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      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 
     16 using namespace llvm;
     17 
     18 void
     19 PPC64LinuxTargetObjectFile::
     20 Initialize(MCContext &Ctx, const TargetMachine &TM) {
     21   TargetLoweringObjectFileELF::Initialize(Ctx, TM);
     22   InitializeELF(TM.Options.UseInitArray);
     23 }
     24 
     25 MCSection *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 
     53 const MCExpr *PPC64LinuxTargetObjectFile::
     54 getDebugThreadLocalSymbol(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