1 //===-- AArch64TargetObjectFile.cpp - AArch64 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 "AArch64TargetObjectFile.h" 10 #include "AArch64TargetMachine.h" 11 #include "MCTargetDesc/AArch64MCExpr.h" 12 #include "llvm/ADT/StringExtras.h" 13 #include "llvm/BinaryFormat/Dwarf.h" 14 #include "llvm/CodeGen/MachineModuleInfoImpls.h" 15 #include "llvm/IR/Mangler.h" 16 #include "llvm/IR/Module.h" 17 #include "llvm/MC/MCContext.h" 18 #include "llvm/MC/MCExpr.h" 19 #include "llvm/MC/MCStreamer.h" 20 #include "llvm/MC/MCValue.h" 21 using namespace llvm; 22 using namespace dwarf; 23 24 void AArch64_ELFTargetObjectFile::Initialize(MCContext &Ctx, 25 const TargetMachine &TM) { 26 TargetLoweringObjectFileELF::Initialize(Ctx, TM); 27 // AARCH64 ELF ABI does not define static relocation type for TLS offset 28 // within a module. Do not generate AT_location for TLS variables. 29 SupportDebugThreadLocalLocation = false; 30 } 31 32 const MCExpr *AArch64_ELFTargetObjectFile::getIndirectSymViaGOTPCRel( 33 const GlobalValue *GV, const MCSymbol *Sym, const MCValue &MV, 34 int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const { 35 int64_t FinalOffset = Offset + MV.getConstant(); 36 const MCExpr *Res = 37 MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOTPCREL, getContext()); 38 const MCExpr *Off = MCConstantExpr::create(FinalOffset, getContext()); 39 return MCBinaryExpr::createAdd(Res, Off, getContext()); 40 } 41 42 AArch64_MachoTargetObjectFile::AArch64_MachoTargetObjectFile() { 43 SupportGOTPCRelWithOffset = false; 44 } 45 46 const MCExpr *AArch64_MachoTargetObjectFile::getTTypeGlobalReference( 47 const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM, 48 MachineModuleInfo *MMI, MCStreamer &Streamer) const { 49 // On Darwin, we can reference dwarf symbols with foo@GOT-., which 50 // is an indirect pc-relative reference. The default implementation 51 // won't reference using the GOT, so we need this target-specific 52 // version. 53 if (Encoding & (DW_EH_PE_indirect | DW_EH_PE_pcrel)) { 54 const MCSymbol *Sym = TM.getSymbol(GV); 55 const MCExpr *Res = 56 MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOT, getContext()); 57 MCSymbol *PCSym = getContext().createTempSymbol(); 58 Streamer.emitLabel(PCSym); 59 const MCExpr *PC = MCSymbolRefExpr::create(PCSym, getContext()); 60 return MCBinaryExpr::createSub(Res, PC, getContext()); 61 } 62 63 return TargetLoweringObjectFileMachO::getTTypeGlobalReference( 64 GV, Encoding, TM, MMI, Streamer); 65 } 66 67 MCSymbol *AArch64_MachoTargetObjectFile::getCFIPersonalitySymbol( 68 const GlobalValue *GV, const TargetMachine &TM, 69 MachineModuleInfo *MMI) const { 70 return TM.getSymbol(GV); 71 } 72 73 const MCExpr *AArch64_MachoTargetObjectFile::getIndirectSymViaGOTPCRel( 74 const GlobalValue *GV, const MCSymbol *Sym, const MCValue &MV, 75 int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const { 76 assert((Offset+MV.getConstant() == 0) && 77 "Arch64 does not support GOT PC rel with extra offset"); 78 // On ARM64 Darwin, we can reference symbols with foo@GOT-., which 79 // is an indirect pc-relative reference. 80 const MCExpr *Res = 81 MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOT, getContext()); 82 MCSymbol *PCSym = getContext().createTempSymbol(); 83 Streamer.emitLabel(PCSym); 84 const MCExpr *PC = MCSymbolRefExpr::create(PCSym, getContext()); 85 return MCBinaryExpr::createSub(Res, PC, getContext()); 86 } 87 88 void AArch64_MachoTargetObjectFile::getNameWithPrefix( 89 SmallVectorImpl<char> &OutName, const GlobalValue *GV, 90 const TargetMachine &TM) const { 91 // AArch64 does not use section-relative relocations so any global symbol must 92 // be accessed via at least a linker-private symbol. 93 getMangler().getNameWithPrefix(OutName, GV, /* CannotUsePrivateLabel */ true); 94 } 95 96 template <typename MachineModuleInfoTarget> 97 static MCSymbol *getAuthPtrSlotSymbolHelper( 98 MCContext &Ctx, const TargetMachine &TM, MachineModuleInfo *MMI, 99 MachineModuleInfoTarget &TargetMMI, const MCSymbol *RawSym, 100 AArch64PACKey::ID Key, uint16_t Discriminator) { 101 const DataLayout &DL = MMI->getModule()->getDataLayout(); 102 103 MCSymbol *StubSym = Ctx.getOrCreateSymbol( 104 DL.getLinkerPrivateGlobalPrefix() + RawSym->getName() + 105 Twine("$auth_ptr$") + AArch64PACKeyIDToString(Key) + Twine('$') + 106 Twine(Discriminator)); 107 108 const MCExpr *&StubAuthPtrRef = TargetMMI.getAuthPtrStubEntry(StubSym); 109 110 if (StubAuthPtrRef) 111 return StubSym; 112 113 const MCExpr *Sym = MCSymbolRefExpr::create(RawSym, Ctx); 114 115 StubAuthPtrRef = 116 AArch64AuthMCExpr::create(Sym, Discriminator, Key, 117 /*HasAddressDiversity=*/false, Ctx); 118 return StubSym; 119 } 120 121 MCSymbol *AArch64_ELFTargetObjectFile::getAuthPtrSlotSymbol( 122 const TargetMachine &TM, MachineModuleInfo *MMI, const MCSymbol *RawSym, 123 AArch64PACKey::ID Key, uint16_t Discriminator) const { 124 auto &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>(); 125 return getAuthPtrSlotSymbolHelper(getContext(), TM, MMI, ELFMMI, RawSym, Key, 126 Discriminator); 127 } 128 129 MCSymbol *AArch64_MachoTargetObjectFile::getAuthPtrSlotSymbol( 130 const TargetMachine &TM, MachineModuleInfo *MMI, const MCSymbol *RawSym, 131 AArch64PACKey::ID Key, uint16_t Discriminator) const { 132 auto &MachOMMI = MMI->getObjFileInfo<MachineModuleInfoMachO>(); 133 return getAuthPtrSlotSymbolHelper(getContext(), TM, MMI, MachOMMI, RawSym, 134 Key, Discriminator); 135 } 136