[Bug tree-optimization/18694] [4.0 regression] loop miscompilation at -O1 (-ftree-ch)

["law at redhat dot com" <gcc-bugzilla@gcc.gnu.org>]

------- Additional Comments From law at redhat dot com  2004-12-10 18:11 -------
Subject: Re:  [4.0 regression] loop
	miscompilation at -O1 (-ftree-ch)

On Thu, 2004-12-09 at 05:24 +0000, kazu at cs dot umass dot edu wrote:
> ------- Additional Comments From kazu at cs dot umass dot edu  2004-12-09 05:24 -------
> Updated the testcase like so:
> 
> /* PR tree-optimization/18694
> 
>    The dominator optimization didn't take the PHI evaluation order
>    into account when threading an edge.  */
> 
> extern void abort (void) __attribute__((noreturn));
> extern void exit (int) __attribute__((noreturn));
> 
> void __attribute__((noinline))
> foo (int i)
> {
>   int next_n = 1;
>   int j = 0;
> 
>   for (; i != 0; i--)
>     {
>       int n;
> 
>       for (n = next_n; j < n; j++)
> 	next_n++;
> 
>       if (j != n)
> 	abort ();
>     }
> }
> 
> int
> main (void)
> {
>   foo (2);
>   exit (0);
> }
> 
> 
Can you go ahead and install this into the testsuite?  No need to xfail
since we ought to have a patch installed for the problem soon.

jeff




-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18694

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