llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.cpp - rust-lang/llvm-project - Git at Google

 //===- 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 "AArch64ELFStreamer.h"
 #include "AArch64MCTargetDesc.h"
 #include "AArch64TargetStreamer.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/StringRef.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/MCELFObjectWriter.h"
 #include "llvm/MC/MCELFStreamer.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCSectionELF.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSubtargetInfo.h"
 #include "llvm/MC/MCSymbolELF.h"
 #include "llvm/MC/MCTargetOptions.h"
 #include "llvm/MC/MCWinCOFFStreamer.h"
 #include "llvm/Support/AArch64BuildAttributes.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;
   std::string VendorTag;

   void emitInst(uint32_t Inst) override;

   void emitDirectiveVariantPCS(MCSymbol *Symbol) override {
     OS << "\t.variant_pcs\t" << Symbol->getName() << "\n";
   }

   void emitARM64WinCFIAllocStack(unsigned Size) override {
     OS << "\t.seh_stackalloc\t" << Size << "\n";
   }
   void emitARM64WinCFISaveR19R20X(int Offset) override {
     OS << "\t.seh_save_r19r20_x\t" << Offset << "\n";
   }
   void emitARM64WinCFISaveFPLR(int Offset) override {
     OS << "\t.seh_save_fplr\t" << Offset << "\n";
   }
   void emitARM64WinCFISaveFPLRX(int Offset) override {
     OS << "\t.seh_save_fplr_x\t" << Offset << "\n";
   }
   void emitARM64WinCFISaveReg(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_reg\tx" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveRegX(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_reg_x\tx" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveRegP(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_regp\tx" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveRegPX(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_regp_x\tx" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveLRPair(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_lrpair\tx" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveFReg(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_freg\td" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveFRegX(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_freg_x\td" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveFRegP(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_fregp\td" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveFRegPX(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_fregp_x\td" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISetFP() override { OS << "\t.seh_set_fp\n"; }
   void emitARM64WinCFIAddFP(unsigned Size) override {
     OS << "\t.seh_add_fp\t" << 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 emitARM64WinCFIECContext() override { OS << "\t.seh_ec_context\n"; }
   void emitARM64WinCFIClearUnwoundToCall() override {
     OS << "\t.seh_clear_unwound_to_call\n";
   }
   void emitARM64WinCFIPACSignLR() override {
     OS << "\t.seh_pac_sign_lr\n";
   }

   void emitARM64WinCFISaveAnyRegI(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_any_reg\tx" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveAnyRegIP(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_any_reg_p\tx" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveAnyRegD(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_any_reg\td" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveAnyRegDP(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_any_reg_p\td" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveAnyRegQ(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_any_reg\tq" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveAnyRegQP(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_any_reg_p\tq" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveAnyRegIX(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_any_reg_x\tx" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveAnyRegIPX(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_any_reg_px\tx" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveAnyRegDX(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_any_reg_x\td" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveAnyRegDPX(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_any_reg_px\td" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveAnyRegQX(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_any_reg_x\tq" << Reg << ", " << Offset << "\n";
   }
   void emitARM64WinCFISaveAnyRegQPX(unsigned Reg, int Offset) override {
     OS << "\t.seh_save_any_reg_px\tq" << Reg << ", " << Offset << "\n";
   }

   void emitAttribute(StringRef VendorName, unsigned Tag, unsigned Value,
                      std::string String, bool Override) override {

     // AArch64 build attributes for assembly attribute form:
     // .aeabi_attribute tag, value
     if (unsigned(-1) == Value && "" == String) {
       assert(0 && "Arguments error");
       return;
     }

     unsigned VendorID = AArch64BuildAttrs::getVendorID(VendorName);

