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 const MCExpr *AArch64_ELFTargetObjectFile::getIndirectSymViaGOTPCRel(
  29     const GlobalValue *GV, const MCSymbol *Sym, const MCValue &MV,
  30     int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const {
  31   int64_t FinalOffset = Offset + MV.getConstant();
  32   const MCExpr *Res =
  33       MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOTPCREL, getContext());
  34   const MCExpr *Off = MCConstantExpr::create(FinalOffset, getContext());
  35   return MCBinaryExpr::createAdd(Res, Off, getContext());
  36 }
  37
  38 AArch64_MachoTargetObjectFile::AArch64_MachoTargetObjectFile() {
  39   SupportGOTPCRelWithOffset = false;
  40 }
  41
  42 const MCExpr *AArch64_MachoTargetObjectFile::getTTypeGlobalReference(
  43     const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM,
  44     MachineModuleInfo *MMI, MCStreamer &Streamer) const {
  45   // On Darwin, we can reference dwarf symbols with foo@GOT-., which
  46   // is an indirect pc-relative reference. The default implementation
  47   // won't reference using the GOT, so we need this target-specific
  48   // version.
  49   if (Encoding & (DW_EH_PE_indirect | DW_EH_PE_pcrel)) {
  50     const MCSymbol *Sym = TM.getSymbol(GV);
  51     const MCExpr *Res =
  52         MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOT, getContext());
  53     MCSymbol *PCSym = getContext().createTempSymbol();
  54     Streamer.emitLabel(PCSym);
  55     const MCExpr *PC = MCSymbolRefExpr::create(PCSym, getContext());
  56     return MCBinaryExpr::createSub(Res, PC, getContext());
  57   }
  58
  59   return TargetLoweringObjectFileMachO::getTTypeGlobalReference(
  60       GV, Encoding, TM, MMI, Streamer);
  61 }
  62
  63 MCSymbol *AArch64_MachoTargetObjectFile::getCFIPersonalitySymbol(
  64     const GlobalValue *GV, const TargetMachine &TM,
  65     MachineModuleInfo *MMI) const {
  66   return TM.getSymbol(GV);
  67 }
  68
  69 const MCExpr *AArch64_MachoTargetObjectFile::getIndirectSymViaGOTPCRel(
  70     const GlobalValue *GV, const MCSymbol *Sym, const MCValue &MV,
  71     int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const {
  72   assert((Offset+MV.getConstant() == 0) &&
  73          "Arch64 does not support GOT PC rel with extra offset");
  74   // On ARM64 Darwin, we can reference symbols with foo@GOT-., which
  75   // is an indirect pc-relative reference.
  76   const MCExpr *Res =
  77       MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOT, getContext());
  78   MCSymbol *PCSym = getContext().createTempSymbol();
  79   Streamer.emitLabel(PCSym);
  80   const MCExpr *PC = MCSymbolRefExpr::create(PCSym, getContext());
  81   return MCBinaryExpr::createSub(Res, PC, getContext());
  82 }
  83
  84 void AArch64_MachoTargetObjectFile::getNameWithPrefix(
  85     SmallVectorImpl<char> &OutName, const GlobalValue *GV,
  86     const TargetMachine &TM) const {
  87   // AArch64 does not use section-relative relocations so any global symbol must
  88   // be accessed via at least a linker-private symbol.
  89   getMangler().getNameWithPrefix(OutName, GV, /* CannotUsePrivateLabel */ true);
  90 }