diff --git a/clang/include/clang/Serialization/ModuleFile.h b/clang/include/clang/Serialization/ModuleFile.h
@@ -454,23 +454,11 @@ class ModuleFile {
   /// by the declaration ID (-1).
   const DeclOffset *DeclOffsets = nullptr;
 
-  /// Base declaration ID for declarations local to this module.
-  serialization::DeclID BaseDeclID = 0;
-
-  /// Remapping table for declaration IDs in this module.
-  ContinuousRangeMap<serialization::DeclID, int, 2> DeclRemap;
-
-  /// Mapping from the module files that this module file depends on
-  /// to the base declaration ID for that module as it is understood within this
-  /// module.
-  ///
-  /// This is effectively a reverse global-to-local mapping for declaration
-  /// IDs, so that we can interpret a true global ID (for this translation unit)
-  /// as a local ID (for this module file).
-  llvm::DenseMap<ModuleFile *, serialization::DeclID> GlobalToLocalDeclIDs;
+  /// Base declaration index in ASTReader for declarations local to this module.
+  unsigned BaseDeclIndex = 0;
 
   /// Array of file-level DeclIDs sorted by file.
-  const LocalDeclID *FileSortedDecls = nullptr;
+  const serialization::unaligned_decl_id_t *FileSortedDecls = nullptr;
   unsigned NumFileSortedDecls = 0;
 
   /// Array of category list location information within this

diff --git a/clang/include/clang/Serialization/ModuleManager.h b/clang/include/clang/Serialization/ModuleManager.h
@@ -45,7 +45,7 @@ namespace serialization {
 /// Manages the set of modules loaded by an AST reader.
 class ModuleManager {
   /// The chain of AST files, in the order in which we started to load
-  /// them (this order isn't really useful for anything).
+  /// them.
   SmallVector<std::unique_ptr<ModuleFile>, 2> Chain;
 
   /// The chain of non-module PCH files. The first entry is the one named

diff --git a/clang/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h b/clang/include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
@@ -781,7 +781,7 @@ class SymbolicRegion : public SubRegion {
       : SubRegion(sreg, SymbolicRegionKind), sym(s) {
     // Because pointer arithmetic is represented by ElementRegion layers,
     // the base symbol here should not contain any arithmetic.
-    assert(s && isa<SymbolData>(s));
+    assert(isa_and_nonnull<SymbolData>(s));
     assert(s->getType()->isAnyPointerType() ||
            s->getType()->isReferenceType() ||
            s->getType()->isBlockPointerType());

diff --git a/clang/include/clang/Tooling/Syntax/Tokens.h b/clang/include/clang/Tooling/Syntax/Tokens.h
@@ -292,9 +292,9 @@ class TokenBuffer {
   ///     "DECL", "(", "a", ")", ";"}
   llvm::ArrayRef<syntax::Token> spelledTokens(FileID FID) const;
 
-  /// Returns the spelled Token starting at Loc, if there are no such tokens
+  /// Returns the spelled Token containing the Loc, if there are no such tokens
   /// returns nullptr.
-  const syntax::Token *spelledTokenAt(SourceLocation Loc) const;
+  const syntax::Token *spelledTokenContaining(SourceLocation Loc) const;
 
   /// Get all tokens that expand a macro in \p FID. For the following input
   ///     #define FOO B

diff --git a/clang/lib/ARCMigrate/TransUnbridgedCasts.cpp b/clang/lib/ARCMigrate/TransUnbridgedCasts.cpp
@@ -371,7 +371,7 @@ class UnbridgedCastRewriter : public RecursiveASTVisitor<UnbridgedCastRewriter>{
       Stmt *parent = E;
       do {
         parent = StmtMap->getParentIgnoreParenImpCasts(parent);
-      } while (parent && isa<FullExpr>(parent));
+      } while (isa_and_nonnull<FullExpr>(parent));
 
       if (ReturnStmt *retS = dyn_cast_or_null<ReturnStmt>(parent)) {
         std::string note = "remove the cast and change return type of function "

diff --git a/clang/lib/AST/ASTDumper.cpp b/clang/lib/AST/ASTDumper.cpp
@@ -360,3 +360,37 @@ LLVM_DUMP_METHOD void ConceptReference::dump(raw_ostream &OS) const {
   ASTDumper P(OS, Ctx, Ctx.getDiagnostics().getShowColors());
   P.Visit(this);
 }
+
+//===----------------------------------------------------------------------===//
+// TemplateName method implementations
+//===----------------------------------------------------------------------===//
+
+// FIXME: These are actually using the TemplateArgument dumper, through
+// an implicit conversion. The dump will claim this is a template argument,
+// which is misleading.
+
+LLVM_DUMP_METHOD void TemplateName::dump() const {
+  ASTDumper Dumper(llvm::errs(), /*ShowColors=*/false);
+  Dumper.Visit(*this);
+}
+
+LLVM_DUMP_METHOD void TemplateName::dump(llvm::raw_ostream &OS,
+                                         const ASTContext &Context) const {
+  ASTDumper Dumper(OS, Context, Context.getDiagnostics().getShowColors());
+  Dumper.Visit(*this);
+}
+
+//===----------------------------------------------------------------------===//
+// TemplateArgument method implementations
+//===----------------------------------------------------------------------===//
+
+LLVM_DUMP_METHOD void TemplateArgument::dump() const {
+  ASTDumper Dumper(llvm::errs(), /*ShowColors=*/false);
+  Dumper.Visit(*this);
+}
+
+LLVM_DUMP_METHOD void TemplateArgument::dump(llvm::raw_ostream &OS,
+                                             const ASTContext &Context) const {
+  ASTDumper Dumper(OS, Context, Context.getDiagnostics().getShowColors());
+  Dumper.Visit(*this);
+}
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
@@ -1505,7 +1505,7 @@ ExpectedType ASTNodeImporter::VisitInjectedClassNameType(
   // The InjectedClassNameType is created in VisitRecordDecl when the
   // T->getDecl() is imported. Here we can return the existing type.
   const Type *Ty = (*ToDeclOrErr)->getTypeForDecl();
-  assert(Ty && isa<InjectedClassNameType>(Ty));
+  assert(isa_and_nonnull<InjectedClassNameType>(Ty));
   return QualType(Ty, 0);
 }
 

diff --git a/clang/lib/AST/CommentParser.cpp b/clang/lib/AST/CommentParser.cpp
@@ -89,6 +89,31 @@ class TextTokenRetokenizer {
     }
   }
 
+  /// Extract a template type
+  bool lexTemplate(SmallString<32> &WordText) {
+    unsigned BracketCount = 0;
+    while (!isEnd()) {
+      const char C = peek();
+      WordText.push_back(C);
+      consumeChar();
+      switch (C) {
+      case '<': {
+        BracketCount++;
+        break;
+      }
+      case '>': {
+        BracketCount--;
+        if (!BracketCount)
+          return true;
+        break;
+      }
+      default:
+        break;
+      }
+    }
+    return false;
+  }
+
   /// Add a token.
   /// Returns true on success, false if there are no interesting tokens to
   /// fetch from lexer.
@@ -149,6 +174,54 @@ class TextTokenRetokenizer {
     addToken();
   }
 
+  /// Extract a type argument
+  bool lexType(Token &Tok) {
+    if (isEnd())
+      return false;
+
+    // Save current position in case we need to rollback because the type is
+    // empty.
+    Position SavedPos = Pos;
+
+    // Consume any leading whitespace.
+    consumeWhitespace();
+    SmallString<32> WordText;
+    const char *WordBegin = Pos.BufferPtr;
+    SourceLocation Loc = getSourceLocation();
+
+    while (!isEnd()) {
+      const char C = peek();
+      // For non-whitespace characters we check if it's a template or otherwise
+      // continue reading the text into a word.
+      if (!isWhitespace(C)) {
+        if (C == '<') {
+          if (!lexTemplate(WordText))
+            return false;
+        } else {
+          WordText.push_back(C);
+          consumeChar();
+        }
+      } else {
+        consumeChar();
+        break;
+      }
+    }
+
+    const unsigned Length = WordText.size();
+    if (Length == 0) {
+      Pos = SavedPos;
+      return false;
+    }
+
+    char *TextPtr = Allocator.Allocate<char>(Length + 1);
+
+    memcpy(TextPtr, WordText.c_str(), Length + 1);
+    StringRef Text = StringRef(TextPtr, Length);
+
+    formTokenWithChars(Tok, Loc, WordBegin, Length, Text);
+    return true;
+  }
+
   /// Extract a word -- sequence of non-whitespace characters.
   bool lexWord(Token &Tok) {
     if (isEnd())
@@ -304,6 +377,23 @@ Parser::parseCommandArgs(TextTokenRetokenizer &Retokenizer, unsigned NumArgs) {
   return llvm::ArrayRef(Args, ParsedArgs);
 }
 
+ArrayRef<Comment::Argument>
+Parser::parseThrowCommandArgs(TextTokenRetokenizer &Retokenizer,
+                              unsigned NumArgs) {
+  auto *Args = new (Allocator.Allocate<Comment::Argument>(NumArgs))
+      Comment::Argument[NumArgs];
+  unsigned ParsedArgs = 0;
+  Token Arg;
+
+  while (ParsedArgs < NumArgs && Retokenizer.lexType(Arg)) {
+    Args[ParsedArgs] = Comment::Argument{
+        SourceRange(Arg.getLocation(), Arg.getEndLocation()), Arg.getText()};
+    ParsedArgs++;
+  }
+
+  return llvm::ArrayRef(Args, ParsedArgs);
+}
+
 BlockCommandComment *Parser::parseBlockCommand() {
   assert(Tok.is(tok::backslash_command) || Tok.is(tok::at_command));
 
@@ -356,6 +446,9 @@ BlockCommandComment *Parser::parseBlockCommand() {
       parseParamCommandArgs(PC, Retokenizer);
     else if (TPC)
       parseTParamCommandArgs(TPC, Retokenizer);
+    else if (Info->IsThrowsCommand)
+      S.actOnBlockCommandArgs(
+          BC, parseThrowCommandArgs(Retokenizer, Info->NumArgs));
     else
       S.actOnBlockCommandArgs(BC, parseCommandArgs(Retokenizer, Info->NumArgs));
 

diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
@@ -74,18 +74,17 @@ void *Decl::operator new(std::size_t Size, const ASTContext &Context,
                          GlobalDeclID ID, std::size_t Extra) {
   // Allocate an extra 8 bytes worth of storage, which ensures that the
   // resulting pointer will still be 8-byte aligned.
-  static_assert(sizeof(unsigned) * 2 >= alignof(Decl),
-                "Decl won't be misaligned");
+  static_assert(sizeof(uint64_t) >= alignof(Decl), "Decl won't be misaligned");
   void *Start = Context.Allocate(Size + Extra + 8);
   void *Result = (char*)Start + 8;
 
-  unsigned *PrefixPtr = (unsigned *)Result - 2;
+  uint64_t *PrefixPtr = (uint64_t *)Result - 1;
 
-  // Zero out the first 4 bytes; this is used to store the owning module ID.
-  PrefixPtr[0] = 0;
+  *PrefixPtr = ID.get();
 
-  // Store the global declaration ID in the second 4 bytes.
-  PrefixPtr[1] = ID.get();
+  // We leave the upper 16 bits to store the module IDs. 48 bits should be
+  // sufficient to store a declaration ID.
+  assert(*PrefixPtr < llvm::maskTrailingOnes<uint64_t>(48));
 
   return Result;
 }
@@ -111,6 +110,29 @@ void *Decl::operator new(std::size_t Size, const ASTContext &Ctx,
   return ::operator new(Size + Extra, Ctx);
 }
 
+GlobalDeclID Decl::getGlobalID() const {
+  if (!isFromASTFile())
+    return GlobalDeclID();
+  // See the comments in `Decl::operator new` for details.
+  uint64_t ID = *((const uint64_t *)this - 1);
+  return GlobalDeclID(ID & llvm::maskTrailingOnes<uint64_t>(48));
+}
+
+unsigned Decl::getOwningModuleID() const {
+  if (!isFromASTFile())
+    return 0;
+
+  uint64_t ID = *((const uint64_t *)this - 1);
+  return ID >> 48;
+}
+
+void Decl::setOwningModuleID(unsigned ID) {
+  assert(isFromASTFile() && "Only works on a deserialized declaration");
+  uint64_t *IDAddress = (uint64_t *)this - 1;
+  *IDAddress &= llvm::maskTrailingOnes<uint64_t>(48);
+  *IDAddress |= (uint64_t)ID << 48;
+}
+
 Module *Decl::getOwningModuleSlow() const {
   assert(isFromASTFile() && "Not from AST file?");
   return getASTContext().getExternalSource()->getModule(getOwningModuleID());
@@ -1094,7 +1116,7 @@ bool Decl::isInExportDeclContext() const {
   while (DC && !isa<ExportDecl>(DC))
     DC = DC->getLexicalParent();
 
-  return DC && isa<ExportDecl>(DC);
+  return isa_and_nonnull<ExportDecl>(DC);
 }
 
 bool Decl::isInAnotherModuleUnit() const {
@@ -2163,3 +2185,7 @@ DependentDiagnostic *DependentDiagnostic::Create(ASTContext &C,
 
   return DD;
 }
+
+unsigned DeclIDBase::getLocalDeclIndex() const {
+  return ID & llvm::maskTrailingOnes<DeclID>(32);
+}
diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
@@ -68,8 +68,8 @@ void LazyASTUnresolvedSet::getFromExternalSource(ASTContext &C) const {
   assert(Source && "getFromExternalSource with no external source");
 
   for (ASTUnresolvedSet::iterator I = Impl.begin(); I != Impl.end(); ++I)
-    I.setDecl(cast<NamedDecl>(Source->GetExternalDecl(
-        GlobalDeclID(reinterpret_cast<uintptr_t>(I.getDecl()) >> 2))));
+    I.setDecl(
+        cast<NamedDecl>(Source->GetExternalDecl(GlobalDeclID(I.getDeclID()))));
   Impl.Decls.setLazy(false);
 }
 

diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
@@ -837,7 +837,7 @@ std::string PredefinedExpr::ComputeName(PredefinedIdentKind IK,
     typedef SmallVector<const ClassTemplateSpecializationDecl *, 8> SpecsTy;
     SpecsTy Specs;
     const DeclContext *Ctx = FD->getDeclContext();
-    while (Ctx && isa<NamedDecl>(Ctx)) {
+    while (isa_and_nonnull<NamedDecl>(Ctx)) {
       const ClassTemplateSpecializationDecl *Spec
                                = dyn_cast<ClassTemplateSpecializationDecl>(Ctx);
       if (Spec && !Spec->isExplicitSpecialization())
@@ -3067,7 +3067,7 @@ Expr *Expr::IgnoreParenCasts() {
 
 Expr *Expr::IgnoreConversionOperatorSingleStep() {
   if (auto *MCE = dyn_cast<CXXMemberCallExpr>(this)) {
-    if (MCE->getMethodDecl() && isa<CXXConversionDecl>(MCE->getMethodDecl()))
+    if (isa_and_nonnull<CXXConversionDecl>(MCE->getMethodDecl()))
       return MCE->getImplicitObjectArgument();
   }
   return this;