     switch (VendorID) {
     default:
       assert(0 && "Subsection name error");
       break;
     case AArch64BuildAttrs::VENDOR_UNKNOWN:
       if (unsigned(-1) != Value) {
         OS << "\t.aeabi_attribute" << "\t" << Tag << ", " << Value;
         AArch64TargetStreamer::emitAttribute(VendorName, Tag, Value, "",
                                              Override);
       }
       if ("" != String) {
         OS << "\t.aeabi_attribute" << "\t" << Tag << ", " << String;
         AArch64TargetStreamer::emitAttribute(VendorName, Tag, unsigned(-1),
                                              String, Override);
       }
       break;
     // Note: AEABI_FEATURE_AND_BITS takes only unsigned values
     case AArch64BuildAttrs::AEABI_FEATURE_AND_BITS:
       switch (Tag) {
       default: // allow emitting any attribute by number
         OS << "\t.aeabi_attribute" << "\t" << Tag << ", " << Value;
         // Keep the data structure consistent with the case of ELF emission
         // (important for llvm-mc asm parsing)
         AArch64TargetStreamer::emitAttribute(VendorName, Tag, Value, "",
                                              Override);
         break;
       case AArch64BuildAttrs::TAG_FEATURE_BTI:
       case AArch64BuildAttrs::TAG_FEATURE_GCS:
       case AArch64BuildAttrs::TAG_FEATURE_PAC:
         OS << "\t.aeabi_attribute" << "\t"
            << AArch64BuildAttrs::getFeatureAndBitsTagsStr(Tag) << ", " << Value;
         AArch64TargetStreamer::emitAttribute(VendorName, Tag, Value, "",
                                              Override);
         break;
       }
       break;
     // Note: AEABI_PAUTHABI takes only unsigned values
     case AArch64BuildAttrs::AEABI_PAUTHABI:
       switch (Tag) {
       default: // allow emitting any attribute by number
         OS << "\t.aeabi_attribute" << "\t" << Tag << ", " << Value;
         // Keep the data structure consistent with the case of ELF emission
         // (important for llvm-mc asm parsing)
         AArch64TargetStreamer::emitAttribute(VendorName, Tag, Value, "",
                                              Override);
         break;
       case AArch64BuildAttrs::TAG_PAUTH_PLATFORM:
       case AArch64BuildAttrs::TAG_PAUTH_SCHEMA:
         OS << "\t.aeabi_attribute" << "\t"
            << AArch64BuildAttrs::getPauthABITagsStr(Tag) << ", " << Value;
         AArch64TargetStreamer::emitAttribute(VendorName, Tag, Value, "",
                                              Override);
         break;
       }
       break;
     }
     OS << "\n";
   }

   void emitAtributesSubsection(
       StringRef SubsectionName, AArch64BuildAttrs::SubsectionOptional Optional,
       AArch64BuildAttrs::SubsectionType ParameterType) override {
     // The AArch64 build attributes assembly subsection header format:
     // ".aeabi_subsection name, optional, parameter type"
     // optional: required (0) optional (1)
     // parameter type: uleb128 or ULEB128 (0) ntbs or NTBS (1)
     unsigned SubsectionID = AArch64BuildAttrs::getVendorID(SubsectionName);

     assert((0 == Optional || 1 == Optional) &&
            AArch64BuildAttrs::getSubsectionOptionalUnknownError().data());
     assert((0 == ParameterType || 1 == ParameterType) &&
            AArch64BuildAttrs::getSubsectionTypeUnknownError().data());

     std::string SubsectionTag = ".aeabi_subsection";
     StringRef OptionalStr = getOptionalStr(Optional);
     StringRef ParameterStr = getTypeStr(ParameterType);

     switch (SubsectionID) {
     default: {
       // Treated as a private subsection
       break;
     }
     case AArch64BuildAttrs::AEABI_PAUTHABI: {
       assert(AArch64BuildAttrs::REQUIRED == Optional &&
              "subsection .aeabi-pauthabi should be marked as "
              "required and not as optional");
       assert(AArch64BuildAttrs::ULEB128 == ParameterType &&
              "subsection .aeabi-pauthabi should be "
              "marked as uleb128 and not as ntbs");
       break;
     }
     case AArch64BuildAttrs::AEABI_FEATURE_AND_BITS: {
       assert(AArch64BuildAttrs::OPTIONAL == Optional &&
              "subsection .aeabi_feature_and_bits should be "
              "marked as optional and not as required");
       assert(AArch64BuildAttrs::ULEB128 == ParameterType &&
              "subsection .aeabi_feature_and_bits should "
              "be marked as uleb128 and not as ntbs");
       break;
     }
     }
     OS << "\t" << SubsectionTag << "\t" << SubsectionName << ", " << OptionalStr
        << ", " << ParameterStr;
     // Keep the data structure consistent with the case of ELF emission
     // (important for llvm-mc asm parsing)
     AArch64TargetStreamer::emitAtributesSubsection(SubsectionName, Optional,
                                                    ParameterType);
     OS << "\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:
   friend AArch64TargetELFStreamer;
   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)),
         LastEMS(EMS_None) {
     auto *TO = getContext().getTargetOptions();
     ImplicitMapSyms = TO && TO->ImplicitMapSyms;
   }

