text: //===--- Builtins.cpp - Builtin function implementation -------------------===//
  //
  // 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 various things for builtin functions.
  //
  //===----------------------------------------------------------------------===//
  
  #include "clang/Basic/Builtins.h"
  #include "clang/Basic/IdentifierTable.h"
  #include "clang/Basic/LangOptions.h"
  #include "clang/Basic/TargetInfo.h"
  #include "llvm/ADT/StringRef.h"
  using namespace clang;
  
  static const Builtin::Info BuiltinInfo[] = {
    { "not a builtin function", nullptr, nullptr, nullptr, ALL_LANGUAGES,nullptr},
  #define BUILTIN(ID, TYPE, ATTRS)                                               \
    { #ID, TYPE, ATTRS, nullptr, ALL_LANGUAGES, nullptr },
  #define LANGBUILTIN(ID, TYPE, ATTRS, LANGS)                                    \
    { #ID, TYPE, ATTRS, nullptr, LANGS, nullptr },
  #define LIBBUILTIN(ID, TYPE, ATTRS, HEADER, LANGS)                             \
    { #ID, TYPE, ATTRS, HEADER, LANGS, nullptr },
  #include "clang/Basic/Builtins.def"
  };
  
  const Builtin::Info &Builtin::Context::getRecord(unsigned ID) const {
    if (ID < Builtin::FirstTSBuiltin)
      return BuiltinInfo[ID];
    assert(((ID - Builtin::FirstTSBuiltin) <
            (TSRecords.size() + AuxTSRecords.size())) &&
           "Invalid builtin ID!");
    if (isAuxBuiltinID(ID))
      return AuxTSRecords[getAuxBuiltinID(ID) - Builtin::FirstTSBuiltin];
    return TSRecords[ID - Builtin::FirstTSBuiltin];
  }
  
  void Builtin::Context::InitializeTarget(const TargetInfo &Target,
                                          const TargetInfo *AuxTarget) {
    assert(TSRecords.empty() && "Already initialized target?");
    TSRecords = Target.getTargetBuiltins();
    if (AuxTarget)
      AuxTSRecords = AuxTarget->getTargetBuiltins();
  }
  
  bool Builtin::Context::isBuiltinFunc(const char *Name) {
    StringRef FuncName(Name);
    for (unsigned i = Builtin::NotBuiltin + 1; i != Builtin::FirstTSBuiltin; ++i)
      if (FuncName.equals(BuiltinInfo[i].Name))
        return strchr(BuiltinInfo[i].Attributes, 'f') != nullptr;
  
    return false;
  }
  
  bool Builtin::Context::builtinIsSupported(const Builtin::Info &BuiltinInfo,
                                            const LangOptions &LangOpts) {
    bool BuiltinsUnsupported =
        (LangOpts.NoBuiltin || LangOpts.isNoBuiltinFunc(BuiltinInfo.Name)) &&
        strchr(BuiltinInfo.Attributes, 'f');
    bool MathBuiltinsUnsupported =
      LangOpts.NoMathBuiltin && BuiltinInfo.HeaderName &&
      llvm::StringRef(BuiltinInfo.HeaderName).equals("math.h");
    bool GnuModeUnsupported = !LangOpts.GNUMode && (BuiltinInfo.Langs & GNU_LANG);
    bool MSModeUnsupported =
        !LangOpts.MicrosoftExt && (BuiltinInfo.Langs & MS_LANG);
    bool ObjCUnsupported = !LangOpts.ObjC && BuiltinInfo.Langs == OBJC_LANG;
    bool OclC1Unsupported = (LangOpts.OpenCLVersion / 100) != 1 &&
                            (BuiltinInfo.Langs & ALL_OCLC_LANGUAGES ) ==  OCLC1X_LANG;
    bool OclC2Unsupported =
        (LangOpts.OpenCLVersion != 200 && !LangOpts.OpenCLCPlusPlus) &&
        (BuiltinInfo.Langs & ALL_OCLC_LANGUAGES) == OCLC20_LANG;
    bool OclCUnsupported = !LangOpts.OpenCL &&
                           (BuiltinInfo.Langs & ALL_OCLC_LANGUAGES);
    bool OpenMPUnsupported = !LangOpts.OpenMP && BuiltinInfo.Langs == OMP_LANG;
    bool CPlusPlusUnsupported =
        !LangOpts.CPlusPlus && BuiltinInfo.Langs == CXX_LANG;
    return !BuiltinsUnsupported && !MathBuiltinsUnsupported && !OclCUnsupported &&
           !OclC1Unsupported && !OclC2Unsupported && !OpenMPUnsupported &&
           !GnuModeUnsupported && !MSModeUnsupported && !ObjCUnsupported &&
           !CPlusPlusUnsupported;
  }
  
