| 1 | //===-- PPCTargetObjectFile.cpp - PPC Object Info -------------------------===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |
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| 9 | #include "PPCTargetObjectFile.h" |
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| 10 | #include "llvm/IR/GlobalVariable.h" |
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| 11 | #include "llvm/IR/Mangler.h" |
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| 12 | #include "llvm/MC/MCContext.h" |
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| 13 | #include "llvm/MC/MCExpr.h" |
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| 14 | #include "llvm/MC/MCSectionELF.h" |
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| 15 | |
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| 16 | using namespace llvm; |
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| 17 | |
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| 18 | void |
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| 19 | PPC64LinuxTargetObjectFile:: |
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| 20 | Initialize(MCContext &Ctx, const TargetMachine &TM) { |
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| 21 | TargetLoweringObjectFileELF::Initialize(Ctx, TM); |
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| 22 | } |
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| 23 | |
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| 24 | MCSection *PPC64LinuxTargetObjectFile::SelectSectionForGlobal( |
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| 25 | const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const { |
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| 26 | // Here override ReadOnlySection to DataRelROSection for PPC64 SVR4 ABI |
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| 27 | // when we have a constant that contains global relocations. This is |
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| 28 | // necessary because of this ABI's handling of pointers to functions in |
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| 29 | // a shared library. The address of a function is actually the address |
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| 30 | // of a function descriptor, which resides in the .opd section. Generated |
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| 31 | // code uses the descriptor directly rather than going via the GOT as some |
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| 32 | // other ABIs do, which means that initialized function pointers must |
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| 33 | // reference the descriptor. The linker must convert copy relocs of |
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| 34 | // pointers to functions in shared libraries into dynamic relocations, |
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| 35 | // because of an ordering problem with initialization of copy relocs and |
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| 36 | // PLT entries. The dynamic relocation will be initialized by the dynamic |
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| 37 | // linker, so we must use DataRelROSection instead of ReadOnlySection. |
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| 38 | // For more information, see the description of ELIMINATE_COPY_RELOCS in |
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| 39 | // GNU ld. |
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| 40 | if (Kind.isReadOnly()) { |
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| 41 | const auto *GVar = dyn_cast<GlobalVariable>(Val: GO); |
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| 42 | |
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| 43 | if (GVar && GVar->isConstant() && |
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| 44 | GVar->getInitializer()->needsDynamicRelocation()) |
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| 45 | Kind = SectionKind::getReadOnlyWithRel(); |
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| 46 | } |
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| 47 | |
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| 48 | return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, Kind, TM); |
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| 49 | } |
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| 50 | |
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| 51 | const MCExpr *PPC64LinuxTargetObjectFile:: |
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| 52 | getDebugThreadLocalSymbol(const MCSymbol *Sym) const { |
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| 53 | const MCExpr *Expr = |
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| 54 | MCSymbolRefExpr::create(Symbol: Sym, Kind: MCSymbolRefExpr::VK_DTPREL, Ctx&: getContext()); |
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| 55 | return MCBinaryExpr::createAdd(LHS: Expr, |
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| 56 | RHS: MCConstantExpr::create(Value: 0x8000, Ctx&: getContext()), |
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| 57 | Ctx&: getContext()); |
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| 58 | } |
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| 59 | |
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| 60 | |
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