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