   void changeSection(MCSection *Section, uint32_t Subsection = 0) override {
     // Save the mapping symbol state for potential reuse when revisiting the
     // section. When ImplicitMapSyms is true, the initial state is
     // EMS_A64 for text sections and EMS_Data for the others.
     LastMappingSymbols[getCurrentSection().first] = LastEMS;
     auto It = LastMappingSymbols.find(Section);
     if (It != LastMappingSymbols.end())
       LastEMS = It->second;
     else if (ImplicitMapSyms)
       LastEMS = Section->isText() ? EMS_A64 : EMS_Data;
     else
       LastEMS = EMS_None;

     MCELFStreamer::changeSection(Section, Subsection);
   }

   // Reset state between object emissions
   void reset() override {
     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 (char &C : Buffer) {
       C = 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;
   }

   MCSymbol *emitMappingSymbol(StringRef Name) {
     auto *Symbol = cast<MCSymbolELF>(getContext().createLocalSymbol(Name));
     emitLabel(Symbol);
     return Symbol;
   }

   DenseMap<const MCSection *, ElfMappingSymbol> LastMappingSymbols;
   ElfMappingSymbol LastEMS;
   bool ImplicitMapSyms;
 };
 } // end anonymous namespace

 AArch64ELFStreamer &AArch64TargetELFStreamer::getStreamer() {
   return static_cast<AArch64ELFStreamer &>(Streamer);
 }

 void AArch64TargetELFStreamer::emitAtributesSubsection(
     StringRef VendorName, AArch64BuildAttrs::SubsectionOptional IsOptional,
     AArch64BuildAttrs::SubsectionType ParameterType) {
   AArch64TargetStreamer::emitAtributesSubsection(VendorName, IsOptional,
                                                  ParameterType);
 }

 void AArch64TargetELFStreamer::emitAttribute(StringRef VendorName, unsigned Tag,
                                              unsigned Value, std::string String,
                                              bool Override) {
   if (unsigned(-1) != Value)
     AArch64TargetStreamer::emitAttribute(VendorName, Tag, Value, "", Override);
   if ("" != String)
     AArch64TargetStreamer::emitAttribute(VendorName, Tag, unsigned(-1), String,
                                          Override);
 }

 void AArch64TargetELFStreamer::emitInst(uint32_t Inst) {
   getStreamer().emitInst(Inst);
 }

 void AArch64TargetELFStreamer::emitDirectiveVariantPCS(MCSymbol *Symbol) {
   getStreamer().getAssembler().registerSymbol(*Symbol);
   cast<MCSymbolELF>(Symbol)->setOther(ELF::STO_AARCH64_VARIANT_PCS);
 }

 void AArch64TargetELFStreamer::finish() {
   AArch64TargetStreamer::finish();
   AArch64ELFStreamer &S = getStreamer();
   MCContext &Ctx = S.getContext();
   auto &Asm = S.getAssembler();

   S.emitAttributesSection(AttributeSection, ".ARM.attributes",
                           ELF::SHT_AARCH64_ATTRIBUTES, AttributeSubSections);

