text: //===-- AsmPrinterInlineAsm.cpp - AsmPrinter Inline Asm Handling ----------===//
  //
  // 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 inline assembler pieces of the AsmPrinter class.
  //
  //===----------------------------------------------------------------------===//
  
  #include "llvm/ADT/SmallString.h"
  #include "llvm/ADT/SmallVector.h"
  #include "llvm/ADT/Twine.h"
  #include "llvm/CodeGen/AsmPrinter.h"
  #include "llvm/CodeGen/MachineBasicBlock.h"
  #include "llvm/CodeGen/MachineFunction.h"
  #include "llvm/CodeGen/MachineModuleInfo.h"
  #include "llvm/CodeGen/TargetRegisterInfo.h"
  #include "llvm/CodeGen/TargetSubtargetInfo.h"
  #include "llvm/IR/Constants.h"
  #include "llvm/IR/DataLayout.h"
  #include "llvm/IR/DiagnosticInfo.h"
  #include "llvm/IR/InlineAsm.h"
  #include "llvm/IR/LLVMContext.h"
  #include "llvm/IR/Module.h"
  #include "llvm/MC/MCAsmInfo.h"
  #include "llvm/MC/MCInstrInfo.h"
  #include "llvm/MC/MCParser/MCAsmLexer.h"
  #include "llvm/MC/MCParser/MCTargetAsmParser.h"
  #include "llvm/MC/MCStreamer.h"
  #include "llvm/MC/MCSymbol.h"
  #include "llvm/MC/TargetRegistry.h"
  #include "llvm/Support/ErrorHandling.h"
  #include "llvm/Support/MemoryBuffer.h"
  #include "llvm/Support/SourceMgr.h"
  #include "llvm/Support/raw_ostream.h"
  #include "llvm/Target/TargetMachine.h"
  using namespace llvm;
  
  #define DEBUG_TYPE "asm-printer"
  
  unsigned AsmPrinter::addInlineAsmDiagBuffer(StringRef AsmStr,
                                              const MDNode *LocMDNode) const {
    MCContext &Context = MMI->getContext();
    Context.initInlineSourceManager();
    SourceMgr &SrcMgr = *Context.getInlineSourceManager();
    std::vector<const MDNode *> &LocInfos = Context.getLocInfos();
  
    std::unique_ptr<MemoryBuffer> Buffer;
    // The inline asm source manager will outlive AsmStr, so make a copy of the
    // string for SourceMgr to own.
    Buffer = MemoryBuffer::getMemBufferCopy(AsmStr, "<inline asm>");
  
    // Tell SrcMgr about this buffer, it takes ownership of the buffer.
    unsigned BufNum = SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
  
    // Store LocMDNode in DiagInfo, using BufNum as an identifier.
    if (LocMDNode) {
      LocInfos.resize(BufNum);
      LocInfos[BufNum - 1] = LocMDNode;
    }
  
    return BufNum;
  }
  
  
  /// EmitInlineAsm - Emit a blob of inline asm to the output streamer.
  void AsmPrinter::emitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
                                 const MCTargetOptions &MCOptions,
                                 const MDNode *LocMDNode,
                                 InlineAsm::AsmDialect Dialect) const {
    assert(!Str.empty() && "Can't emit empty inline asm block");
  
    // Remember if the buffer is nul terminated or not so we can avoid a copy.
    bool isNullTerminated = Str.back() == 0;
    if (isNullTerminated)
      Str = Str.substr(0, Str.size()-1);
  
    // If the output streamer does not have mature MC support or the integrated
    // assembler has been disabled or not required, just emit the blob textually.
    // Otherwise parse the asm and emit it via MC support.
    // This is useful in case the asm parser doesn't handle something but the
    // system assembler does.
    const MCAsmInfo *MCAI = TM.getMCAsmInfo();
    assert(MCAI && "No MCAsmInfo");
    if (!MCAI->useIntegratedAssembler() &&
        !MCAI->parseInlineAsmUsingAsmParser() &&
        !OutStreamer->isIntegratedAssemblerRequired()) {
      emitInlineAsmStart();
      OutStreamer->emitRawText(Str);
      emitInlineAsmEnd(STI, nullptr);
      return;
    }
  
    unsigned BufNum = addInlineAsmDiagBuffer(Str, LocMDNode);
    SourceMgr &SrcMgr = *MMI->getContext().getInlineSourceManager();
    SrcMgr.setIncludeDirs(MCOptions.IASSearchPaths);
  
    std::unique_ptr<MCAsmParser> Parser(
        createMCAsmParser(SrcMgr, OutContext, *OutStreamer, *MAI, BufNum));
  
