[clang][bytecode] Use OptPrimType instead of std::optional<PrimType> (#149812)

tbaederr · web-flow · commit e39ee62c5bdb · 2025-07-21T17:16:13.000+02:00
We use this construct a lot. Use something similar to clang's UnsignedOrNone. This results in some slighy compile time improvements: https://llvm-compile-time-tracker.com/compare.php?from=17a4b0399d161a3b89d8f0ce82add1638f23f5d4&to=a251d81ecd0ed45dd190462663155fdb303ef04d&stat=instructions:u
diff --git a/clang/lib/AST/ByteCode/ByteCodeEmitter.cpp b/clang/lib/AST/ByteCode/ByteCodeEmitter.cpp
@@ -62,7 +62,7 @@ void ByteCodeEmitter::compileFunc(const FunctionDecl *FuncDecl,
                   (Func->hasThisPointer() && !Func->isThisPointerExplicit());
   for (auto ParamOffset : llvm::drop_begin(Func->ParamOffsets, Drop)) {
     const ParmVarDecl *PD = FuncDecl->parameters()[ParamIndex];
-    std::optional<PrimType> T = Ctx.classify(PD->getType());
+    OptPrimType T = Ctx.classify(PD->getType());
     this->Params.insert({PD, {ParamOffset, T != std::nullopt}});
     ++ParamIndex;
   }
diff --git a/clang/lib/AST/ByteCode/Compiler.cpp b/clang/lib/AST/ByteCode/Compiler.cpp
diff --git a/clang/lib/AST/ByteCode/Compiler.h b/clang/lib/AST/ByteCode/Compiler.h
@@ -254,12 +254,8 @@ class Compiler : public ConstStmtVisitor<Compiler<Emitter>, bool>,
   /// If the function does not exist yet, it is compiled.
   const Function *getFunction(const FunctionDecl *FD);
 
-  std::optional<PrimType> classify(const Expr *E) const {
-    return Ctx.classify(E);
-  }
-  std::optional<PrimType> classify(QualType Ty) const {
-    return Ctx.classify(Ty);
-  }
+  OptPrimType classify(const Expr *E) const { return Ctx.classify(E); }
+  OptPrimType classify(QualType Ty) const { return Ctx.classify(Ty); }
 
   /// Classifies a known primitive type.
   PrimType classifyPrim(QualType Ty) const {
@@ -306,7 +302,7 @@ class Compiler : public ConstStmtVisitor<Compiler<Emitter>, bool>,
   bool visitInitList(ArrayRef<const Expr *> Inits, const Expr *ArrayFiller,
                      const Expr *E);
   bool visitArrayElemInit(unsigned ElemIndex, const Expr *Init,
-                          std::optional<PrimType> InitT);
+                          OptPrimType InitT);
   bool visitCallArgs(ArrayRef<const Expr *> Args, const FunctionDecl *FuncDecl,
                      bool Activate);
 
@@ -435,7 +431,7 @@ class Compiler : public ConstStmtVisitor<Compiler<Emitter>, bool>,
   bool InitStackActive = false;
 
   /// Type of the expression returned by the function.
-  std::optional<PrimType> ReturnType;
+  OptPrimType ReturnType;
 
   /// Switch case mapping.
   CaseMap CaseLabels;
diff --git a/clang/lib/AST/ByteCode/Context.cpp b/clang/lib/AST/ByteCode/Context.cpp
@@ -306,7 +306,7 @@ static PrimType integralTypeToPrimTypeU(unsigned BitWidth) {
   llvm_unreachable("Unhandled BitWidth");
 }
 
-std::optional<PrimType> Context::classify(QualType T) const {
+OptPrimType Context::classify(QualType T) const {
 
   if (const auto *BT = dyn_cast<BuiltinType>(T.getCanonicalType())) {
     auto Kind = BT->getKind();
@@ -542,7 +542,7 @@ const Function *Context::getOrCreateFunction(const FunctionDecl *FuncDecl) {
   // Assign descriptors to all parameters.
   // Composite objects are lowered to pointers.
   for (const ParmVarDecl *PD : FuncDecl->parameters()) {
-    std::optional<PrimType> T = classify(PD->getType());
+    OptPrimType T = classify(PD->getType());
     PrimType PT = T.value_or(PT_Ptr);
     Descriptor *Desc = P->createDescriptor(PD, PT);
     ParamDescriptors.insert({ParamOffset, {PT, Desc}});
@@ -570,7 +570,7 @@ const Function *Context::getOrCreateObjCBlock(const BlockExpr *E) {
   // Assign descriptors to all parameters.
   // Composite objects are lowered to pointers.
   for (const ParmVarDecl *PD : BD->parameters()) {
-    std::optional<PrimType> T = classify(PD->getType());
+    OptPrimType T = classify(PD->getType());
     PrimType PT = T.value_or(PT_Ptr);
     Descriptor *Desc = P->createDescriptor(PD, PT);
     ParamDescriptors.insert({ParamOffset, {PT, Desc}});
diff --git a/clang/lib/AST/ByteCode/Context.h b/clang/lib/AST/ByteCode/Context.h
@@ -82,10 +82,10 @@ class Context final {
   uint32_t getBitWidth(QualType T) const { return Ctx.getIntWidth(T); }
 
