[Bug tree-optimization/93681] Wrong optimization: instability of x87 floating-point results leads to nonsense

[ch3root at openwall dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93681

Alexander Cherepanov <ch3root at openwall dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=323,
                   |                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=85957,
                   |                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=93682

--- Comment #3 from Alexander Cherepanov <ch3root at openwall dot com> ---
Bug 85957 is definitely similar. I've added it and a couple of others to "See
Also".

Some differences:
- testcases here use comparisons to jump from FPs to integers while bug 85957
uses casts;
- the exploited discrepancy here is between in-register and in-memory
(run-time) results of type `double` while in bug 85957 it's between
compile-time and run-time results;
- it's probably possible to fix bug 85957 by enhancing the dom2 pass while it
will probably not help here.
Whether it warrants a separate bug report it's hard for me to say.