   // If ImplicitMapSyms is specified, ensure that text sections end with
   // the A64 state while non-text sections end with the data state. When
   // sections are combined by the linker, the subsequent section will start with
   // the right state. The ending mapping symbol is added right after the last
   // symbol relative to the section. When a dumb linker combines (.text.0; .word
   // 0) and (.text.1; .word 0), the ending $x of .text.0 precedes the $d of
   // .text.1, even if they have the same address.
   if (S.ImplicitMapSyms) {
     auto &Syms = Asm.getSymbols();
     const size_t NumSyms = Syms.size();
     DenseMap<MCSection *, std::pair<size_t, MCSymbol *>> EndMapSym;
     for (MCSection &Sec : Asm) {
       S.switchSection(&Sec);
       if (S.LastEMS == (Sec.isText() ? AArch64ELFStreamer::EMS_Data
                                      : AArch64ELFStreamer::EMS_A64))
         EndMapSym.insert(
             {&Sec, {NumSyms, S.emitMappingSymbol(Sec.isText() ? "$x" : "$d")}});
     }
     if (Syms.size() != NumSyms) {
       SmallVector<const MCSymbol *, 0> NewSyms;
       DenseMap<MCSection *, size_t> Cnt;
       Syms.truncate(NumSyms);
       // Find the last symbol index for each candidate section.
       for (auto [I, Sym] : llvm::enumerate(Syms)) {
         if (!Sym->isInSection())
           continue;
         auto It = EndMapSym.find(&Sym->getSection());
         if (It != EndMapSym.end())
           It->second.first = I;
       }
       SmallVector<size_t, 0> Idx;
       for (auto [I, Sym] : llvm::enumerate(Syms)) {
         NewSyms.push_back(Sym);
         if (!Sym->isInSection())
           continue;
         auto It = EndMapSym.find(&Sym->getSection());
         // If `Sym` is the last symbol relative to the section, add the ending
         // mapping symbol after `Sym`.
         if (It != EndMapSym.end() && I == It->second.first) {
           NewSyms.push_back(It->second.second);
           Idx.push_back(I);
         }
       }
       Syms = std::move(NewSyms);
       // F.second holds the number of symbols added before the FILE symbol.
       // Take into account the inserted mapping symbols.
       for (auto &F : S.getWriter().getFileNames())
         F.second += llvm::lower_bound(Idx, F.second) - Idx.begin();
     }
   }

   MCSectionELF *MemtagSec = nullptr;
   for (const MCSymbol &Symbol : Asm.symbols()) {
     const auto &Sym = cast<MCSymbolELF>(Symbol);
     if (Sym.isMemtag()) {
       MemtagSec = Ctx.getELFSection(".memtag.globals.static",
                                     ELF::SHT_AARCH64_MEMTAG_GLOBALS_STATIC, 0);
       break;
     }
   }
   if (!MemtagSec)
     return;

   // switchSection registers the section symbol and invalidates symbols(). We
   // need a separate symbols() loop.
   S.switchSection(MemtagSec);
   const auto *Zero = MCConstantExpr::create(0, Ctx);
   for (const MCSymbol &Symbol : Asm.symbols()) {
     const auto &Sym = cast<MCSymbolELF>(Symbol);
     if (!Sym.isMemtag())
       continue;
     auto *SRE = MCSymbolRefExpr::create(&Sym, MCSymbolRefExpr::VK_None, Ctx);
     (void)S.emitRelocDirective(*Zero, "BFD_RELOC_NONE", SRE, SMLoc(),
                                *Ctx.getSubtargetInfo());
   }
 }

 MCTargetStreamer *
 llvm::createAArch64AsmTargetStreamer(MCStreamer &S, formatted_raw_ostream &OS,
                                      MCInstPrinter *InstPrint) {
   return new AArch64TargetAsmStreamer(S, OS);
 }

