrs::AllowFPv3B:
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Features.AddFeature("vfp3");
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break;
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case ARMBuildAttrs::AllowFPv4A:
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case ARMBuildAttrs::AllowFPv4B:
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Features.AddFeature("vfp4");
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break;
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}
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}
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if (Attributes.hasAttribute(ARMBuildAttrs::Advanced_SIMD_arch)) {
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switch(Attributes.getAttributeValue(ARMBuildAttrs::Advanced_SIMD_arch)) {
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default:
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break;
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case ARMBuildAttrs::Not_Allowed:
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Features.AddFeature("neon", false);
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Features.AddFeature("fp16", false);
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break;
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case ARMBuildAttrs::AllowNeon:
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Features.AddFeature("neon");
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break;
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case ARMBuildAttrs::AllowNeon2:
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Features.AddFeature("neon");
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Features.AddFeature("fp16");
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break;
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}
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}
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if (Attributes.hasAttribute(ARMBuildAttrs::DIV_use)) {
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switch(Attributes.getAttributeValue(ARMBuildAttrs::DIV_use)) {
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default:
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break;
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case ARMBuildAttrs::DisallowDIV:
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Features.AddFeature("hwdiv", false);
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Features.AddFeature("hwdiv-arm", false);
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break;
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case ARMBuildAttrs::AllowDIVExt:
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Features.AddFeature("hwdiv");
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Features.AddFeature("hwdiv-arm");
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break;
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}
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}
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return Features;
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}
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SubtargetFeatures ELFObjectFileBase::getRISCVFeatures() const {
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SubtargetFeatures Features;
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unsigned PlatformFlags = getPlatformFlags();
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if (PlatformFlags & ELF::EF_RISCV_RVC) {
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Features.AddFeature("c");
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}
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return Features;
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}
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SubtargetFeatures ELFObjectFileBase::getFeatures() const {
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switch (getEMachine()) {
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case ELF::EM_MIPS:
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return getMIPSFeatures();
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case ELF::EM_ARM:
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return getARMFeatures();
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case ELF::EM_RISCV:
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return getRISCVFeatures();
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default:
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return SubtargetFeatures();
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}
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}
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// FIXME Encode from a tablegen description or target parser.
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void ELFObjectFileBase::setARMSubArch(Triple &TheTriple) const {
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if (TheTriple.getSubArch() != Triple::NoSubArch)
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return;
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ARMAttributeParser Attributes;
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std::error_code EC = getBuildAttributes(Attributes);
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if (EC)
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return;
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std::string Triple;
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// Default to ARM, but use the triple if it's been set.
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if (TheTriple.isThumb())
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Triple = "thumb";
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else
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Triple = "arm";
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if (Attributes.hasAttribute(ARMBuildAttrs::CPU_arch)) {
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switch(Attributes.getAttributeValue(ARMBuildAttrs::CPU_arch)) {
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case ARMBuildAttrs::v4:
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Triple += "v4";
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break;
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case ARMBuildAttrs::v4T:
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Triple += "v4t";
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break;
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case ARMBuildAttrs::v5T:
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Triple += "v5t";
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break;
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case ARMBuildAttrs::v5TE:
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Triple += "v5te";
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break;
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case ARMBuildAttrs::v5TEJ:
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Triple += "v5tej";
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break;
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case ARMBuildAttrs::v6:
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Triple += "v6";
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break;
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case ARMBuildAttrs::v6KZ:
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Triple += "v6kz";
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break;
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case ARMBuildAttrs::v6T2:
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Triple += "v6t2";
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break;
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case ARMBuildAttrs::v6K:
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Triple += "v6k";
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break;
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case ARMBuildAttrs::v7:
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Triple += "v7";
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break;
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case ARMBuildAttrs::v6_M:
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Triple += "v6m";
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break;
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case ARMBuildAttrs::v6S_M:
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Triple += "v6sm";
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break;
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case ARMBuildAttrs::v7E_M:
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Triple += "v7em";
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break;
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}
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}
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if (!isLittleEndian())
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Triple += "eb";
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TheTriple.setArchName(Triple);
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}
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std::vector<std::pair<DataRefImpl, uint64_t>>
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ELFObjectFileBase::getPltAddresses() const {
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std::string Err;
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const auto Triple = makeTriple();
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const auto *T = TargetRegistry::lookupTarget(Triple.str(), Err);
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if (!T)
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return {};
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uint64_t JumpSlotReloc = 0;
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switch (Triple.getArch()) {
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case Triple::x86:
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JumpSlotReloc = ELF::R_386_JUMP_SLOT;
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break;
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case Triple::x86_64:
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JumpSlotReloc = ELF::R_X86_64_JUMP_SLOT;
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break;
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case Triple::aarch64:
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JumpSlotReloc = ELF::R_AARCH64_JUMP_SLOT;
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break;
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default:
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return {};
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}
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std::unique_ptr<const MCInstrInfo> MII(T->createMCInstrInfo());
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std::unique_ptr<const MCInstrAnalysis> MIA(
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T->createMCInstrAnalysis(MII.get()));
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if (!MIA)
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return {};
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Optional<SectionRef> Plt = None, RelaPlt = None, GotPlt = None;
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for (const SectionRef &Section : sections()) {
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StringRef Name;
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if (Section.getName(Name))
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continue;
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if (Name == ".plt")
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Plt = Section;
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else if (Name == ".rela.plt" || Name == ".rel.plt")
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RelaPlt = Section;
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else if (Name == ".got.plt")
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GotPlt = Section;
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}
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if (!Plt || !RelaPlt || !GotPlt)
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return {};
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StringRef PltContents;
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if (Plt->getContents(PltContents))
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return {};
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ArrayRef<uint8_t> PltBytes((const uint8_t *)PltContents.data(),
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Plt->getSize());
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auto PltEntries = MIA->findPltEntries(Plt->getAddress(), PltBytes,
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GotPlt->getAddress(), Triple);
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// Build a map from GOT entry virtual address to PLT entry virtual address.
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DenseMap<uint64_t, uint64_t> GotToPlt;
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for (const auto &Entry : PltEntries)
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GotToPlt.insert(std::make_pair(Entry.second, Entry.first));
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// Find the relocations in the dynamic relocation table that point to
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// locations in the GOT for which we know the corresponding PLT entry.
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std::vector<std::pair<DataRefImpl, uint64_t>> Result;
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for (const auto &Relocation : RelaPlt->relocations()) {
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if (Relocation.getType() != JumpSlotReloc)
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continue;
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auto PltEntryIter = GotToPlt.find(Relocation.getOffset());
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if (PltEntryIter != GotToPlt.end())
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Result.push_back(std::make_pair(
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Relocation.getSymbol()->getRawDataRefImpl(), PltEntryIter->second));
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}
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return Result;
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}
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