1 //===-- llvm/Target/ARMTargetObjectFile.cpp - ARM Object Info Impl --------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "ARMTargetObjectFile.h"
11 #include "ARMSubtarget.h"
12 #include "ARMTargetMachine.h"
13 #include "llvm/BinaryFormat/Dwarf.h"
14 #include "llvm/BinaryFormat/ELF.h"
15 #include "llvm/MC/MCAsmInfo.h"
16 #include "llvm/MC/MCContext.h"
17 #include "llvm/MC/MCExpr.h"
18 #include "llvm/MC/MCSectionELF.h"
19 #include "llvm/MC/MCTargetOptions.h"
20 #include "llvm/MC/SectionKind.h"
21 #include "llvm/Target/TargetMachine.h"
22 #include <cassert>
23 
24 using namespace llvm;
25 using namespace dwarf;
26 
27 //===----------------------------------------------------------------------===//
28 //                               ELF Target
29 //===----------------------------------------------------------------------===//
30 
31 void ARMElfTargetObjectFile::Initialize(MCContext &Ctx,
32                                         const TargetMachine &TM) {
33   const ARMBaseTargetMachine &ARM_TM = static_cast<const ARMBaseTargetMachine &>(TM);
34   bool isAAPCS_ABI = ARM_TM.TargetABI == ARMBaseTargetMachine::ARMABI::ARM_ABI_AAPCS;
35   //  genExecuteOnly = ARM_TM.getSubtargetImpl()->genExecuteOnly();
36 
37   TargetLoweringObjectFileELF::Initialize(Ctx, TM);
38   InitializeELF(isAAPCS_ABI);
39 
40   if (isAAPCS_ABI) {
41     LSDASection = nullptr;
42   }
43 
44   AttributesSection =
45       getContext().getELFSection(".ARM.attributes", ELF::SHT_ARM_ATTRIBUTES, 0);
46 }
47 
48 const MCExpr *ARMElfTargetObjectFile::getTTypeGlobalReference(
49     const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM,
50     MachineModuleInfo *MMI, MCStreamer &Streamer) const {
51   if (TM.getMCAsmInfo()->getExceptionHandlingType() != ExceptionHandling::ARM)
52     return TargetLoweringObjectFileELF::getTTypeGlobalReference(
53         GV, Encoding, TM, MMI, Streamer);
54 
55   assert(Encoding == DW_EH_PE_absptr && "Can handle absptr encoding only");
56 
57   return MCSymbolRefExpr::create(TM.getSymbol(GV),
58                                  MCSymbolRefExpr::VK_ARM_TARGET2, getContext());
59 }
60 
61 const MCExpr *ARMElfTargetObjectFile::
62 getDebugThreadLocalSymbol(const MCSymbol *Sym) const {
63   return MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_ARM_TLSLDO,
64                                  getContext());
65 }
66 
67 static bool isExecuteOnlyFunction(const GlobalObject *GO, SectionKind SK,
68                                   const TargetMachine &TM) {
69   if (const Function *F = dyn_cast<Function>(GO))
70     if (TM.getSubtarget<ARMSubtarget>(*F).genExecuteOnly() && SK.isText())
71       return true;
72   return false;
73 }
74 
75 MCSection *ARMElfTargetObjectFile::getExplicitSectionGlobal(
76     const GlobalObject *GO, SectionKind SK, const TargetMachine &TM) const {
77   // Set execute-only access for the explicit section
78   if (isExecuteOnlyFunction(GO, SK, TM))
79     SK = SectionKind::getExecuteOnly();
80 
81   return TargetLoweringObjectFileELF::getExplicitSectionGlobal(GO, SK, TM);
82 }
83 
84 MCSection *ARMElfTargetObjectFile::SelectSectionForGlobal(
85     const GlobalObject *GO, SectionKind SK, const TargetMachine &TM) const {
86   // Place the global in the execute-only text section
87   if (isExecuteOnlyFunction(GO, SK, TM))
88     SK = SectionKind::getExecuteOnly();
89 
90   return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, SK, TM);
91 }
92