    // Do not use assembler-level information for parsing inline assembly.
    OutStreamer->setUseAssemblerInfoForParsing(false);
  
    // We create a new MCInstrInfo here since we might be at the module level
    // and not have a MachineFunction to initialize the TargetInstrInfo from and
    // we only need MCInstrInfo for asm parsing. We create one unconditionally
    // because it's not subtarget dependent.
    std::unique_ptr<MCInstrInfo> MII(TM.getTarget().createMCInstrInfo());
    assert(MII && "Failed to create instruction info");
    std::unique_ptr<MCTargetAsmParser> TAP(TM.getTarget().createMCAsmParser(
        STI, *Parser, *MII, MCOptions));
    if (!TAP)
      report_fatal_error("Inline asm not supported by this streamer because"
                         " we don't have an asm parser for this target\n");
    Parser->setAssemblerDialect(Dialect);
    Parser->setTargetParser(*TAP.get());
    // Enable lexing Masm binary and hex integer literals in intel inline
    // assembly.
    if (Dialect == InlineAsm::AD_Intel)
      Parser->getLexer().setLexMasmIntegers(true);
  
    emitInlineAsmStart();
    // Don't implicitly switch to the text section before the asm.
    (void)Parser->Run(/*NoInitialTextSection*/ true,
                      /*NoFinalize*/ true);
    emitInlineAsmEnd(STI, &TAP->getSTI());
  }
  
  static void EmitInlineAsmStr(const char *AsmStr, const MachineInstr *MI,
                               MachineModuleInfo *MMI, const MCAsmInfo *MAI,
                               AsmPrinter *AP, uint64_t LocCookie,
                               raw_ostream &OS) {
    bool InputIsIntelDialect = MI->getInlineAsmDialect() == InlineAsm::AD_Intel;
  
    if (InputIsIntelDialect) {
      // Switch to the inline assembly variant.
      OS << "\t.intel_syntax\n\t";
    }
  
    int CurVariant = -1; // The number of the {.|.|.} region we are in.
    const char *LastEmitted = AsmStr; // One past the last character emitted.
    unsigned NumOperands = MI->getNumOperands();
  
    int AsmPrinterVariant;
    if (InputIsIntelDialect)
      AsmPrinterVariant = 1; // X86MCAsmInfo.cpp's AsmWriterFlavorTy::Intel.
    else
      AsmPrinterVariant = MMI->getTarget().unqualifiedInlineAsmVariant();
  
    // FIXME: Should this happen for `asm inteldialect` as well?
    if (!InputIsIntelDialect && MAI->getEmitGNUAsmStartIndentationMarker())
      OS << '\t';
  
    while (*LastEmitted) {
      switch (*LastEmitted) {
      default: {
        // Not a special case, emit the string section literally.
        const char *LiteralEnd = LastEmitted+1;
        while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
               *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
          ++LiteralEnd;
        if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
          OS.write(LastEmitted, LiteralEnd - LastEmitted);
        LastEmitted = LiteralEnd;
        break;
      }
      case '\n':
        ++LastEmitted;   // Consume newline character.
        OS << '\n';      // Indent code with newline.
        break;
      case '$': {
        ++LastEmitted;   // Consume '$' character.
        bool Done = true;
  