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
@@ -2130,7 +2130,7 @@ static bool IsWeakLValue(const LValue &Value) {
 
 static bool isZeroSized(const LValue &Value) {
   const ValueDecl *Decl = GetLValueBaseDecl(Value);
-  if (Decl && isa<VarDecl>(Decl)) {
+  if (isa_and_nonnull<VarDecl>(Decl)) {
     QualType Ty = Decl->getType();
     if (Ty->isArrayType())
       return Ty->isIncompleteType() ||
@@ -15209,11 +15209,21 @@ bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
       APFloat &ResI = Result.getComplexFloatImag();
       if (LHSReal) {
         assert(!RHSReal && "Cannot have two real operands for a complex op!");
-        ResR = A * C;
-        ResI = A * D;
+        ResR = A;
+        ResI = A;
+        // ResR = A * C;
+        // ResI = A * D;
+        if (!handleFloatFloatBinOp(Info, E, ResR, BO_Mul, C) ||
+            !handleFloatFloatBinOp(Info, E, ResI, BO_Mul, D))
+          return false;
       } else if (RHSReal) {
-        ResR = C * A;
-        ResI = C * B;
+        // ResR = C * A;
+        // ResI = C * B;
+        ResR = C;
+        ResI = C;
+        if (!handleFloatFloatBinOp(Info, E, ResR, BO_Mul, A) ||
+            !handleFloatFloatBinOp(Info, E, ResI, BO_Mul, B))
+          return false;
       } else {
         // In the fully general case, we need to handle NaNs and infinities
         // robustly.
@@ -15289,8 +15299,13 @@ bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
       APFloat &ResR = Result.getComplexFloatReal();
       APFloat &ResI = Result.getComplexFloatImag();
       if (RHSReal) {
-        ResR = A / C;
-        ResI = B / C;
+        ResR = A;
+        ResI = B;
+        // ResR = A / C;
+        // ResI = B / C;
+        if (!handleFloatFloatBinOp(Info, E, ResR, BO_Div, C) ||
+            !handleFloatFloatBinOp(Info, E, ResI, BO_Div, C))
+          return false;
       } else {
         if (LHSReal) {
           // No real optimizations we can do here, stub out with zero.

diff --git a/clang/lib/AST/Interp/ByteCodeExprGen.cpp b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
@@ -318,15 +318,24 @@ bool ByteCodeExprGen<Emitter>::VisitCastExpr(const CastExpr *CE) {
     if (DiscardResult)
       return this->discard(SubExpr);
 
-    std::optional<PrimType> FromT = classify(SubExpr->getType());
+    QualType SubExprTy = SubExpr->getType();
+    std::optional<PrimType> FromT = classify(SubExprTy);
     std::optional<PrimType> ToT = classify(CE->getType());
     if (!FromT || !ToT)
       return false;
 
     assert(isPtrType(*FromT));
     assert(isPtrType(*ToT));
-    if (FromT == ToT)
-      return this->delegate(SubExpr);
+    if (FromT == ToT) {
+      if (CE->getType()->isVoidPointerType())
+        return this->delegate(SubExpr);
+
+      if (!this->visit(SubExpr))
+        return false;
+      if (FromT == PT_Ptr)
+        return this->emitPtrPtrCast(SubExprTy->isVoidPointerType(), CE);
+      return true;
+    }
 
     if (!this->visit(SubExpr))
       return false;
@@ -1104,14 +1113,9 @@ bool ByteCodeExprGen<Emitter>::visitInitList(ArrayRef<const Expr *> Inits,
       if (!this->visit(Init))
         return false;
 
-      if (FieldToInit->isBitField()) {
-        if (!this->emitInitBitField(T, FieldToInit, E))
-          return false;
-      } else {
-        if (!this->emitInitField(T, FieldToInit->Offset, E))
-          return false;
-      }
-      return this->emitPopPtr(E);
+      if (FieldToInit->isBitField())
+        return this->emitInitBitField(T, FieldToInit, E);
+      return this->emitInitField(T, FieldToInit->Offset, E);
     };
 
     auto initCompositeField = [=](const Record::Field *FieldToInit,
@@ -1147,9 +1151,6 @@ bool ByteCodeExprGen<Emitter>::visitInitList(ArrayRef<const Expr *> Inits,
         else
           FToInit = cast<CXXParenListInitExpr>(E)->getInitializedFieldInUnion();
 
-        if (!this->emitDupPtr(E))
-          return false;
-
         const Record::Field *FieldToInit = R->getField(FToInit);
         if (std::optional<PrimType> T = classify(Init)) {
           if (!initPrimitiveField(FieldToInit, Init, *T))
@@ -1169,8 +1170,6 @@ bool ByteCodeExprGen<Emitter>::visitInitList(ArrayRef<const Expr *> Inits,
       while (InitIndex < R->getNumFields() &&
              R->getField(InitIndex)->Decl->isUnnamedBitField())
         ++InitIndex;
-      if (!this->emitDupPtr(E))
-        return false;
 
       if (std::optional<PrimType> T = classify(Init)) {
         const Record::Field *FieldToInit = R->getField(InitIndex);
@@ -1180,7 +1179,7 @@ bool ByteCodeExprGen<Emitter>::visitInitList(ArrayRef<const Expr *> Inits,
       } else {
         // Initializer for a direct base class.
         if (const Record::Base *B = R->getBase(Init->getType())) {
-          if (!this->emitGetPtrBasePop(B->Offset, Init))
+          if (!this->emitGetPtrBase(B->Offset, Init))
             return false;
 
           if (!this->visitInitializer(Init))
@@ -1513,7 +1512,7 @@ bool ByteCodeExprGen<Emitter>::VisitMemberExpr(const MemberExpr *E) {
     // Leave a pointer to the field on the stack.
     if (F->Decl->getType()->isReferenceType())
       return this->emitGetFieldPop(PT_Ptr, F->Offset, E) && maybeLoadValue();
-    return this->emitGetPtrField(F->Offset, E) && maybeLoadValue();
+    return this->emitGetPtrFieldPop(F->Offset, E) && maybeLoadValue();
   }
 
   return false;
@@ -1844,6 +1843,9 @@ bool ByteCodeExprGen<Emitter>::VisitCompoundAssignOperator(
   std::optional<PrimType> RT = classify(RHS->getType());
   std::optional<PrimType> ResultT = classify(E->getType());
 
+  if (!Ctx.getLangOpts().CPlusPlus14)
+    return this->visit(RHS) && this->visit(LHS) && this->emitError(E);
+
   if (!LT || !RT || !ResultT || !LHSComputationT)
     return false;
 
@@ -2147,9 +2149,6 @@ bool ByteCodeExprGen<Emitter>::VisitLambdaExpr(const LambdaExpr *E) {
       if (!this->emitInitField(*T, F.Offset, E))
         return false;
     } else {
-      if (!this->emitDupPtr(E))
-        return false;
-
       if (!this->emitGetPtrField(F.Offset, E))
         return false;
 
@@ -2846,9 +2845,6 @@ bool ByteCodeExprGen<Emitter>::visitZeroRecordInitializer(const Record *R,
       continue;
     }
 
-    // TODO: Add GetPtrFieldPop and get rid of this dup.
-    if (!this->emitDupPtr(E))
-      return false;
     if (!this->emitGetPtrField(Field.Offset, E))
       return false;
 
@@ -3218,9 +3214,18 @@ bool ByteCodeExprGen<Emitter>::visitAPValue(const APValue &Val,
     return this->emitConst(Val.getInt(), ValType, E);
 
   if (Val.isLValue()) {
+    if (Val.isNullPointer())
+      return this->emitNull(ValType, nullptr, E);
     APValue::LValueBase Base = Val.getLValueBase();
     if (const Expr *BaseExpr = Base.dyn_cast<const Expr *>())
       return this->visit(BaseExpr);
+    else if (const auto *VD = Base.dyn_cast<const ValueDecl *>()) {
+      return this->visitDeclRef(VD, E);
+    }
+  } else if (Val.isMemberPointer()) {
+    if (const ValueDecl *MemberDecl = Val.getMemberPointerDecl())
+      return this->emitGetMemberPtr(MemberDecl, E);
+    return this->emitNullMemberPtr(nullptr, E);
   }
 
   return false;
@@ -3229,15 +3234,15 @@ bool ByteCodeExprGen<Emitter>::visitAPValue(const APValue &Val,
 template <class Emitter>
 bool ByteCodeExprGen<Emitter>::visitAPValueInitializer(const APValue &Val,
                                                        const Expr *E) {
+
   if (Val.isStruct()) {
     const Record *R = this->getRecord(E->getType());
     assert(R);
-
     for (unsigned I = 0, N = Val.getStructNumFields(); I != N; ++I) {
       const APValue &F = Val.getStructField(I);
       const Record::Field *RF = R->getField(I);
 
-      if (F.isInt() || F.isLValue()) {
+      if (F.isInt() || F.isLValue() || F.isMemberPointer()) {
         PrimType T = classifyPrim(RF->Decl->getType());
         if (!this->visitAPValue(F, T, E))
           return false;
@@ -3249,8 +3254,6 @@ bool ByteCodeExprGen<Emitter>::visitAPValueInitializer(const APValue &Val,
         PrimType ElemT = classifyPrim(ArrType->getElementType());
         assert(ArrType);
 
-        if (!this->emitDupPtr(E))
-          return false;
         if (!this->emitGetPtrField(RF->Offset, E))
           return false;
 
@@ -3263,11 +3266,28 @@ bool ByteCodeExprGen<Emitter>::visitAPValueInitializer(const APValue &Val,
 
         if (!this->emitPopPtr(E))
           return false;
+      } else if (F.isStruct() || F.isUnion()) {
+        if (!this->emitGetPtrField(RF->Offset, E))
+          return false;
+        if (!this->visitAPValueInitializer(F, E))
+          return false;
+        if (!this->emitPopPtr(E))
+          return false;
       } else {
         assert(false && "I don't think this should be possible");
       }
     }
     return true;
+  } else if (Val.isUnion()) {
+    const FieldDecl *UnionField = Val.getUnionField();
+    const Record *R = this->getRecord(UnionField->getParent());
+    assert(R);
+    const APValue &F = Val.getUnionValue();
+    const Record::Field *RF = R->getField(UnionField);
+    PrimType T = classifyPrim(RF->Decl->getType());
+    if (!this->visitAPValue(F, T, E))
+      return false;
+    return this->emitInitElem(T, 0, E);
   }
   // TODO: Other types.
 
@@ -3819,6 +3839,21 @@ bool ByteCodeExprGen<Emitter>::VisitComplexUnaryOperator(
     // we sometimes have to do the lvalue-to-rvalue conversion here manually.
     return this->emitArrayElemPop(classifyPrim(E->getType()), 1, E);
 
+  case UO_Not: // ~x
+    if (!this->visit(SubExpr))
+      return false;
+    // Negate the imaginary component.
+    if (!this->emitArrayElem(ElemT, 1, E))
+      return false;
+    if (!this->emitNeg(ElemT, E))
+      return false;
+    if (!this->emitInitElem(ElemT, 1, E))
+      return false;
+    return DiscardResult ? this->emitPopPtr(E) : true;
+
+  case UO_Extension:
+    return this->delegate(SubExpr);
+
   default:
     return this->emitInvalid(E);
   }
@@ -3827,12 +3862,10 @@ bool ByteCodeExprGen<Emitter>::VisitComplexUnaryOperator(
 }
 
 template <class Emitter>
-bool ByteCodeExprGen<Emitter>::VisitDeclRefExpr(const DeclRefExpr *E) {
+bool ByteCodeExprGen<Emitter>::visitDeclRef(const ValueDecl *D, const Expr *E) {
   if (DiscardResult)
     return true;
 
-  const auto *D = E->getDecl();
-
   if (const auto *ECD = dyn_cast<EnumConstantDecl>(D)) {
     return this->emitConst(ECD->getInitVal(), E);
   } else if (const auto *BD = dyn_cast<BindingDecl>(D)) {
@@ -3888,6 +3921,14 @@ bool ByteCodeExprGen<Emitter>::VisitDeclRefExpr(const DeclRefExpr *E) {
     if (IsPtr)
       return this->emitGetThisFieldPtr(Offset, E);
     return this->emitGetPtrThisField(Offset, E);
+  } else if (const auto *DRE = dyn_cast<DeclRefExpr>(E);
+             DRE && DRE->refersToEnclosingVariableOrCapture()) {
+    if (const auto *VD = dyn_cast<VarDecl>(D); VD && VD->isInitCapture()) {
+      if (!this->visitVarDecl(cast<VarDecl>(D)))
+        return false;
+      // Retry.
+      return this->visitDeclRef(D, E);
+    }
   }
 
   // Try to lazily visit (or emit dummy pointers for) declarations
@@ -3900,7 +3941,7 @@ bool ByteCodeExprGen<Emitter>::VisitDeclRefExpr(const DeclRefExpr *E) {
         if (!this->visitVarDecl(VD))
           return false;
         // Retry.
-        return this->VisitDeclRefExpr(E);
+        return this->visitDeclRef(VD, E);
       }
     }
   } else {
@@ -3910,7 +3951,7 @@ bool ByteCodeExprGen<Emitter>::VisitDeclRefExpr(const DeclRefExpr *E) {
       if (!this->visitVarDecl(VD))
         return false;
       // Retry.
-      return this->VisitDeclRefExpr(E);
+      return this->visitDeclRef(VD, E);
     }
   }
 
@@ -3927,7 +3968,15 @@ bool ByteCodeExprGen<Emitter>::VisitDeclRefExpr(const DeclRefExpr *E) {
     return true;
   }
 
-  return this->emitInvalidDeclRef(E, E);
+  if (const auto *DRE = dyn_cast<DeclRefExpr>(E))
+    return this->emitInvalidDeclRef(DRE, E);
+  return false;
+}
+
+template <class Emitter>
+bool ByteCodeExprGen<Emitter>::VisitDeclRefExpr(const DeclRefExpr *E) {
+  const auto *D = E->getDecl();
+  return this->visitDeclRef(D, E);
 }
 
 template <class Emitter>
@@ -4167,8 +4216,6 @@ bool ByteCodeExprGen<Emitter>::emitRecordDestruction(const Record *R) {
   for (const Record::Field &Field : llvm::reverse(R->fields())) {
     const Descriptor *D = Field.Desc;
     if (!D->isPrimitive() && !D->isPrimitiveArray()) {
-      if (!this->emitDupPtr(SourceInfo{}))
-        return false;
       if (!this->emitGetPtrField(Field.Offset, SourceInfo{}))
         return false;
       if (!this->emitDestruction(D))

diff --git a/clang/lib/AST/Interp/ByteCodeExprGen.h b/clang/lib/AST/Interp/ByteCodeExprGen.h
@@ -189,6 +189,8 @@ class ByteCodeExprGen : public ConstStmtVisitor<ByteCodeExprGen<Emitter>, bool>,
   /// Visit an APValue.
   bool visitAPValue(const APValue &Val, PrimType ValType, const Expr *E);
   bool visitAPValueInitializer(const APValue &Val, const Expr *E);
+  /// Visit the given decl as if we have a reference to it.
+  bool visitDeclRef(const ValueDecl *D, const Expr *E);
 
