https://gcc.gnu.org/bugzilla/show_bug.cgi?id=37242
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot
gnu.org
--- Comment #25 from Richard Biener <rguenth at gcc dot gnu.org> ---
I think parts of this was fixed with the fix for PR45397 (r245752). I can't
really figure if the issue in the benchmark is fixed though. I still see
in PRE
<bb 3> [local count: 1014686024]:
# top_52 = PHI <top_36(D)(2), maxIdx_31(6)>
# maxIdx_54 = PHI <maxIdx_47(2), maxIdx_40(6)>
_4 = (long unsigned int) maxIdx_54;
_5 = _4 * 4;
_6 = numbers_37(D) + _5;
_7 = *_6;
_8 = _4 + 1;
_9 = _8 * 4;
_10 = numbers_37(D) + _9;
_11 = *_10;
if (_7 < _11)
goto <bb 4>; [50.00%]
else
goto <bb 5>; [50.00%]
<bb 4> [local count: 507343012]:
maxIdx_42 = maxIdx_54 + 1;
_68 = (long unsigned int) maxIdx_42;
_70 = _68 * 4;
_72 = numbers_37(D) + _70;
pretmp_74 = *_72;
suggesting it is not fixed in GCC 8 at least. Same with GCC 9 and trunk.
Testcase:
unsigned long a, b;
void foo (int m, int f)
{
unsigned long tem = (unsigned long)m;
a = tem + 1;
if (f)
{
int tem2 = m + 1;
b = (unsigned long)tem2;
}
}
note to value-number the expressions the same you need to apply knowledge
that in if (f), m + 1 cannot overflow.
