322799aa50
There's an existing check in LLVM that can replace an offset to a DSO-local symbol that is just a pointer to another symbol with a GOTPCREL reloc. This is exactly what the RTTI proxy in the relative vtables ABI is. This feature is supported for different macho platforms, but not for ELF. This extends that support.
69 lines
2.8 KiB
C++
69 lines
2.8 KiB
C++
//===-- X86TargetObjectFile.cpp - X86 Object Info -------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "X86TargetObjectFile.h"
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#include "llvm/BinaryFormat/Dwarf.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCValue.h"
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#include "llvm/Target/TargetMachine.h"
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using namespace llvm;
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using namespace dwarf;
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const MCExpr *X86_64MachoTargetObjectFile::getTTypeGlobalReference(
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const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM,
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MachineModuleInfo *MMI, 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) && (Encoding & DW_EH_PE_pcrel)) {
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const MCSymbol *Sym = TM.getSymbol(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::getTTypeGlobalReference(
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GV, Encoding, TM, MMI, Streamer);
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}
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MCSymbol *X86_64MachoTargetObjectFile::getCFIPersonalitySymbol(
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const GlobalValue *GV, const TargetMachine &TM,
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MachineModuleInfo *MMI) const {
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return TM.getSymbol(GV);
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}
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const MCExpr *X86_64MachoTargetObjectFile::getIndirectSymViaGOTPCRel(
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const GlobalValue *GV, const MCSymbol *Sym, const MCValue &MV,
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int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const {
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// On Darwin/X86-64, we need to use foo@GOTPCREL+4 to access the got entry
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// from a data section. In case there's an additional offset, then use
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// foo@GOTPCREL+4+<offset>.
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unsigned FinalOff = Offset+MV.getConstant()+4;
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const MCExpr *Res =
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MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOTPCREL, getContext());
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const MCExpr *Off = MCConstantExpr::create(FinalOff, getContext());
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return MCBinaryExpr::createAdd(Res, Off, getContext());
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}
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const MCExpr *X86ELFTargetObjectFile::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 *X86ELFTargetObjectFile::getIndirectSymViaGOTPCRel(
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const GlobalValue *GV, const MCSymbol *Sym, const MCValue &MV,
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int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const {
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int64_t FinalOffset = Offset + MV.getConstant();
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const MCExpr *Res =
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MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOTPCREL, getContext());
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const MCExpr *Off = MCConstantExpr::create(FinalOffset, getContext());
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return MCBinaryExpr::createAdd(Res, Off, getContext());
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}
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