libstdc++: Add [[unlikely]] attributes to std::random_device routines

libstdc++-v3/ChangeLog:

	* src/c++11/random.cc (__x86_rdrand, __x86_rdseed): Add
	[[unlikely]] attribute.

diff --git a/libstdc++-v3/src/c++11/random.cc b/libstdc++-v3/src/c++11/random.cc
index 55a73c51fcaae8bf4dcda97c39ed4fcc41b7ead7..4b88818646f14fef3996ddd7521166b3501963a0 100644 (file)
--- a/libstdc++-v3/src/c++11/random.cc
+++ b/libstdc++-v3/src/c++11/random.cc
@@ -97,7 +97,7 @@ namespace std _GLIBCXX_VISIBILITY(default)
       unsigned int retries = 100;
       unsigned int val;
 
-      while (__builtin_ia32_rdrand32_step(&val) == 0)
+      while (__builtin_ia32_rdrand32_step(&val) == 0) [[__unlikely__]]
        if (--retries == 0)
          std::__throw_runtime_error(__N("random_device: rdrand failed"));
 
@@ -113,7 +113,7 @@ namespace std _GLIBCXX_VISIBILITY(default)
       unsigned int retries = 100;
       unsigned int val;
 
-      while (__builtin_ia32_rdseed_si_step(&val) == 0)
+      while (__builtin_ia32_rdseed_si_step(&val) == 0) [[__unlikely__]]
        {
          if (--retries == 0)
            {