On Tue, Nov 18, 2014 at 06:38:49AM -0600, Segher Boessenkool wrote:
> > Does it help pr52714 where we'd like to rip apart a PARALLEL with two 
> > sets, one of which is dead.  If so, it might allow us to  optimize that 
> > code better.
> 
> It does not seem to fix the testcase.  I'll investigate why not.
> You're talking about the
> 
>   (parallel [(set (pc) (pc))
>              (set (X) (sp))])
> 
> right?  I guess the "set pc pc" is not marked as unused...

The very first thing that is checked for is !(added_sets_2 && i1 == 0)
which matches in this case.  I wonder what that condition is supposed
to accomplish -- "optimisation" I suppose?

Hacking that out, it still won't match because the "set pc pc" is not
considered dead.  It's a no-op, not the same thing.  I'll try to widen
the condition...


Segher

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