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