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