https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70527
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2016-04-04
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Note the issue is (non-)canonicalization of (long)(x + 1). For optimal
re-assoc you'd want to canonicalize this to (long)x + 1L (with x + 1
having undefined behavior on overflow) and then to (long)x * 12 + 12.
But generally you do _not_ want to do this because you lose value-range info
and carry out the op in a larger mode (the former means the reverse transform
is not valid).
Generic folding has very limited capabilities here and GIMPLE reassoc currently
refuses to associate signed ops at all.
