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 "llvm/IR/Mangler.h"
11#include "llvm/MC/MCContext.h"
12#include "llvm/MC/MCExpr.h"
13#include "llvm/MC/MCSectionELF.h"
14
15using namespace llvm;
16
17void
18PPC64LinuxTargetObjectFile::
19Initialize(MCContext &Ctx, const TargetMachine &TM) {
20  TargetLoweringObjectFileELF::Initialize(Ctx, TM);
21  InitializeELF(TM.Options.UseInitArray);
22}
23
24MCSection *PPC64LinuxTargetObjectFile::SelectSectionForGlobal(
25    const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
26  // Here override ReadOnlySection to DataRelROSection for PPC64 SVR4 ABI
27  // when we have a constant that contains global relocations.  This is
28  // necessary because of this ABI's handling of pointers to functions in
29  // a shared library.  The address of a function is actually the address
30  // of a function descriptor, which resides in the .opd section.  Generated
31  // code uses the descriptor directly rather than going via the GOT as some
32  // other ABIs do, which means that initialized function pointers must
33  // reference the descriptor.  The linker must convert copy relocs of
34  // pointers to functions in shared libraries into dynamic relocations,
35  // because of an ordering problem with initialization of copy relocs and
36  // PLT entries.  The dynamic relocation will be initialized by the dynamic
37  // linker, so we must use DataRelROSection instead of ReadOnlySection.
38  // For more information, see the description of ELIMINATE_COPY_RELOCS in
39  // GNU ld.
40  if (Kind.isReadOnly()) {
41    const auto *GVar = dyn_cast<GlobalVariable>(GO);
42
43    if (GVar && GVar->isConstant() && GVar->getInitializer()->needsRelocation())
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(Sym, MCSymbolRefExpr::VK_DTPREL, getContext());
54  return MCBinaryExpr::createAdd(Expr,
55                                 MCConstantExpr::create(0x8000, getContext()),
56                                 getContext());
57}
58
59