[clang] [Clang] Speed up Sema virtual-method no-work paths (NFC) (PR #223045)

[Eli Friedman via cfe-commits]

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@@ -10648,7 +10648,9 @@ static void AddMostOverridenMethods(const CXXMethodDecl *MD,
 
 void Sema::FindHiddenVirtualMethods(CXXMethodDecl *MD,
                           SmallVectorImpl<CXXMethodDecl*> &OverloadedMethods) {
-  if (!MD->getDeclName().isIdentifier())
+  CXXRecordDecl *DC = MD->getParent();
+  if (DC->getNumBases() == 0 || !DC->isPolymorphic() ||
+      !MD->getDeclName().isIdentifier())
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efriedma-quic wrote:

It's hard for me to believe this helps.  `!MD->getDeclName().isIdentifier()` can be lowered to a TEST.

https://github.com/llvm/llvm-project/pull/223045