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//===- AArch64TargetStreamer.cpp - AArch64TargetStreamer class ------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements the AArch64TargetStreamer class.
//
//===----------------------------------------------------------------------===//
#include "AArch64TargetStreamer.h"
#include "AArch64MCAsmInfo.h"
#include "AArch64Subtarget.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/MC/ConstantPools.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/Support/CommandLine.h"
using namespace llvm;
static cl::opt<bool> MarkBTIProperty(
"aarch64-mark-bti-property", cl::Hidden,
cl::desc("Add .note.gnu.property with BTI to assembly files"),
cl::init(false));
//
// AArch64TargetStreamer Implemenation
//
AArch64TargetStreamer::AArch64TargetStreamer(MCStreamer &S)
: MCTargetStreamer(S), ConstantPools(new AssemblerConstantPools()) {}
AArch64TargetStreamer::~AArch64TargetStreamer() = default;
// The constant pool handling is shared by all AArch64TargetStreamer
// implementations.
const MCExpr *AArch64TargetStreamer::addConstantPoolEntry(const MCExpr *Expr,
unsigned Size,
SMLoc Loc) {
return ConstantPools->addEntry(Streamer, Expr, Size, Loc);
}
void AArch64TargetStreamer::emitCurrentConstantPool() {
ConstantPools->emitForCurrentSection(Streamer);
}
// finish() - write out any non-empty assembler constant pools and
// write out note.gnu.properties if need.
void AArch64TargetStreamer::finish() {
ConstantPools->emitAll(Streamer);
if (MarkBTIProperty)
emitNoteSection(ELF::GNU_PROPERTY_AARCH64_FEATURE_1_BTI);
}
void AArch64TargetStreamer::emitNoteSection(unsigned Flags) {
if (Flags == 0)
return;
MCStreamer &OutStreamer = getStreamer();
MCContext &Context = OutStreamer.getContext();
// Emit a .note.gnu.property section with the flags.
MCSectionELF *Nt = Context.getELFSection(".note.gnu.property", ELF::SHT_NOTE,
ELF::SHF_ALLOC);
if (Nt->isRegistered()) {
SMLoc Loc;
Context.reportWarning(
Loc,
"The .note.gnu.property is not emitted because it is already present.");
return;
}
MCSection *Cur = OutStreamer.getCurrentSectionOnly();
OutStreamer.SwitchSection(Nt);
// Emit the note header.
OutStreamer.emitValueToAlignment(Align(8).value());
OutStreamer.emitIntValue(4, 4); // data size for "GNU\0"
OutStreamer.emitIntValue(4 * 4, 4); // Elf_Prop size
OutStreamer.emitIntValue(ELF::NT_GNU_PROPERTY_TYPE_0, 4);
OutStreamer.emitBytes(StringRef("GNU", 4)); // note name
// Emit the PAC/BTI properties.
OutStreamer.emitIntValue(ELF::GNU_PROPERTY_AARCH64_FEATURE_1_AND, 4);
OutStreamer.emitIntValue(4, 4); // data size
OutStreamer.emitIntValue(Flags, 4); // data
OutStreamer.emitIntValue(0, 4); // pad
OutStreamer.endSection(Nt);
OutStreamer.SwitchSection(Cur);
}
void AArch64TargetStreamer::emitInst(uint32_t Inst) {
char Buffer[4];
// We can't just use EmitIntValue here, as that will swap the
// endianness on big-endian systems (instructions are always
// little-endian).
for (unsigned I = 0; I < 4; ++I) {
Buffer[I] = uint8_t(Inst);
Inst >>= 8;
}
getStreamer().emitBytes(StringRef(Buffer, 4));
}
namespace llvm {
MCTargetStreamer *
createAArch64ObjectTargetStreamer(MCStreamer &S, const MCSubtargetInfo &STI) {
const Triple &TT = STI.getTargetTriple();
if (TT.isOSBinFormatELF())
return new AArch64TargetELFStreamer(S);
if (TT.isOSBinFormatCOFF())
return new AArch64TargetWinCOFFStreamer(S);
return nullptr;
}
} // end namespace llvm
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