[Bug tree-optimization/66422] [5 Regression] -Warray-bounds false positive with -O3

[hubicka at ucw dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66422

--- Comment #8 from Jan Hubicka <hubicka at ucw dot cz> ---
> 
> run_foo ()
> {
> ...
>   <bb 10>:
>   _33 = myfoo_28->buf[3];
>   if (_33 != 1)
>     goto <bb 13>;
>   else
>     goto <bb 11>;
> 
>   <bb 11>:
>   _34 = (int) _27;
>   if (_34 > 4)
>     goto <bb 12>;
>   else
>     goto <bb 13>;
> 
>   <bb 12>:
>   __builtin_unreachable ();
>   _35 = myfoo_28->buf[4];
> 
>   <bb 13>:
>   # _36 = PHI <0(2), 1(3), 0(4), 1(5), 0(6), 1(7), 0(8), 1(9), 0(10), 1(11),
> 0(12)>
>   if (_36 != 0)
>     goto <bb 15>;
>   else
>     goto <bb 14>;
> 
>   <bb 14>:
>   i_37 = 1;
> 
>   <bb 15>:
>   # _2 = PHI <0(13), -1(14)>
>   return _2;
> 
> and the unreachable () remains in the CFG.
> 
> Honza - it seems that remove_exits_and_undefined_stmts inserts these
> unreachable calls but fails to split the BBs.
> 
> I have a patch.

Hmm, Indeed. I have expected cleanup_cfg to get rid of _35 = myfoo_28->buf[4];.
I suppose this changed with your compile time work for GCC 5?

Honza