libstdc++: Disable cacheline alignment for DJGPP [PR109741]

[thirdparty/gcc.git] / libstdc++-v3 / src / c++11 / shared_ptr.cc

diff --git a/libstdc++-v3/src/c++11/shared_ptr.cc b/libstdc++-v3/src/c++11/shared_ptr.cc
index 74e879e58289696136f6ac67c289ed2ca246f7fd..ae47ca033010de202c07683ce9f0c49e43695382 100644 (file)
--- a/libstdc++-v3/src/c++11/shared_ptr.cc
+++ b/libstdc++-v3/src/c++11/shared_ptr.cc
@@ -34,8 +34,12 @@ namespace __gnu_internal _GLIBCXX_VISIBILITY(hidden)
   __gnu_cxx::__mutex&
   get_mutex(unsigned char i)
   {
-    // increase alignment to put each lock on a separate cache line
-    struct alignas(64) M : __gnu_cxx::__mutex { };
+#ifdef _GLIBCXX_CAN_ALIGNAS_DESTRUCTIVE_SIZE
+    // Increase alignment to put each lock on a separate cache line.
+    struct alignas(__GCC_DESTRUCTIVE_SIZE) M : __gnu_cxx::__mutex { };
+#else
+    using M = __gnu_cxx::__mutex;
+#endif
     // Use a static buffer, so that the mutexes are not destructed
     // before potential users (or at all)
     static __attribute__ ((aligned(__alignof__(M))))