   /// Visits an expression and converts it to a boolean.
   bool visitBool(const Expr *E);

diff --git a/clang/lib/AST/Interp/EvalEmitter.cpp b/clang/lib/AST/Interp/EvalEmitter.cpp
@@ -40,7 +40,8 @@ void EvalEmitter::cleanup() { S.cleanup(); }
 EvaluationResult EvalEmitter::interpretExpr(const Expr *E,
                                             bool ConvertResultToRValue) {
   S.setEvalLocation(E->getExprLoc());
-  this->ConvertResultToRValue = ConvertResultToRValue;
+  this->ConvertResultToRValue = ConvertResultToRValue && !isa<ConstantExpr>(E);
+  this->CheckFullyInitialized = isa<ConstantExpr>(E);
   EvalResult.setSource(E);
 
   if (!this->visitExpr(E)) {
@@ -55,10 +56,14 @@ EvaluationResult EvalEmitter::interpretExpr(const Expr *E,
 EvaluationResult EvalEmitter::interpretDecl(const VarDecl *VD,
                                             bool CheckFullyInitialized) {
   this->CheckFullyInitialized = CheckFullyInitialized;
-  this->ConvertResultToRValue =
-      VD->getAnyInitializer() &&
-      (VD->getAnyInitializer()->getType()->isAnyComplexType() ||
-       VD->getAnyInitializer()->getType()->isVectorType());
+
+  if (const Expr *Init = VD->getAnyInitializer()) {
+    QualType T = VD->getType();
+    this->ConvertResultToRValue = !Init->isGLValue() && !T->isPointerType() &&
+                                  !T->isObjCObjectPointerType();
+  } else
+    this->ConvertResultToRValue = false;
+
   EvalResult.setSource(VD);
 
   if (!this->visitDecl(VD) && EvalResult.empty())
@@ -137,6 +142,10 @@ template <> bool EvalEmitter::emitRet<PT_Ptr>(const SourceInfo &Info) {
     return true;
 
   const Pointer &Ptr = S.Stk.pop<Pointer>();
+
+  if (CheckFullyInitialized && !EvalResult.checkFullyInitialized(S, Ptr))
+    return false;
+
   // Implicitly convert lvalue to rvalue, if requested.
   if (ConvertResultToRValue) {
     if (std::optional<APValue> V = Ptr.toRValue(Ctx)) {
@@ -145,17 +154,7 @@ template <> bool EvalEmitter::emitRet<PT_Ptr>(const SourceInfo &Info) {
       return false;
     }
   } else {
-    if (CheckFullyInitialized) {
-      if (!EvalResult.checkFullyInitialized(S, Ptr))
-        return false;
-
-      std::optional<APValue> RValueResult = Ptr.toRValue(Ctx);
-      if (!RValueResult)
-        return false;
-      EvalResult.setValue(*RValueResult);
-    } else {
-      EvalResult.setValue(Ptr.toAPValue());
-    }
+    EvalResult.setValue(Ptr.toAPValue());
   }
 
   return true;
@@ -175,6 +174,10 @@ bool EvalEmitter::emitRetVoid(const SourceInfo &Info) {
 
 bool EvalEmitter::emitRetValue(const SourceInfo &Info) {
   const auto &Ptr = S.Stk.pop<Pointer>();
+
+  if (CheckFullyInitialized && !EvalResult.checkFullyInitialized(S, Ptr))
+    return false;
+
   if (std::optional<APValue> APV = Ptr.toRValue(S.getCtx())) {
     EvalResult.setValue(*APV);
     return true;

diff --git a/clang/lib/AST/Interp/EvaluationResult.cpp b/clang/lib/AST/Interp/EvaluationResult.cpp
@@ -141,21 +141,22 @@ bool EvaluationResult::checkFullyInitialized(InterpState &S,
                                              const Pointer &Ptr) const {
   assert(Source);
   assert(empty());
-
-  // Our Source must be a VarDecl.
-  const Decl *SourceDecl = Source.dyn_cast<const Decl *>();
-  assert(SourceDecl);
-  const auto *VD = cast<VarDecl>(SourceDecl);
-  assert(VD->getType()->isRecordType() || VD->getType()->isArrayType());
-  SourceLocation InitLoc = VD->getAnyInitializer()->getExprLoc();
-
   assert(!Ptr.isZero());
 
+  SourceLocation InitLoc;
+  if (const auto *D = Source.dyn_cast<const Decl *>())
+    InitLoc = cast<VarDecl>(D)->getAnyInitializer()->getExprLoc();
+  else if (const auto *E = Source.dyn_cast<const Expr *>())
+    InitLoc = E->getExprLoc();
+
   if (const Record *R = Ptr.getRecord())
     return CheckFieldsInitialized(S, InitLoc, Ptr, R);
-  const auto *CAT =
-      cast<ConstantArrayType>(Ptr.getType()->getAsArrayTypeUnsafe());
-  return CheckArrayInitialized(S, InitLoc, Ptr, CAT);
+
+  if (const auto *CAT = dyn_cast_if_present<ConstantArrayType>(
+          Ptr.getType()->getAsArrayTypeUnsafe()))
+    return CheckArrayInitialized(S, InitLoc, Ptr, CAT);
+
+  return true;
 }
 
 } // namespace interp

diff --git a/clang/lib/AST/Interp/Interp.h b/clang/lib/AST/Interp/Interp.h
@@ -1283,9 +1283,32 @@ inline bool GetPtrGlobal(InterpState &S, CodePtr OpPC, uint32_t I) {
   return true;
 }
 
-/// 1) Pops a Pointer from the stack
+/// 1) Peeks a Pointer
 /// 2) Pushes Pointer.atField(Off) on the stack
 inline bool GetPtrField(InterpState &S, CodePtr OpPC, uint32_t Off) {
+  const Pointer &Ptr = S.Stk.peek<Pointer>();
+
+  if (S.getLangOpts().CPlusPlus && S.inConstantContext() &&
+      !CheckNull(S, OpPC, Ptr, CSK_Field))
+    return false;
+
+  if (!CheckExtern(S, OpPC, Ptr))
+    return false;
+  if (!CheckRange(S, OpPC, Ptr, CSK_Field))
+    return false;
+  if (!CheckArray(S, OpPC, Ptr))
+    return false;
+  if (!CheckSubobject(S, OpPC, Ptr, CSK_Field))
+    return false;
+
+  if (Ptr.isBlockPointer() && Off > Ptr.block()->getSize())
+    return false;
+
+  S.Stk.push<Pointer>(Ptr.atField(Off));
+  return true;
+}
+
+inline bool GetPtrFieldPop(InterpState &S, CodePtr OpPC, uint32_t Off) {
   const Pointer &Ptr = S.Stk.pop<Pointer>();
 
   if (S.getLangOpts().CPlusPlus && S.inConstantContext() &&
@@ -1914,6 +1937,9 @@ template <PrimType Name, class T = typename PrimConv<Name>::T>
 bool CastPointerIntegral(InterpState &S, CodePtr OpPC) {
   const Pointer &Ptr = S.Stk.pop<Pointer>();
 
+  if (Ptr.isDummy())
+    return false;
+
   const SourceInfo &E = S.Current->getSource(OpPC);
   S.CCEDiag(E, diag::note_constexpr_invalid_cast)
       << 2 << S.getLangOpts().CPlusPlus << S.Current->getRange(OpPC);
@@ -1926,6 +1952,9 @@ static inline bool CastPointerIntegralAP(InterpState &S, CodePtr OpPC,
                                          uint32_t BitWidth) {
   const Pointer &Ptr = S.Stk.pop<Pointer>();
 
+  if (Ptr.isDummy())
+    return false;
+
   const SourceInfo &E = S.Current->getSource(OpPC);
   S.CCEDiag(E, diag::note_constexpr_invalid_cast)
       << 2 << S.getLangOpts().CPlusPlus << S.Current->getRange(OpPC);
@@ -1939,6 +1968,9 @@ static inline bool CastPointerIntegralAPS(InterpState &S, CodePtr OpPC,
                                           uint32_t BitWidth) {
   const Pointer &Ptr = S.Stk.pop<Pointer>();
 
+  if (Ptr.isDummy())
+    return false;
+
   const SourceInfo &E = S.Current->getSource(OpPC);
   S.CCEDiag(E, diag::note_constexpr_invalid_cast)
       << 2 << S.getLangOpts().CPlusPlus << S.Current->getRange(OpPC);
@@ -1948,6 +1980,28 @@ static inline bool CastPointerIntegralAPS(InterpState &S, CodePtr OpPC,
   return true;
 }
 
+static inline bool PtrPtrCast(InterpState &S, CodePtr OpPC, bool SrcIsVoidPtr) {
+  const auto &Ptr = S.Stk.peek<Pointer>();
+
+  if (SrcIsVoidPtr && S.getLangOpts().CPlusPlus) {
+    bool HasValidResult = !Ptr.isZero();
+
+    if (HasValidResult) {
+      // FIXME: note_constexpr_invalid_void_star_cast
+    } else if (!S.getLangOpts().CPlusPlus26) {
+      const SourceInfo &E = S.Current->getSource(OpPC);
+      S.CCEDiag(E, diag::note_constexpr_invalid_cast)
+          << 3 << "'void *'" << S.Current->getRange(OpPC);
+    }
+  } else {
+    const SourceInfo &E = S.Current->getSource(OpPC);
+    S.CCEDiag(E, diag::note_constexpr_invalid_cast)
+        << 2 << S.getLangOpts().CPlusPlus << S.Current->getRange(OpPC);
+  }
+
+  return true;
+}
+
 //===----------------------------------------------------------------------===//
 // Zero, Nullptr
 //===----------------------------------------------------------------------===//

diff --git a/clang/lib/AST/Interp/MemberPointer.h b/clang/lib/AST/Interp/MemberPointer.h
@@ -86,7 +86,7 @@ class MemberPointer final {
   bool hasBase() const { return !Base.isZero(); }
 
   void print(llvm::raw_ostream &OS) const {
-    OS << "MemberPtr(" << Base << " " << (void *)Dcl << " + " << PtrOffset
+    OS << "MemberPtr(" << Base << " " << (const void *)Dcl << " + " << PtrOffset
        << ")";
   }
 

diff --git a/clang/lib/AST/Interp/Opcodes.td b/clang/lib/AST/Interp/Opcodes.td
@@ -281,53 +281,31 @@ def Null : Opcode {
 //===----------------------------------------------------------------------===//
 // Pointer generation
 //===----------------------------------------------------------------------===//
+class OffsetOpcode : Opcode {
+  let Args = [ArgUint32];
+}
 
 // [] -> [Pointer]
-def GetPtrLocal : Opcode {
-  // Offset of local.
-  let Args = [ArgUint32];
+def GetPtrLocal : OffsetOpcode {
   bit HasCustomEval = 1;
 }
 // [] -> [Pointer]
-def GetPtrParam : Opcode {
-  // Offset of parameter.
-  let Args = [ArgUint32];
-}
+def GetPtrParam : OffsetOpcode;
 // [] -> [Pointer]
-def GetPtrGlobal : Opcode {
-  // Index of global.
-  let Args = [ArgUint32];
-}
+def GetPtrGlobal : OffsetOpcode;
 // [Pointer] -> [Pointer]
-def GetPtrField : Opcode {
-  // Offset of field.
-  let Args = [ArgUint32];
-}
+def GetPtrField : OffsetOpcode;
+def GetPtrFieldPop : OffsetOpcode;
 // [Pointer] -> [Pointer]
-def GetPtrActiveField : Opcode {
-  // Offset of field.
-  let Args = [ArgUint32];
-}
+def GetPtrActiveField : OffsetOpcode;
 // [] -> [Pointer]
-def GetPtrActiveThisField : Opcode {
-  // Offset of field.
-  let Args = [ArgUint32];
-}
+def GetPtrActiveThisField : OffsetOpcode;
 // [] -> [Pointer]
-def GetPtrThisField : Opcode {
-  // Offset of field.
-  let Args = [ArgUint32];
-}
+def GetPtrThisField : OffsetOpcode;
 // [Pointer] -> [Pointer]
-def GetPtrBase : Opcode {
-  // Offset of field, which is a base.
-  let Args = [ArgUint32];
-}
+def GetPtrBase : OffsetOpcode;
 // [Pointer] -> [Pointer]
-def GetPtrBasePop : Opcode {
-  // Offset of field, which is a base.
-  let Args = [ArgUint32];
-}
+def GetPtrBasePop : OffsetOpcode;
 def GetMemberPtrBasePop : Opcode {
   // Offset of field, which is a base.
   let Args = [ArgSint32];
@@ -687,6 +665,10 @@ def CastPointerIntegralAPS : Opcode {
   let HasGroup = 0;
   let Args = [ArgUint32];
 }
+def PtrPtrCast : Opcode {
+  let Args = [ArgBool];
+
+}
 
 def DecayPtr : Opcode {
   let Types = [PtrTypeClass, PtrTypeClass];

diff --git a/clang/lib/AST/Interp/Pointer.cpp b/clang/lib/AST/Interp/Pointer.cpp
@@ -64,53 +64,55 @@ Pointer::~Pointer() {
 }
 
 void Pointer::operator=(const Pointer &P) {
-  if (!this->isIntegralPointer() || !P.isBlockPointer())
-    assert(P.StorageKind == StorageKind || (this->isZero() && P.isZero()));
-
+  // If the current storage type is Block, we need to remove
+  // this pointer from the block.
   bool WasBlockPointer = isBlockPointer();
-  StorageKind = P.StorageKind;
   if (StorageKind == Storage::Block) {
     Block *Old = PointeeStorage.BS.Pointee;
-    if (WasBlockPointer && PointeeStorage.BS.Pointee)
+    if (WasBlockPointer && Old) {
       PointeeStorage.BS.Pointee->removePointer(this);
+      Old->cleanup();
+    }
+  }
 
-    Offset = P.Offset;
+  StorageKind = P.StorageKind;
+  Offset = P.Offset;
+
+  if (P.isBlockPointer()) {
     PointeeStorage.BS = P.PointeeStorage.BS;
+    PointeeStorage.BS.Pointee = P.PointeeStorage.BS.Pointee;
 
     if (PointeeStorage.BS.Pointee)
       PointeeStorage.BS.Pointee->addPointer(this);
-
-    if (WasBlockPointer && Old)
-      Old->cleanup();
-
-  } else if (StorageKind == Storage::Int) {
+  } else if (P.isIntegralPointer()) {
     PointeeStorage.Int = P.PointeeStorage.Int;
   } else {
     assert(false && "Unhandled storage kind");
   }
 }
 
 void Pointer::operator=(Pointer &&P) {
-  if (!this->isIntegralPointer() || !P.isBlockPointer())
-    assert(P.StorageKind == StorageKind || (this->isZero() && P.isZero()));
-
+  // If the current storage type is Block, we need to remove
+  // this pointer from the block.
   bool WasBlockPointer = isBlockPointer();
-  StorageKind = P.StorageKind;
   if (StorageKind == Storage::Block) {
     Block *Old = PointeeStorage.BS.Pointee;
-    if (WasBlockPointer && PointeeStorage.BS.Pointee)
+    if (WasBlockPointer && Old) {
       PointeeStorage.BS.Pointee->removePointer(this);
+      Old->cleanup();
+    }
+  }
 
-    Offset = P.Offset;
+  StorageKind = P.StorageKind;
+  Offset = P.Offset;
+
+  if (P.isBlockPointer()) {
     PointeeStorage.BS = P.PointeeStorage.BS;
+    PointeeStorage.BS.Pointee = P.PointeeStorage.BS.Pointee;
 
     if (PointeeStorage.BS.Pointee)
       PointeeStorage.BS.Pointee->addPointer(this);
-
-    if (WasBlockPointer && Old)
-      Old->cleanup();
-
-  } else if (StorageKind == Storage::Int) {
+  } else if (P.isIntegralPointer()) {
     PointeeStorage.Int = P.PointeeStorage.Int;
   } else {
     assert(false && "Unhandled storage kind");

diff --git a/clang/lib/AST/Mangle.cpp b/clang/lib/AST/Mangle.cpp
@@ -301,9 +301,8 @@ void MangleContext::mangleBlock(const DeclContext *DC, const BlockDecl *BD,
   } else {
     assert((isa<NamedDecl>(DC) || isa<BlockDecl>(DC)) &&
            "expected a NamedDecl or BlockDecl");
-    if (isa<BlockDecl>(DC))
-      for (; DC && isa<BlockDecl>(DC); DC = DC->getParent())
-        (void) getBlockId(cast<BlockDecl>(DC), true);
+    for (; isa_and_nonnull<BlockDecl>(DC); DC = DC->getParent())
+      (void)getBlockId(cast<BlockDecl>(DC), true);
     assert((isa<TranslationUnitDecl>(DC) || isa<NamedDecl>(DC)) &&
            "expected a TranslationUnitDecl or a NamedDecl");
     if (const auto *CD = dyn_cast<CXXConstructorDecl>(DC))

diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
@@ -899,6 +899,8 @@ void MicrosoftCXXNameMangler::mangleFloat(llvm::APFloat Number) {
   case APFloat::S_Float8E4M3FNUZ:
   case APFloat::S_Float8E4M3B11FNUZ:
   case APFloat::S_FloatTF32:
+  case APFloat::S_Float6E3M2FN:
+  case APFloat::S_Float6E2M3FN:
     llvm_unreachable("Tried to mangle unexpected APFloat semantics");
   }
 
