[Bug tree-optimization/92131] incorrect assumption that (ao >= 0) is always false

[arigo at tunes dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92131

--- Comment #8 from Armin Rigo <arigo at tunes dot org> ---
I'd like to point out that the problem only shows up with all the extra lines
of code that appear unrelated: everything before the loop, and the first half
of the loop itself (the switch-with-goto with cases 8 and 4).  For example, we
can't remove any if in the chain "if(i) if(g) if(h) if(e)".  And we can't
replace "goto bh;" with the apparently equivalent "break;".