lib/Target/AArch64/AArch64TargetObjectFile.cpp

   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 "llvm/BinaryFormat/Dwarf.h"
  12 #include "llvm/IR/Mangler.h"
  13 #include "llvm/MC/MCContext.h"
  14 #include "llvm/MC/MCExpr.h"
  15 #include "llvm/MC/MCStreamer.h"
  16 #include "llvm/MC/MCValue.h"
  17 using namespace llvm;
  18 using namespace dwarf;
  19
  20 void AArch64_ELFTargetObjectFile::Initialize(MCContext &Ctx,
  21                                              const TargetMachine &TM) {
  22   TargetLoweringObjectFileELF::Initialize(Ctx, TM);
  23   InitializeELF(TM.Options.UseInitArray);
  24   // AARCH64 ELF ABI does not define static relocation type for TLS offset
  25   // within a module.  Do not generate AT_location for TLS variables.
  26   SupportDebugThreadLocalLocation = false;
  27 }
  28
  29 AArch64_MachoTargetObjectFile::AArch64_MachoTargetObjectFile()
  30   : TargetLoweringObjectFileMachO() {
  31   SupportGOTPCRelWithOffset = false;
  32 }
  33
  34 const MCExpr *AArch64_MachoTargetObjectFile::getTTypeGlobalReference(
  35     const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM,
  36     MachineModuleInfo *MMI, MCStreamer &Streamer) const {
  37   // On Darwin, we can reference dwarf symbols with foo@GOT-., which
  38   // is an indirect pc-relative reference. The default implementation
  39   // won't reference using the GOT, so we need this target-specific
  40   // version.
  41   if (Encoding & (DW_EH_PE_indirect | DW_EH_PE_pcrel)) {
  42     const MCSymbol *Sym = TM.getSymbol(GV);
  43     const MCExpr *Res =
  44         MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOT, getContext());
  45     MCSymbol *PCSym = getContext().createTempSymbol();
  46     Streamer.EmitLabel(PCSym);
  47     const MCExpr *PC = MCSymbolRefExpr::create(PCSym, getContext());
  48     return MCBinaryExpr::createSub(Res, PC, getContext());
  49   }
  50
  51   return TargetLoweringObjectFileMachO::getTTypeGlobalReference(
  52       GV, Encoding, TM, MMI, Streamer);
  53 }
  54
  55 MCSymbol *AArch64_MachoTargetObjectFile::getCFIPersonalitySymbol(
  56     const GlobalValue *GV, const TargetMachine &TM,
  57     MachineModuleInfo *MMI) const {
  58   return TM.getSymbol(GV);
  59 }
  60
  61 const MCExpr *AArch64_MachoTargetObjectFile::getIndirectSymViaGOTPCRel(
  62     const GlobalValue *GV, const MCSymbol *Sym, const MCValue &MV,
  63     int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const {
  64   assert((Offset+MV.getConstant() == 0) &&
  65          "Arch64 does not support GOT PC rel with extra offset");
  66   // On ARM64 Darwin, we can reference symbols with foo@GOT-., which
  67   // is an indirect pc-relative reference.
  68   const MCExpr *Res =
  69       MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOT, getContext());
  70   MCSymbol *PCSym = getContext().createTempSymbol();
  71   Streamer.EmitLabel(PCSym);
  72   const MCExpr *PC = MCSymbolRefExpr::create(PCSym, getContext());
  73   return MCBinaryExpr::createSub(Res, PC, getContext());
  74 }
  75
  76 void AArch64_MachoTargetObjectFile::getNameWithPrefix(
  77     SmallVectorImpl<char> &OutName, const GlobalValue *GV,
  78     const TargetMachine &TM) const {
  79   // AArch64 does not use section-relative relocations so any global symbol must
  80   // be accessed via at least a linker-private symbol.
  81   getMangler().getNameWithPrefix(OutName, GV, /* CannotUsePrivateLabel */ true);
  82 }