Merge pull request #1983 from apple/eliminate-global-constructor-from-runtime

Author: swift-ci

stdlib/public/stubs/LibcShims.cpp

@@ -66,18 +66,21 @@ size_t _swift_stdlib_malloc_size(const void *ptr) {
 #error No malloc_size analog known for this platform/libc.
 #endif
 
-static std::mt19937 MersenneRandom;
+static std::mt19937 &getGlobalMT19937() {
+  static std::mt19937 MersenneRandom;
+  return MersenneRandom;
+}
 
-__swift_uint32_t _swift_stdlib_cxx11_mt19937(void) {
-  return MersenneRandom();
+__swift_uint32_t _swift_stdlib_cxx11_mt19937() {
+  return getGlobalMT19937()();
 }
 
 __swift_uint32_t
 _swift_stdlib_cxx11_mt19937_uniform(__swift_uint32_t upper_bound) {
   if (upper_bound > 0)
     upper_bound--;
   std::uniform_int_distribution<__swift_uint32_t> RandomUniform(0, upper_bound);
-  return RandomUniform(MersenneRandom);
+  return RandomUniform(getGlobalMT19937());
 }
 
 } // namespace swift