[Bug tree-optimization/22326] promotions (from float to double) are not removed when they should be able to

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=22326

--- Comment #12 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
(In reply to rguenther@suse.de from comment #11)
> The larger expressions should be subject to a propagation pass and not
> arbitrarily complex static pattern matching.  Maybe backprop is a suitable
> one to wire this in.
Sounds good.  backprop was originally added to deal with a similar
“move things out of fold-const.c” problem (which is why it's currently
so special-purpose).