123 lines · cpp
1//===-- llvm/Target/ARMTargetObjectFile.cpp - ARM Object Info Impl --------===//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-exception6//7//===----------------------------------------------------------------------===//8 9#include "ARMTargetObjectFile.h"10#include "ARMSubtarget.h"11#include "ARMTargetMachine.h"12#include "MCTargetDesc/ARMMCAsmInfo.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/MCValue.h"20#include "llvm/MC/SectionKind.h"21#include "llvm/Target/TargetMachine.h"22#include <cassert>23 24using namespace llvm;25using namespace dwarf;26 27//===----------------------------------------------------------------------===//28// ELF Target29//===----------------------------------------------------------------------===//30 31ARMElfTargetObjectFile::ARMElfTargetObjectFile() {32 PLTRelativeSpecifier = ARM::S_PREL31;33 SupportIndirectSymViaGOTPCRel = true;34}35 36void ARMElfTargetObjectFile::Initialize(MCContext &Ctx,37 const TargetMachine &TM) {38 const ARMBaseTargetMachine &ARM_TM = static_cast<const ARMBaseTargetMachine &>(TM);39 bool isAAPCS_ABI = ARM_TM.TargetABI == ARM::ARMABI::ARM_ABI_AAPCS;40 bool genExecuteOnly =41 ARM_TM.getMCSubtargetInfo()->hasFeature(ARM::FeatureExecuteOnly);42 43 TargetLoweringObjectFileELF::Initialize(Ctx, TM);44 InitializeELF(isAAPCS_ABI);45 46 if (isAAPCS_ABI) {47 LSDASection = nullptr;48 }49 50 // Make code section unreadable when in execute-only mode51 if (genExecuteOnly) {52 unsigned Type = ELF::SHT_PROGBITS;53 unsigned Flags =54 ELF::SHF_EXECINSTR | ELF::SHF_ALLOC | ELF::SHF_ARM_PURECODE;55 // Since we cannot modify flags for an existing section, we create a new56 // section with the right flags, and use 0 as the unique ID for57 // execute-only text58 TextSection =59 Ctx.getELFSection(".text", Type, Flags, 0, "", false, 0U, nullptr);60 }61}62 63MCRegister ARMElfTargetObjectFile::getStaticBase() const { return ARM::R9; }64 65const MCExpr *ARMElfTargetObjectFile::getIndirectSymViaGOTPCRel(66 const GlobalValue *GV, const MCSymbol *Sym, const MCValue &MV,67 int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const {68 int64_t FinalOffset = Offset + MV.getConstant();69 const MCExpr *Res =70 MCSymbolRefExpr::create(Sym, ARM::S_GOT_PREL, getContext());71 const MCExpr *Off = MCConstantExpr::create(FinalOffset, getContext());72 return MCBinaryExpr::createAdd(Res, Off, getContext());73}74 75const MCExpr *ARMElfTargetObjectFile::76getIndirectSymViaRWPI(const MCSymbol *Sym) const {77 return MCSymbolRefExpr::create(Sym, ARM::S_SBREL, getContext());78}79 80const MCExpr *ARMElfTargetObjectFile::getTTypeGlobalReference(81 const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM,82 MachineModuleInfo *MMI, MCStreamer &Streamer) const {83 if (TM.getMCAsmInfo()->getExceptionHandlingType() != ExceptionHandling::ARM)84 return TargetLoweringObjectFileELF::getTTypeGlobalReference(85 GV, Encoding, TM, MMI, Streamer);86 87 assert(Encoding == DW_EH_PE_absptr && "Can handle absptr encoding only");88 89 return MCSymbolRefExpr::create(TM.getSymbol(GV), ARM::S_TARGET2,90 getContext());91}92 93const MCExpr *ARMElfTargetObjectFile::94getDebugThreadLocalSymbol(const MCSymbol *Sym) const {95 return MCSymbolRefExpr::create(Sym, ARM::S_TLSLDO, getContext());96}97 98static bool isExecuteOnlyFunction(const GlobalObject *GO, SectionKind SK,99 const TargetMachine &TM) {100 if (const Function *F = dyn_cast<Function>(GO))101 if (TM.getSubtarget<ARMSubtarget>(*F).genExecuteOnly() && SK.isText())102 return true;103 return false;104}105 106MCSection *ARMElfTargetObjectFile::getExplicitSectionGlobal(107 const GlobalObject *GO, SectionKind SK, const TargetMachine &TM) const {108 // Set execute-only access for the explicit section109 if (isExecuteOnlyFunction(GO, SK, TM))110 SK = SectionKind::getExecuteOnly();111 112 return TargetLoweringObjectFileELF::getExplicitSectionGlobal(GO, SK, TM);113}114 115MCSection *ARMElfTargetObjectFile::SelectSectionForGlobal(116 const GlobalObject *GO, SectionKind SK, const TargetMachine &TM) const {117 // Place the global in the execute-only text section118 if (isExecuteOnlyFunction(GO, SK, TM))119 SK = SectionKind::getExecuteOnly();120 121 return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, SK, TM);122}123