https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120360
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
CC| |rguenth at gcc dot gnu.org
Last reconfirmed| |2025-05-20
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
int f1(type *b)
{
type a = *b;
*b = a - 24;
if (*b == 1)
return g();
return 0;
}
is similarly "bad". This is about us not realizing it's worth canonicalizing
compares to ==/!= 0, aka reduce them to the various CCmode tests.
For 'f' it could work to pattern-match SSA == CST in FRE and see whether
there's SSA - CST available and then re-write as == 0. Of course folding
would immediately undo that unless restricted by single-use (but after CSE
it should have multiple uses).
I don't think this is a target thing. I'm not sure it's easily possible
to handle this on the RTL side (in CSE, again), it might be detrimental
before combine.
