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d4602dc254
- Improved parameter names for clarity - Added comments - emitCommonSymbols should return void because its return value is not being used anywhere - Attempt to reduce the usage of the RelocationValueRef type. Restricts it for a single goal and may serve as a step for eventual removal. llvm-svn: 155908
441 lines
16 KiB
C++
441 lines
16 KiB
C++
//===-- RuntimeDyldELF.cpp - Run-time dynamic linker for MC-JIT -*- C++ -*-===//
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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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// Implementation of ELF support for the MC-JIT runtime dynamic linker.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "dyld"
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#include "llvm/ADT/OwningPtr.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/IntervalMap.h"
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#include "RuntimeDyldELF.h"
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#include "llvm/Object/ObjectFile.h"
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#include "llvm/Support/ELF.h"
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#include "llvm/ADT/Triple.h"
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#include "llvm/Object/ELF.h"
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#include "JITRegistrar.h"
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using namespace llvm;
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using namespace llvm::object;
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namespace {
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template<support::endianness target_endianness, bool is64Bits>
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class DyldELFObject : public ELFObjectFile<target_endianness, is64Bits> {
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LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
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typedef Elf_Shdr_Impl<target_endianness, is64Bits> Elf_Shdr;
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typedef Elf_Sym_Impl<target_endianness, is64Bits> Elf_Sym;
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typedef Elf_Rel_Impl<target_endianness, is64Bits, false> Elf_Rel;
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typedef Elf_Rel_Impl<target_endianness, is64Bits, true> Elf_Rela;
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typedef typename ELFObjectFile<target_endianness, is64Bits>::
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Elf_Ehdr Elf_Ehdr;
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typedef typename ELFDataTypeTypedefHelper<
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target_endianness, is64Bits>::value_type addr_type;
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protected:
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// This duplicates the 'Data' member in the 'Binary' base class
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// but it is necessary to workaround a bug in gcc 4.2
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MemoryBuffer *InputData;
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public:
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DyldELFObject(MemoryBuffer *Object, error_code &ec);
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void updateSectionAddress(const SectionRef &Sec, uint64_t Addr);
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void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr);
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const MemoryBuffer& getBuffer() const { return *InputData; }
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// Methods for type inquiry through isa, cast, and dyn_cast
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static inline bool classof(const Binary *v) {
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return (isa<ELFObjectFile<target_endianness, is64Bits> >(v)
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&& classof(cast<ELFObjectFile<target_endianness, is64Bits> >(v)));
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}
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static inline bool classof(
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const ELFObjectFile<target_endianness, is64Bits> *v) {
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return v->isDyldType();
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}
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static inline bool classof(const DyldELFObject *v) {
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return true;
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}
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};
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template<support::endianness target_endianness, bool is64Bits>
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class ELFObjectImage : public ObjectImage {
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protected:
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DyldELFObject<target_endianness, is64Bits> *DyldObj;
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bool Registered;
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public:
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ELFObjectImage(DyldELFObject<target_endianness, is64Bits> *Obj)
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: ObjectImage(Obj),
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DyldObj(Obj),
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Registered(false) {}
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virtual ~ELFObjectImage() {
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if (Registered)
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deregisterWithDebugger();
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}
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// Subclasses can override these methods to update the image with loaded
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// addresses for sections and common symbols
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virtual void updateSectionAddress(const SectionRef &Sec, uint64_t Addr)
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{
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DyldObj->updateSectionAddress(Sec, Addr);
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}
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virtual void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr)
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{
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DyldObj->updateSymbolAddress(Sym, Addr);
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}
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virtual void registerWithDebugger()
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{
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JITRegistrar::getGDBRegistrar().registerObject(DyldObj->getBuffer());
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Registered = true;
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}
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virtual void deregisterWithDebugger()
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{
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JITRegistrar::getGDBRegistrar().deregisterObject(DyldObj->getBuffer());
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}
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};
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template<support::endianness target_endianness, bool is64Bits>
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DyldELFObject<target_endianness, is64Bits>::DyldELFObject(MemoryBuffer *Object,
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error_code &ec)
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: ELFObjectFile<target_endianness, is64Bits>(Object, ec),
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InputData(Object) {
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this->isDyldELFObject = true;
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}
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template<support::endianness target_endianness, bool is64Bits>
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void DyldELFObject<target_endianness, is64Bits>::updateSectionAddress(
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const SectionRef &Sec,
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uint64_t Addr) {
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DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
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Elf_Shdr *shdr = const_cast<Elf_Shdr*>(
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reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
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// This assumes the address passed in matches the target address bitness
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// The template-based type cast handles everything else.
