[Bug rtl-optimization/70873] [7 Regressio] 20% performance regression at 482.sphinx3 after r235442 with -O2 -m32 on Haswell.

[bernds at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70873

Bernd Schmidt <bernds at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |UNCONFIRMED
     Ever confirmed|1                           |0

--- Comment #6 from Bernd Schmidt <bernds at gcc dot gnu.org> ---
So the problem seems to be peep2 runs before regrename. If you always want to
generate two instructions there, then yes, a splitter would probably be better.
Actually just changing define_peephole2 to define_split seems to do the trick,
can you try whether that fixes the performance regression (I don't have a
Haswell machine)?