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llvm-for-llvmta/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.cpp

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//===- lib/MC/AArch64ELFStreamer.cpp - ELF Object Output for AArch64 ------===//
//
// 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 assembles .s files and emits AArch64 ELF .o object files. Different
// from generic ELF streamer in emitting mapping symbols ($x and $d) to delimit
// regions of data and code.
//
//===----------------------------------------------------------------------===//
#include "AArch64TargetStreamer.h"
#include "AArch64WinCOFFStreamer.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Triple.h"
#include "llvm/ADT/Twine.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCELFStreamer.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCSymbolELF.h"
#include "llvm/MC/MCWinCOFFStreamer.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace {
class AArch64ELFStreamer;
class AArch64TargetAsmStreamer : public AArch64TargetStreamer {
formatted_raw_ostream &OS;
void emitInst(uint32_t Inst) override;
void emitDirectiveVariantPCS(MCSymbol *Symbol) override {
OS << "\t.variant_pcs " << Symbol->getName() << "\n";
}
void EmitARM64WinCFIAllocStack(unsigned Size) override {
OS << "\t.seh_stackalloc " << Size << "\n";
}
void EmitARM64WinCFISaveR19R20X(int Offset) override {
OS << "\t.seh_save_r19r20_x " << Offset << "\n";
}
void EmitARM64WinCFISaveFPLR(int Offset) override {
OS << "\t.seh_save_fplr " << Offset << "\n";
}
void EmitARM64WinCFISaveFPLRX(int Offset) override {
OS << "\t.seh_save_fplr_x " << Offset << "\n";
}
void EmitARM64WinCFISaveReg(unsigned Reg, int Offset) override {
OS << "\t.seh_save_reg x" << Reg << ", " << Offset << "\n";
}
void EmitARM64WinCFISaveRegX(unsigned Reg, int Offset) override {
OS << "\t.seh_save_reg_x x" << Reg << ", " << Offset << "\n";
}
void EmitARM64WinCFISaveRegP(unsigned Reg, int Offset) override {
OS << "\t.seh_save_regp x" << Reg << ", " << Offset << "\n";
}
void EmitARM64WinCFISaveRegPX(unsigned Reg, int Offset) override {
OS << "\t.seh_save_regp_x x" << Reg << ", " << Offset << "\n";
}
void EmitARM64WinCFISaveLRPair(unsigned Reg, int Offset) override {
OS << "\t.seh_save_lrpair x" << Reg << ", " << Offset << "\n";
}
void EmitARM64WinCFISaveFReg(unsigned Reg, int Offset) override {
OS << "\t.seh_save_freg d" << Reg << ", " << Offset << "\n";
}
void EmitARM64WinCFISaveFRegX(unsigned Reg, int Offset) override {
OS << "\t.seh_save_freg_x d" << Reg << ", " << Offset << "\n";
}
void EmitARM64WinCFISaveFRegP(unsigned Reg, int Offset) override {
OS << "\t.seh_save_fregp d" << Reg << ", " << Offset << "\n";
}
void EmitARM64WinCFISaveFRegPX(unsigned Reg, int Offset) override {
OS << "\t.seh_save_fregp_x d" << Reg << ", " << Offset << "\n";
}
void EmitARM64WinCFISetFP() override { OS << "\t.seh_set_fp\n"; }
void EmitARM64WinCFIAddFP(unsigned Size) override {
OS << "\t.seh_add_fp " << Size << "\n";
}
void EmitARM64WinCFINop() override { OS << "\t.seh_nop\n"; }
void EmitARM64WinCFISaveNext() override { OS << "\t.seh_save_next\n"; }
void EmitARM64WinCFIPrologEnd() override { OS << "\t.seh_endprologue\n"; }
void EmitARM64WinCFIEpilogStart() override { OS << "\t.seh_startepilogue\n"; }
void EmitARM64WinCFIEpilogEnd() override { OS << "\t.seh_endepilogue\n"; }
void EmitARM64WinCFITrapFrame() override { OS << "\t.seh_trap_frame\n"; }
void EmitARM64WinCFIMachineFrame() override { OS << "\t.seh_pushframe\n"; }
void EmitARM64WinCFIContext() override { OS << "\t.seh_context\n"; }
void EmitARM64WinCFIClearUnwoundToCall() override {
OS << "\t.seh_clear_unwound_to_call\n";
}
public:
AArch64TargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS);
};
AArch64TargetAsmStreamer::AArch64TargetAsmStreamer(MCStreamer &S,
formatted_raw_ostream &OS)
: AArch64TargetStreamer(S), OS(OS) {}
void AArch64TargetAsmStreamer::emitInst(uint32_t Inst) {
OS << "\t.inst\t0x" << Twine::utohexstr(Inst) << "\n";
}
/// Extend the generic ELFStreamer class so that it can emit mapping symbols at
/// the appropriate points in the object files. These symbols are defined in the
/// AArch64 ELF ABI:
/// infocenter.arm.com/help/topic/com.arm.doc.ihi0056a/IHI0056A_aaelf64.pdf
///
/// In brief: $x or $d should be emitted at the start of each contiguous region
/// of A64 code or data in a section. In practice, this emission does not rely
/// on explicit assembler directives but on inherent properties of the
/// directives doing the emission (e.g. ".byte" is data, "add x0, x0, x0" an
/// instruction).