@@ -2748,7 +2750,7 @@ void MicrosoftCXXNameMangler::mangleFunctionType(const FunctionType *T,
       return;
     }
     Out << '@';
-  } else if (IsInLambda && D && isa<CXXConversionDecl>(D)) {
+  } else if (IsInLambda && isa_and_nonnull<CXXConversionDecl>(D)) {
     // The only lambda conversion operators are to function pointers, which
     // can differ by their calling convention and are typically deduced.  So
     // we make sure that this type gets mangled properly.

diff --git a/clang/lib/AST/ParentMap.cpp b/clang/lib/AST/ParentMap.cpp
@@ -139,7 +139,9 @@ Stmt* ParentMap::getParent(Stmt* S) const {
 }
 
 Stmt *ParentMap::getParentIgnoreParens(Stmt *S) const {
-  do { S = getParent(S); } while (S && isa<ParenExpr>(S));
+  do {
+    S = getParent(S);
+  } while (isa_and_nonnull<ParenExpr>(S));
   return S;
 }
 
@@ -155,7 +157,8 @@ Stmt *ParentMap::getParentIgnoreParenCasts(Stmt *S) const {
 Stmt *ParentMap::getParentIgnoreParenImpCasts(Stmt *S) const {
   do {
     S = getParent(S);
-  } while (S && isa<Expr>(S) && cast<Expr>(S)->IgnoreParenImpCasts() != S);
+  } while (isa_and_nonnull<Expr>(S) &&
+           cast<Expr>(S)->IgnoreParenImpCasts() != S);
 
   return S;
 }

diff --git a/clang/lib/AST/StmtPrinter.cpp b/clang/lib/AST/StmtPrinter.cpp
@@ -84,7 +84,7 @@ namespace {
 
     void PrintStmt(Stmt *S, int SubIndent) {
       IndentLevel += SubIndent;
-      if (S && isa<Expr>(S)) {
+      if (isa_and_nonnull<Expr>(S)) {
         // If this is an expr used in a stmt context, indent and newline it.
         Indent();
         Visit(S);
@@ -1939,7 +1939,7 @@ void StmtPrinter::VisitCXXOperatorCallExpr(CXXOperatorCallExpr *Node) {
 void StmtPrinter::VisitCXXMemberCallExpr(CXXMemberCallExpr *Node) {
   // If we have a conversion operator call only print the argument.
   CXXMethodDecl *MD = Node->getMethodDecl();
-  if (MD && isa<CXXConversionDecl>(MD)) {
+  if (isa_and_nonnull<CXXConversionDecl>(MD)) {
     PrintExpr(Node->getImplicitObjectArgument());
     return;
   }

diff --git a/clang/lib/AST/TemplateBase.cpp b/clang/lib/AST/TemplateBase.cpp
@@ -577,15 +577,6 @@ void TemplateArgument::print(const PrintingPolicy &Policy, raw_ostream &Out,
   }
 }
 
-void TemplateArgument::dump(raw_ostream &Out) const {
-  LangOptions LO; // FIXME! see also TemplateName::dump().
-  LO.CPlusPlus = true;
-  LO.Bool = true;
-  print(PrintingPolicy(LO), Out, /*IncludeType*/ true);
-}
-
-LLVM_DUMP_METHOD void TemplateArgument::dump() const { dump(llvm::errs()); }
-
 //===----------------------------------------------------------------------===//
 // TemplateArgumentLoc Implementation
 //===----------------------------------------------------------------------===//

diff --git a/clang/lib/AST/TemplateName.cpp b/clang/lib/AST/TemplateName.cpp
@@ -360,14 +360,3 @@ const StreamingDiagnostic &clang::operator<<(const StreamingDiagnostic &DB,
   OS.flush();
   return DB << NameStr;
 }
-
-void TemplateName::dump(raw_ostream &OS) const {
-  LangOptions LO;  // FIXME!
-  LO.CPlusPlus = true;
-  LO.Bool = true;
-  print(OS, PrintingPolicy(LO));
-}
-
-LLVM_DUMP_METHOD void TemplateName::dump() const {
-  dump(llvm::errs());
-}
diff --git a/clang/lib/Analysis/FlowSensitive/ASTOps.cpp b/clang/lib/Analysis/FlowSensitive/ASTOps.cpp
@@ -100,7 +100,8 @@ getFieldsForInitListExpr(const InitListT *InitList) {
   std::vector<const FieldDecl *> Fields;
 
   if (InitList->getType()->isUnionType()) {
-    Fields.push_back(InitList->getInitializedFieldInUnion());
+    if (const FieldDecl *Field = InitList->getInitializedFieldInUnion())
+      Fields.push_back(Field);
     return Fields;
   }
 
@@ -137,9 +138,11 @@ RecordInitListHelper::RecordInitListHelper(
   // it doesn't do this -- so we create an `ImplicitValueInitExpr` ourselves.
   SmallVector<Expr *> InitsForUnion;
   if (Ty->isUnionType() && Inits.empty()) {
-    assert(Fields.size() == 1);
-    ImplicitValueInitForUnion.emplace(Fields.front()->getType());
-    InitsForUnion.push_back(&*ImplicitValueInitForUnion);
+    assert(Fields.size() <= 1);
+    if (!Fields.empty()) {
+      ImplicitValueInitForUnion.emplace(Fields.front()->getType());
+      InitsForUnion.push_back(&*ImplicitValueInitForUnion);
+    }
     Inits = InitsForUnion;
   }
 

diff --git a/clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp b/clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp
@@ -415,7 +415,7 @@ class ResultObjectVisitor : public AnalysisASTVisitor<ResultObjectVisitor> {
     // below them can initialize the same object (or part of it).
     if (isa<CXXConstructExpr>(E) || isa<CallExpr>(E) || isa<LambdaExpr>(E) ||
         isa<CXXDefaultArgExpr>(E) || isa<CXXDefaultInitExpr>(E) ||
-        isa<CXXStdInitializerListExpr>(E) ||
+        isa<CXXStdInitializerListExpr>(E) || isa<AtomicExpr>(E) ||
         // We treat `BuiltinBitCastExpr` as an "original initializer" too as
         // it may not even be casting from a record type -- and even if it is,
         // the two objects are in general of unrelated type.

diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
@@ -673,8 +673,11 @@ std::unique_ptr<TargetInfo> AllocateTarget(const llvm::Triple &Triple,
   }
   case llvm::Triple::spirv64: {
     if (os != llvm::Triple::UnknownOS ||
-        Triple.getEnvironment() != llvm::Triple::UnknownEnvironment)
+        Triple.getEnvironment() != llvm::Triple::UnknownEnvironment) {
+      if (os == llvm::Triple::OSType::AMDHSA)
+        return std::make_unique<SPIRV64AMDGCNTargetInfo>(Triple, Opts);
       return nullptr;
+    }
     return std::make_unique<SPIRV64TargetInfo>(Triple, Opts);
   }
   case llvm::Triple::wasm32:

diff --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp
@@ -286,7 +286,6 @@ void AArch64TargetInfo::getTargetDefinesARMV84A(const LangOptions &Opts,
 void AArch64TargetInfo::getTargetDefinesARMV85A(const LangOptions &Opts,
                                                 MacroBuilder &Builder) const {
   Builder.defineMacro("__ARM_FEATURE_FRINT", "1");
-  Builder.defineMacro("__ARM_FEATURE_BTI", "1");
   // Also include the Armv8.4 defines
   getTargetDefinesARMV84A(Opts, Builder);
 }
@@ -499,6 +498,9 @@ void AArch64TargetInfo::getTargetDefines(const LangOptions &Opts,
   if (HasPAuthLR)
     Builder.defineMacro("__ARM_FEATURE_PAUTH_LR", "1");
 
+  if (HasBTI)
+    Builder.defineMacro("__ARM_FEATURE_BTI", "1");
+
   if (HasUnalignedAccess)
     Builder.defineMacro("__ARM_FEATURE_UNALIGNED", "1");
 
@@ -1085,7 +1087,7 @@ bool AArch64TargetInfo::initFeatureMap(
       std::string UpdatedFeature = Feature;
       if (Feature[0] == '+') {
         std::optional<llvm::AArch64::ExtensionInfo> Extension =
-          llvm::AArch64::parseArchExtension(Feature.substr(1));
+            llvm::AArch64::parseArchExtension(Feature.substr(1));
         if (Extension)
           UpdatedFeature = Extension->Feature.str();
       }

diff --git a/clang/lib/Basic/Targets/SPIR.cpp b/clang/lib/Basic/Targets/SPIR.cpp
@@ -11,7 +11,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "SPIR.h"
+#include "AMDGPU.h"
 #include "Targets.h"
+#include "llvm/TargetParser/TargetParser.h"
 
 using namespace clang;
 using namespace clang::targets;
@@ -54,3 +56,76 @@ void SPIRV64TargetInfo::getTargetDefines(const LangOptions &Opts,
   BaseSPIRVTargetInfo::getTargetDefines(Opts, Builder);
   DefineStd(Builder, "SPIRV64", Opts);
 }
+
+static const AMDGPUTargetInfo AMDGPUTI(llvm::Triple("amdgcn-amd-amdhsa"), {});
+
+ArrayRef<const char *> SPIRV64AMDGCNTargetInfo::getGCCRegNames() const {
+  return AMDGPUTI.getGCCRegNames();
+}
+
+bool SPIRV64AMDGCNTargetInfo::initFeatureMap(
+    llvm::StringMap<bool> &Features, DiagnosticsEngine &Diags, StringRef,
+    const std::vector<std::string> &FeatureVec) const {
+  llvm::AMDGPU::fillAMDGPUFeatureMap({}, getTriple(), Features);
+
+  return TargetInfo::initFeatureMap(Features, Diags, {}, FeatureVec);
+}
+
+bool SPIRV64AMDGCNTargetInfo::validateAsmConstraint(
+    const char *&Name, TargetInfo::ConstraintInfo &Info) const {
+  return AMDGPUTI.validateAsmConstraint(Name, Info);
+}
+
+std::string
+SPIRV64AMDGCNTargetInfo::convertConstraint(const char *&Constraint) const {
+  return AMDGPUTI.convertConstraint(Constraint);
+}
+
+ArrayRef<Builtin::Info> SPIRV64AMDGCNTargetInfo::getTargetBuiltins() const {
+  return AMDGPUTI.getTargetBuiltins();
+}
+
+void SPIRV64AMDGCNTargetInfo::getTargetDefines(const LangOptions &Opts,
+                                               MacroBuilder &Builder) const {
+  BaseSPIRVTargetInfo::getTargetDefines(Opts, Builder);
+  DefineStd(Builder, "SPIRV64", Opts);
+
+  Builder.defineMacro("__AMD__");
+  Builder.defineMacro("__AMDGPU__");
+  Builder.defineMacro("__AMDGCN__");
+}
+
+void SPIRV64AMDGCNTargetInfo::setAuxTarget(const TargetInfo *Aux) {
+  assert(Aux && "Cannot invoke setAuxTarget without a valid auxiliary target!");
+
+  // This is a 1:1 copy of AMDGPUTargetInfo::setAuxTarget()
+  assert(HalfFormat == Aux->HalfFormat);
+  assert(FloatFormat == Aux->FloatFormat);
+  assert(DoubleFormat == Aux->DoubleFormat);
+
+  // On x86_64 long double is 80-bit extended precision format, which is
+  // not supported by AMDGPU. 128-bit floating point format is also not
+  // supported by AMDGPU. Therefore keep its own format for these two types.
+  auto SaveLongDoubleFormat = LongDoubleFormat;
+  auto SaveFloat128Format = Float128Format;
+  auto SaveLongDoubleWidth = LongDoubleWidth;
+  auto SaveLongDoubleAlign = LongDoubleAlign;
+  copyAuxTarget(Aux);
+  LongDoubleFormat = SaveLongDoubleFormat;
+  Float128Format = SaveFloat128Format;
+  LongDoubleWidth = SaveLongDoubleWidth;
+  LongDoubleAlign = SaveLongDoubleAlign;
+  // For certain builtin types support on the host target, claim they are
+  // supported to pass the compilation of the host code during the device-side
+  // compilation.
+  // FIXME: As the side effect, we also accept `__float128` uses in the device
+  // code. To reject these builtin types supported in the host target but not in
+  // the device target, one approach would support `device_builtin` attribute
+  // so that we could tell the device builtin types from the host ones. This
+  // also solves the different representations of the same builtin type, such
+  // as `size_t` in the MSVC environment.
+  if (Aux->hasFloat128Type()) {
+    HasFloat128 = true;
+    Float128Format = DoubleFormat;
+  }
+}
diff --git a/clang/lib/Basic/Targets/SPIR.h b/clang/lib/Basic/Targets/SPIR.h
@@ -364,6 +364,57 @@ class LLVM_LIBRARY_VISIBILITY SPIRV64TargetInfo : public BaseSPIRVTargetInfo {
                         MacroBuilder &Builder) const override;
 };
 
+class LLVM_LIBRARY_VISIBILITY SPIRV64AMDGCNTargetInfo final
+    : public BaseSPIRVTargetInfo {
+public:
+  SPIRV64AMDGCNTargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
+      : BaseSPIRVTargetInfo(Triple, Opts) {
+    assert(Triple.getArch() == llvm::Triple::spirv64 &&
+           "Invalid architecture for 64-bit AMDGCN SPIR-V.");
+    assert(Triple.getVendor() == llvm::Triple::VendorType::AMD &&
+           "64-bit AMDGCN SPIR-V target must use AMD vendor");
+    assert(getTriple().getOS() == llvm::Triple::OSType::AMDHSA &&
+           "64-bit AMDGCN SPIR-V target must use AMDHSA OS");
+    assert(getTriple().getEnvironment() == llvm::Triple::UnknownEnvironment &&
+           "64-bit SPIR-V target must use unknown environment type");
+    PointerWidth = PointerAlign = 64;
+    SizeType = TargetInfo::UnsignedLong;
+    PtrDiffType = IntPtrType = TargetInfo::SignedLong;
+
+    resetDataLayout("e-i64:64-v16:16-v24:32-v32:32-v48:64-"
+                    "v96:128-v192:256-v256:256-v512:512-v1024:1024-G1-P4-A0");
+
+    BFloat16Width = BFloat16Align = 16;
+    BFloat16Format = &llvm::APFloat::BFloat();
+
+    HasLegalHalfType = true;
+    HasFloat16 = true;
+    HalfArgsAndReturns = true;
+  }
+
+  bool hasBFloat16Type() const override { return true; }
+
+  ArrayRef<const char *> getGCCRegNames() const override;
+
+  bool initFeatureMap(llvm::StringMap<bool> &Features, DiagnosticsEngine &Diags,
+                      StringRef,
+                      const std::vector<std::string> &) const override;
+
+  bool validateAsmConstraint(const char *&Name,
+                             TargetInfo::ConstraintInfo &Info) const override;
+
+  std::string convertConstraint(const char *&Constraint) const override;
+
+  ArrayRef<Builtin::Info> getTargetBuiltins() const override;
+
+  void getTargetDefines(const LangOptions &Opts,
+                        MacroBuilder &Builder) const override;
+
+  void setAuxTarget(const TargetInfo *Aux) override;
+
+  bool hasInt128Type() const override { return TargetInfo::hasInt128Type(); }
+};
+
 } // namespace targets
 } // namespace clang
 #endif // LLVM_CLANG_LIB_BASIC_TARGETS_SPIR_H
diff --git a/clang/lib/CodeGen/CGBlocks.cpp b/clang/lib/CodeGen/CGBlocks.cpp
@@ -577,7 +577,7 @@ static void computeBlockInfo(CodeGenModule &CGM, CodeGenFunction *CGF,
 