 MCELFStreamer *
 llvm::createAArch64ELFStreamer(MCContext &Context,
                                std::unique_ptr<MCAsmBackend> TAB,
                                std::unique_ptr<MCObjectWriter> OW,
                                std::unique_ptr<MCCodeEmitter> Emitter) {
   AArch64ELFStreamer *S = new AArch64ELFStreamer(
       Context, std::move(TAB), std::move(OW), std::move(Emitter));
   return S;
 }
	//===- 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 "AArch64ELFStreamer.h"
	#include "AArch64MCTargetDesc.h"
	#include "AArch64TargetStreamer.h"
	#include "llvm/ADT/DenseMap.h"
	#include "llvm/ADT/StringRef.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/MCELFObjectWriter.h"
	#include "llvm/MC/MCELFStreamer.h"
	#include "llvm/MC/MCExpr.h"
	#include "llvm/MC/MCInst.h"
	#include "llvm/MC/MCSectionELF.h"
	#include "llvm/MC/MCStreamer.h"
	#include "llvm/MC/MCSubtargetInfo.h"
	#include "llvm/MC/MCSymbolELF.h"
	#include "llvm/MC/MCTargetOptions.h"
	#include "llvm/MC/MCWinCOFFStreamer.h"
	#include "llvm/Support/AArch64BuildAttributes.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;
	std::string VendorTag;

	void emitInst(uint32_t Inst) override;

	void emitDirectiveVariantPCS(MCSymbol *Symbol) override {
	OS << "\t.variant_pcs\t" << Symbol->getName() << "\n";
	}

	void emitARM64WinCFIAllocStack(unsigned Size) override {
	OS << "\t.seh_stackalloc\t" << Size << "\n";
	}
	void emitARM64WinCFISaveR19R20X(int Offset) override {
	OS << "\t.seh_save_r19r20_x\t" << Offset << "\n";
	}
	void emitARM64WinCFISaveFPLR(int Offset) override {
	OS << "\t.seh_save_fplr\t" << Offset << "\n";
	}
	void emitARM64WinCFISaveFPLRX(int Offset) override {
	OS << "\t.seh_save_fplr_x\t" << Offset << "\n";
	}
	void emitARM64WinCFISaveReg(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_reg\tx" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveRegX(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_reg_x\tx" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveRegP(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_regp\tx" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveRegPX(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_regp_x\tx" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveLRPair(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_lrpair\tx" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveFReg(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_freg\td" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveFRegX(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_freg_x\td" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveFRegP(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_fregp\td" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveFRegPX(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_fregp_x\td" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISetFP() override { OS << "\t.seh_set_fp\n"; }
	void emitARM64WinCFIAddFP(unsigned Size) override {
	OS << "\t.seh_add_fp\t" << 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 emitARM64WinCFIECContext() override { OS << "\t.seh_ec_context\n"; }
	void emitARM64WinCFIClearUnwoundToCall() override {
	OS << "\t.seh_clear_unwound_to_call\n";
	}
	void emitARM64WinCFIPACSignLR() override {
	OS << "\t.seh_pac_sign_lr\n";
	}

	void emitARM64WinCFISaveAnyRegI(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_any_reg\tx" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveAnyRegIP(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_any_reg_p\tx" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveAnyRegD(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_any_reg\td" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveAnyRegDP(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_any_reg_p\td" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveAnyRegQ(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_any_reg\tq" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveAnyRegQP(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_any_reg_p\tq" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveAnyRegIX(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_any_reg_x\tx" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveAnyRegIPX(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_any_reg_px\tx" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveAnyRegDX(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_any_reg_x\td" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveAnyRegDPX(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_any_reg_px\td" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveAnyRegQX(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_any_reg_x\tq" << Reg << ", " << Offset << "\n";
	}
	void emitARM64WinCFISaveAnyRegQPX(unsigned Reg, int Offset) override {
	OS << "\t.seh_save_any_reg_px\tq" << Reg << ", " << Offset << "\n";
	}

	void emitAttribute(StringRef VendorName, unsigned Tag, unsigned Value,
	std::string String, bool Override) override {

