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//===-- PPCTargetObjectFile.cpp - PPC Object Info -------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "PPCTargetObjectFile.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Mangler.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSectionELF.h"
using namespace llvm;
void
PPC64LinuxTargetObjectFile::
Initialize(MCContext &Ctx, const TargetMachine &TM) {
TargetLoweringObjectFileELF::Initialize(Ctx, TM);
}
MCSection *PPC64LinuxTargetObjectFile::SelectSectionForGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
// Here override ReadOnlySection to DataRelROSection for PPC64 SVR4 ABI
// when we have a constant that contains global relocations. This is
// necessary because of this ABI's handling of pointers to functions in
// a shared library. The address of a function is actually the address
// of a function descriptor, which resides in the .opd section. Generated
// code uses the descriptor directly rather than going via the GOT as some
// other ABIs do, which means that initialized function pointers must
// reference the descriptor. The linker must convert copy relocs of
// pointers to functions in shared libraries into dynamic relocations,
// because of an ordering problem with initialization of copy relocs and
// PLT entries. The dynamic relocation will be initialized by the dynamic
// linker, so we must use DataRelROSection instead of ReadOnlySection.
// For more information, see the description of ELIMINATE_COPY_RELOCS in
// GNU ld.
if (Kind.isReadOnly()) {
const auto *GVar = dyn_cast<GlobalVariable>(GO);
if (GVar && GVar->isConstant() &&
GVar->getInitializer()->needsDynamicRelocation())
Kind = SectionKind::getReadOnlyWithRel();
}
return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, Kind, TM);
}
const MCExpr *PPC64LinuxTargetObjectFile::
getDebugThreadLocalSymbol(const MCSymbol *Sym) const {
const MCExpr *Expr =
MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_DTPREL, getContext());
return MCBinaryExpr::createAdd(Expr,
MCConstantExpr::create(0x8000, getContext()),
getContext());
}
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