[Bug target/100182] [8/9/10/11/12 Regression] Miscompilation of atomic_float/1.cc and atomic_float/wait_notify.cc on i686

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100182

--- Comment #17 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Uroš Bizjak from comment #16)
> (In reply to Jakub Jelinek from comment #15)
> > Yes, but do they preserve all the bits and never modify any bit patterns,
> > including qNaNs and sNaNs?  I thought the point of using the fistp was that
> > it preserves everything.
> 
> Hm, they don't...

This probably means we have to remove x87 peepholes, where an atomic store is
followed by a DFmode read. x87 can't load and store DFmode untouched without
fild/fistp pair.