It would be good to have this fixed for jessie. Correct handling of denormals which are controlled via this register is very important for the performance of e.g. audio applications.If we have a patch I guess it can still be included for Jessie.
It is slightly different to #761175 as the initial value of sse control word is same in main() and in newly created thread.The posix says (since Issue 6) http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_create.html
"The floating-point environment shall be inherited from the creating thread." I am unsure whether the proper fix should be in libc or kernel. Especially as there might be more and more CPU specific settings. Petr