https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120280
--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Replaced redundant PHI node defining c_3 with c_6
Replaced redundant PHI node defining b_13 with 0
Removing unexecutable edge from if (b_13 != 0)
Removing dead stmt b_13 = PHI <0(3)>
Removing dead stmt c_3 = PHI <c_6(3)>
(gdb) p debug_tree(t)
<ssa_name 0x7ffff740d8b8 type <error_mark 0x7ffff7402f48>
nothrow
def_stmt
version:3 in-free-list>
c_19 = PHI <_3(4), c_1(7), c_15(6)>
So FRE removes _3 definition and the bb(4) is not reachable any more.
We are doing cleanup cfg and we call gimple_simplify on the cond:
```
# c_6 = PHI <0(2), c_19(8)>
# .MEM_9 = PHI <.MEM_12(D)(2), .MEM_18(8)>
if (c_6 < d_14(D))
goto <bb 5>; [INV]
else
goto <bb 4>; [INV]
```
Where we are trying to match first tree_expr_nonnegative_p.
So the easy workaround is not use tree_expr_nonnegative_p as predicate here and
just do:
```
(simplify
(cmp @0 zerop@1)
(if (tree_expr_nonnegative_p (@0) && !fixed_zerop (@1)
```
Though I am not 100% sure this will workaround all of the issues.
