[clang-tools-extra] [clang-doc] Improve performance by adding a short circuit (PR #96809)

[Paul Kirth via cfe-commits]

================
@@ -12,16 +12,31 @@
 #include "clang/AST/Comment.h"
 #include "clang/Index/USRGeneration.h"
 #include "llvm/ADT/StringExtras.h"
-#include "llvm/Support/Error.h"
+#include "llvm/ADT/StringSet.h"
+#include "llvm/Support/Mutex.h"
 
 namespace clang {
 namespace doc {
 
+static llvm::StringSet USRVisited;
+static llvm::sys::Mutex USRVisitedGuard;
+
+
+template <typename T> bool isTypedefAnonRecord(const T* D) {
+  if (const auto *C = dyn_cast<CXXRecordDecl>(D)) {
+    if (const TypedefNameDecl *TD = C->getTypedefNameForAnonDecl()) {
+      return true;
+    }
----------------
ilovepi wrote:

```suggestion
    return C->getTypedefNameForAnonDecl();
```
Isn't this just the same. You still need the outer return, but this doesn't need a branch and temporary.

https://github.com/llvm/llvm-project/pull/96809