Messages in this thread | | | Date | Fri, 07 Aug 2009 21:09:36 -0600 | From | Robert Hancock <> | Subject | Re: [PATCH] Make shr to divide by power of 2 |
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On 08/07/2009 12:50 AM, Andi Kleen wrote: > Sergey Senozhatsky<sergey.senozhatsky@gmail.com> writes: >> Of course, compiler supposed to do something like >> add $0x7,%eax >> shr $0x3,%eax >> instead of div. Should we rely on this? > > Yes. We should rely on this.
It may depend on the selected CPU type that gcc is optimizing for - I believe that on some P4s the shift may actually be slower than the divide..
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