https://gcc.gnu.org/bugzilla/show_bug.cgi?id=76957
--- Comment #9 from amker at gcc dot gnu.org ---
(In reply to amker from comment #8)
> I will have a look. Thanks.
Tree dump is as below:
;; Function dsyr2k (dsyr2k, funcdef_no=0, decl_uid=4135, cgraph_uid=0,
symbol_order=3)
dsyr2k (long int N)
{
int k;
int j;
int i;
double _1;
double _9;
<bb 2> [0.47%]:
if (N_17(D) > 0)
goto <bb 3>; [85.00%]
else
goto <bb 12>; [15.00%]
<bb 3> [0.40%]:
goto <bb 11>; [100.00%]
<bb 4> [12.75%]:
<bb 5> [15.00%]:
# j_3 = PHI <j_19(4), 0(11)>
<bb 6> [85.00%]:
# k_22 = PHI <k_21(7), j_3(5)>
_1 = c[j_3][k_22];
_9 = _1 + 0.0;
c[j_3][k_22] = _9;
k_21 = k_22 + 1;
if (N_17(D) > k_21)
goto <bb 7>; [82.35%]
else
goto <bb 8>; [17.65%]
<bb 7> [70.00%]:
goto <bb 6>; [100.00%]
<bb 8> [15.00%]:
j_19 = j_3 + 1;
if (N_17(D) > j_19)
goto <bb 4>; [85.00%]
else
goto <bb 9>; [15.00%]
<bb 9> [2.65%]:
i_18 = i_8 + 1;
if (N_17(D) > i_18)
goto <bb 10>; [85.00%]
else
goto <bb 12>; [15.00%]
<bb 10> [2.25%]:
<bb 11> [2.65%]:
# i_8 = PHI <i_18(10), 0(3)>
goto <bb 5>; [100.00%]
<bb 12> [0.47%]:
return;
}
the information is already there that (long int)j_3 >= N_17(D) is always false:
# j_3 = PHI <j_19(4), 0(11)>
and we have dominant condition for both PHI arguments:
if (N_17(D) > j_19)
and
if (N_17(D) > 0)
We just need to find a way to use it.
It would be easy to fix if we have flow-sensitive value range, and support
symbolic range better in VRP. Which we don't have either one for now.
Another choice is to improve simplify_using_initial_conditions or
simplify_using_outer_evolutions. Function fact simplify_using_outer_evolutions
doesn't help at all in this case.
