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::
Initialize(MCContext & Ctx,const TargetMachine & TM)19 Initialize(MCContext &Ctx, const TargetMachine &TM) {
20 TargetLoweringObjectFileELF::Initialize(Ctx, TM);
21 }
22
SelectSectionForGlobal(const GlobalObject * GO,SectionKind Kind,const TargetMachine & TM) const23 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::
getDebugThreadLocalSymbol(const MCSymbol * Sym) const51 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