On Wed, 12 Oct 2022 17:00:15 GMT, Andrew Haley <a...@openjdk.org> wrote:
>> A bug in GCC causes shared libraries linked with -ffast-math to disable >> denormal arithmetic. This breaks Java's floating-point semantics. >> >> The bug is https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55522 >> >> One solution is to save and restore the floating-point control word around >> System.loadLibrary(). This isn't perfect, because some shared library might >> load another shared library at runtime, but it's a lot better than what we >> do now. >> >> However, this fix is not complete. `dlopen()` is called from many places in >> the JDK. I guess the best thing to do is find and wrap them all. I'd like to >> hear people's opinions. > > Andrew Haley has updated the pull request incrementally with one additional > commit since the last revision: > > 8295159: DSO created with -ffast-math breaks Java floating-point arithmetic And this is Xeon CPU E5-2430 (Ivy Bridge-EN) @ 2.20GHz, with my `-XX:+RestoreMXCSROnJNICalls` code: Benchmark Mode Cnt Score Error Units CallOverheadConstant.jni_blank avgt 40 16.669 ± 0.011 ns/op CallOverheadConstant.panama_blank avgt 40 15.262 ± 0.052 ns/op Benchmark Mode Cnt Score Error Units CallOverheadConstant.jni_blank avgt 40 18.015 ± 1.671 ns/op CallOverheadConstant.panama_blank avgt 40 16.658 ± 0.566 ns/op ------------- PR: https://git.openjdk.org/jdk/pull/10661
