[Bug tree-optimization/18046] Missed jump threading optimization

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

------- Additional Comments From law at redhat dot com  2004-10-19 20:16 -------
Subject: Re:  Missed jump threading
	optimization

On Mon, 2004-10-18 at 16:50, stevenb at suse dot de wrote:
> ------- Additional Comments From stevenb at suse dot de  2004-10-18 22:50 -------
> Subject: Re:  Missed jump threading optimization
> 
> Hmm, threading the default case sounds interesting, but the real
> reason why the RTL threader catches this and the tree threader does
> not is because on RTL the test case basically looks like this:
> 
> extern void foo (void);
> extern int i;
> void
> bar (void)
> {
>   if (i == 0)
>     foo ();
> 
>   if (i == 0)
>     foo ();
> }
> 
> Hey, I can thread that!  :-)
> 
> So perhaps we should consider lowering SWITCH_EXPRs with only two
> targets to COND_EXPRs after all...?  That would be quite easy to
> do.
Jan and maybe others have talked about lowering SWITCH_EXPRs
earlier.  I don't recall if it ever got implemented.

jeff



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18046