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Re: SSA implementation
- To: Richard Kenner <kenner at vlsi1 dot ultra dot nyu dot edu>
- Subject: Re: SSA implementation
- From: Bruce Korb <bkorb at sco dot COM>
- Date: Fri, 30 Jun 2000 08:29:44 -0700
- CC: mark at codesourcery dot com, gcc at gcc dot gnu dot org
- Organization: Santa Cruz Operations
- References: <10006301052.AA25097@vlsi1.ultra.nyu.edu>
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).