[PATCH]: Implement must-def kill operand

Diego Novillo dnovillo@redhat.com
Wed Oct 20 21:04:00 GMT 2004


On Wed, 2004-10-20 at 16:55, Daniel Berlin wrote:

> That will, in turn, mark the *feeders* of the phi as necessary, because 
> they will be added to the worklist, and propagate_necessity doesn't 
> know that it doesn't need to mark the feeders unless they are phi 
> nodes, thus you will miss dead code being eliminated.
> 
Ah, good point.  Sigh.  I think I'm about to ask you to just let the
regular renamer run and insert needed PHIs, but I agree that PHI node
churn should be avoided.

How much additional code are we talking about?  A good chunk of the
algorithm you described already exists in DCE.  Can it be factored?


Diego.



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