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https://github.com/c64scene-ar/llvm-6502.git
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f62176f047
MSVC on x64 requires that we create image relative symbol references to refer to RTTI data. Seeing as how there is no way to explicitly make reference to a given relocation type in LLVM IR, pattern match expressions of the form &foo - &__ImageBase. Differential Revision: http://llvm-reviews.chandlerc.com/D2523 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199312 91177308-0d34-0410-b5e6-96231b3b80d8
108 lines
3.8 KiB
C++
108 lines
3.8 KiB
C++
//===-- X86TargetObjectFile.cpp - X86 Object Info -------------------------===//
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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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#include "X86TargetObjectFile.h"
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#include "llvm/IR/Mangler.h"
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#include "llvm/IR/Operator.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCSectionELF.h"
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#include "llvm/Support/Dwarf.h"
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using namespace llvm;
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using namespace dwarf;
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const MCExpr *X86_64MachoTargetObjectFile::
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getTTypeGlobalReference(const GlobalValue *GV, Mangler *Mang,
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MachineModuleInfo *MMI, unsigned Encoding,
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MCStreamer &Streamer) const {
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// On Darwin/X86-64, we can reference dwarf symbols with foo@GOTPCREL+4, which
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// is an indirect pc-relative reference.
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if (Encoding & (DW_EH_PE_indirect | DW_EH_PE_pcrel)) {
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const MCSymbol *Sym = getSymbol(*Mang, GV);
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const MCExpr *Res =
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MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_GOTPCREL, getContext());
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const MCExpr *Four = MCConstantExpr::Create(4, getContext());
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return MCBinaryExpr::CreateAdd(Res, Four, getContext());
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}
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return TargetLoweringObjectFileMachO::
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getTTypeGlobalReference(GV, Mang, MMI, Encoding, Streamer);
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}
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MCSymbol *X86_64MachoTargetObjectFile::
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getCFIPersonalitySymbol(const GlobalValue *GV, Mangler *Mang,
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MachineModuleInfo *MMI) const {
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return getSymbol(*Mang, GV);
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}
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void
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X86LinuxTargetObjectFile::Initialize(MCContext &Ctx, const TargetMachine &TM) {
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TargetLoweringObjectFileELF::Initialize(Ctx, TM);
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InitializeELF(TM.Options.UseInitArray);
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}
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const MCExpr *
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X86LinuxTargetObjectFile::getDebugThreadLocalSymbol(
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const MCSymbol *Sym) const {
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return MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_DTPOFF, getContext());
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}
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const MCExpr *
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X86WindowsTargetObjectFile::getExecutableRelativeSymbol(const ConstantExpr *CE,
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Mangler *Mang) const {
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// We are looking for the difference of two symbols, need a subtraction
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// operation.
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const SubOperator *Sub = dyn_cast<SubOperator>(CE);
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if (!Sub)
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return 0;
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// Symbols must first be numbers before we can subtract them, we need to see a
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// ptrtoint on both subtraction operands.
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const PtrToIntOperator *SubLHS =
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dyn_cast<PtrToIntOperator>(Sub->getOperand(0));
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const PtrToIntOperator *SubRHS =
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dyn_cast<PtrToIntOperator>(Sub->getOperand(1));
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if (!SubLHS || !SubRHS)
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return 0;
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// Our symbols should exist in address space zero, cowardly no-op if
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// otherwise.
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if (SubLHS->getPointerAddressSpace() != 0 ||
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SubRHS->getPointerAddressSpace() != 0)
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return 0;
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// Both ptrtoint instructions must wrap global variables:
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// - Only global variables are eligible for image relative relocations.
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// - The subtrahend refers to the special symbol __ImageBase, a global.
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const GlobalVariable *GVLHS =
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dyn_cast<GlobalVariable>(SubLHS->getPointerOperand());
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const GlobalVariable *GVRHS =
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dyn_cast<GlobalVariable>(SubRHS->getPointerOperand());
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if (!GVLHS || !GVRHS)
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return 0;
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// We expect __ImageBase to be a global variable without a section, externally
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// defined.
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//
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// It should look something like this: @__ImageBase = external constant i8
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if (GVRHS->isThreadLocal() || GVRHS->getName() != "__ImageBase" ||
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!GVRHS->hasExternalLinkage() || GVRHS->hasInitializer() ||
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GVRHS->hasSection())
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return 0;
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// An image-relative, thread-local, symbol makes no sense.
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if (GVLHS->isThreadLocal())
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return 0;
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return MCSymbolRefExpr::Create(
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getSymbol(*Mang, GVLHS), MCSymbolRefExpr::VK_COFF_IMGREL32, getContext());
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}
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