	// AArch64 build attributes for assembly attribute form:
	// .aeabi_attribute tag, value
	if (unsigned(-1) == Value && "" == String) {
	assert(0 && "Arguments error");
	return;
	}

	unsigned VendorID = AArch64BuildAttrs::getVendorID(VendorName);

	switch (VendorID) {
	default:
	assert(0 && "Subsection name error");
	break;
	case AArch64BuildAttrs::VENDOR_UNKNOWN:
	if (unsigned(-1) != Value) {
	OS << "\t.aeabi_attribute" << "\t" << Tag << ", " << Value;
	AArch64TargetStreamer::emitAttribute(VendorName, Tag, Value, "",
	Override);
	}
	if ("" != String) {
	OS << "\t.aeabi_attribute" << "\t" << Tag << ", " << String;
	AArch64TargetStreamer::emitAttribute(VendorName, Tag, unsigned(-1),
	String, Override);
	}
	break;
	// Note: AEABI_FEATURE_AND_BITS takes only unsigned values
	case AArch64BuildAttrs::AEABI_FEATURE_AND_BITS:
	switch (Tag) {
	default: // allow emitting any attribute by number
	OS << "\t.aeabi_attribute" << "\t" << Tag << ", " << Value;
	// Keep the data structure consistent with the case of ELF emission
	// (important for llvm-mc asm parsing)
	AArch64TargetStreamer::emitAttribute(VendorName, Tag, Value, "",
	Override);
	break;
	case AArch64BuildAttrs::TAG_FEATURE_BTI:
	case AArch64BuildAttrs::TAG_FEATURE_GCS:
	case AArch64BuildAttrs::TAG_FEATURE_PAC:
	OS << "\t.aeabi_attribute" << "\t"
	<< AArch64BuildAttrs::getFeatureAndBitsTagsStr(Tag) << ", " << Value;
	AArch64TargetStreamer::emitAttribute(VendorName, Tag, Value, "",
	Override);
	break;
	}
	break;
	// Note: AEABI_PAUTHABI takes only unsigned values
	case AArch64BuildAttrs::AEABI_PAUTHABI:
	switch (Tag) {
	default: // allow emitting any attribute by number
	OS << "\t.aeabi_attribute" << "\t" << Tag << ", " << Value;
	// Keep the data structure consistent with the case of ELF emission
	// (important for llvm-mc asm parsing)
	AArch64TargetStreamer::emitAttribute(VendorName, Tag, Value, "",
	Override);
	break;
	case AArch64BuildAttrs::TAG_PAUTH_PLATFORM:
	case AArch64BuildAttrs::TAG_PAUTH_SCHEMA:
	OS << "\t.aeabi_attribute" << "\t"
	<< AArch64BuildAttrs::getPauthABITagsStr(Tag) << ", " << Value;
	AArch64TargetStreamer::emitAttribute(VendorName, Tag, Value, "",
	Override);
	break;
	}
	break;
	}
	OS << "\n";
	}

	void emitAtributesSubsection(
	StringRef SubsectionName, AArch64BuildAttrs::SubsectionOptional Optional,
	AArch64BuildAttrs::SubsectionType ParameterType) override {
	// The AArch64 build attributes assembly subsection header format:
	// ".aeabi_subsection name, optional, parameter type"
	// optional: required (0) optional (1)
	// parameter type: uleb128 or ULEB128 (0) ntbs or NTBS (1)
	unsigned SubsectionID = AArch64BuildAttrs::getVendorID(SubsectionName);

	assert((0 == Optional \|\| 1 == Optional) &&
	AArch64BuildAttrs::getSubsectionOptionalUnknownError().data());
	assert((0 == ParameterType \|\| 1 == ParameterType) &&
	AArch64BuildAttrs::getSubsectionTypeUnknownError().data());

	std::string SubsectionTag = ".aeabi_subsection";
	StringRef OptionalStr = getOptionalStr(Optional);
	StringRef ParameterStr = getTypeStr(ParameterType);

