* [committed] libstdc++: Add [[unlikely]] attributes to std::random_device routines
@ 2021-11-05 18:17 Jonathan Wakely
0 siblings, 0 replies; only message in thread
From: Jonathan Wakely @ 2021-11-05 18:17 UTC (permalink / raw)
To: libstdc++, gcc-patches
Tested x86+64-linux, pushed to trunk.
libstdc++-v3/ChangeLog:
* src/c++11/random.cc (__x86_rdrand, __x86_rdseed): Add
[[unlikely]] attribute.
---
libstdc++-v3/src/c++11/random.cc | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/libstdc++-v3/src/c++11/random.cc b/libstdc++-v3/src/c++11/random.cc
index 55a73c51fca..4b88818646f 100644
--- 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)
{
--
2.31.1
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