///
/// As a result this system is orthogonal to the DataRegion infrastructure used
/// by MachO. Beware!
class AArch64ELFStreamer : public MCELFStreamer {
public:
AArch64ELFStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> TAB,
std::unique_ptr<MCObjectWriter> OW,
std::unique_ptr<MCCodeEmitter> Emitter)
: MCELFStreamer(Context, std::move(TAB), std::move(OW),
std::move(Emitter)),
MappingSymbolCounter(0), LastEMS(EMS_None) {}
void changeSection(MCSection *Section, const MCExpr *Subsection) override {
// We have to keep track of the mapping symbol state of any sections we
// use. Each one should start off as EMS_None, which is provided as the
// default constructor by DenseMap::lookup.
LastMappingSymbols[getPreviousSection().first] = LastEMS;
LastEMS = LastMappingSymbols.lookup(Section);
MCELFStreamer::changeSection(Section, Subsection);
}
// Reset state between object emissions
void reset() override {
MappingSymbolCounter = 0;
MCELFStreamer::reset();
LastMappingSymbols.clear();
LastEMS = EMS_None;
}
/// This function is the one used to emit instruction data into the ELF
/// streamer. We override it to add the appropriate mapping symbol if
/// necessary.
void emitInstruction(const MCInst &Inst,
const MCSubtargetInfo &STI) override {
EmitA64MappingSymbol();
MCELFStreamer::emitInstruction(Inst, STI);
}
/// Emit a 32-bit value as an instruction. This is only used for the .inst
/// directive, EmitInstruction should be used in other cases.
void emitInst(uint32_t Inst) {
char Buffer[4];
// We can't just use EmitIntValue here, as that will emit a data mapping
// symbol, and 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;
}
EmitA64MappingSymbol();
MCELFStreamer::emitBytes(StringRef(Buffer, 4));
}
/// This is one of the functions used to emit data into an ELF section, so the
/// AArch64 streamer overrides it to add the appropriate mapping symbol ($d)
/// if necessary.
void emitBytes(StringRef Data) override {
emitDataMappingSymbol();
MCELFStreamer::emitBytes(Data);
}
/// This is one of the functions used to emit data into an ELF section, so the
/// AArch64 streamer overrides it to add the appropriate mapping symbol ($d)
/// if necessary.
void emitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) override {
emitDataMappingSymbol();
MCELFStreamer::emitValueImpl(Value, Size, Loc);
}
void emitFill(const MCExpr &NumBytes, uint64_t FillValue,
SMLoc Loc) override {
emitDataMappingSymbol();
MCObjectStreamer::emitFill(NumBytes, FillValue, Loc);
}
private:
enum ElfMappingSymbol {
EMS_None,
EMS_A64,
EMS_Data
};
void emitDataMappingSymbol() {
if (LastEMS == EMS_Data)
return;
EmitMappingSymbol("$d");
LastEMS = EMS_Data;
}
void EmitA64MappingSymbol() {
if (LastEMS == EMS_A64)
return;
EmitMappingSymbol("$x");
LastEMS = EMS_A64;
}
void EmitMappingSymbol(StringRef Name) {
auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol(
Name + "." + Twine(MappingSymbolCounter++)));
emitLabel(Symbol);
Symbol->setType(ELF::STT_NOTYPE);
Symbol->setBinding(ELF::STB_LOCAL);
Symbol->setExternal(false);
}
int64_t MappingSymbolCounter;
DenseMap<const MCSection *, ElfMappingSymbol> LastMappingSymbols;
ElfMappingSymbol LastEMS;
};
} // end anonymous namespace
namespace llvm {
AArch64ELFStreamer &AArch64TargetELFStreamer::getStreamer() {
return static_cast<AArch64ELFStreamer &>(Streamer);
}
void AArch64TargetELFStreamer::emitInst(uint32_t Inst) {
getStreamer().emitInst(Inst);
}
void AArch64TargetELFStreamer::emitDirectiveVariantPCS(MCSymbol *Symbol) {
cast<MCSymbolELF>(Symbol)->setOther(ELF::STO_AARCH64_VARIANT_PCS);
}
MCTargetStreamer *createAArch64AsmTargetStreamer(MCStreamer &S,
formatted_raw_ostream &OS,
MCInstPrinter *InstPrint,
bool isVerboseAsm) {
return new AArch64TargetAsmStreamer(S, OS);
}
MCELFStreamer *createAArch64ELFStreamer(MCContext &Context,
std::unique_ptr<MCAsmBackend> TAB,
std::unique_ptr<MCObjectWriter> OW,
std::unique_ptr<MCCodeEmitter> Emitter,
bool RelaxAll) {
AArch64ELFStreamer *S = new AArch64ELFStreamer(
Context, std::move(TAB), std::move(OW), std::move(Emitter));
if (RelaxAll)
S->getAssembler().setRelaxAll(true);
return S;
}
} // end namespace llvm
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