	switch (SubsectionID) {
	default: {
	// Treated as a private subsection
	break;
	}
	case AArch64BuildAttrs::AEABI_PAUTHABI: {
	assert(AArch64BuildAttrs::REQUIRED == Optional &&
	"subsection .aeabi-pauthabi should be marked as "
	"required and not as optional");
	assert(AArch64BuildAttrs::ULEB128 == ParameterType &&
	"subsection .aeabi-pauthabi should be "
	"marked as uleb128 and not as ntbs");
	break;
	}
	case AArch64BuildAttrs::AEABI_FEATURE_AND_BITS: {
	assert(AArch64BuildAttrs::OPTIONAL == Optional &&
	"subsection .aeabi_feature_and_bits should be "
	"marked as optional and not as required");
	assert(AArch64BuildAttrs::ULEB128 == ParameterType &&
	"subsection .aeabi_feature_and_bits should "
	"be marked as uleb128 and not as ntbs");
	break;
	}
	}
	OS << "\t" << SubsectionTag << "\t" << SubsectionName << ", " << OptionalStr
	<< ", " << ParameterStr;
	// Keep the data structure consistent with the case of ELF emission
	// (important for llvm-mc asm parsing)
	AArch64TargetStreamer::emitAtributesSubsection(SubsectionName, Optional,
	ParameterType);
	OS << "\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:
	friend AArch64TargetELFStreamer;
	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)),
	LastEMS(EMS_None) {
	auto *TO = getContext().getTargetOptions();
	ImplicitMapSyms = TO && TO->ImplicitMapSyms;
	}

	void changeSection(MCSection *Section, uint32_t Subsection = 0) override {
	// Save the mapping symbol state for potential reuse when revisiting the
	// section. When ImplicitMapSyms is true, the initial state is
	// EMS_A64 for text sections and EMS_Data for the others.
	LastMappingSymbols[getCurrentSection().first] = LastEMS;
	auto It = LastMappingSymbols.find(Section);
	if (It != LastMappingSymbols.end())
	LastEMS = It->second;
	else if (ImplicitMapSyms)
	LastEMS = Section->isText() ? EMS_A64 : EMS_Data;
	else
	LastEMS = EMS_None;

	MCELFStreamer::changeSection(Section, Subsection);
	}

	// Reset state between object emissions
	void reset() override {
	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 (char &C : Buffer) {
	C = 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;
	}

	MCSymbol *emitMappingSymbol(StringRef Name) {
	auto *Symbol = cast<MCSymbolELF>(getContext().createLocalSymbol(Name));
	emitLabel(Symbol);
	return Symbol;
	}

	DenseMap<const MCSection *, ElfMappingSymbol> LastMappingSymbols;
	ElfMappingSymbol LastEMS;
	bool ImplicitMapSyms;
	};
	} // end anonymous namespace

	AArch64ELFStreamer &AArch64TargetELFStreamer::getStreamer() {
	return static_cast<AArch64ELFStreamer &>(Streamer);
	}

	void AArch64TargetELFStreamer::emitAtributesSubsection(
	StringRef VendorName, AArch64BuildAttrs::SubsectionOptional IsOptional,
	AArch64BuildAttrs::SubsectionType ParameterType) {
	AArch64TargetStreamer::emitAtributesSubsection(VendorName, IsOptional,
	ParameterType);
	}

	void AArch64TargetELFStreamer::emitAttribute(StringRef VendorName, unsigned Tag,
	unsigned Value, std::string String,
	bool Override) {
	if (unsigned(-1) != Value)
	AArch64TargetStreamer::emitAttribute(VendorName, Tag, Value, "", Override);
	if ("" != String)
	AArch64TargetStreamer::emitAttribute(VendorName, Tag, unsigned(-1), String,
	Override);
	}

	void AArch64TargetELFStreamer::emitInst(uint32_t Inst) {
	getStreamer().emitInst(Inst);
	}

	void AArch64TargetELFStreamer::emitDirectiveVariantPCS(MCSymbol *Symbol) {
	getStreamer().getAssembler().registerSymbol(*Symbol);
	cast<MCSymbolELF>(Symbol)->setOther(ELF::STO_AARCH64_VARIANT_PCS);
	}

	void AArch64TargetELFStreamer::finish() {
	AArch64TargetStreamer::finish();
	AArch64ELFStreamer &S = getStreamer();
	MCContext &Ctx = S.getContext();
	auto &Asm = S.getAssembler();

	S.emitAttributesSection(AttributeSection, ".ARM.attributes",
	ELF::SHT_AARCH64_ATTRIBUTES, AttributeSubSections);

