[Bug rtl-optimization/102178] [12 Regression] SPECFP 2006 470.lbm regressions on AMD Zen CPUs after r12-897-gde56f95afaaa22

[vmakarov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102178

--- Comment #26 from Vladimir Makarov <vmakarov at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #7)
> make costs in a way that IRA/LRA prefer re-materialization of constants
> from the constant pool over spilling to GPRs (if that's possible at all -
> Vlad?)

LRA rematerialization can not rematerialize constant value from memory pool. 
It can rematerialize value of expression only consisting of other pseudos
(currently assigned to hard regs) and constants.

I guess rematerialization pass can be extended to work for constants from
constant memory pool.  It is pretty doable project opposite to
rematerialization of any memory which would require a lot analysis including
aliasing and complicated cost calculation benefits.  May be somebody could pick
this project up.