[PATCH] D44698: [Support/Parallel] Use lock_guard which has less overhead than unique_lock.

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
MaskRay added reviewers: grimar, zturner.
Herald added a subscriber: llvm-commits.

unique_lock has the overhead of tracking ownership status and the owner.


Repository:
  rL LLVM

https://reviews.llvm.org/D44698

Files:
  include/llvm/Support/Parallel.h


Index: include/llvm/Support/Parallel.h
===================================================================
--- include/llvm/Support/Parallel.h
+++ include/llvm/Support/Parallel.h
@@ -56,12 +56,12 @@
   ~Latch() { sync(); }
 
   void inc() {
-    std::unique_lock<std::mutex> lock(Mutex);
+    std::lock_guard<std::mutex> lock(Mutex);
     ++Count;
   }
 
   void dec() {
-    std::unique_lock<std::mutex> lock(Mutex);
+    std::lock_guard<std::mutex> lock(Mutex);
     if (--Count == 0)
       Cond.notify_all();
   }


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