        // Handle escapes.
        switch (*LastEmitted) {
        default: Done = false; break;
        case '$':     // $$ -> $
          if (!InputIsIntelDialect)
            if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
              OS << '$';
          ++LastEmitted;  // Consume second '$' character.
          break;
        case '(':        // $( -> same as GCC's { character.
          ++LastEmitted; // Consume '(' character.
          if (CurVariant != -1)
            report_fatal_error("Nested variants found in inline asm string: '" +
                               Twine(AsmStr) + "'");
          CurVariant = 0; // We're in the first variant now.
          break;
        case '|':
          ++LastEmitted; // Consume '|' character.
          if (CurVariant == -1)
            OS << '|'; // This is gcc's behavior for | outside a variant.
          else
            ++CurVariant; // We're in the next variant.
          break;
        case ')':        // $) -> same as GCC's } char.
          ++LastEmitted; // Consume ')' character.
          if (CurVariant == -1)
            OS << '}'; // This is gcc's behavior for } outside a variant.
          else
            CurVariant = -1;
          break;
        }
        if (Done) break;
  
        bool HasCurlyBraces = false;
        if (*LastEmitted == '{') {     // ${variable}
          ++LastEmitted;               // Consume '{' character.
          HasCurlyBraces = true;
        }
  
        // If we have ${:foo}, then this is not a real operand reference, it is a
        // "magic" string reference, just like in .td files.  Arrange to call
        // PrintSpecial.
        if (HasCurlyBraces && *LastEmitted == ':') {
          ++LastEmitted;
          const char *StrStart = LastEmitted;
          const char *StrEnd = strchr(StrStart, '}');
          if (!StrEnd)
            report_fatal_error("Unterminated ${:foo} operand in inline asm"
                               " string: '" + Twine(AsmStr) + "'");
          if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
            AP->PrintSpecial(MI, OS, StringRef(StrStart, StrEnd - StrStart));
          LastEmitted = StrEnd+1;
          break;
        }
  
        const char *IDStart = LastEmitted;
        const char *IDEnd = IDStart;
        while (isDigit(*IDEnd))
          ++IDEnd;
  
        unsigned Val;
        if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
          report_fatal_error("Bad $ operand number in inline asm string: '" +
                             Twine(AsmStr) + "'");
        LastEmitted = IDEnd;
  
        if (Val >= NumOperands - 1)
          report_fatal_error("Invalid $ operand number in inline asm string: '" +
                             Twine(AsmStr) + "'");
  
        char Modifier[2] = { 0, 0 };
  
        if (HasCurlyBraces) {
          // If we have curly braces, check for a modifier character.  This
          // supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
          if (*LastEmitted == ':') {
            ++LastEmitted;    // Consume ':' character.
            if (*LastEmitted == 0)
              report_fatal_error("Bad ${:} expression in inline asm string: '" +
                                 Twine(AsmStr) + "'");
  
            Modifier[0] = *LastEmitted;
            ++LastEmitted;    // Consume modifier character.
          }
  
          if (*LastEmitted != '}')
            report_fatal_error("Bad ${} expression in inline asm string: '" +
                               Twine(AsmStr) + "'");
          ++LastEmitted;    // Consume '}' character.
        }
  
        // Okay, we finally have a value number.  Ask the target to print this
        // operand!
        if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
          unsigned OpNo = InlineAsm::MIOp_FirstOperand;
  
          bool Error = false;
  
          // Scan to find the machine operand number for the operand.
          for (; Val; --Val) {
            if (OpNo >= MI->getNumOperands())
              break;
            unsigned OpFlags = MI->getOperand(OpNo).getImm();
            OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
          }
  
          // We may have a location metadata attached to the end of the
          // instruction, and at no point should see metadata at any
          // other point while processing. It's an error if so.
          if (OpNo >= MI->getNumOperands() || MI->getOperand(OpNo).isMetadata()) {
            Error = true;
          } else {
            unsigned OpFlags = MI->getOperand(OpNo).getImm();
            ++OpNo; // Skip over the ID number.
  
            // FIXME: Shouldn't arch-independent output template handling go into
            // PrintAsmOperand?
            // Labels are target independent.
            if (MI->getOperand(OpNo).isBlockAddress()) {
              const BlockAddress *BA = MI->getOperand(OpNo).getBlockAddress();
              MCSymbol *Sym = AP->GetBlockAddressSymbol(BA);
              Sym->print(OS, AP->MAI);
              MMI->getContext().registerInlineAsmLabel(Sym);
            } else if (MI->getOperand(OpNo).isMBB()) {
              const MCSymbol *Sym = MI->getOperand(OpNo).getMBB()->getSymbol();
              Sym->print(OS, AP->MAI);
            } else if (InlineAsm::isMemKind(OpFlags)) {
              Error = AP->PrintAsmMemoryOperand(
                  MI, OpNo, Modifier[0] ? Modifier : nullptr, OS);
            } else {
              Error = AP->PrintAsmOperand(MI, OpNo,
                                          Modifier[0] ? Modifier : nullptr, OS);
            }
          }
          if (Error) {
            std::string msg;
            raw_string_ostream Msg(msg);
            Msg << "invalid operand in inline asm: '" << AsmStr << "'";
            MMI->getModule()->getContext().emitError(LocCookie, Msg.str());
          }
        }
        break;
      }
      }
    }
    if (InputIsIntelDialect)
      OS << "\n\t.att_syntax";
    OS << '\n' << (char)0;  // null terminate string.
  }
  
