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/MC/MCContext.h" 12 #include "llvm/MC/MCExpr.h" 13 #include "llvm/MC/MCSectionELF.h" 14 #include "llvm/Target/Mangler.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 const MCSection * PPC64LinuxTargetObjectFile:: 26 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 27 Mangler *Mang, const TargetMachine &TM) const { 28 29 const MCSection *DefaultSection = 30 TargetLoweringObjectFileELF::SelectSectionForGlobal(GV, Kind, Mang, TM); 31 32 if (DefaultSection != ReadOnlySection) 33 return DefaultSection; 34 35 // Here override ReadOnlySection to DataRelROSection for PPC64 SVR4 ABI 36 // when we have a constant that contains global relocations. This is 37 // necessary because of this ABI's handling of pointers to functions in 38 // a shared library. The address of a function is actually the address 39 // of a function descriptor, which resides in the .opd section. Generated 40 // code uses the descriptor directly rather than going via the GOT as some 41 // other ABIs do, which means that initialized function pointers must 42 // reference the descriptor. The linker must convert copy relocs of 43 // pointers to functions in shared libraries into dynamic relocations, 44 // because of an ordering problem with initialization of copy relocs and 45 // PLT entries. The dynamic relocation will be initialized by the dynamic 46 // linker, so we must use DataRelROSection instead of ReadOnlySection. 47 // For more information, see the description of ELIMINATE_COPY_RELOCS in 48 // GNU ld. 49 const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV); 50 51 if (GVar && GVar->isConstant() && 52 (GVar->getInitializer()->getRelocationInfo() == 53 Constant::GlobalRelocations)) 54 return DataRelROSection; 55 56 return DefaultSection; 57 } 58 59 const MCExpr *PPC64LinuxTargetObjectFile:: 60 getDebugThreadLocalSymbol(const MCSymbol *Sym) const { 61 const MCExpr *Expr = 62 MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_PPC_DTPREL, getContext()); 63 return MCBinaryExpr::CreateAdd(Expr, 64 MCConstantExpr::Create(0x8000, getContext()), 65 getContext()); 66 } 67 68
