mirror of
https://github.com/c64scene-ar/llvm-6502.git
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of zero-initialized sections, virtual sections and common symbols and preventing the loading of sections which are not required for execution such as debug information. Patch by Andy Kaylor! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154610 91177308-0d34-0410-b5e6-96231b3b80d8
263 lines
9.7 KiB
C++
263 lines
9.7 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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using namespace llvm;
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using namespace llvm::object;
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namespace llvm {
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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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const ObjectFile &Obj,
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ObjSectionToIDMap &ObjSectionToID,
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LocalSymbolMap &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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RelocationValueRef Value;
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StringRef TargetName;
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const SymbolRef &Symbol = Rel.Symbol;
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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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// First look the symbol in object file symbols.
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LocalSymbolMap::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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// Second look the symbol in global symbol table.
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StringMap<SymbolLoc>::iterator gsi = SymbolTable.find(TargetName.data());
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if (gsi != SymbolTable.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((*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, Section.LoadAddress, (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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AddRelocation(Value, Rel.SectionID,
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StubTargetAddr - Section.Address, ELF::R_ARM_ABS32);
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resolveRelocation(Target, Section.LoadAddress, (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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AddRelocation(Value, Rel.SectionID, Rel.Offset, RelType);
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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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