  /// This method formats and emits the specified machine instruction that is an
  /// inline asm.
  void AsmPrinter::emitInlineAsm(const MachineInstr *MI) const {
    assert(MI->isInlineAsm() && "printInlineAsm only works on inline asms");
  
    // Count the number of register definitions to find the asm string.
    unsigned NumDefs = 0;
    for (; MI->getOperand(NumDefs).isReg() && MI->getOperand(NumDefs).isDef();
         ++NumDefs)
      assert(NumDefs != MI->getNumOperands()-2 && "No asm string?");
  
    assert(MI->getOperand(NumDefs).isSymbol() && "No asm string?");
  
    // Disassemble the AsmStr, printing out the literal pieces, the operands, etc.
    const char *AsmStr = MI->getOperand(NumDefs).getSymbolName();
  
    // If this asmstr is empty, just print the #APP/#NOAPP markers.
    // These are useful to see where empty asm's wound up.
    if (AsmStr[0] == 0) {
      OutStreamer->emitRawComment(MAI->getInlineAsmStart());
      OutStreamer->emitRawComment(MAI->getInlineAsmEnd());
      return;
    }
  
    // Emit the #APP start marker.  This has to happen even if verbose-asm isn't
    // enabled, so we use emitRawComment.
    OutStreamer->emitRawComment(MAI->getInlineAsmStart());
  
    // Get the !srcloc metadata node if we have it, and decode the loc cookie from
    // it.
    uint64_t LocCookie = 0;
    const MDNode *LocMD = nullptr;
    for (const MachineOperand &MO : llvm::reverse(MI->operands())) {
      if (MO.isMetadata() && (LocMD = MO.getMetadata()) &&
          LocMD->getNumOperands() != 0) {
        if (const ConstantInt *CI =
                mdconst::dyn_extract<ConstantInt>(LocMD->getOperand(0))) {
          LocCookie = CI->getZExtValue();
          break;
        }
      }
    }
  
    // Emit the inline asm to a temporary string so we can emit it through
    // EmitInlineAsm.
    SmallString<256> StringData;
    raw_svector_ostream OS(StringData);
  
    AsmPrinter *AP = const_cast<AsmPrinter*>(this);
    EmitInlineAsmStr(AsmStr, MI, MMI, MAI, AP, LocCookie, OS);
  
    // Emit warnings if we use reserved registers on the clobber list, as
    // that might lead to undefined behaviour.
    SmallVector<Register, 8> RestrRegs;
    const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
    // Start with the first operand descriptor, and iterate over them.
    for (unsigned I = InlineAsm::MIOp_FirstOperand, NumOps = MI->getNumOperands();
         I < NumOps; ++I) {
      const MachineOperand &MO = MI->getOperand(I);
      if (!MO.isImm())
        continue;
      unsigned Flags = MO.getImm();
      if (InlineAsm::getKind(Flags) == InlineAsm::Kind_Clobber) {
        Register Reg = MI->getOperand(I + 1).getReg();
        if (!TRI->isAsmClobberable(*MF, Reg))
          RestrRegs.push_back(Reg);
      }
      // Skip to one before the next operand descriptor, if it exists.
      I += InlineAsm::getNumOperandRegisters(Flags);
    }
  
    if (!RestrRegs.empty()) {
      std::string Msg = "inline asm clobber list contains reserved registers: ";
      ListSeparator LS;
      for (const Register RR : RestrRegs) {
        Msg += LS;
        Msg += TRI->getRegAsmName(RR);
      }
      const char *Note =
          "Reserved registers on the clobber list may not be "
          "preserved across the asm statement, and clobbering them may "
          "lead to undefined behaviour.";
      MMI->getModule()->getContext().diagnose(DiagnosticInfoInlineAsm(
          LocCookie, Msg, DiagnosticSeverity::DS_Warning));
      MMI->getModule()->getContext().diagnose(
          DiagnosticInfoInlineAsm(LocCookie, Note, DiagnosticSeverity::DS_Note));
    }
  
    emitInlineAsm(OS.str(), getSubtargetInfo(), TM.Options.MCOptions, LocMD,
                  MI->getInlineAsmDialect());
  