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shdr->sh_addr = static_cast<addr_type>(Addr);
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}
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template<support::endianness target_endianness, bool is64Bits>
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void DyldELFObject<target_endianness, is64Bits>::updateSymbolAddress(
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const SymbolRef &SymRef,
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uint64_t Addr) {
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Elf_Sym *sym = const_cast<Elf_Sym*>(
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ELFObjectFile<target_endianness, is64Bits>::
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getSymbol(SymRef.getRawDataRefImpl()));
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// This assumes the address passed in matches the target address bitness
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// The template-based type cast handles everything else.
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sym->st_value = static_cast<addr_type>(Addr);
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}
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} // namespace
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namespace llvm {
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ObjectImage *RuntimeDyldELF::createObjectImage(
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const MemoryBuffer *ConstInputBuffer) {
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MemoryBuffer *InputBuffer = const_cast<MemoryBuffer*>(ConstInputBuffer);
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std::pair<unsigned char, unsigned char> Ident = getElfArchType(InputBuffer);
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error_code ec;
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if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2LSB) {
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DyldELFObject<support::little, false> *Obj =
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new DyldELFObject<support::little, false>(InputBuffer, ec);
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return new ELFObjectImage<support::little, false>(Obj);
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}
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else if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2MSB) {
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DyldELFObject<support::big, false> *Obj =
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new DyldELFObject<support::big, false>(InputBuffer, ec);
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return new ELFObjectImage<support::big, false>(Obj);
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}
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else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2MSB) {
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DyldELFObject<support::big, true> *Obj =
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new DyldELFObject<support::big, true>(InputBuffer, ec);
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return new ELFObjectImage<support::big, true>(Obj);
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}
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else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2LSB) {
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DyldELFObject<support::little, true> *Obj =
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new DyldELFObject<support::little, true>(InputBuffer, ec);
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return new ELFObjectImage<support::little, true>(Obj);
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}
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else
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llvm_unreachable("Unexpected ELF format");
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}
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void RuntimeDyldELF::handleObjectLoaded(ObjectImage *Obj)
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{
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Obj->registerWithDebugger();
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// Save the loaded object. It will deregister itself when deleted
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LoadedObject = Obj;
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}
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RuntimeDyldELF::~RuntimeDyldELF() {
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if (LoadedObject)
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delete LoadedObject;
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}
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void RuntimeDyldELF::resolveX86_64Relocation(uint8_t *LocalAddress,
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uint64_t FinalAddress,
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uint64_t Value,
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uint32_t Type,
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int64_t Addend) {
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switch (Type) {
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default:
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llvm_unreachable("Relocation type not implemented yet!");
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break;
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case ELF::R_X86_64_64: {
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uint64_t *Target = (uint64_t*)(LocalAddress);
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*Target = Value + Addend;
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break;
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}
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case ELF::R_X86_64_32:
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case ELF::R_X86_64_32S: {
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Value += Addend;
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// FIXME: Handle the possibility of this assertion failing
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assert((Type == ELF::R_X86_64_32 && !(Value & 0xFFFFFFFF00000000ULL)) ||
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(Type == ELF::R_X86_64_32S &&
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(Value & 0xFFFFFFFF00000000ULL) == 0xFFFFFFFF00000000ULL));
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uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
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uint32_t *Target = reinterpret_cast<uint32_t*>(LocalAddress);
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*Target = TruncatedAddr;
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break;
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}
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case ELF::R_X86_64_PC32: {
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uint32_t *Placeholder = reinterpret_cast<uint32_t*>(LocalAddress);
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int64_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
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assert(RealOffset <= 214783647 && RealOffset >= -214783648);
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int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
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*Placeholder = TruncOffset;
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break;
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}
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}
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}
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void RuntimeDyldELF::resolveX86Relocation(uint8_t *LocalAddress,
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uint32_t FinalAddress,
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uint32_t Value,
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uint32_t Type,
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int32_t Addend) {
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switch (Type) {
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case ELF::R_386_32: {
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uint32_t *Target = (uint32_t*)(LocalAddress);
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uint32_t Placeholder = *Target;
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*Target = Placeholder + Value + Addend;
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break;
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}
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case ELF::R_386_PC32: {
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uint32_t *Placeholder = reinterpret_cast<uint32_t*>(LocalAddress);
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uint32_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
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*Placeholder = RealOffset;
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break;
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}
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default:
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// There are other relocation types, but it appears these are the
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// only ones currently used by the LLVM ELF object writer
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llvm_unreachable("Relocation type not implemented yet!");
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break;
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}
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}
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void RuntimeDyldELF::resolveARMRelocation(uint8_t *LocalAddress,
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uint32_t FinalAddress,
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uint32_t Value,
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uint32_t Type,
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int32_t Addend) {
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// TODO: Add Thumb relocations.