   /// Classifies a type.
-  std::optional<PrimType> classify(QualType T) const;
+  OptPrimType classify(QualType T) const;
 
   /// Classifies an expression.
-  std::optional<PrimType> classify(const Expr *E) const {
+  OptPrimType classify(const Expr *E) const {
     assert(E);
     if (E->isGLValue())
       return PT_Ptr;
diff --git a/clang/lib/AST/ByteCode/Descriptor.h b/clang/lib/AST/ByteCode/Descriptor.h
@@ -164,7 +164,7 @@ struct Descriptor final {
   /// The primitive type this descriptor was created for,
   /// or the primitive element type in case this is
   /// a primitive array.
-  const std::optional<PrimType> PrimT = std::nullopt;
+  const OptPrimType PrimT = std::nullopt;
   /// Flag indicating if the block is mutable.
   const bool IsConst = false;
   /// Flag indicating if a field is mutable.
diff --git a/clang/lib/AST/ByteCode/EvalEmitter.cpp b/clang/lib/AST/ByteCode/EvalEmitter.cpp
@@ -324,7 +324,7 @@ void EvalEmitter::updateGlobalTemporaries() {
       const Pointer &Ptr = P.getPtrGlobal(*GlobalIndex);
       APValue *Cached = Temp->getOrCreateValue(true);
 
-      if (std::optional<PrimType> T = Ctx.classify(E->getType())) {
+      if (OptPrimType T = Ctx.classify(E->getType())) {
         TYPE_SWITCH(
             *T, { *Cached = Ptr.deref<T>().toAPValue(Ctx.getASTContext()); });
       } else {
diff --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
@@ -53,7 +53,7 @@ static APSInt popToAPSInt(InterpStack &Stk, PrimType T) {
 static void pushInteger(InterpState &S, const APSInt &Val, QualType QT) {
   assert(QT->isSignedIntegerOrEnumerationType() ||
          QT->isUnsignedIntegerOrEnumerationType());
-  std::optional<PrimType> T = S.getContext().classify(QT);
+  OptPrimType T = S.getContext().classify(QT);
   assert(T);
 
   unsigned BitWidth = S.getASTContext().getTypeSize(QT);
@@ -1530,7 +1530,7 @@ static bool interp__builtin_operator_new(InterpState &S, CodePtr OpPC,
     return false;
 
   bool IsArray = NumElems.ugt(1);
-  std::optional<PrimType> ElemT = S.getContext().classify(ElemType);
+  OptPrimType ElemT = S.getContext().classify(ElemType);
   DynamicAllocator &Allocator = S.getAllocator();
   if (ElemT) {
     Block *B =
@@ -2879,7 +2879,7 @@ static bool copyRecord(InterpState &S, CodePtr OpPC, const Pointer &Src,
 
   auto copyField = [&](const Record::Field &F, bool Activate) -> bool {
     Pointer DestField = Dest.atField(F.Offset);
-    if (std::optional<PrimType> FT = S.Ctx.classify(F.Decl->getType())) {
+    if (OptPrimType FT = S.Ctx.classify(F.Decl->getType())) {
       TYPE_SWITCH(*FT, {
         DestField.deref<T>() = Src.atField(F.Offset).deref<T>();
         if (Src.atField(F.Offset).isInitialized())
diff --git a/clang/lib/AST/ByteCode/Pointer.cpp b/clang/lib/AST/ByteCode/Pointer.cpp
@@ -665,7 +665,7 @@ std::optional<APValue> Pointer::toRValue(const Context &Ctx,
       return false;
 
