[clang-tools-extra] [clang-doc] Use SmartMutex when visiting the AST (PR #135514)

[Paul Kirth via cfe-commits]

https://github.com/ilovepi created https://github.com/llvm/llvm-project/pull/135514

The SmartMutex will allow us to have a cheap mutex implementation when
using the Standalone executor, since it's single threaded. Performance
should be about the same for AllTUs executor.

>From f3a86d88bd89ba281fc301734ef24a79d9821f7b Mon Sep 17 00:00:00 2001
From: Paul Kirth <paulkirth at google.com>
Date: Sat, 12 Apr 2025 19:12:06 -0700
Subject: [PATCH] [clang-doc][NFC] Use SmartMutex when visiting the AST

The SmartMutex will allow us to have a cheap mutex implementation when
using the Standalone executor, since it's single threaded. Performance
should be about the same for AllTUs executor.
---
 clang-tools-extra/clang-doc/Mapper.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang-tools-extra/clang-doc/Mapper.cpp b/clang-tools-extra/clang-doc/Mapper.cpp
index 6c90db03424c6..022e3b12d82bc 100644
--- a/clang-tools-extra/clang-doc/Mapper.cpp
+++ b/clang-tools-extra/clang-doc/Mapper.cpp
@@ -19,7 +19,7 @@ namespace clang {
 namespace doc {
 
 static llvm::StringSet<> USRVisited;
-static llvm::sys::Mutex USRVisitedGuard;
+static llvm::sys::SmartMutex<true> USRVisitedGuard;
 
 template <typename T> bool isTypedefAnonRecord(const T *D) {
   if (const auto *C = dyn_cast<CXXRecordDecl>(D)) {
@@ -48,7 +48,7 @@ bool MapASTVisitor::mapDecl(const T *D, bool IsDefinition) {
     return true;
   // Prevent Visiting USR twice
   {
-    std::lock_guard<llvm::sys::Mutex> Guard(USRVisitedGuard);
+    llvm::sys::SmartScopedLock<true> Guard(USRVisitedGuard);
     StringRef Visited = USR.str();
     if (USRVisited.count(Visited) && !isTypedefAnonRecord<T>(D))
       return true;