123 lines
4.0 KiB
C++
123 lines
4.0 KiB
C++
//===- AArch64TargetStreamer.cpp - AArch64TargetStreamer class ------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the AArch64TargetStreamer class.
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//
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//===----------------------------------------------------------------------===//
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#include "AArch64TargetStreamer.h"
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#include "AArch64MCAsmInfo.h"
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#include "AArch64Subtarget.h"
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#include "llvm/BinaryFormat/ELF.h"
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#include "llvm/MC/ConstantPools.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCSection.h"
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#include "llvm/MC/MCSectionELF.h"
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#include "llvm/MC/MCSubtargetInfo.h"
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#include "llvm/Support/CommandLine.h"
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using namespace llvm;
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static cl::opt<bool> MarkBTIProperty(
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"aarch64-mark-bti-property", cl::Hidden,
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cl::desc("Add .note.gnu.property with BTI to assembly files"),
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cl::init(false));
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//
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// AArch64TargetStreamer Implemenation
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//
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AArch64TargetStreamer::AArch64TargetStreamer(MCStreamer &S)
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: MCTargetStreamer(S), ConstantPools(new AssemblerConstantPools()) {}
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AArch64TargetStreamer::~AArch64TargetStreamer() = default;
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// The constant pool handling is shared by all AArch64TargetStreamer
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// implementations.
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const MCExpr *AArch64TargetStreamer::addConstantPoolEntry(const MCExpr *Expr,
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unsigned Size,
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SMLoc Loc) {
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return ConstantPools->addEntry(Streamer, Expr, Size, Loc);
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}
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void AArch64TargetStreamer::emitCurrentConstantPool() {
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ConstantPools->emitForCurrentSection(Streamer);
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}
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// finish() - write out any non-empty assembler constant pools and
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// write out note.gnu.properties if need.
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void AArch64TargetStreamer::finish() {
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ConstantPools->emitAll(Streamer);
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if (MarkBTIProperty)
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emitNoteSection(ELF::GNU_PROPERTY_AARCH64_FEATURE_1_BTI);
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}
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void AArch64TargetStreamer::emitNoteSection(unsigned Flags) {
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if (Flags == 0)
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return;
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MCStreamer &OutStreamer = getStreamer();
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MCContext &Context = OutStreamer.getContext();
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// Emit a .note.gnu.property section with the flags.
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MCSectionELF *Nt = Context.getELFSection(".note.gnu.property", ELF::SHT_NOTE,
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ELF::SHF_ALLOC);
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if (Nt->isRegistered()) {
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SMLoc Loc;
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Context.reportWarning(
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Loc,
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"The .note.gnu.property is not emitted because it is already present.");
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return;
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}
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MCSection *Cur = OutStreamer.getCurrentSectionOnly();
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OutStreamer.SwitchSection(Nt);
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// Emit the note header.
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OutStreamer.emitValueToAlignment(Align(8).value());
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OutStreamer.emitIntValue(4, 4); // data size for "GNU\0"
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OutStreamer.emitIntValue(4 * 4, 4); // Elf_Prop size
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OutStreamer.emitIntValue(ELF::NT_GNU_PROPERTY_TYPE_0, 4);
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OutStreamer.emitBytes(StringRef("GNU", 4)); // note name
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// Emit the PAC/BTI properties.
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OutStreamer.emitIntValue(ELF::GNU_PROPERTY_AARCH64_FEATURE_1_AND, 4);
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OutStreamer.emitIntValue(4, 4); // data size
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OutStreamer.emitIntValue(Flags, 4); // data
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OutStreamer.emitIntValue(0, 4); // pad
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OutStreamer.endSection(Nt);
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OutStreamer.SwitchSection(Cur);
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}
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void AArch64TargetStreamer::emitInst(uint32_t Inst) {
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char Buffer[4];
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// We can't just use EmitIntValue here, as that will swap the
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// endianness on big-endian systems (instructions are always
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// little-endian).
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for (unsigned I = 0; I < 4; ++I) {
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Buffer[I] = uint8_t(Inst);
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Inst >>= 8;
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}
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getStreamer().emitBytes(StringRef(Buffer, 4));
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}
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namespace llvm {
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MCTargetStreamer *
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createAArch64ObjectTargetStreamer(MCStreamer &S, const MCSubtargetInfo &STI) {
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const Triple &TT = STI.getTargetTriple();
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if (TT.isOSBinFormatELF())
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return new AArch64TargetELFStreamer(S);
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if (TT.isOSBinFormatCOFF())
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return new AArch64TargetWinCOFFStreamer(S);
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return nullptr;
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}
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} // end namespace llvm
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