   // First, 'this'.
   if (block->capturesCXXThis()) {
-    assert(CGF && CGF->CurFuncDecl && isa<CXXMethodDecl>(CGF->CurFuncDecl) &&
+    assert(CGF && isa_and_nonnull<CXXMethodDecl>(CGF->CurFuncDecl) &&
            "Can't capture 'this' outside a method");
     QualType thisType = cast<CXXMethodDecl>(CGF->CurFuncDecl)->getThisType();
 

diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -2923,6 +2923,18 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
       SetSqrtFPAccuracy(Call);
       return RValue::get(Call);
     }
+
+    case Builtin::BItan:
+    case Builtin::BItanf:
+    case Builtin::BItanl:
+    case Builtin::BI__builtin_tan:
+    case Builtin::BI__builtin_tanf:
+    case Builtin::BI__builtin_tanf16:
+    case Builtin::BI__builtin_tanl:
+    case Builtin::BI__builtin_tanf128:
+      return RValue::get(emitUnaryMaybeConstrainedFPBuiltin(
+          *this, E, Intrinsic::tan, Intrinsic::experimental_constrained_tan));
+
     case Builtin::BItrunc:
     case Builtin::BItruncf:
     case Builtin::BItruncl:
@@ -6012,6 +6024,9 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
       llvm::Triple::getArchTypePrefix(getTarget().getTriple().getArch());
   if (!Prefix.empty()) {
     IntrinsicID = Intrinsic::getIntrinsicForClangBuiltin(Prefix.data(), Name);
+    if (IntrinsicID == Intrinsic::not_intrinsic && Prefix == "spv" &&
+        getTarget().getTriple().getOS() == llvm::Triple::OSType::AMDHSA)
+      IntrinsicID = Intrinsic::getIntrinsicForClangBuiltin("amdgcn", Name);
     // NOTE we don't need to perform a compatibility flag check here since the
     // intrinsics are declared in Builtins*.def via LANGBUILTIN which filter the
     // MS builtins via ALL_MS_LANGUAGES and are filtered earlier.
@@ -6182,6 +6197,10 @@ static Value *EmitTargetArchBuiltinExpr(CodeGenFunction *CGF,
   case llvm::Triple::riscv32:
   case llvm::Triple::riscv64:
     return CGF->EmitRISCVBuiltinExpr(BuiltinID, E, ReturnValue);
+  case llvm::Triple::spirv64:
+    if (CGF->getTarget().getTriple().getOS() != llvm::Triple::OSType::AMDHSA)
+      return nullptr;
+    return CGF->EmitAMDGPUBuiltinExpr(BuiltinID, E);
   default:
     return nullptr;
   }

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
@@ -1917,6 +1917,7 @@ static void getTrivialDefaultFunctionAttributes(
     case CodeGenOptions::FramePointerKind::None:
       // This is the default behavior.
       break;
+    case CodeGenOptions::FramePointerKind::Reserved:
     case CodeGenOptions::FramePointerKind::NonLeaf:
     case CodeGenOptions::FramePointerKind::All:
       FuncAttrs.addAttribute("frame-pointer",

diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
@@ -859,7 +859,7 @@ void CodeGenFunction::EmitConstructorBody(FunctionArgList &Args) {
 
   // Enter the function-try-block before the constructor prologue if
   // applicable.
-  bool IsTryBody = (Body && isa<CXXTryStmt>(Body));
+  bool IsTryBody = isa_and_nonnull<CXXTryStmt>(Body);
   if (IsTryBody)
     EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
 
@@ -1475,7 +1475,7 @@ void CodeGenFunction::EmitDestructorBody(FunctionArgList &Args) {
 
   // If the body is a function-try-block, enter the try before
   // anything else.
-  bool isTryBody = (Body && isa<CXXTryStmt>(Body));
+  bool isTryBody = isa_and_nonnull<CXXTryStmt>(Body);
   if (isTryBody)
     EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
   EmitAsanPrologueOrEpilogue(false);

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -58,7 +58,16 @@ using namespace clang::CodeGen;
 
 static uint32_t getTypeAlignIfRequired(const Type *Ty, const ASTContext &Ctx) {
   auto TI = Ctx.getTypeInfo(Ty);
-  return TI.isAlignRequired() ? TI.Align : 0;
+  if (TI.isAlignRequired())
+    return TI.Align;
+
+  // MaxFieldAlignmentAttr is the attribute added to types
+  // declared after #pragma pack(n).
+  if (auto *Decl = Ty->getAsRecordDecl())
+    if (Decl->hasAttr<MaxFieldAlignmentAttr>())
+      return TI.Align;
+
+  return 0;
 }
 
 static uint32_t getTypeAlignIfRequired(QualType Ty, const ASTContext &Ctx) {
@@ -5757,28 +5766,16 @@ void CGDebugInfo::EmitPseudoVariable(CGBuilderTy &Builder,
   // it is loaded upon use, so we identify such pattern here.
   if (llvm::LoadInst *Load = dyn_cast<llvm::LoadInst>(Value)) {
     llvm::Value *Var = Load->getPointerOperand();
-    if (llvm::Metadata *MDValue = llvm::ValueAsMetadata::getIfExists(Var)) {
-      if (llvm::Value *DbgValue = llvm::MetadataAsValue::getIfExists(
-              CGM.getLLVMContext(), MDValue)) {
-        for (llvm::User *U : DbgValue->users()) {
-          if (llvm::CallInst *DbgDeclare = dyn_cast<llvm::CallInst>(U)) {
-            if (DbgDeclare->getCalledFunction()->getIntrinsicID() ==
-                    llvm::Intrinsic::dbg_declare &&
-                DbgDeclare->getArgOperand(0) == DbgValue) {
-              // There can be implicit type cast applied on a variable if it is
-              // an opaque ptr, in this case its debug info may not match the
-              // actual type of object being used as in the next instruction, so
-              // we will need to emit a pseudo variable for type-casted value.
-              llvm::DILocalVariable *MDNode = cast<llvm::DILocalVariable>(
-                  cast<llvm::MetadataAsValue>(DbgDeclare->getOperand(1))
-                      ->getMetadata());
-              if (MDNode->getType() == Type)
-                return;
-            }
-          }
-        }
-      }
-    }
+    // There can be implicit type cast applied on a variable if it is an opaque
+    // ptr, in this case its debug info may not match the actual type of object
+    // being used as in the next instruction, so we will need to emit a pseudo
+    // variable for type-casted value.
+    auto DeclareTypeMatches = [&](auto *DbgDeclare) {
+      return DbgDeclare->getVariable()->getType() == Type;
+    };
+    if (any_of(llvm::findDbgDeclares(Var), DeclareTypeMatches) ||
+        any_of(llvm::findDVRDeclares(Var), DeclareTypeMatches))
+      return;
   }
 
   // Find the correct location to insert a sequence of instructions to

diff --git a/clang/lib/CodeGen/CGDeclCXX.cpp b/clang/lib/CodeGen/CGDeclCXX.cpp
@@ -476,6 +476,10 @@ llvm::Function *CodeGenModule::CreateGlobalInitOrCleanUpFunction(
       !isInNoSanitizeList(SanitizerKind::Thread, Fn, Loc))
     Fn->addFnAttr(llvm::Attribute::SanitizeThread);
 
+  if (getLangOpts().Sanitize.has(SanitizerKind::NumericalStability) &&
+      !isInNoSanitizeList(SanitizerKind::NumericalStability, Fn, Loc))
+    Fn->addFnAttr(llvm::Attribute::SanitizeNumericalStability);
+
   if (getLangOpts().Sanitize.has(SanitizerKind::Memory) &&
       !isInNoSanitizeList(SanitizerKind::Memory, Fn, Loc))
     Fn->addFnAttr(llvm::Attribute::SanitizeMemory);

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
@@ -3571,9 +3571,8 @@ void CodeGenFunction::EmitCheck(
   llvm::BasicBlock *Handlers = createBasicBlock("handler." + CheckName);
   llvm::Instruction *Branch = Builder.CreateCondBr(JointCond, Cont, Handlers);
   // Give hint that we very much don't expect to execute the handler
-  // Value chosen to match UR_NONTAKEN_WEIGHT, see BranchProbabilityInfo.cpp
   llvm::MDBuilder MDHelper(getLLVMContext());
-  llvm::MDNode *Node = MDHelper.createBranchWeights((1U << 20) - 1, 1);
+  llvm::MDNode *Node = MDHelper.createLikelyBranchWeights();
   Branch->setMetadata(llvm::LLVMContext::MD_prof, Node);
   EmitBlock(Handlers);
 
@@ -3641,7 +3640,7 @@ void CodeGenFunction::EmitCfiSlowPathCheck(
   llvm::BranchInst *BI = Builder.CreateCondBr(Cond, Cont, CheckBB);
 
   llvm::MDBuilder MDHelper(getLLVMContext());
-  llvm::MDNode *Node = MDHelper.createBranchWeights((1U << 20) - 1, 1);
+  llvm::MDNode *Node = MDHelper.createLikelyBranchWeights();
   BI->setMetadata(llvm::LLVMContext::MD_prof, Node);
 
   EmitBlock(CheckBB);

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -513,15 +513,6 @@ void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
 
   QualType elementType =
       CGF.getContext().getAsArrayType(ArrayQTy)->getElementType();
-
-  // DestPtr is an array*.  Construct an elementType* by drilling
-  // down a level.
-  llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0);
-  llvm::Value *indices[] = { zero, zero };
-  llvm::Value *begin = Builder.CreateInBoundsGEP(DestPtr.getElementType(),
-                                                 DestPtr.emitRawPointer(CGF),
-                                                 indices, "arrayinit.begin");
-
   CharUnits elementSize = CGF.getContext().getTypeSizeInChars(elementType);
   CharUnits elementAlign =
     DestPtr.getAlignment().alignmentOfArrayElement(elementSize);
@@ -562,6 +553,7 @@ void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
   Address endOfInit = Address::invalid();
   CodeGenFunction::CleanupDeactivationScope deactivation(CGF);
 
+  llvm::Value *begin = DestPtr.emitRawPointer(CGF);
   if (dtorKind) {
     CodeGenFunction::AllocaTrackerRAII allocaTracker(CGF);
     // In principle we could tell the cleanup where we are more
@@ -585,19 +577,13 @@ void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
 
   llvm::Value *one = llvm::ConstantInt::get(CGF.SizeTy, 1);
 
-  // The 'current element to initialize'.  The invariants on this
-  // variable are complicated.  Essentially, after each iteration of
-  // the loop, it points to the last initialized element, except
-  // that it points to the beginning of the array before any
-  // elements have been initialized.
-  llvm::Value *element = begin;
-
   // Emit the explicit initializers.
   for (uint64_t i = 0; i != NumInitElements; ++i) {
-    // Advance to the next element.
+    llvm::Value *element = begin;
     if (i > 0) {
-      element = Builder.CreateInBoundsGEP(
-          llvmElementType, element, one, "arrayinit.element");
+      element = Builder.CreateInBoundsGEP(llvmElementType, begin,
+                                          llvm::ConstantInt::get(CGF.SizeTy, i),
+                                          "arrayinit.element");
 
       // Tell the cleanup that it needs to destroy up to this
       // element.  TODO: some of these stores can be trivially
@@ -624,9 +610,12 @@ void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
     //   do { *array++ = filler; } while (array != end);
 
     // Advance to the start of the rest of the array.
+    llvm::Value *element = begin;
     if (NumInitElements) {
       element = Builder.CreateInBoundsGEP(
-          llvmElementType, element, one, "arrayinit.start");
+          llvmElementType, element,
+          llvm::ConstantInt::get(CGF.SizeTy, NumInitElements),
+          "arrayinit.start");
       if (endOfInit.isValid()) Builder.CreateStore(element, endOfInit);
     }
 

diff --git a/clang/lib/CodeGen/CGExprComplex.cpp b/clang/lib/CodeGen/CGExprComplex.cpp
@@ -856,8 +856,7 @@ ComplexPairTy ComplexExprEmitter::EmitBinMul(const BinOpInfo &Op) {
       llvm::BasicBlock *OrigBB = Branch->getParent();
 
       // Give hint that we very much don't expect to see NaNs.
-      // Value chosen to match UR_NONTAKEN_WEIGHT, see BranchProbabilityInfo.cpp
-      llvm::MDNode *BrWeight = MDHelper.createBranchWeights(1, (1U << 20) - 1);
+      llvm::MDNode *BrWeight = MDHelper.createUnlikelyBranchWeights();
       Branch->setMetadata(llvm::LLVMContext::MD_prof, BrWeight);
 
       // Now test the imaginary part and create its branch.

diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp
@@ -715,7 +715,7 @@ bool ConstStructBuilder::Build(const InitListExpr *ILE, bool AllowOverwrite) {
     const Expr *Init = nullptr;
     if (ElementNo < ILE->getNumInits())
       Init = ILE->getInit(ElementNo++);
-    if (Init && isa<NoInitExpr>(Init))
+    if (isa_and_nonnull<NoInitExpr>(Init))
       continue;
 
     // Zero-sized fields are not emitted, but their initializers may still

diff --git a/clang/lib/CodeGen/CGHLSLRuntime.cpp b/clang/lib/CodeGen/CGHLSLRuntime.cpp
@@ -313,7 +313,7 @@ void clang::CodeGen::CGHLSLRuntime::setHLSLEntryAttributes(
   assert(ShaderAttr && "All entry functions must have a HLSLShaderAttr");
   const StringRef ShaderAttrKindStr = "hlsl.shader";
   Fn->addFnAttr(ShaderAttrKindStr,
-                ShaderAttr->ConvertShaderTypeToStr(ShaderAttr->getType()));
+                llvm::Triple::getEnvironmentTypeName(ShaderAttr->getType()));
   if (HLSLNumThreadsAttr *NumThreadsAttr = FD->getAttr<HLSLNumThreadsAttr>()) {
     const StringRef NumThreadsKindStr = "hlsl.numthreads";
     std::string NumThreadsStr =

diff --git a/clang/lib/CodeGen/CGObjCGNU.cpp b/clang/lib/CodeGen/CGObjCGNU.cpp
@@ -2069,7 +2069,7 @@ class CGObjCGNUstep2 : public CGObjCGNUstep {
 
         Builder.CreateCondBr(Builder.CreateICmpEQ(selfValue, Zero),
                              SelfIsNilBlock, ContBlock,
-                             MDHelper.createBranchWeights(1, 1 << 20));
+                             MDHelper.createUnlikelyBranchWeights());
 
