RFR: 8295159: DSO created with -ffast-math breaks Java floating-point arithmetic [v20]

[Matthias Baesken]

On Fri, 3 Nov 2023 14:46:39 GMT, Andrew Haley <aph at 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:
> 
>   Delete src/hotspot/os/linux/.#os_linux.cpp

This leads now to lots of assertions in the jdk tier4 javax/sound tests on our RHEL 9.3 Linux aarch64 box.
Opened 
https://bugs.openjdk.org/browse/JDK-8319708
8319708: Assertion 'fsetenv didn't work' in jdk tier4 tests after 8295159 on Linux aarch64 RHEL9.3

Unfortunately , the shared libs loaded by the JDK native C code (and the dependencies of those libs) are not covered at all, so it is unclear to me what exactly caused the issue. Maybe some sound-related lib on RHEL ?

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PR Comment: https://git.openjdk.org/jdk/pull/10661#issuecomment-1803816232