SSA implementation

Bruce Korb bkorb@sco.COM
Fri Jun 30 08:38:00 GMT 2000


Richard Kenner wrote:
> 
>     We will be contributing a dead-code elimination pass in the very near
>     future that operates on the SSA form.  One big improvement is that
>     this algorithm is a) very fast and b) can eliminate loops in things
>     like:
> 
>   void f () {
>     int i;
>     for (i = 0; i < 100; ++i)
>       ;
>   }
> 
> We could always have eliminated such loops, but as I understood it, we
> chose not to under the assumption they were there for timing delay
> purposes.  Has this policy chaged?

This won't work for timing delay on advanced processors anyway.
You would have to make "i" be "volatile" or the processor itself
will optimize it away (essentially).


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