|Loop Unroll firstname.lastname@example.org (Alkaid) (2001-05-18)|
|Re: Loop Unroll email@example.com (Mike Dimmick) (2001-05-21)|
|Re: Loop Unroll firstname.lastname@example.org (Venkatesha Murthy G.) (2001-05-21)|
|Re: Loop Unroll email@example.com (Scott Moore) (2001-05-21)|
|Re: Loop Unroll firstname.lastname@example.org (2001-05-21)|
|Re: Loop Unroll email@example.com (Christian Bau) (2001-05-22)|
|From:||Scott Moore <firstname.lastname@example.org>|
|Date:||21 May 2001 02:06:00 -0400|
|Organization:||Cisco Systems Inc.|
|Keywords:||optimize, question, comment|
|Posted-Date:||21 May 2001 02:06:00 EDT|
I'm probally showing my ignorance, but what are you saving by
splitting a loop into multiple separate loops ? Unrolling a loop saves
you the overhead of the loop code in time (but not storage). Splitting
a loop would not eliminate the overhead, but infact multiply that along
with the rest of the loop contents. I'm not sure how that qualifies
as loop unrolling at all.
> When we do ILP optimization, loop unrolling is a kind of method.
> But there is a question: if loop time is a big prime number, how to unroll
> the loop?
> e.g. when loop time is 100, I can unroll the loop 4 times to get a new one
> which has 25 iterations. What shall I do if the loop time is 101?
[It gives you more opportunity to schedule loads and stores. -John]
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