[clang][bytecode] Save Constexpr bit in Function (#142793)

Rename isConstexpr to isValid, the former was always a bad name. Save a
constexpr bit in Function so we don't have to access the decl in
CheckCallable.

Author: tbaederr

clang/lib/AST/ByteCode/Context.cpp

@@ -49,7 +49,7 @@ bool Context::isPotentialConstantExpr(State &Parent, const FunctionDecl *FD) {
   if (!Run(Parent, Func))
     return false;
 
-  return Func->isConstexpr();
+  return Func->isValid();
 }
 
 bool Context::evaluateAsRValue(State &Parent, const Expr *E, APValue &Result) {

clang/lib/AST/ByteCode/Function.cpp

@@ -27,6 +27,7 @@ Function::Function(Program &P, FunctionDeclTy Source, unsigned ArgSize,
   if (const auto *F = dyn_cast<const FunctionDecl *>(Source)) {
     Variadic = F->isVariadic();
     Immediate = F->isImmediateFunction();
+    Constexpr = F->isConstexpr() || F->hasAttr<MSConstexprAttr>();
     if (const auto *CD = dyn_cast<CXXConstructorDecl>(F)) {
       Virtual = CD->isVirtual();
       Kind = FunctionKind::Ctor;
@@ -48,6 +49,7 @@ Function::Function(Program &P, FunctionDeclTy Source, unsigned ArgSize,
     Variadic = false;
     Virtual = false;
     Immediate = false;
+    Constexpr = false;
   }
 }
 

clang/lib/AST/ByteCode/Function.h

@@ -150,12 +150,13 @@ class Function final {
   /// Returns the source information at a given PC.
   SourceInfo getSource(CodePtr PC) const;
 
-  /// Checks if the function is valid to call in constexpr.
-  bool isConstexpr() const { return IsValid || isLambdaStaticInvoker(); }
+  /// Checks if the function is valid to call.
+  bool isValid() const { return IsValid || isLambdaStaticInvoker(); }
 
   /// Checks if the function is virtual.
   bool isVirtual() const { return Virtual; };
   bool isImmediate() const { return Immediate; }
+  bool isConstexpr() const { return Constexpr; }
 
   /// Checks if the function is a constructor.
   bool isConstructor() const { return Kind == FunctionKind::Ctor; }
@@ -303,6 +304,8 @@ class Function final {
   unsigned Virtual : 1;
   LLVM_PREFERRED_TYPE(bool)
   unsigned Immediate : 1;
+  LLVM_PREFERRED_TYPE(bool)
+  unsigned Constexpr : 1;
 
 public:
   /// Dumps the disassembled bytecode to \c llvm::errs().

clang/lib/AST/ByteCode/Interp.cpp

@@ -857,23 +857,22 @@ bool CheckCallable(InterpState &S, CodePtr OpPC, const Function *F) {
     return false;
   }
 
-  // Bail out if the function declaration itself is invalid.  We will
-  // have produced a relevant diagnostic while parsing it, so just
-  // note the problematic sub-expression.
-  if (F->getDecl()->isInvalidDecl())
-    return Invalid(S, OpPC);
-
   if (S.checkingPotentialConstantExpression() && S.Current->getDepth() != 0)
     return false;
 
-  if (F->isConstexpr() && F->hasBody() &&
-      (F->getDecl()->isConstexpr() || F->getDecl()->hasAttr<MSConstexprAttr>()))
+  if (F->isValid() && F->hasBody() && F->isConstexpr())
     return true;
 
   // Implicitly constexpr.
   if (F->isLambdaStaticInvoker())
     return true;
 
+  // Bail out if the function declaration itself is invalid.  We will
+  // have produced a relevant diagnostic while parsing it, so just
+  // note the problematic sub-expression.
+  if (F->getDecl()->isInvalidDecl())
+    return Invalid(S, OpPC);
+
   // Diagnose failed assertions specially.
   if (S.Current->getLocation(OpPC).isMacroID() &&
       F->getDecl()->getIdentifier()) {
@@ -923,7 +922,8 @@ bool CheckCallable(InterpState &S, CodePtr OpPC, const Function *F) {
       // for a constant expression. It might be defined at the point we're
       // actually calling it.
       bool IsExtern = DiagDecl->getStorageClass() == SC_Extern;
-      if (!DiagDecl->isDefined() && !IsExtern && DiagDecl->isConstexpr() &&
+      bool IsDefined = F->isDefined();
+      if (!IsDefined && !IsExtern && DiagDecl->isConstexpr() &&
           S.checkingPotentialConstantExpression())
         return false;