https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119780
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Slightly cleaned up & simplified:
int a = 1, b = -__INT_MAX__, c;
int
main ()
{
goto d;
e:
a = 0;
f:
if (a + c <= 0)
goto g;
h:
goto i;
d:
if (b >= 0)
goto e;
goto j;
i:
if (c - __INT_MAX__ * a >= 0)
goto h;
goto d;
j:
b = 7;
goto f;
g:;
}
The slrs change is
<bb 9> [local count: 118111600]:
- _12 = a_lsm.8_15 * -2147483647;
- _13 = c.1_2 + _12;
+ slsr_7 = a_lsm.8_15 * -2147483648;
+ _13 = _3 - slsr_7;
if (_13 >= 0)
goto <bb 10>; [0.00%]
else
where _3 is
_3 = c.1_2 + a_lsm.8_15;
c.1_2 is 1, a_lsm.8_15 is 1, so before slsr this is 1 + (1 * -2147483647) which
is
well defined -2147483646, while after that change it is 2 - (1 * -2147483648),
which is UB.
