1//===-- PPCTargetObjectFile.cpp - PPC Object Info -------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "PPCTargetObjectFile.h"
11#include "llvm/IR/Mangler.h"
12#include "llvm/MC/MCContext.h"
13#include "llvm/MC/MCExpr.h"
14#include "llvm/MC/MCSectionELF.h"
15
16using namespace llvm;
17
18void
19PPC64LinuxTargetObjectFile::
20Initialize(MCContext &Ctx, const TargetMachine &TM) {
21  TargetLoweringObjectFileELF::Initialize(Ctx, TM);
22  InitializeELF(TM.Options.UseInitArray);
23}
24
25MCSection *PPC64LinuxTargetObjectFile::SelectSectionForGlobal(
26    const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
27    const TargetMachine &TM) const {
28  // Here override ReadOnlySection to DataRelROSection for PPC64 SVR4 ABI
29  // when we have a constant that contains global relocations.  This is
30  // necessary because of this ABI's handling of pointers to functions in
31  // a shared library.  The address of a function is actually the address
32  // of a function descriptor, which resides in the .opd section.  Generated
33  // code uses the descriptor directly rather than going via the GOT as some
34  // other ABIs do, which means that initialized function pointers must
35  // reference the descriptor.  The linker must convert copy relocs of
36  // pointers to functions in shared libraries into dynamic relocations,
37  // because of an ordering problem with initialization of copy relocs and
38  // PLT entries.  The dynamic relocation will be initialized by the dynamic
39  // linker, so we must use DataRelROSection instead of ReadOnlySection.
40  // For more information, see the description of ELIMINATE_COPY_RELOCS in
41  // GNU ld.
42  if (Kind.isReadOnly()) {
43    const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
44
45    if (GVar && GVar->isConstant() && GVar->getInitializer()->needsRelocation())
46      Kind = SectionKind::getReadOnlyWithRel();
47  }
48
49  return TargetLoweringObjectFileELF::SelectSectionForGlobal(GV, Kind,
50                                                             Mang, TM);
51}
52
53const MCExpr *PPC64LinuxTargetObjectFile::
54getDebugThreadLocalSymbol(const MCSymbol *Sym) const {
55  const MCExpr *Expr =
56    MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_PPC_DTPREL, getContext());
57  return MCBinaryExpr::createAdd(Expr,
58                                 MCConstantExpr::create(0x8000, getContext()),
59                                 getContext());
60}
61
62