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//===-- X86TargetObjectFile.cpp - X86 Object Info -------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "X86TargetObjectFile.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Operator.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Target/TargetLowering.h"
using namespace llvm;
using namespace dwarf;
const MCExpr *X86_64MachoTargetObjectFile::getTTypeGlobalReference(
const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
const TargetMachine &TM, MachineModuleInfo *MMI,
MCStreamer &Streamer) const {
// On Darwin/X86-64, we can reference dwarf symbols with foo@GOTPCREL+4, which
// is an indirect pc-relative reference.
if ((Encoding & DW_EH_PE_indirect) && (Encoding & DW_EH_PE_pcrel)) {
const MCSymbol *Sym = TM.getSymbol(GV, Mang);
const MCExpr *Res =
MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_GOTPCREL, getContext());
const MCExpr *Four = MCConstantExpr::Create(4, getContext());
return MCBinaryExpr::CreateAdd(Res, Four, getContext());
}
return TargetLoweringObjectFileMachO::getTTypeGlobalReference(
GV, Encoding, Mang, TM, MMI, Streamer);
}
MCSymbol *X86_64MachoTargetObjectFile::getCFIPersonalitySymbol(
const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM,
MachineModuleInfo *MMI) const {
return TM.getSymbol(GV, Mang);
}
void
X86LinuxTargetObjectFile::Initialize(MCContext &Ctx, const TargetMachine &TM) {
TargetLoweringObjectFileELF::Initialize(Ctx, TM);
InitializeELF(TM.Options.UseInitArray);
}
const MCExpr *
X86LinuxTargetObjectFile::getDebugThreadLocalSymbol(
const MCSymbol *Sym) const {
return MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_DTPOFF, getContext());
}
const MCExpr *X86WindowsTargetObjectFile::getExecutableRelativeSymbol(
const ConstantExpr *CE, Mangler &Mang, const TargetMachine &TM) const {
// We are looking for the difference of two symbols, need a subtraction
// operation.
const SubOperator *Sub = dyn_cast<SubOperator>(CE);
if (!Sub)
return nullptr;
// Symbols must first be numbers before we can subtract them, we need to see a
// ptrtoint on both subtraction operands.
const PtrToIntOperator *SubLHS =
dyn_cast<PtrToIntOperator>(Sub->getOperand(0));
const PtrToIntOperator *SubRHS =
dyn_cast<PtrToIntOperator>(Sub->getOperand(1));
if (!SubLHS || !SubRHS)
return nullptr;
// Our symbols should exist in address space zero, cowardly no-op if
// otherwise.
if (SubLHS->getPointerAddressSpace() != 0 ||
SubRHS->getPointerAddressSpace() != 0)
return nullptr;
// Both ptrtoint instructions must wrap global variables:
// - Only global variables are eligible for image relative relocations.
// - The subtrahend refers to the special symbol __ImageBase, a global.
const GlobalVariable *GVLHS =
dyn_cast<GlobalVariable>(SubLHS->getPointerOperand());
const GlobalVariable *GVRHS =
dyn_cast<GlobalVariable>(SubRHS->getPointerOperand());
if (!GVLHS || !GVRHS)
return nullptr;
// We expect __ImageBase to be a global variable without a section, externally
// defined.
//
// It should look something like this: @__ImageBase = external constant i8
if (GVRHS->isThreadLocal() || GVRHS->getName() != "__ImageBase" ||
!GVRHS->hasExternalLinkage() || GVRHS->hasInitializer() ||
GVRHS->hasSection())
return nullptr;
// An image-relative, thread-local, symbol makes no sense.
if (GVLHS->isThreadLocal())
return nullptr;
return MCSymbolRefExpr::Create(TM.getSymbol(GVLHS, Mang),
MCSymbolRefExpr::VK_COFF_IMGREL32,
getContext());
}
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