https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98848
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rsandifo at gcc dot gnu.org
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
Blocks| |53947
Last reconfirmed| |2021-01-27
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Probably because
t.c:9:16: note: vect_recog_over_widening_pattern: detected: _9 = MIN_EXPR
<_3, b_14>;
t.c:9:16: note: demoting int to signed short
t.c:9:16: note: created pattern stmt: patt_11 = MIN_EXPR <_2, patt_12>;
t.c:9:16: note: over_widening pattern recognized: patt_6 = (int) patt_11;
t.c:9:16: note: extra pattern stmt: patt_12 = (signed short) b_14;
t.c:9:16: note: extra pattern stmt: patt_11 = MIN_EXPR <_2, patt_12>;
which makes the reduction unhandled (we only support sign changing conversions,
not truncations).
We can restrict the over-widen pattern to not apply for reductions or see
to use range-info (like pattern recog does) in the reduction handling somehow.
I don't see a obvious place to add a reduction def check to
vect_recog_over_widening_pattern, maybe Richard does.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53947
[Bug 53947] [meta-bug] vectorizer missed-optimizations