  /// initializeBuiltins - Mark the identifiers for all the builtins with their
  /// appropriate builtin ID # and mark any non-portable builtin identifiers as
  /// such.
  void Builtin::Context::initializeBuiltins(IdentifierTable &Table,
                                            const LangOptions& LangOpts) {
    // Step #1: mark all target-independent builtins with their ID's.
    for (unsigned i = Builtin::NotBuiltin+1; i != Builtin::FirstTSBuiltin; ++i)
      if (builtinIsSupported(BuiltinInfo[i], LangOpts)) {
        Table.get(BuiltinInfo[i].Name).setBuiltinID(i);
      }
  
    // Step #2: Register target-specific builtins.
    for (unsigned i = 0, e = TSRecords.size(); i != e; ++i)
      if (builtinIsSupported(TSRecords[i], LangOpts))
        Table.get(TSRecords[i].Name).setBuiltinID(i + Builtin::FirstTSBuiltin);
  
    // Step #3: Register target-specific builtins for AuxTarget.
    for (unsigned i = 0, e = AuxTSRecords.size(); i != e; ++i)
      Table.get(AuxTSRecords[i].Name)
          .setBuiltinID(i + Builtin::FirstTSBuiltin + TSRecords.size());
  }
  
  void Builtin::Context::forgetBuiltin(unsigned ID, IdentifierTable &Table) {
    Table.get(getRecord(ID).Name).setBuiltinID(0);
  }
  
  unsigned Builtin::Context::getRequiredVectorWidth(unsigned ID) const {
    const char *WidthPos = ::strchr(getRecord(ID).Attributes, 'V');
    if (!WidthPos)
      return 0;
  
    ++WidthPos;
    assert(*WidthPos == ':' &&
           "Vector width specifier must be followed by a ':'");
    ++WidthPos;
  
    char *EndPos;
    unsigned Width = ::strtol(WidthPos, &EndPos, 10);
    assert(*EndPos == ':' && "Vector width specific must end with a ':'");
    return Width;
  }
  
  bool Builtin::Context::isLike(unsigned ID, unsigned &FormatIdx,
                                bool &HasVAListArg, const char *Fmt) const {
    assert(Fmt && "Not passed a format string");
    assert(::strlen(Fmt) == 2 &&
           "Format string needs to be two characters long");
    assert(::toupper(Fmt[0]) == Fmt[1] &&
           "Format string is not in the form \"xX\"");
  
    const char *Like = ::strpbrk(getRecord(ID).Attributes, Fmt);
    if (!Like)
      return false;
  
    HasVAListArg = (*Like == Fmt[1]);
  
    ++Like;
    assert(*Like == ':' && "Format specifier must be followed by a ':'");
    ++Like;
  
    assert(::strchr(Like, ':') && "Format specifier must end with a ':'");
    FormatIdx = ::strtol(Like, nullptr, 10);
    return true;
  }
  
  bool Builtin::Context::isPrintfLike(unsigned ID, unsigned &FormatIdx,
                                      bool &HasVAListArg) {
    return isLike(ID, FormatIdx, HasVAListArg, "pP");
  }
  
  bool Builtin::Context::isScanfLike(unsigned ID, unsigned &FormatIdx,
                                     bool &HasVAListArg) {
    return isLike(ID, FormatIdx, HasVAListArg, "sS");
  }
  
  bool Builtin::Context::performsCallback(unsigned ID,
                                          SmallVectorImpl<int> &Encoding) const {
    const char *CalleePos = ::strchr(getRecord(ID).Attributes, 'C');
    if (!CalleePos)
      return false;
  
    ++CalleePos;
    assert(*CalleePos == '<' &&
           "Callback callee specifier must be followed by a '<'");
    ++CalleePos;
  
    char *EndPos;
    int CalleeIdx = ::strtol(CalleePos, &EndPos, 10);
    assert(CalleeIdx >= 0 && "Callee index is supposed to be positive!");
    Encoding.push_back(CalleeIdx);
  
    while (*EndPos == ',') {
      const char *PayloadPos = EndPos + 1;
  
      int PayloadIdx = ::strtol(PayloadPos, &EndPos, 10);
      Encoding.push_back(PayloadIdx);
    }
  
    assert(*EndPos == '>' && "Callback callee specifier must end with a '>'");
    return true;
  }
  
  bool Builtin::Context::canBeRedeclared(unsigned ID) const {
    return ID == Builtin::NotBuiltin ||
           ID == Builtin::BI__va_start ||
           (!hasReferenceArgsOrResult(ID) &&
            !hasCustomTypechecking(ID));
  }
  