         CGF.EmitBlock(SelfIsNilBlock);
 
@@ -2104,7 +2104,7 @@ class CGObjCGNUstep2 : public CGObjCGNUstep {
             CGF.createBasicBlock("objc_direct_method.class_initialized");
         Builder.CreateCondBr(Builder.CreateICmpEQ(isInitialized, Zeros[0]),
                              notInitializedBlock, initializedBlock,
-                             MDHelper.createBranchWeights(1, 1 << 20));
+                             MDHelper.createUnlikelyBranchWeights());
         CGF.EmitBlock(notInitializedBlock);
         Builder.SetInsertPoint(notInitializedBlock);
         CGF.EmitRuntimeCall(SentInitializeFn, selfValue);

diff --git a/clang/lib/CodeGen/CGObjCMac.cpp b/clang/lib/CodeGen/CGObjCMac.cpp
@@ -4072,7 +4072,7 @@ void CGObjCCommonMac::GenerateDirectMethodPrologue(
 
     llvm::MDBuilder MDHelper(CGM.getLLVMContext());
     Builder.CreateCondBr(Builder.CreateICmpEQ(selfValue, Zero), SelfIsNilBlock,
-                         ContBlock, MDHelper.createBranchWeights(1, 1 << 20));
+                         ContBlock, MDHelper.createUnlikelyBranchWeights());
 
     CGF.EmitBlock(SelfIsNilBlock);
 

diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
@@ -414,7 +414,8 @@ void CodeGenFunction::EmitStmt(const Stmt *S, ArrayRef<const Attr *> Attrs) {
     CGM.ErrorUnsupported(S, "OpenMP dispatch directive");
     break;
   case Stmt::OMPScopeDirectiveClass:
-    llvm_unreachable("scope not supported with FE outlining");
+    CGM.ErrorUnsupported(S, "scope with FE outlining");
+    break;
   case Stmt::OMPMaskedDirectiveClass:
     EmitOMPMaskedDirective(cast<OMPMaskedDirective>(*S));
     break;

diff --git a/clang/lib/CodeGen/CGStmtOpenMP.cpp b/clang/lib/CodeGen/CGStmtOpenMP.cpp
@@ -72,7 +72,7 @@ class OMPLexicalScope : public CodeGenFunction::LexicalScope {
   static bool isCapturedVar(CodeGenFunction &CGF, const VarDecl *VD) {
     return CGF.LambdaCaptureFields.lookup(VD) ||
            (CGF.CapturedStmtInfo && CGF.CapturedStmtInfo->lookup(VD)) ||
-           (CGF.CurCodeDecl && isa<BlockDecl>(CGF.CurCodeDecl) &&
+           (isa_and_nonnull<BlockDecl>(CGF.CurCodeDecl) &&
             cast<BlockDecl>(CGF.CurCodeDecl)->capturesVariable(VD));
   }
 
@@ -227,7 +227,7 @@ class OMPSimdLexicalScope : public CodeGenFunction::LexicalScope {
   static bool isCapturedVar(CodeGenFunction &CGF, const VarDecl *VD) {
     return CGF.LambdaCaptureFields.lookup(VD) ||
            (CGF.CapturedStmtInfo && CGF.CapturedStmtInfo->lookup(VD)) ||
-           (CGF.CurCodeDecl && isa<BlockDecl>(CGF.CurCodeDecl) &&
+           (isa_and_nonnull<BlockDecl>(CGF.CurCodeDecl) &&
             cast<BlockDecl>(CGF.CurCodeDecl)->capturesVariable(VD));
   }
 
@@ -315,7 +315,7 @@ LValue CodeGenFunction::EmitOMPSharedLValue(const Expr *E) {
       bool IsCaptured =
           LambdaCaptureFields.lookup(OrigVD) ||
           (CapturedStmtInfo && CapturedStmtInfo->lookup(OrigVD)) ||
-          (CurCodeDecl && isa<BlockDecl>(CurCodeDecl));
+          (isa_and_nonnull<BlockDecl>(CurCodeDecl));
       DeclRefExpr DRE(getContext(), const_cast<VarDecl *>(OrigVD), IsCaptured,
                       OrigDRE->getType(), VK_LValue, OrigDRE->getExprLoc());
       return EmitLValue(&DRE);

diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -818,6 +818,8 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
       Fn->addFnAttr(llvm::Attribute::SanitizeMemTag);
     if (SanOpts.has(SanitizerKind::Thread))
       Fn->addFnAttr(llvm::Attribute::SanitizeThread);
+    if (SanOpts.has(SanitizerKind::NumericalStability))
+      Fn->addFnAttr(llvm::Attribute::SanitizeNumericalStability);
     if (SanOpts.hasOneOf(SanitizerKind::Memory | SanitizerKind::KernelMemory))
       Fn->addFnAttr(llvm::Attribute::SanitizeMemory);
   }
@@ -2951,7 +2953,7 @@ void CodeGenFunction::emitAlignmentAssumptionCheck(
     SourceLocation SecondaryLoc, llvm::Value *Alignment,
     llvm::Value *OffsetValue, llvm::Value *TheCheck,
     llvm::Instruction *Assumption) {
-  assert(Assumption && isa<llvm::CallInst>(Assumption) &&
+  assert(isa_and_nonnull<llvm::CallInst>(Assumption) &&
          cast<llvm::CallInst>(Assumption)->getCalledOperand() ==
              llvm::Intrinsic::getDeclaration(
                  Builder.GetInsertBlock()->getParent()->getParent(),

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1328,6 +1328,9 @@ void CodeGenModule::Release() {
   case CodeGenOptions::FramePointerKind::None:
     // 0 ("none") is the default.
     break;
+  case CodeGenOptions::FramePointerKind::Reserved:
+    getModule().setFramePointer(llvm::FramePointerKind::Reserved);
+    break;
   case CodeGenOptions::FramePointerKind::NonLeaf:
     getModule().setFramePointer(llvm::FramePointerKind::NonLeaf);
     break;
@@ -4509,6 +4512,19 @@ llvm::Constant *CodeGenModule::GetOrCreateMultiVersionResolver(GlobalDecl GD) {
   return Resolver;
 }
 
+bool CodeGenModule::shouldDropDLLAttribute(const Decl *D,
+                                           const llvm::GlobalValue *GV) const {
+  auto SC = GV->getDLLStorageClass();
+  if (SC == llvm::GlobalValue::DefaultStorageClass)
+    return false;
+  const Decl *MRD = D->getMostRecentDecl();
+  return (((SC == llvm::GlobalValue::DLLImportStorageClass &&
+            !MRD->hasAttr<DLLImportAttr>()) ||
+           (SC == llvm::GlobalValue::DLLExportStorageClass &&
+            !MRD->hasAttr<DLLExportAttr>())) &&
+          !shouldMapVisibilityToDLLExport(cast<NamedDecl>(MRD)));
+}
+
 /// GetOrCreateLLVMFunction - If the specified mangled name is not in the
 /// module, create and return an llvm Function with the specified type. If there
 /// is something in the module with the specified name, return it potentially
@@ -4561,8 +4577,7 @@ llvm::Constant *CodeGenModule::GetOrCreateLLVMFunction(
     }
 
     // Handle dropped DLL attributes.
-    if (D && !D->hasAttr<DLLImportAttr>() && !D->hasAttr<DLLExportAttr>() &&
-        !shouldMapVisibilityToDLLExport(cast_or_null<NamedDecl>(D))) {
+    if (D && shouldDropDLLAttribute(D, Entry)) {
       Entry->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
       setDSOLocal(Entry);
     }
@@ -4856,8 +4871,7 @@ CodeGenModule::GetOrCreateLLVMGlobal(StringRef MangledName, llvm::Type *Ty,
     }
 
     // Handle dropped DLL attributes.
-    if (D && !D->hasAttr<DLLImportAttr>() && !D->hasAttr<DLLExportAttr>() &&
-        !shouldMapVisibilityToDLLExport(D))
+    if (D && shouldDropDLLAttribute(D, Entry))
       Entry->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
 
     if (LangOpts.OpenMP && !LangOpts.OpenMPSimd && D)

diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
@@ -1594,6 +1594,8 @@ class CodeGenModule : public CodeGenTypeCache {
   }
 
 private:
+  bool shouldDropDLLAttribute(const Decl *D, const llvm::GlobalValue *GV) const;
+
   llvm::Constant *GetOrCreateLLVMFunction(
       StringRef MangledName, llvm::Type *Ty, GlobalDecl D, bool ForVTable,
       bool DontDefer = false, bool IsThunk = false,

diff --git a/clang/lib/Driver/SanitizerArgs.cpp b/clang/lib/Driver/SanitizerArgs.cpp
@@ -41,7 +41,8 @@ static const SanitizerMask NotAllowedWithExecuteOnly =
     SanitizerKind::Function | SanitizerKind::KCFI;
 static const SanitizerMask NeedsUnwindTables =
     SanitizerKind::Address | SanitizerKind::HWAddress | SanitizerKind::Thread |
-    SanitizerKind::Memory | SanitizerKind::DataFlow;
+    SanitizerKind::Memory | SanitizerKind::DataFlow |
+    SanitizerKind::NumericalStability;
 static const SanitizerMask SupportsCoverage =
     SanitizerKind::Address | SanitizerKind::HWAddress |
     SanitizerKind::KernelAddress | SanitizerKind::KernelHWAddress |
@@ -53,7 +54,8 @@ static const SanitizerMask SupportsCoverage =
     SanitizerKind::DataFlow | SanitizerKind::Fuzzer |
     SanitizerKind::FuzzerNoLink | SanitizerKind::FloatDivideByZero |
     SanitizerKind::SafeStack | SanitizerKind::ShadowCallStack |
-    SanitizerKind::Thread | SanitizerKind::ObjCCast | SanitizerKind::KCFI;
+    SanitizerKind::Thread | SanitizerKind::ObjCCast | SanitizerKind::KCFI |
+    SanitizerKind::NumericalStability;
 static const SanitizerMask RecoverableByDefault =
     SanitizerKind::Undefined | SanitizerKind::Integer |
     SanitizerKind::ImplicitConversion | SanitizerKind::Nullability |
@@ -175,6 +177,7 @@ static void addDefaultIgnorelists(const Driver &D, SanitizerMask Kinds,
                      {"hwasan_ignorelist.txt", SanitizerKind::HWAddress},
                      {"memtag_ignorelist.txt", SanitizerKind::MemTag},
                      {"msan_ignorelist.txt", SanitizerKind::Memory},
+                     {"nsan_ignorelist.txt", SanitizerKind::NumericalStability},
                      {"tsan_ignorelist.txt", SanitizerKind::Thread},
                      {"dfsan_abilist.txt", SanitizerKind::DataFlow},
                      {"cfi_ignorelist.txt", SanitizerKind::CFI},

diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
@@ -104,7 +104,8 @@ ToolChain::ToolChain(const Driver &D, const llvm::Triple &T,
 }
 
 llvm::Expected<std::unique_ptr<llvm::MemoryBuffer>>
-ToolChain::executeToolChainProgram(StringRef Executable) const {
+ToolChain::executeToolChainProgram(StringRef Executable,
+                                   unsigned SecondsToWait) const {
   llvm::SmallString<64> OutputFile;
   llvm::sys::fs::createTemporaryFile("toolchain-program", "txt", OutputFile);
   llvm::FileRemover OutputRemover(OutputFile.c_str());
@@ -115,9 +116,8 @@ ToolChain::executeToolChainProgram(StringRef Executable) const {
   };
 
   std::string ErrorMessage;
-  if (llvm::sys::ExecuteAndWait(Executable, {}, {}, Redirects,
-                                /* SecondsToWait */ 0,
-                                /*MemoryLimit*/ 0, &ErrorMessage))
+  if (llvm::sys::ExecuteAndWait(Executable, {}, {}, Redirects, SecondsToWait,
+                                /*MemoryLimit=*/0, &ErrorMessage))
     return llvm::createStringError(std::error_code(),
                                    Executable + ": " + ErrorMessage);
 

diff --git a/clang/lib/Driver/ToolChains/AMDGPU.cpp b/clang/lib/Driver/ToolChains/AMDGPU.cpp
@@ -645,7 +645,11 @@ void amdgpu::getAMDGPUTargetFeatures(const Driver &D,
                                      std::vector<StringRef> &Features) {
   // Add target ID features to -target-feature options. No diagnostics should
   // be emitted here since invalid target ID is diagnosed at other places.
-  StringRef TargetID = Args.getLastArgValue(options::OPT_mcpu_EQ);
+  StringRef TargetID;
+  if (Args.hasArg(options::OPT_mcpu_EQ))
+    TargetID = Args.getLastArgValue(options::OPT_mcpu_EQ);
+  else if (Args.hasArg(options::OPT_march_EQ))
+    TargetID = Args.getLastArgValue(options::OPT_march_EQ);
   if (!TargetID.empty()) {
     llvm::StringMap<bool> FeatureMap;
     auto OptionalGpuArch = parseTargetID(Triple, TargetID, &FeatureMap);
@@ -877,7 +881,7 @@ AMDGPUToolChain::getSystemGPUArchs(const ArgList &Args) const {
   else
     Program = GetProgramPath("amdgpu-arch");
 
-  auto StdoutOrErr = executeToolChainProgram(Program);
+  auto StdoutOrErr = executeToolChainProgram(Program, /*SecondsToWait=*/10);
   if (!StdoutOrErr)
     return StdoutOrErr.takeError();
 

diff --git a/clang/lib/Driver/ToolChains/AMDGPUOpenMP.cpp b/clang/lib/Driver/ToolChains/AMDGPUOpenMP.cpp
@@ -44,14 +44,9 @@ void AMDGPUOpenMPToolChain::addClangTargetOptions(
     Action::OffloadKind DeviceOffloadingKind) const {
   HostTC.addClangTargetOptions(DriverArgs, CC1Args, DeviceOffloadingKind);
 
-  StringRef GPUArch = DriverArgs.getLastArgValue(options::OPT_march_EQ);
-  assert(!GPUArch.empty() && "Must have an explicit GPU arch.");
-
   assert(DeviceOffloadingKind == Action::OFK_OpenMP &&
          "Only OpenMP offloading kinds are supported.");
 
-  CC1Args.push_back("-target-cpu");
-  CC1Args.push_back(DriverArgs.MakeArgStringRef(GPUArch));
   CC1Args.push_back("-fcuda-is-device");
 
   if (DriverArgs.hasArg(options::OPT_nogpulib))

diff --git a/clang/lib/Driver/ToolChains/Arch/ARM.cpp b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
@@ -799,8 +799,6 @@ llvm::ARM::FPUKind arm::getARMTargetFeatures(const Driver &D,
     StringRef FrameChainOption = A->getValue();
     if (FrameChainOption.starts_with("aapcs"))
       Features.push_back("+aapcs-frame-chain");
-    if (FrameChainOption == "aapcs+leaf")
-      Features.push_back("+aapcs-frame-chain-leaf");
   }
 
   // CMSE: Check for target 8M (for -mcmse to be applicable) is performed later.

diff --git a/clang/lib/Driver/ToolChains/Arch/RISCV.cpp b/clang/lib/Driver/ToolChains/Arch/RISCV.cpp
@@ -67,11 +67,6 @@ static void getRISCFeaturesFromMcpu(const Driver &D, const Arg *A,
       D.Diag(clang::diag::err_drv_unsupported_option_argument)
           << A->getSpelling() << Mcpu;
   }
-
-  if (llvm::RISCV::hasFastUnalignedAccess(Mcpu)) {
-    Features.push_back("+unaligned-scalar-mem");
-    Features.push_back("+unaligned-vector-mem");
-  }
 }
 
 void riscv::getRISCVTargetFeatures(const Driver &D, const llvm::Triple &Triple,
@@ -82,6 +77,8 @@ void riscv::getRISCVTargetFeatures(const Driver &D, const llvm::Triple &Triple,
   if (!getArchFeatures(D, MArch, Features, Args))
     return;
 
