[libcxx-commits] [libcxx] [libc++] Speed up classic locale (PR #72112)

[Louis Dionne via libcxx-commits]

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@@ -14,17 +15,73 @@ double istream_numbers() {
   double f1 = 0.0, f2 = 0.0, q = 0.0;
   for (int i = 0; i < 3; i++) {
     std::istringstream s(a[i]);
+    if (loc)
+      s.imbue(*loc);
     s >> a1 >> a2 >> a3 >> f1 >> a4 >> a5 >> f2 >> a6 >> a7;
     q += (a1 + a2 + a3 + a4 + a5 + a6 + a7 + f1 + f2) / 1000000;
   }
   return q;
 }
 
+struct LocaleSelector {
+  std::locale* imbue;
+  std::locale old;
+  static std::mutex mutex;
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ldionne wrote:

@dvyukov Can you confirm that this mutex should be global to the class? Previously you were creating a function-local static mutex inside the constructor and one inside the destructor, which seemed wrong.

https://github.com/llvm/llvm-project/pull/72112