update address taken: don't drop clobbers

Jeff Law law@redhat.com
Thu Oct 16 18:37:00 GMT 2014


On 10/16/14 11:52, Richard Biener wrote:
>> I'd walk the SSA_NAMEs at the end checking for zero uses.  I'm
>> curious how often that will trigger  :-)
>
> Most often for the initial into SSA I guess. After that only for the
> cases we rename a variable which does not happen often. SRA and
> update-address-taken cone to my mind.
That'd be my guess too.  Jump threading probably creates them as well 
since we don't try to find any of the code that becomes dead in the 
duplicates after we remove the conditional.  Which means after DOM and VRP.

I don't suppose we have a map of newly created names handy anywhere :-)


>
> BTW, I dislike having multiple DCE implementations...
Similarly.  The proposal above was just to determine if we should 
schedule DCE or not.

jeff



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