https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93013
Bill Schmidt <wschmidt at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2019-12-19
CC| |meissner at gcc dot gnu.org,
| |segher at gcc dot gnu.org
Component|c++ |tree-optimization
Ever confirmed|0 |1
--- Comment #1 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
The branch is removed by the middle end, as the optimized dump shows:
;; Function mod (_Z3modiiRi, funcdef_no=0, decl_uid=3256, cgraph_uid=1,
symbol_\
order=0)
mod (int x, int y, int & z)
{
int _1;
bool _3;
int _9;
<bb 2> [local count: 1073741824]:
_1 = x_4(D) % y_5(D);
*z_7(D) = _1;
_3 = y_5(D) == 0;
_9 = (int) _3;
return _9;
}
On POWER9 we will get the expected answer given the use of the modsw
instruction. For POWER8 we get the codegen with divw which is indeed undefined
for these inputs. I guess the issue would be in the expander for mod<mode>3.
Confirmed.
