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_DTPREL, getContext()); 57 return MCBinaryExpr::createAdd(Expr, 58 MCConstantExpr::create(0x8000, getContext()), 59 getContext()); 60 } 61 62
