Merge commit 'adf845300c9c' from llvm.org/release/11.x into apple/stable/20200714

Author: git apple-llvm automerger

clang/include/clang/Basic/Attr.td

@@ -3594,3 +3594,11 @@ def ReleaseHandle : InheritableParamAttr {
   let Subjects = SubjectList<[ParmVar]>;
   let Documentation = [ReleaseHandleDocs];
 }
+
+def Builtin : InheritableAttr {
+  let Spellings = [];
+  let Args = [UnsignedArgument<"ID">];
+  let Subjects = SubjectList<[Function]>;
+  let SemaHandler = 0;
+  let Documentation = [Undocumented];
+}

clang/include/clang/Basic/Builtins.def

@@ -1017,6 +1017,7 @@ LIBBUILTIN(strncasecmp, "icC*cC*z", "f",   "strings.h", ALL_GNU_LANGUAGES)
 LIBBUILTIN(_exit, "vi",           "fr",    "unistd.h", ALL_GNU_LANGUAGES)
 LIBBUILTIN(vfork, "p",            "fj",    "unistd.h", ALL_LANGUAGES)
 // POSIX pthread.h
+// FIXME: Should specify argument types.
 LIBBUILTIN(pthread_create, "",  "fC<2,3>", "pthread.h", ALL_GNU_LANGUAGES)
 
 // POSIX setjmp.h

clang/include/clang/Basic/IdentifierTable.h

@@ -221,18 +221,6 @@ class alignas(IdentifierInfoAlignment) IdentifierInfo {
   }
   void setObjCKeywordID(tok::ObjCKeywordKind ID) { ObjCOrBuiltinID = ID; }
 
-  /// True if setNotBuiltin() was called.
-  bool hasRevertedBuiltin() const {
-    return ObjCOrBuiltinID == tok::NUM_OBJC_KEYWORDS;
-  }
-
-  /// Revert the identifier to a non-builtin identifier. We do this if
-  /// the name of a known builtin library function is used to declare that
-  /// function, but an unexpected type is specified.
-  void revertBuiltin() {
-    setBuiltinID(0);
-  }
-
   /// Return a value indicating whether this is a builtin function.
   ///
   /// 0 is not-built-in. 1+ are specific builtin functions.

clang/include/clang/Sema/Sema.h

@@ -3990,6 +3990,8 @@ class Sema final {
   ObjCInterfaceDecl *getObjCInterfaceDecl(IdentifierInfo *&Id,
                                           SourceLocation IdLoc,
                                           bool TypoCorrection = false);
+  FunctionDecl *CreateBuiltin(IdentifierInfo *II, QualType Type, unsigned ID,
+                              SourceLocation Loc);
   NamedDecl *LazilyCreateBuiltin(IdentifierInfo *II, unsigned ID,
                                  Scope *S, bool ForRedeclaration,
                                  SourceLocation Loc);

clang/lib/AST/Decl.cpp

@@ -3163,44 +3163,24 @@ FunctionDecl *FunctionDecl::getCanonicalDecl() { return getFirstDecl(); }
 /// functions as their wrapped builtins. This shouldn't be done in general, but
 /// it's useful in Sema to diagnose calls to wrappers based on their semantics.
 unsigned FunctionDecl::getBuiltinID(bool ConsiderWrapperFunctions) const {
-  unsigned BuiltinID;
+  unsigned BuiltinID = 0;
 
   if (const auto *ABAA = getAttr<ArmBuiltinAliasAttr>()) {
     BuiltinID = ABAA->getBuiltinName()->getBuiltinID();
-  } else {
-    if (!getIdentifier())
-      return 0;
-
-    BuiltinID = getIdentifier()->getBuiltinID();
+  } else if (const auto *A = getAttr<BuiltinAttr>()) {
+    BuiltinID = A->getID();
   }
 
   if (!BuiltinID)
     return 0;
 
-  ASTContext &Context = getASTContext();
-  if (Context.getLangOpts().CPlusPlus) {
-    const auto *LinkageDecl =
-        dyn_cast<LinkageSpecDecl>(getFirstDecl()->getDeclContext());
-    // In C++, the first declaration of a builtin is always inside an implicit
-    // extern "C".
-    // FIXME: A recognised library function may not be directly in an extern "C"
-    // declaration, for instance "extern "C" { namespace std { decl } }".
-    if (!LinkageDecl) {
-      if (BuiltinID == Builtin::BI__GetExceptionInfo &&
-          Context.getTargetInfo().getCXXABI().isMicrosoft())
-        return Builtin::BI__GetExceptionInfo;
-      return 0;
-    }
-    if (LinkageDecl->getLanguage() != LinkageSpecDecl::lang_c)
-      return 0;
-  }
-
   // If the function is marked "overloadable", it has a different mangled name
   // and is not the C library function.
   if (!ConsiderWrapperFunctions && hasAttr<OverloadableAttr>() &&
       !hasAttr<ArmBuiltinAliasAttr>())
     return 0;
 
+  ASTContext &Context = getASTContext();
   if (!Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID))
     return BuiltinID;