     // Primitive values.
-    if (std::optional<PrimType> T = Ctx.classify(Ty)) {
+    if (OptPrimType T = Ctx.classify(Ty)) {
       TYPE_SWITCH(*T, R = Ptr.deref<T>().toAPValue(ASTCtx));
       return true;
     }
@@ -682,7 +682,7 @@ std::optional<APValue> Pointer::toRValue(const Context &Ctx,
           const Pointer &FP = Ptr.atField(F.Offset);
           QualType FieldTy = F.Decl->getType();
           if (FP.isActive()) {
-            if (std::optional<PrimType> T = Ctx.classify(FieldTy)) {
+            if (OptPrimType T = Ctx.classify(FieldTy)) {
               TYPE_SWITCH(*T, Value = FP.deref<T>().toAPValue(ASTCtx));
             } else {
               Ok &= Composite(FieldTy, FP, Value);
@@ -705,7 +705,7 @@ std::optional<APValue> Pointer::toRValue(const Context &Ctx,
           const Pointer &FP = Ptr.atField(FD->Offset);
           APValue &Value = R.getStructField(I);
 
-          if (std::optional<PrimType> T = Ctx.classify(FieldTy)) {
+          if (OptPrimType T = Ctx.classify(FieldTy)) {
             TYPE_SWITCH(*T, Value = FP.deref<T>().toAPValue(ASTCtx));
           } else {
             Ok &= Composite(FieldTy, FP, Value);
@@ -743,7 +743,7 @@ std::optional<APValue> Pointer::toRValue(const Context &Ctx,
       for (unsigned I = 0; I < NumElems; ++I) {
         APValue &Slot = R.getArrayInitializedElt(I);
         const Pointer &EP = Ptr.atIndex(I);
-        if (std::optional<PrimType> T = Ctx.classify(ElemTy)) {
+        if (OptPrimType T = Ctx.classify(ElemTy)) {
           TYPE_SWITCH(*T, Slot = EP.deref<T>().toAPValue(ASTCtx));
         } else {
           Ok &= Composite(ElemTy, EP.narrow(), Slot);
@@ -757,7 +757,7 @@ std::optional<APValue> Pointer::toRValue(const Context &Ctx,
       QualType ElemTy = CT->getElementType();
 
       if (ElemTy->isIntegerType()) {
-        std::optional<PrimType> ElemT = Ctx.classify(ElemTy);
+        OptPrimType ElemT = Ctx.classify(ElemTy);
         assert(ElemT);
         INT_TYPE_SWITCH(*ElemT, {
           auto V1 = Ptr.elem<T>(0);
@@ -803,7 +803,7 @@ std::optional<APValue> Pointer::toRValue(const Context &Ctx,
     return toAPValue(ASTCtx);
 
   // Just load primitive types.
-  if (std::optional<PrimType> T = Ctx.classify(ResultType)) {
+  if (OptPrimType T = Ctx.classify(ResultType)) {
     TYPE_SWITCH(*T, return this->deref<T>().toAPValue(ASTCtx));
   }
 
diff --git a/clang/lib/AST/ByteCode/PrimType.h b/clang/lib/AST/ByteCode/PrimType.h
@@ -13,6 +13,7 @@
 #ifndef LLVM_CLANG_AST_INTERP_TYPE_H
 #define LLVM_CLANG_AST_INTERP_TYPE_H
 
+#include "clang/Basic/UnsignedOrNone.h"
 #include "llvm/Support/raw_ostream.h"
 #include <climits>
 #include <cstddef>
@@ -49,6 +50,38 @@ enum PrimType : unsigned {
   PT_MemberPtr = 14,
 };
 
+// Like std::optional<PrimType>, but only sizeof(PrimType).
+class OptPrimType final {
+  unsigned V = ~0u;
+
+public:
+  OptPrimType() = default;
+  OptPrimType(std::nullopt_t) {}
+  OptPrimType(PrimType T) : V(static_cast<unsigned>(T)) {}
+
+  explicit constexpr operator bool() const { return V != ~0u; }
+  PrimType operator*() const {
+    assert(operator bool());
+    return static_cast<PrimType>(V);
+  }
+
+  PrimType value_or(PrimType PT) const {
+    if (operator bool())
+      return static_cast<PrimType>(V);
+    return PT;
+  }
+
+  bool operator==(PrimType PT) const {
+    if (!operator bool())
+      return false;
+    return V == static_cast<unsigned>(PT);
+  }
+  bool operator==(OptPrimType OPT) const { return V == OPT.V; }
+  bool operator!=(PrimType PT) const { return !(*this == PT); }
+  bool operator!=(OptPrimType OPT) const { return V != OPT.V; }
+};
+static_assert(sizeof(OptPrimType) == sizeof(PrimType));
+
 inline constexpr bool isPtrType(PrimType T) {
   return T == PT_Ptr || T == PT_MemberPtr;
 }
diff --git a/clang/lib/AST/ByteCode/Program.cpp b/clang/lib/AST/ByteCode/Program.cpp
@@ -169,7 +169,7 @@ unsigned Program::getOrCreateDummy(const DeclTy &D) {
   assert(!QT.isNull());
 
