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

[Paul Kirth via cfe-commits]

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@@ -34,13 +43,26 @@ template <typename T> bool MapASTVisitor::mapDecl(const T *D) {
   // If there is an error generating a USR for the decl, skip this decl.
   if (index::generateUSRForDecl(D, USR))
     return true;
+
+  // Prevent Visiting USR twice
+  {
+    std::lock_guard<llvm::sys::Mutex> Guard(USRVisitedGuard);
+    std::string Visited = USR.str().str();
+    if (USRVisited.count(Visited))
+      return true;
+    // We considered a USR to be visited only when its defined
+    if (IsDefinition)
+      USRVisited.insert(Visited);
+  }
+
   bool IsFileInRootDir;
   llvm::SmallString<128> File =
       getFile(D, D->getASTContext(), CDCtx.SourceRoot, IsFileInRootDir);
   auto I = serialize::emitInfo(D, getComment(D, D->getASTContext()),
                                getLine(D, D->getASTContext()), File,
                                IsFileInRootDir, CDCtx.PublicOnly);
 
+
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ilovepi wrote:

nit: newline

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