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uint32_t* TargetPtr = (uint32_t*)LocalAddress;
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Value += Addend;
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DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: " << LocalAddress
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<< " FinalAddress: " << format("%p",FinalAddress)
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<< " Value: " << format("%x",Value)
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<< " Type: " << format("%x",Type)
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<< " Addend: " << format("%x",Addend)
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<< "\n");
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switch(Type) {
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default:
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llvm_unreachable("Not implemented relocation type!");
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// Just write 32bit value to relocation address
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case ELF::R_ARM_ABS32 :
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*TargetPtr = Value;
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break;
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// Write first 16 bit of 32 bit value to the mov instruction.
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// Last 4 bit should be shifted.
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case ELF::R_ARM_MOVW_ABS_NC :
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Value = Value & 0xFFFF;
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*TargetPtr |= Value & 0xFFF;
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*TargetPtr |= ((Value >> 12) & 0xF) << 16;
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break;
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// Write last 16 bit of 32 bit value to the mov instruction.
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// Last 4 bit should be shifted.
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case ELF::R_ARM_MOVT_ABS :
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Value = (Value >> 16) & 0xFFFF;
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*TargetPtr |= Value & 0xFFF;
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*TargetPtr |= ((Value >> 12) & 0xF) << 16;
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break;
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// Write 24 bit relative value to the branch instruction.
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case ELF::R_ARM_PC24 : // Fall through.
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case ELF::R_ARM_CALL : // Fall through.
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case ELF::R_ARM_JUMP24 :
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int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
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RelValue = (RelValue & 0x03FFFFFC) >> 2;
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*TargetPtr &= 0xFF000000;
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*TargetPtr |= RelValue;
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break;
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}
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}
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void RuntimeDyldELF::resolveRelocation(uint8_t *LocalAddress,
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uint64_t FinalAddress,
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uint64_t Value,
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uint32_t Type,
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int64_t Addend) {
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switch (Arch) {
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case Triple::x86_64:
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resolveX86_64Relocation(LocalAddress, FinalAddress, Value, Type, Addend);
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break;
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case Triple::x86:
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resolveX86Relocation(LocalAddress, (uint32_t)(FinalAddress & 0xffffffffL),
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(uint32_t)(Value & 0xffffffffL), Type,
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(uint32_t)(Addend & 0xffffffffL));
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break;
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case Triple::arm: // Fall through.