+  bool CPUFastUnaligned = false;
+
   // If users give march and mcpu, get std extension feature from MArch
   // and other features (ex. mirco architecture feature) from mcpu
   if (Arg *A = Args.getLastArg(options::OPT_mcpu_EQ)) {
@@ -90,6 +87,9 @@ void riscv::getRISCVTargetFeatures(const Driver &D, const llvm::Triple &Triple,
       CPU = llvm::sys::getHostCPUName();
 
     getRISCFeaturesFromMcpu(D, A, Triple, CPU, Features);
+
+    if (llvm::RISCV::hasFastUnalignedAccess(CPU))
+      CPUFastUnaligned = true;
   }
 
   // Handle features corresponding to "-ffixed-X" options
@@ -169,18 +169,23 @@ void riscv::getRISCVTargetFeatures(const Driver &D, const llvm::Triple &Triple,
     Features.push_back("-relax");
   }
 
-  // Android requires fast unaligned access on RISCV64.
-  if (Triple.isAndroid()) {
+  // If -mstrict-align or -mno-strict-align is passed, use it. Otherwise, the
+  // unaligned-*-mem is enabled if the CPU supports it or the target is
+  // Android.
+  if (const Arg *A = Args.getLastArg(options::OPT_mno_strict_align,
+                                     options::OPT_mstrict_align)) {
+    if (A->getOption().matches(options::OPT_mno_strict_align)) {
+      Features.push_back("+unaligned-scalar-mem");
+      Features.push_back("+unaligned-vector-mem");
+    } else {
+      Features.push_back("-unaligned-scalar-mem");
+      Features.push_back("-unaligned-vector-mem");
+    }
+  } else if (CPUFastUnaligned || Triple.isAndroid()) {
     Features.push_back("+unaligned-scalar-mem");
     Features.push_back("+unaligned-vector-mem");
   }
 
-  // -mstrict-align is default, unless -mno-strict-align is specified.
-  AddTargetFeature(Args, Features, options::OPT_mno_strict_align,
-                   options::OPT_mstrict_align, "unaligned-scalar-mem");
-  AddTargetFeature(Args, Features, options::OPT_mno_strict_align,
-                   options::OPT_mstrict_align, "unaligned-vector-mem");
-
   // Now add any that the user explicitly requested on the command line,
   // which may override the defaults.
   handleTargetFeaturesGroup(D, Triple, Args, Features,

diff --git a/clang/lib/Driver/ToolChains/BareMetal.cpp b/clang/lib/Driver/ToolChains/BareMetal.cpp
@@ -429,6 +429,7 @@ void baremetal::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   ArgStringList CmdArgs;
 
   auto &TC = static_cast<const toolchains::BareMetal &>(getToolChain());
+  const Driver &D = getToolChain().getDriver();
   const llvm::Triple::ArchType Arch = TC.getArch();
   const llvm::Triple &Triple = getToolChain().getEffectiveTriple();
 
@@ -466,6 +467,19 @@ void baremetal::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     TC.AddLinkRuntimeLib(Args, CmdArgs);
   }
 
+  if (D.isUsingLTO()) {
+    assert(!Inputs.empty() && "Must have at least one input.");
+    // Find the first filename InputInfo object.
+    auto Input = llvm::find_if(
+        Inputs, [](const InputInfo &II) -> bool { return II.isFilename(); });
+    if (Input == Inputs.end())
+      // For a very rare case, all of the inputs to the linker are
+      // InputArg. If that happens, just use the first InputInfo.
+      Input = Inputs.begin();
+
+    addLTOOptions(TC, Args, CmdArgs, Output, *Input,
+                  D.getLTOMode() == LTOK_Thin);
+  }
   if (TC.getTriple().isRISCV())
     CmdArgs.push_back("-X");
 

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -5678,6 +5678,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   case CodeGenOptions::FramePointerKind::None:
     FPKeepKindStr = "-mframe-pointer=none";
     break;
+  case CodeGenOptions::FramePointerKind::Reserved:
+    FPKeepKindStr = "-mframe-pointer=reserved";
+    break;
   case CodeGenOptions::FramePointerKind::NonLeaf:
     FPKeepKindStr = "-mframe-pointer=non-leaf";
     break;

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -164,6 +164,14 @@ static bool useFramePointerForTargetByDefault(const llvm::opt::ArgList &Args,
   return true;
 }
 
+static bool useLeafFramePointerForTargetByDefault(const llvm::Triple &Triple) {
+  if (Triple.isAArch64() || Triple.isPS() || Triple.isVE() ||
+      (Triple.isAndroid() && Triple.isRISCV64()))
+    return false;
+
+  return true;
+}
+
 static bool mustUseNonLeafFramePointerForTarget(const llvm::Triple &Triple) {
   switch (Triple.getArch()) {
   default:
@@ -176,38 +184,91 @@ static bool mustUseNonLeafFramePointerForTarget(const llvm::Triple &Triple) {
   }
 }
 
+// True if a target-specific option requires the frame chain to be preserved,
+// even if new frame records are not created.
+static bool mustMaintainValidFrameChain(const llvm::opt::ArgList &Args,
+                                        const llvm::Triple &Triple) {
+  if (Triple.isARM() || Triple.isThumb()) {
+    // For 32-bit Arm, the -mframe-chain=aapcs and -mframe-chain=aapcs+leaf
+    // options require the frame pointer register to be reserved (or point to a
+    // new AAPCS-compilant frame record), even with	-fno-omit-frame-pointer.
+    if (Arg *A = Args.getLastArg(options::OPT_mframe_chain)) {
+      StringRef V = A->getValue();
+      return V != "none";
+    }
+    return false;
+  }
+  return false;
+}
+
+// True if a target-specific option causes -fno-omit-frame-pointer to also
+// cause frame records to be created in leaf functions.
+static bool framePointerImpliesLeafFramePointer(const llvm::opt::ArgList &Args,
+                                                const llvm::Triple &Triple) {
+  if (Triple.isARM() || Triple.isThumb()) {
+    // For 32-bit Arm, the -mframe-chain=aapcs+leaf option causes the
+    // -fno-omit-frame-pointer optiion to imply -mno-omit-leaf-frame-pointer,
+    // but does not by itself imply either option.
+    if (Arg *A = Args.getLastArg(options::OPT_mframe_chain)) {
+      StringRef V = A->getValue();
+      return V == "aapcs+leaf";
+    }
+    return false;
+  }
+  return false;
+}
+
 clang::CodeGenOptions::FramePointerKind
 getFramePointerKind(const llvm::opt::ArgList &Args,
                     const llvm::Triple &Triple) {
-  // We have 4 states:
+  // There are three things to consider here:
+  // * Should a frame record be created for non-leaf functions?
+  // * Should a frame record be created for leaf functions?
+  // * Is the frame pointer register reserved, i.e. must it always point to
+  //   either a new, valid frame record or be un-modified?
   //
-  //  00) leaf retained, non-leaf retained
-  //  01) leaf retained, non-leaf omitted (this is invalid)
-  //  10) leaf omitted, non-leaf retained
-  //      (what -momit-leaf-frame-pointer was designed for)
-  //  11) leaf omitted, non-leaf omitted
+  //  Not all combinations of these are valid:
+  //  * It's not useful to have leaf frame records without non-leaf ones.
+  //  * It's not useful to have frame records without reserving the frame
+  //    pointer.
   //
-  //  "omit" options taking precedence over "no-omit" options is the only way
-  //  to make 3 valid states representable
-  llvm::opt::Arg *A =
-      Args.getLastArg(clang::driver::options::OPT_fomit_frame_pointer,
-                      clang::driver::options::OPT_fno_omit_frame_pointer);
-
-  bool OmitFP = A && A->getOption().matches(
-                         clang::driver::options::OPT_fomit_frame_pointer);
-  bool NoOmitFP = A && A->getOption().matches(
-                           clang::driver::options::OPT_fno_omit_frame_pointer);
-  bool OmitLeafFP =
-      Args.hasFlag(clang::driver::options::OPT_momit_leaf_frame_pointer,
-                   clang::driver::options::OPT_mno_omit_leaf_frame_pointer,
-                   Triple.isAArch64() || Triple.isPS() || Triple.isVE() ||
-                       (Triple.isAndroid() && Triple.isRISCV64()));
-  if (NoOmitFP || mustUseNonLeafFramePointerForTarget(Triple) ||
-      (!OmitFP && useFramePointerForTargetByDefault(Args, Triple))) {
-    if (OmitLeafFP)
-      return clang::CodeGenOptions::FramePointerKind::NonLeaf;
-    return clang::CodeGenOptions::FramePointerKind::All;
-  }
+  // | Non-leaf | Leaf | Reserved |
+  // | N        | N    | N        | FramePointerKind::None
+  // | N        | N    | Y        | FramePointerKind::Reserved
+  // | N        | Y    | N        | Invalid
+  // | N        | Y    | Y        | Invalid
+  // | Y        | N    | N        | Invalid
+  // | Y        | N    | Y        | FramePointerKind::NonLeaf
+  // | Y        | Y    | N        | Invalid
+  // | Y        | Y    | Y        | FramePointerKind::All
+  //
+  // The FramePointerKind::Reserved case is currently only reachable for Arm,
+  // which has the -mframe-chain= option which can (in combination with
+  // -fno-omit-frame-pointer) specify that the frame chain must be valid,
+  // without requiring new frame records to be created.
+
+  bool DefaultFP = useFramePointerForTargetByDefault(Args, Triple);
+  bool EnableFP =
+      mustUseNonLeafFramePointerForTarget(Triple) ||
+      Args.hasFlag(clang::driver::options::OPT_fno_omit_frame_pointer,
+                   clang::driver::options::OPT_fomit_frame_pointer, DefaultFP);
+
+  bool DefaultLeafFP =
+      useLeafFramePointerForTargetByDefault(Triple) ||
+      (EnableFP && framePointerImpliesLeafFramePointer(Args, Triple));
+  bool EnableLeafFP = Args.hasFlag(
+      clang::driver::options::OPT_mno_omit_leaf_frame_pointer,
+      clang::driver::options::OPT_momit_leaf_frame_pointer, DefaultLeafFP);
+
+  bool FPRegReserved = EnableFP || mustMaintainValidFrameChain(Args, Triple);
+
+  if (EnableFP) {
+    if (EnableLeafFP)
+      return clang::CodeGenOptions::FramePointerKind::All;
+    return clang::CodeGenOptions::FramePointerKind::NonLeaf;
+  }
+  if (FPRegReserved)
+    return clang::CodeGenOptions::FramePointerKind::Reserved;
   return clang::CodeGenOptions::FramePointerKind::None;
 }
 

diff --git a/clang/lib/Driver/ToolChains/Cuda.cpp b/clang/lib/Driver/ToolChains/Cuda.cpp
@@ -826,7 +826,7 @@ NVPTXToolChain::getSystemGPUArchs(const ArgList &Args) const {
   else
     Program = GetProgramPath("nvptx-arch");
 
-  auto StdoutOrErr = executeToolChainProgram(Program);
+  auto StdoutOrErr = executeToolChainProgram(Program, /*SecondsToWait=*/10);
   if (!StdoutOrErr)
     return StdoutOrErr.takeError();
 

diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -3448,6 +3448,7 @@ SanitizerMask Darwin::getSupportedSanitizers() const {
   Res |= SanitizerKind::PointerCompare;
   Res |= SanitizerKind::PointerSubtract;
   Res |= SanitizerKind::Leak;
+  Res |= SanitizerKind::NumericalStability;
   Res |= SanitizerKind::Fuzzer;
   Res |= SanitizerKind::FuzzerNoLink;
   Res |= SanitizerKind::ObjCCast;

diff --git a/clang/lib/Driver/ToolChains/Flang.cpp b/clang/lib/Driver/ToolChains/Flang.cpp
@@ -802,6 +802,9 @@ void Flang::ConstructJob(Compilation &C, const JobAction &JA,
   case CodeGenOptions::FramePointerKind::None:
     FPKeepKindStr = "-mframe-pointer=none";
     break;
+   case CodeGenOptions::FramePointerKind::Reserved:
+    FPKeepKindStr = "-mframe-pointer=reserved";
+    break;
   case CodeGenOptions::FramePointerKind::NonLeaf:
     FPKeepKindStr = "-mframe-pointer=non-leaf";
     break;

diff --git a/clang/lib/Driver/ToolChains/Linux.cpp b/clang/lib/Driver/ToolChains/Linux.cpp
@@ -826,6 +826,9 @@ SanitizerMask Linux::getSupportedSanitizers() const {
   if (IsX86_64 || IsAArch64) {
     Res |= SanitizerKind::KernelHWAddress;
   }
+  if (IsX86_64 || IsAArch64)
+    Res |= SanitizerKind::NumericalStability;
+
   // Work around "Cannot represent a difference across sections".
   if (getTriple().getArch() == llvm::Triple::ppc64)
     Res &= ~SanitizerKind::Function;

diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
@@ -1257,6 +1257,11 @@ unsigned ContinuationIndenter::getNewLineColumn(const LineState &State) {
     }
     return CurrentState.Indent;
   }
+  if (Current.is(TT_TrailingReturnArrow) &&
+      Previous.isOneOf(tok::kw_noexcept, tok::kw_mutable, tok::kw_constexpr,
+                       tok::kw_consteval, tok::kw_static, TT_AttributeSquare)) {
+    return ContinuationIndent;
+  }
   if ((Current.isOneOf(tok::r_brace, tok::r_square) ||
        (Current.is(tok::greater) && (Style.isProto() || Style.isTableGen()))) &&
       State.Stack.size() > 1) {

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
@@ -1358,6 +1358,8 @@ class AnnotatingParser {
           Line.First->startsSequence(tok::kw_export, Keywords.kw_module) ||
           Line.First->startsSequence(tok::kw_export, Keywords.kw_import)) {
         Tok->setType(TT_ModulePartitionColon);
+      } else if (Line.First->is(tok::kw_asm)) {
+        Tok->setType(TT_InlineASMColon);
       } else if (Contexts.back().ColonIsDictLiteral || Style.isProto()) {
         Tok->setType(TT_DictLiteral);
         if (Style.Language == FormatStyle::LK_TextProto) {
@@ -1425,13 +1427,6 @@ class AnnotatingParser {
         // This handles a special macro in ObjC code where selectors including
         // the colon are passed as macro arguments.
         Tok->setType(TT_ObjCMethodExpr);
-      } else if (Contexts.back().ContextKind == tok::l_paren &&
-                 !Line.InPragmaDirective) {
-        if (Style.isTableGen() && Contexts.back().IsTableGenDAGArg) {
-          Tok->setType(TT_TableGenDAGArgListColon);
-          break;
-        }
-        Tok->setType(TT_InlineASMColon);
       }
       break;
     case tok::pipe:

diff --git a/clang/lib/Index/CommentToXML.cpp b/clang/lib/Index/CommentToXML.cpp
@@ -546,7 +546,8 @@ class CommentASTToXMLConverter :
   void visitParagraphComment(const ParagraphComment *C);
 
   void appendParagraphCommentWithKind(const ParagraphComment *C,
-                                      StringRef Kind);
+                                      StringRef ParagraphKind,
+                                      StringRef PrependBodyText);
 
   void visitBlockCommandComment(const BlockCommandComment *C);
   void visitParamCommandComment(const ParamCommandComment *C);
@@ -680,24 +681,27 @@ CommentASTToXMLConverter::visitHTMLEndTagComment(const HTMLEndTagComment *C) {
   Result << ">&lt;/" << C->getTagName() << "&gt;</rawHTML>";
 }
 
