[libcxx-commits] [libcxx] r356512 - [libc++] Speed up certain locale functions on Windows

Thomas Anderson via libcxx-commits libcxx-commits at lists.llvm.org
Tue Mar 19 13:30:58 PDT 2019

Author: thomasanderson
Date: Tue Mar 19 13:30:58 2019
New Revision: 356512

URL: http://llvm.org/viewvc/llvm-project?rev=356512&view=rev
[libc++] Speed up certain locale functions on Windows

The issue is that __libcpp_locale_guard makes some slow calls to setlocale().
This change avoids using __libcpp_locale_guard in snprintf_l().

Fixes https://bugs.llvm.org/show_bug.cgi?id=41131

Differential Revision: https://reviews.llvm.org/D59525


Modified: libcxx/trunk/src/support/win32/locale_win32.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/src/support/win32/locale_win32.cpp?rev=356512&r1=356511&r2=356512&view=diff
--- libcxx/trunk/src/support/win32/locale_win32.cpp (original)
+++ libcxx/trunk/src/support/win32/locale_win32.cpp Tue Mar 19 13:30:58 2019
@@ -87,10 +87,16 @@ int wctob_l( wint_t c, locale_t loc )
 int snprintf_l(char *ret, size_t n, locale_t loc, const char *format, ...)
+#if !defined(_LIBCPP_MSVCRT)
     __libcpp_locale_guard __current(loc);
     va_list ap;
     va_start( ap, format );
+#if defined(_LIBCPP_MSVCRT)
+    int result = _vsnprintf_l( ret, n, format, loc, ap );
     int result = vsnprintf( ret, n, format, ap );
     return result;

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