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| //===-- llvm/Target/ARMTargetObjectFile.cpp - ARM Object Info Impl --------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "ARMTargetObjectFile.h"
#include "ARMSubtarget.h"
#include "ARMTargetMachine.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCTargetOptions.h"
#include "llvm/MC/SectionKind.h"
#include "llvm/Target/TargetMachine.h"
#include <cassert>
using namespace llvm;
using namespace dwarf;
//===----------------------------------------------------------------------===//
// ELF Target
//===----------------------------------------------------------------------===//
void ARMElfTargetObjectFile::Initialize(MCContext &Ctx,
const TargetMachine &TM) {
const ARMBaseTargetMachine &ARM_TM = static_cast<const ARMBaseTargetMachine &>(TM);
bool isAAPCS_ABI = ARM_TM.TargetABI == ARMBaseTargetMachine::ARMABI::ARM_ABI_AAPCS;
bool genExecuteOnly =
ARM_TM.getMCSubtargetInfo()->hasFeature(ARM::FeatureExecuteOnly);
TargetLoweringObjectFileELF::Initialize(Ctx, TM);
InitializeELF(isAAPCS_ABI);
if (isAAPCS_ABI) {
LSDASection = nullptr;
}
// Make code section unreadable when in execute-only mode
if (genExecuteOnly) {
unsigned Type = ELF::SHT_PROGBITS;
unsigned Flags =
ELF::SHF_EXECINSTR | ELF::SHF_ALLOC | ELF::SHF_ARM_PURECODE;
// Since we cannot modify flags for an existing section, we create a new
// section with the right flags, and use 0 as the unique ID for
// execute-only text
TextSection = Ctx.getELFSection(".text", Type, Flags, 0, "", 0U);
}
}
const MCExpr *ARMElfTargetObjectFile::getTTypeGlobalReference(
const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM,
MachineModuleInfo *MMI, MCStreamer &Streamer) const {
if (TM.getMCAsmInfo()->getExceptionHandlingType() != ExceptionHandling::ARM)
return TargetLoweringObjectFileELF::getTTypeGlobalReference(
GV, Encoding, TM, MMI, Streamer);
assert(Encoding == DW_EH_PE_absptr && "Can handle absptr encoding only");
return MCSymbolRefExpr::create(TM.getSymbol(GV),
MCSymbolRefExpr::VK_ARM_TARGET2, getContext());
}
const MCExpr *ARMElfTargetObjectFile::
getDebugThreadLocalSymbol(const MCSymbol *Sym) const {
return MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_ARM_TLSLDO,
getContext());
}
static bool isExecuteOnlyFunction(const GlobalObject *GO, SectionKind SK,
const TargetMachine &TM) {
if (const Function *F = dyn_cast<Function>(GO))
if (TM.getSubtarget<ARMSubtarget>(*F).genExecuteOnly() && SK.isText())
return true;
return false;
}
MCSection *ARMElfTargetObjectFile::getExplicitSectionGlobal(
const GlobalObject *GO, SectionKind SK, const TargetMachine &TM) const {
// Set execute-only access for the explicit section
if (isExecuteOnlyFunction(GO, SK, TM))
SK = SectionKind::getExecuteOnly();
return TargetLoweringObjectFileELF::getExplicitSectionGlobal(GO, SK, TM);
}
MCSection *ARMElfTargetObjectFile::SelectSectionForGlobal(
const GlobalObject *GO, SectionKind SK, const TargetMachine &TM) const {
// Place the global in the execute-only text section
if (isExecuteOnlyFunction(GO, SK, TM))
SK = SectionKind::getExecuteOnly();
return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, SK, TM);
}
|