1//===-- PPCTargetObjectFile.cpp - PPC Object Info -------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "PPCTargetObjectFile.h"
10#include "MCTargetDesc/PPCMCAsmInfo.h"
11#include "llvm/IR/GlobalVariable.h"
12#include "llvm/MC/MCContext.h"
13#include "llvm/MC/MCExpr.h"
14
15using namespace llvm;
16
17void
18PPC64LinuxTargetObjectFile::
19Initialize(MCContext &Ctx, const TargetMachine &TM) {
20 TargetLoweringObjectFileELF::Initialize(Ctx, TM);
21}
22
23MCSection *PPC64LinuxTargetObjectFile::SelectSectionForGlobal(
24 const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
25 // Here override ReadOnlySection to DataRelROSection for PPC64 SVR4 ABI
26 // when we have a constant that contains global relocations. This is
27 // necessary because of this ABI's handling of pointers to functions in
28 // a shared library. The address of a function is actually the address
29 // of a function descriptor, which resides in the .opd section. Generated
30 // code uses the descriptor directly rather than going via the GOT as some
31 // other ABIs do, which means that initialized function pointers must
32 // reference the descriptor. The linker must convert copy relocs of
33 // pointers to functions in shared libraries into dynamic relocations,
34 // because of an ordering problem with initialization of copy relocs and
35 // PLT entries. The dynamic relocation will be initialized by the dynamic
36 // linker, so we must use DataRelROSection instead of ReadOnlySection.
37 // For more information, see the description of ELIMINATE_COPY_RELOCS in
38 // GNU ld.
39 if (Kind.isReadOnly()) {
40 const auto *GVar = dyn_cast<GlobalVariable>(Val: GO);
41
42 if (GVar && GVar->isConstant() &&
43 GVar->getInitializer()->needsDynamicRelocation())
44 Kind = SectionKind::getReadOnlyWithRel();
45 }
46
47 return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, Kind, TM);
48}
49
50const MCExpr *PPC64LinuxTargetObjectFile::
51getDebugThreadLocalSymbol(const MCSymbol *Sym) const {
52 const MCExpr *Expr =
53 MCSymbolRefExpr::create(Symbol: Sym, specifier: PPC::S_DTPREL, Ctx&: getContext());
54 return MCBinaryExpr::createAdd(LHS: Expr,
55 RHS: MCConstantExpr::create(Value: 0x8000, Ctx&: getContext()),
56 Ctx&: getContext());
57}
58
59