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case Triple::thumb:
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resolveARMRelocation(LocalAddress, (uint32_t)(FinalAddress & 0xffffffffL),
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(uint32_t)(Value & 0xffffffffL), Type,
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(uint32_t)(Addend & 0xffffffffL));
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break;
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default: llvm_unreachable("Unsupported CPU type!");
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}
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}
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void RuntimeDyldELF::processRelocationRef(const ObjRelocationInfo &Rel,
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ObjectImage &Obj,
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ObjSectionToIDMap &ObjSectionToID,
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const SymbolTableMap &Symbols,
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StubMap &Stubs) {
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uint32_t RelType = (uint32_t)(Rel.Type & 0xffffffffL);
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intptr_t Addend = (intptr_t)Rel.AdditionalInfo;
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const SymbolRef &Symbol = Rel.Symbol;
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// Obtain the symbol name which is referenced in the relocation
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StringRef TargetName;
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Symbol.getName(TargetName);
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DEBUG(dbgs() << "\t\tRelType: " << RelType
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<< " Addend: " << Addend
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<< " TargetName: " << TargetName
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<< "\n");
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RelocationValueRef Value;
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// First search for the symbol in the local symbol table
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SymbolTableMap::const_iterator lsi = Symbols.find(TargetName.data());
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if (lsi != Symbols.end()) {
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Value.SectionID = lsi->second.first;
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Value.Addend = lsi->second.second;
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} else {
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// Search for the symbol in the global symbol table
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SymbolTableMap::const_iterator gsi =
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GlobalSymbolTable.find(TargetName.data());
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if (gsi != GlobalSymbolTable.end()) {
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Value.SectionID = gsi->second.first;
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Value.Addend = gsi->second.second;
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} else {
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SymbolRef::Type SymType;
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Symbol.getType(SymType);
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switch (SymType) {
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case SymbolRef::ST_Debug: {
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// TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
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// and can be changed by another developers. Maybe best way is add
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// a new symbol type ST_Section to SymbolRef and use it.
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section_iterator si(Obj.end_sections());
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Symbol.getSection(si);
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if (si == Obj.end_sections())
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llvm_unreachable("Symbol section not found, bad object file format!");
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DEBUG(dbgs() << "\t\tThis is section symbol\n");
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Value.SectionID = findOrEmitSection(Obj, (*si), true, ObjSectionToID);
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Value.Addend = Addend;
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break;
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}
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case SymbolRef::ST_Unknown: {
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Value.SymbolName = TargetName.data();
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Value.Addend = Addend;
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break;
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}
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default:
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llvm_unreachable("Unresolved symbol type!");
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break;
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}
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}
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}
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DEBUG(dbgs() << "\t\tRel.SectionID: " << Rel.SectionID
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<< " Rel.Offset: " << Rel.Offset
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<< "\n");
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if (Arch == Triple::arm &&
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(RelType == ELF::R_ARM_PC24 ||
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RelType == ELF::R_ARM_CALL ||
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RelType == ELF::R_ARM_JUMP24)) {
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// This is an ARM branch relocation, need to use a stub function.
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DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.");
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SectionEntry &Section = Sections[Rel.SectionID];
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uint8_t *Target = Section.Address + Rel.Offset;
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// Look up for existing stub.
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StubMap::const_iterator i = Stubs.find(Value);
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if (i != Stubs.end()) {
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resolveRelocation(Target, (uint64_t)Target, (uint64_t)Section.Address +
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i->second, RelType, 0);
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DEBUG(dbgs() << " Stub function found\n");
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} else {
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// Create a new stub function.
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DEBUG(dbgs() << " Create a new stub function\n");
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Stubs[Value] = Section.StubOffset;
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uint8_t *StubTargetAddr = createStubFunction(Section.Address +
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Section.StubOffset);
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RelocationEntry RE(Rel.SectionID, StubTargetAddr - Section.Address,
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ELF::R_ARM_ABS32, Value.Addend);
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if (Value.SymbolName)
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addRelocationForSymbol(RE, Value.SymbolName);
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else
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addRelocationForSection(RE, Value.SectionID);
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resolveRelocation(Target, (uint64_t)Target, (uint64_t)Section.Address +
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Section.StubOffset, RelType, 0);
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Section.StubOffset += getMaxStubSize();
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}
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} else {
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RelocationEntry RE(Rel.SectionID, Rel.Offset, RelType, Value.Addend);
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if (Value.SymbolName)
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addRelocationForSymbol(RE, Value.SymbolName);
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else
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addRelocationForSection(RE, Value.SectionID);
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}
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}
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bool RuntimeDyldELF::isCompatibleFormat(const MemoryBuffer *InputBuffer) const {
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StringRef Magic = InputBuffer->getBuffer().slice(0, ELF::EI_NIDENT);
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return (memcmp(Magic.data(), ELF::ElfMagic, strlen(ELF::ElfMagic))) == 0;
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}
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} // namespace llvm
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