   Descriptor *Desc;
-  if (std::optional<PrimType> T = Ctx.classify(QT))
+  if (OptPrimType T = Ctx.classify(QT))
     Desc = createDescriptor(D, *T, /*SourceTy=*/nullptr, std::nullopt,
                             /*IsConst=*/QT.isConstQualified());
   else
@@ -248,7 +248,7 @@ std::optional<unsigned> Program::createGlobal(const DeclTy &D, QualType Ty,
   const bool IsConst = Ty.isConstQualified();
   const bool IsTemporary = D.dyn_cast<const Expr *>();
   const bool IsVolatile = Ty.isVolatileQualified();
-  if (std::optional<PrimType> T = Ctx.classify(Ty))
+  if (OptPrimType T = Ctx.classify(Ty))
     Desc = createDescriptor(D, *T, nullptr, Descriptor::GlobalMD, IsConst,
                             IsTemporary, /*IsMutable=*/false, IsVolatile);
   else
@@ -371,7 +371,7 @@ Record *Program::getOrCreateRecord(const RecordDecl *RD) {
     const bool IsMutable = FD->isMutable();
     const bool IsVolatile = FT.isVolatileQualified();
     const Descriptor *Desc;
-    if (std::optional<PrimType> T = Ctx.classify(FT)) {
+    if (OptPrimType T = Ctx.classify(FT)) {
       Desc = createDescriptor(FD, *T, nullptr, std::nullopt, IsConst,
                               /*isTemporary=*/false, IsMutable, IsVolatile);
     } else {
@@ -410,7 +410,7 @@ Descriptor *Program::createDescriptor(const DeclTy &D, const Type *Ty,
     // Array of well-known bounds.
     if (const auto *CAT = dyn_cast<ConstantArrayType>(ArrayType)) {
       size_t NumElems = CAT->getZExtSize();
-      if (std::optional<PrimType> T = Ctx.classify(ElemTy)) {
+      if (OptPrimType T = Ctx.classify(ElemTy)) {
         // Arrays of primitives.
         unsigned ElemSize = primSize(*T);
         if (std::numeric_limits<unsigned>::max() / ElemSize <= NumElems) {
@@ -437,7 +437,7 @@ Descriptor *Program::createDescriptor(const DeclTy &D, const Type *Ty,
     // is forbidden on pointers to such objects.
     if (isa<IncompleteArrayType>(ArrayType) ||
         isa<VariableArrayType>(ArrayType)) {
-      if (std::optional<PrimType> T = Ctx.classify(ElemTy)) {
+      if (OptPrimType T = Ctx.classify(ElemTy)) {
         return allocateDescriptor(D, *T, MDSize, IsConst, IsTemporary,
                                   Descriptor::UnknownSize{});
       } else {
@@ -460,7 +460,7 @@ Descriptor *Program::createDescriptor(const DeclTy &D, const Type *Ty,
 
   // Complex types - represented as arrays of elements.
   if (const auto *CT = Ty->getAs<ComplexType>()) {
-    std::optional<PrimType> ElemTy = Ctx.classify(CT->getElementType());
+    OptPrimType ElemTy = Ctx.classify(CT->getElementType());
     if (!ElemTy)
       return nullptr;
 
@@ -470,7 +470,7 @@ Descriptor *Program::createDescriptor(const DeclTy &D, const Type *Ty,
 
   // Same with vector types.
   if (const auto *VT = Ty->getAs<VectorType>()) {
-    std::optional<PrimType> ElemTy = Ctx.classify(VT->getElementType());
+    OptPrimType ElemTy = Ctx.classify(VT->getElementType());
     if (!ElemTy)
       return nullptr;
 

Original file line number	Diff line number	Diff line change
`@@ -62,7 +62,7 @@ void ByteCodeEmitter::compileFunc(const FunctionDecl *FuncDecl,`
`62`	`62`	`(Func->hasThisPointer() && !Func->isThisPointerExplicit());`
`63`	`63`	`for (auto ParamOffset : llvm::drop_begin(Func->ParamOffsets, Drop)) {`
`64`	`64`	`const ParmVarDecl *PD = FuncDecl->parameters()[ParamIndex];`
`65`		`- std::optional<PrimType> T = Ctx.classify(PD->getType());`
	`65`	`+ OptPrimType T = Ctx.classify(PD->getType());`
`66`	`66`	`this->Params.insert({PD, {ParamOffset, T != std::nullopt}});`
`67`	`67`	`++ParamIndex;`
`68`	`68`	`}`