RFR: 8129920 - Vectorized loop unrolling

[Vladimir Kozlov]

This looks good.

Thanks,
Vladimir

On 6/30/15 12:06 PM, Berg, Michael C wrote:
> Vladimir, please have a look at http://cr.openjdk.java.net/~mcberg/8129920/webrev.02
>
> It addresses the issues below.
>
> Regards,
> Michael
>
> -----Original Message-----
> From: hotspot-compiler-dev [mailto:hotspot-compiler-dev-bounces at openjdk.java.net] On Behalf Of Berg, Michael C
> Sent: Monday, June 29, 2015 5:46 PM
> To: Vladimir Kozlov; 'hotspot-compiler-dev at openjdk.java.net'
> Subject: RE: RFR: 8129920 - Vectorized loop unrolling
>
> Vladimir, sure I will change to reflect we are only allowing unrolling.
> For the unroll only case,  we are allowing all the standard logic for unrolling to apply without unroll queries and its cases.  We would need (cl->has_passed_slp() && !cl->unroll_only()) to make both the guarded cases equivalent. We have less code the way I have it.  I could word it differently, but it would work out about the same in new code.
>
> Thanks,
> Michael
>
> -----Original Message-----
> From: Vladimir Kozlov [mailto:vladimir.kozlov at oracle.com]
> Sent: Monday, June 29, 2015 2:00 PM
> To: Berg, Michael C; 'hotspot-compiler-dev at openjdk.java.net'
> Subject: Re: RFR: 8129920 - Vectorized loop unrolling
>
> ignore_slp() and NoMoreSlp whould be fine names if they guard only superword optimization. You use it to skipp all loop optimizations except unrolling. It should be named differently. allow_unroll_only ?
>
> why you need set_notpassed_slp()?:
>
> +        // For atomic unrolled loops which are vector mapped, instigate
> more unrolling.
> +        cl->set_notpassed_slp();
>
> Thanks,
> Vladimir
>
> On 6/26/15 12:43 PM, Berg, Michael C wrote:
>> Hi Folks,
>>
>> I would like to contribute Vectorized loop unrolling. I need two
>> reviewers to review this patch and comment as needed:
>>
>> Bug-id: https://bugs.openjdk.java.net/browse/JDK-8129920
>>
>> webrev:
>>
>> http://cr.openjdk.java.net/~mcberg/8129920/webrev.01/
>>
>> With this change we leverage superword unrolling queries and superword
>> to stage re-entrance to ideal loop optimization. We do this when
>> superword succeeds on vectorizing a loop which was unroll query mapped.
>> When we re-enter ideal loop optimization, we have already done all
>> major optimizations such as peeling, splitting, rce and superword on
>> the vector map candidate loop. Thus we only unroll the loop. We
>> utilize the standard loop unrolling environment to accomplish this
>> with default and any applicable user settings. In this way we leverage
>> unroll factors from the baseline loop which are much larger to obtain
>> optimum throughput on x86 architectures. The uplift range on
>> SpecJvm2008 is seen on scimark.lu.{small,large} with uplift noted at 3% and 8% respectively.
>> We see as much as 1.5x uplift on vector centric micros like reductions
>> on default optimizations.
>>
>> Thanks,
>>
>> Michael
>>