    // Emit the #NOAPP end marker.  This has to happen even if verbose-asm isn't
    // enabled, so we use emitRawComment.
    OutStreamer->emitRawComment(MAI->getInlineAsmEnd());
  }
  
  /// PrintSpecial - Print information related to the specified machine instr
  /// that is independent of the operand, and may be independent of the instr
  /// itself.  This can be useful for portably encoding the comment character
  /// or other bits of target-specific knowledge into the asmstrings.  The
  /// syntax used is ${:comment}.  Targets can override this to add support
  /// for their own strange codes.
  void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
                                StringRef Code) const {
    if (Code == "private") {
      const DataLayout &DL = MF->getDataLayout();
      OS << DL.getPrivateGlobalPrefix();
    } else if (Code == "comment") {
      OS << MAI->getCommentString();
    } else if (Code == "uid") {
      // Comparing the address of MI isn't sufficient, because machineinstrs may
      // be allocated to the same address across functions.
  
      // If this is a new LastFn instruction, bump the counter.
      if (LastMI != MI || LastFn != getFunctionNumber()) {
        ++Counter;
        LastMI = MI;
        LastFn = getFunctionNumber();
      }
      OS << Counter;
    } else {
      std::string msg;
      raw_string_ostream Msg(msg);
      Msg << "Unknown special formatter '" << Code
           << "' for machine instr: " << *MI;
      report_fatal_error(Twine(Msg.str()));
    }
  }
  
  void AsmPrinter::PrintSymbolOperand(const MachineOperand &MO, raw_ostream &OS) {
    assert(MO.isGlobal() && "caller should check MO.isGlobal");
    getSymbolPreferLocal(*MO.getGlobal())->print(OS, MAI);
    printOffset(MO.getOffset(), OS);
  }
  
  /// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
  /// instruction, using the specified assembler variant.  Targets should
  /// override this to format as appropriate for machine specific ExtraCodes
  /// or when the arch-independent handling would be too complex otherwise.
  bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                                   const char *ExtraCode, raw_ostream &O) {
    // Does this asm operand have a single letter operand modifier?
    if (ExtraCode && ExtraCode[0]) {
      if (ExtraCode[1] != 0) return true; // Unknown modifier.
  
      // https://gcc.gnu.org/onlinedocs/gccint/Output-Template.html
      const MachineOperand &MO = MI->getOperand(OpNo);
      switch (ExtraCode[0]) {
      default:
        return true;  // Unknown modifier.
      case 'a': // Print as memory address.
        if (MO.isReg()) {
          PrintAsmMemoryOperand(MI, OpNo, nullptr, O);
          return false;
        }
        LLVM_FALLTHROUGH; // GCC allows '%a' to behave like '%c' with immediates.
      case 'c': // Substitute immediate value without immediate syntax
        if (MO.isImm()) {
          O << MO.getImm();
          return false;
        }
        if (MO.isGlobal()) {
          PrintSymbolOperand(MO, O);
          return false;
        }
        return true;
      case 'n':  // Negate the immediate constant.
        if (!MO.isImm())
          return true;
        O << -MO.getImm();
        return false;
      case 's':  // The GCC deprecated s modifier
        if (!MO.isImm())
          return true;
        O << ((32 - MO.getImm()) & 31);
        return false;
      }
    }
    return true;
  }
  
  bool AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
                                         const char *ExtraCode, raw_ostream &O) {
    // Target doesn't support this yet!
    return true;
  }
  
  void AsmPrinter::emitInlineAsmStart() const {}
  
  void AsmPrinter::emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
                                    const MCSubtargetInfo *EndInfo) const {}
  