-void
-CommentASTToXMLConverter::visitParagraphComment(const ParagraphComment *C) {
-  appendParagraphCommentWithKind(C, StringRef());
+void CommentASTToXMLConverter::visitParagraphComment(
+    const ParagraphComment *C) {
+  appendParagraphCommentWithKind(C, StringRef(), StringRef());
 }
 
 void CommentASTToXMLConverter::appendParagraphCommentWithKind(
-                                  const ParagraphComment *C,
-                                  StringRef ParagraphKind) {
-  if (C->isWhitespace())
+    const ParagraphComment *C, StringRef ParagraphKind,
+    StringRef PrependBodyText) {
+  if (C->isWhitespace() && PrependBodyText.empty())
     return;
 
   if (ParagraphKind.empty())
     Result << "<Para>";
   else
     Result << "<Para kind=\"" << ParagraphKind << "\">";
 
-  for (Comment::child_iterator I = C->child_begin(), E = C->child_end();
-       I != E; ++I) {
+  if (!PrependBodyText.empty())
+    Result << PrependBodyText << " ";
+
+  for (Comment::child_iterator I = C->child_begin(), E = C->child_end(); I != E;
+       ++I) {
     visit(*I);
   }
   Result << "</Para>";
@@ -706,8 +710,15 @@ void CommentASTToXMLConverter::appendParagraphCommentWithKind(
 void CommentASTToXMLConverter::visitBlockCommandComment(
     const BlockCommandComment *C) {
   StringRef ParagraphKind;
+  StringRef ExceptionType;
 
-  switch (C->getCommandID()) {
+  const unsigned CommandID = C->getCommandID();
+  const CommandInfo *Info = Traits.getCommandInfo(CommandID);
+  if (Info->IsThrowsCommand && C->getNumArgs() > 0) {
+    ExceptionType = C->getArgText(0);
+  }
+
+  switch (CommandID) {
   case CommandTraits::KCI_attention:
   case CommandTraits::KCI_author:
   case CommandTraits::KCI_authors:
@@ -732,7 +743,8 @@ void CommentASTToXMLConverter::visitBlockCommandComment(
     break;
   }
 
-  appendParagraphCommentWithKind(C->getParagraph(), ParagraphKind);
+  appendParagraphCommentWithKind(C->getParagraph(), ParagraphKind,
+                                 ExceptionType);
 }
 
 void CommentASTToXMLConverter::visitParamCommandComment(

diff --git a/clang/lib/Index/IndexBody.cpp b/clang/lib/Index/IndexBody.cpp
@@ -268,7 +268,7 @@ class BodyIndexer : public RecursiveASTVisitor<BodyIndexer> {
         }
         return true;
       };
-      bool IsPropCall = Containing && isa<PseudoObjectExpr>(Containing);
+      bool IsPropCall = isa_and_nonnull<PseudoObjectExpr>(Containing);
       // Implicit property message sends are not 'implicit'.
       if ((E->isImplicit() || IsPropCall) &&
           !(IsPropCall &&

diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -226,7 +226,7 @@ void Preprocessor::updateModuleMacroInfo(const IdentifierInfo *II,
   bool IsSystemMacro = true;
   bool IsAmbiguous = false;
   if (auto *MD = Info.MD) {
-    while (MD && isa<VisibilityMacroDirective>(MD))
+    while (isa_and_nonnull<VisibilityMacroDirective>(MD))
       MD = MD->getPrevious();
     if (auto *DMD = dyn_cast_or_null<DefMacroDirective>(MD)) {
       MI = DMD->getInfo();

diff --git a/clang/lib/Sema/AnalysisBasedWarnings.cpp b/clang/lib/Sema/AnalysisBasedWarnings.cpp
@@ -442,7 +442,7 @@ static ControlFlowKind CheckFallThrough(AnalysisDeclContext &AC) {
       if (!live[B->getBlockID()]) {
         if (B->pred_begin() == B->pred_end()) {
           const Stmt *Term = B->getTerminatorStmt();
-          if (Term && isa<CXXTryStmt>(Term))
+          if (isa_and_nonnull<CXXTryStmt>(Term))
             // When not adding EH edges from calls, catch clauses
             // can otherwise seem dead.  Avoid noting them as dead.
             count += reachable_code::ScanReachableFromBlock(B, live);
@@ -1100,7 +1100,7 @@ namespace {
       // issue a warn_fallthrough_attr_unreachable for them.
       for (const auto *B : *Cfg) {
         const Stmt *L = B->getLabel();
-        if (L && isa<SwitchCase>(L) && ReachableBlocks.insert(B).second)
+        if (isa_and_nonnull<SwitchCase>(L) && ReachableBlocks.insert(B).second)
           BlockQueue.push_back(B);
       }
 
@@ -1128,7 +1128,7 @@ namespace {
         if (!P) continue;
 
         const Stmt *Term = P->getTerminatorStmt();
-        if (Term && isa<SwitchStmt>(Term))
+        if (isa_and_nonnull<SwitchStmt>(Term))
           continue; // Switch statement, good.
 
         const SwitchCase *SW = dyn_cast_or_null<SwitchCase>(P->getLabel());
@@ -1327,7 +1327,7 @@ static void DiagnoseSwitchLabelsFallthrough(Sema &S, AnalysisDeclContext &AC,
         B = *B->succ_begin();
         Term = B->getTerminatorStmt();
       }
-      if (!(B->empty() && Term && isa<BreakStmt>(Term))) {
+      if (!(B->empty() && isa_and_nonnull<BreakStmt>(Term))) {
         Preprocessor &PP = S.getPreprocessor();
         StringRef AnnotationSpelling = getFallthroughAttrSpelling(PP, L);
         SmallString<64> TextToInsert(AnnotationSpelling);

diff --git a/clang/lib/Sema/SemaAvailability.cpp b/clang/lib/Sema/SemaAvailability.cpp
@@ -12,6 +12,7 @@
 
 #include "clang/AST/Attr.h"
 #include "clang/AST/Decl.h"
+#include "clang/AST/DeclTemplate.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/Basic/DiagnosticSema.h"
 #include "clang/Basic/IdentifierTable.h"
@@ -46,6 +47,10 @@ static const AvailabilityAttr *getAttrForPlatform(ASTContext &Context,
   // Check each AvailabilityAttr to find the one for this platform.
   // For multiple attributes with the same platform try to find one for this
   // environment.
+  // The attribute is always on the FunctionDecl, not on the
+  // FunctionTemplateDecl.
+  if (const auto *FTD = dyn_cast<FunctionTemplateDecl>(D))
+    D = FTD->getTemplatedDecl();
   for (const auto *A : D->attrs()) {
     if (const auto *Avail = dyn_cast<AvailabilityAttr>(A)) {
       // FIXME: this is copied from CheckAvailability. We should try to

diff --git a/clang/lib/Sema/SemaCUDA.cpp b/clang/lib/Sema/SemaCUDA.cpp
@@ -1018,24 +1018,33 @@ void SemaCUDA::checkTargetOverload(FunctionDecl *NewFD,
     // HD/global functions "exist" in some sense on both the host and device, so
     // should have the same implementation on both sides.
     if (NewTarget != OldTarget &&
-        ((NewTarget == CUDAFunctionTarget::HostDevice &&
-          !(getLangOpts().OffloadImplicitHostDeviceTemplates &&
-            isImplicitHostDeviceFunction(NewFD) &&
-            OldTarget == CUDAFunctionTarget::Device)) ||
-         (OldTarget == CUDAFunctionTarget::HostDevice &&
-          !(getLangOpts().OffloadImplicitHostDeviceTemplates &&
-            isImplicitHostDeviceFunction(OldFD) &&
-            NewTarget == CUDAFunctionTarget::Device)) ||
-         (NewTarget == CUDAFunctionTarget::Global) ||
-         (OldTarget == CUDAFunctionTarget::Global)) &&
         !SemaRef.IsOverload(NewFD, OldFD, /* UseMemberUsingDeclRules = */ false,
                             /* ConsiderCudaAttrs = */ false)) {
-      Diag(NewFD->getLocation(), diag::err_cuda_ovl_target)
-          << llvm::to_underlying(NewTarget) << NewFD->getDeclName()
-          << llvm::to_underlying(OldTarget) << OldFD;
-      Diag(OldFD->getLocation(), diag::note_previous_declaration);
-      NewFD->setInvalidDecl();
-      break;
+      if ((NewTarget == CUDAFunctionTarget::HostDevice &&
+           !(getLangOpts().OffloadImplicitHostDeviceTemplates &&
+             isImplicitHostDeviceFunction(NewFD) &&
+             OldTarget == CUDAFunctionTarget::Device)) ||
+          (OldTarget == CUDAFunctionTarget::HostDevice &&
+           !(getLangOpts().OffloadImplicitHostDeviceTemplates &&
+             isImplicitHostDeviceFunction(OldFD) &&
+             NewTarget == CUDAFunctionTarget::Device)) ||
+          (NewTarget == CUDAFunctionTarget::Global) ||
+          (OldTarget == CUDAFunctionTarget::Global)) {
+        Diag(NewFD->getLocation(), diag::err_cuda_ovl_target)
+            << llvm::to_underlying(NewTarget) << NewFD->getDeclName()
+            << llvm::to_underlying(OldTarget) << OldFD;
+        Diag(OldFD->getLocation(), diag::note_previous_declaration);
+        NewFD->setInvalidDecl();
+        break;
+      }
+      if ((NewTarget == CUDAFunctionTarget::Host &&
+           OldTarget == CUDAFunctionTarget::Device) ||
+          (NewTarget == CUDAFunctionTarget::Device &&
+           OldTarget == CUDAFunctionTarget::Host)) {
+        Diag(NewFD->getLocation(), diag::warn_offload_incompatible_redeclare)
+            << llvm::to_underlying(NewTarget) << llvm::to_underlying(OldTarget);
+        Diag(OldFD->getLocation(), diag::note_previous_declaration);
+      }
     }
   }
 }

diff --git a/clang/lib/Sema/SemaCXXScopeSpec.cpp b/clang/lib/Sema/SemaCXXScopeSpec.cpp
@@ -974,7 +974,7 @@ bool Sema::ActOnCXXNestedNameSpecifier(Scope *S,
       R.setBegin(SS.getRange().getBegin());
 
     Diag(CCLoc, diag::err_non_type_template_in_nested_name_specifier)
-      << (TD && isa<VarTemplateDecl>(TD)) << Template << R;
+        << isa_and_nonnull<VarTemplateDecl>(TD) << Template << R;
     NoteAllFoundTemplates(Template);
     return true;
   }

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
@@ -3839,11 +3839,11 @@ void Sema::checkCall(NamedDecl *FDecl, const FunctionProtoType *Proto,
   if (CallType != VariadicDoesNotApply &&
       (!FD || FD->getBuiltinID() != Builtin::BI__noop)) {
     unsigned NumParams = Proto ? Proto->getNumParams()
-                       : FDecl && isa<FunctionDecl>(FDecl)
-                           ? cast<FunctionDecl>(FDecl)->getNumParams()
-                       : FDecl && isa<ObjCMethodDecl>(FDecl)
-                           ? cast<ObjCMethodDecl>(FDecl)->param_size()
-                       : 0;
+                         : isa_and_nonnull<FunctionDecl>(FDecl)
+                             ? cast<FunctionDecl>(FDecl)->getNumParams()
+                         : isa_and_nonnull<ObjCMethodDecl>(FDecl)
+                             ? cast<ObjCMethodDecl>(FDecl)->param_size()
+                             : 0;
 
     for (unsigned ArgIdx = NumParams; ArgIdx < Args.size(); ++ArgIdx) {
       // Args[ArgIdx] can be null in malformed code.

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -1806,6 +1806,7 @@ static unsigned getRecordDiagFromTagKind(TagTypeKind Tag) {
 static bool CheckConstexprFunctionBody(Sema &SemaRef, const FunctionDecl *Dcl,
                                        Stmt *Body,
                                        Sema::CheckConstexprKind Kind);
+static bool CheckConstexprMissingReturn(Sema &SemaRef, const FunctionDecl *Dcl);
 
 // Check whether a function declaration satisfies the requirements of a
 // constexpr function definition or a constexpr constructor definition. If so,
@@ -2411,20 +2412,9 @@ static bool CheckConstexprFunctionBody(Sema &SemaRef, const FunctionDecl *Dcl,
     }
   } else {
     if (ReturnStmts.empty()) {
-      // C++1y doesn't require constexpr functions to contain a 'return'
-      // statement. We still do, unless the return type might be void, because
-      // otherwise if there's no return statement, the function cannot
-      // be used in a core constant expression.
-      bool OK = SemaRef.getLangOpts().CPlusPlus14 &&
-                (Dcl->getReturnType()->isVoidType() ||
-                 Dcl->getReturnType()->isDependentType());
       switch (Kind) {
       case Sema::CheckConstexprKind::Diagnose:
-        SemaRef.Diag(Dcl->getLocation(),
-                     OK ? diag::warn_cxx11_compat_constexpr_body_no_return
-                        : diag::err_constexpr_body_no_return)
-            << Dcl->isConsteval();
-        if (!OK)
+        if (!CheckConstexprMissingReturn(SemaRef, Dcl))
           return false;
         break;
 
@@ -2494,6 +2484,28 @@ static bool CheckConstexprFunctionBody(Sema &SemaRef, const FunctionDecl *Dcl,
   return true;
 }
 
+static bool CheckConstexprMissingReturn(Sema &SemaRef,
+                                        const FunctionDecl *Dcl) {
+  bool IsVoidOrDependentType = Dcl->getReturnType()->isVoidType() ||
+                               Dcl->getReturnType()->isDependentType();
+  // Skip emitting a missing return error diagnostic for non-void functions
+  // since C++23 no longer mandates constexpr functions to yield constant
+  // expressions.
+  if (SemaRef.getLangOpts().CPlusPlus23 && !IsVoidOrDependentType)
+    return true;
+
+  // C++14 doesn't require constexpr functions to contain a 'return'
+  // statement. We still do, unless the return type might be void, because
+  // otherwise if there's no return statement, the function cannot
+  // be used in a core constant expression.
+  bool OK = SemaRef.getLangOpts().CPlusPlus14 && IsVoidOrDependentType;
+  SemaRef.Diag(Dcl->getLocation(),
+               OK ? diag::warn_cxx11_compat_constexpr_body_no_return
+                  : diag::err_constexpr_body_no_return)
+      << Dcl->isConsteval();
+  return OK;
+}
+
 bool Sema::CheckImmediateEscalatingFunctionDefinition(
     FunctionDecl *FD, const sema::FunctionScopeInfo *FSI) {
   if (!getLangOpts().CPlusPlus20 || !FD->isImmediateEscalating())
@@ -13079,7 +13091,10 @@ NamedDecl *Sema::BuildUsingDeclaration(
   // A using-declaration shall not name a namespace.
   if (R.getAsSingle<NamespaceDecl>()) {
     Diag(IdentLoc, diag::err_using_decl_can_not_refer_to_namespace)
-      << SS.getRange();
+        << SS.getRange();
+    // Suggest using 'using namespace ...' instead.
+    Diag(SS.getBeginLoc(), diag::note_namespace_using_decl)
+        << FixItHint::CreateInsertion(SS.getBeginLoc(), "namespace ");
     return BuildInvalid();
   }