	// If ImplicitMapSyms is specified, ensure that text sections end with
	// the A64 state while non-text sections end with the data state. When
	// sections are combined by the linker, the subsequent section will start with
	// the right state. The ending mapping symbol is added right after the last
	// symbol relative to the section. When a dumb linker combines (.text.0; .word
	// 0) and (.text.1; .word 0), the ending $x of .text.0 precedes the $d of
	// .text.1, even if they have the same address.
	if (S.ImplicitMapSyms) {
	auto &Syms = Asm.getSymbols();
	const size_t NumSyms = Syms.size();
	DenseMap<MCSection , std::pair<size_t, MCSymbol >> EndMapSym;
	for (MCSection &Sec : Asm) {
	S.switchSection(&Sec);
	if (S.LastEMS == (Sec.isText() ? AArch64ELFStreamer::EMS_Data
	: AArch64ELFStreamer::EMS_A64))
	EndMapSym.insert(
	{&Sec, {NumSyms, S.emitMappingSymbol(Sec.isText() ? "$x" : "$d")}});
	}
	if (Syms.size() != NumSyms) {
	SmallVector<const MCSymbol *, 0> NewSyms;
	DenseMap<MCSection *, size_t> Cnt;
	Syms.truncate(NumSyms);
	// Find the last symbol index for each candidate section.
	for (auto [I, Sym] : llvm::enumerate(Syms)) {
	if (!Sym->isInSection())
	continue;
	auto It = EndMapSym.find(&Sym->getSection());
	if (It != EndMapSym.end())
	It->second.first = I;
	}
	SmallVector<size_t, 0> Idx;
	for (auto [I, Sym] : llvm::enumerate(Syms)) {
	NewSyms.push_back(Sym);
	if (!Sym->isInSection())
	continue;
	auto It = EndMapSym.find(&Sym->getSection());
	// If `Sym` is the last symbol relative to the section, add the ending
	// mapping symbol after `Sym`.
	if (It != EndMapSym.end() && I == It->second.first) {
	NewSyms.push_back(It->second.second);
	Idx.push_back(I);
	}
	}
	Syms = std::move(NewSyms);
	// F.second holds the number of symbols added before the FILE symbol.
	// Take into account the inserted mapping symbols.
	for (auto &F : S.getWriter().getFileNames())
	F.second += llvm::lower_bound(Idx, F.second) - Idx.begin();
	}
	}

	MCSectionELF *MemtagSec = nullptr;
	for (const MCSymbol &Symbol : Asm.symbols()) {
	const auto &Sym = cast<MCSymbolELF>(Symbol);
	if (Sym.isMemtag()) {
	MemtagSec = Ctx.getELFSection(".memtag.globals.static",
	ELF::SHT_AARCH64_MEMTAG_GLOBALS_STATIC, 0);
	break;
	}
	}
	if (!MemtagSec)
	return;

	// switchSection registers the section symbol and invalidates symbols(). We
	// need a separate symbols() loop.
	S.switchSection(MemtagSec);
	const auto *Zero = MCConstantExpr::create(0, Ctx);
	for (const MCSymbol &Symbol : Asm.symbols()) {
	const auto &Sym = cast<MCSymbolELF>(Symbol);
	if (!Sym.isMemtag())
	continue;
	auto *SRE = MCSymbolRefExpr::create(&Sym, MCSymbolRefExpr::VK_None, Ctx);
	(void)S.emitRelocDirective(*Zero, "BFD_RELOC_NONE", SRE, SMLoc(),
	*Ctx.getSubtargetInfo());
	}
	}

	MCTargetStreamer *
	llvm::createAArch64AsmTargetStreamer(MCStreamer &S, formatted_raw_ostream &OS,
	MCInstPrinter *InstPrint) {
	return new AArch64TargetAsmStreamer(S, OS);
	}

	MCELFStreamer *
	llvm::createAArch64ELFStreamer(MCContext &Context,
	std::unique_ptr<MCAsmBackend> TAB,
	std::unique_ptr<MCObjectWriter> OW,
	std::unique_ptr<MCCodeEmitter> Emitter) {
	AArch64ELFStreamer *S = new AArch64ELFStreamer(
	Context, std::move(TAB), std::move(OW), std::move(Emitter));
	return S;
	}