https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103037
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
We have:
var_3.2_4 = var_3;
iftmp.1_14 = (int) var_3.2_4;
var_11_lsm.14_8 = _7(D);
<bb 3> [local count: 955630225]:
# RANGE [0, 24] NONZERO 31
# a_20 = PHI <a_18(10), 0(9)>
_19 = MEM <short unsigned int[23]> [(short unsigned int &)&arr_4][a_20];
if (_19 > 1)
goto <bb 5>; [50.00%]
else
goto <bb 4>; [50.00%]
<bb 4> [local count: 477815112]:
# RANGE [0, 1] NONZERO 1
_3 = (int) _19;
if (_19 != 0)
goto <bb 5>; [20.00%]
else
goto <bb 6>; [80.00%]
<bb 5> [local count: 477815112]:
# RANGE [0, 1] NONZERO 1
# _24 = PHI <_3(4), 1(3)>
# RANGE [1, 65535] NONZERO 65535
iftmp.1_15 = (int) _19;
goto <bb 7>; [100.00%]
<bb 6> [local count: 477815112]:
<bb 7> [local count: 955630225]:
# RANGE [-32768, 65535]
# iftmp.1_10 = PHI <iftmp.1_15(5), iftmp.1_14(6)>
# RANGE [0, 1] NONZERO 1
# _25 = PHI <_24(5), 0(6)>
# RANGE [-1, 1]
_5 = _25 / iftmp.1_10;
and seems PRE is trying top simplify 1 / _3 and _3 / _3. _3 has correctly
range of [0, 1] - in that bb _19 can't be anything but 0 or 1 given the
condition, but
iftmp.1_15 = (int) _19; isn't equivalent to that, because it is reachable from
other bbs, even when it is also (int) _19.
So, does PRE need to temporarily reset_flow_sensitive_info in such cases and
restore if it didn't succeed?
