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