[aarch64-port-dev ] RFR: 8144587: aarch64: generate vectorized MLA/MLS instructions

[Edward Nevill]

Hi Felix,

Thanks for this.

This optimisation looks good to me.

Could we have an official reviewer please.

Thanks,
Ed.

On Mon, 2015-12-07 at 23:26 +0800, Felix Yang wrote:
> Hi,
> 
>   I have corrected the webrev issues in my previous mail. Thanks Edward for
> providing the help.
>   Now I am resending this mail:
> 
>   Can someone help review and sponsor this code generation improvement for
> aarch64 port?
>   Bug: https://bugs.openjdk.java.net/browse/JDK-8144587
>   Webrev: http://cr.openjdk.java.net/~fyang/8144587/webrev.02
> 
>   The hotspot/test/compiler/loopopts/superword/SumRed_Int.java can server
> as a test case.
>   With this patch, the following code snippet by C2:
>     0x0000007f6cec12cc: mul v19.4s, v16.4s, v17.4s
>     0x0000007f6cec12d0: mul v16.4s, v16.4s, v18.4s
>     0x0000007f6cec12d4: mul v17.4s, v18.4s, v17.4s
>     0x0000007f6cec12d8: add v16.4s, v19.4s, v16.4s
>     0x0000007f6cec12dc: add v16.4s, v16.4s, v17.4s
>   will be further optimized into:
>     0x0000007f9cdb86dc: mul      v19.4s, v16.4s, v17.4s
>     0x0000007f9cdb86e0: mla      v19.4s, v16.4s, v18.4s
>     0x0000007f9cdb86e4: mla      v19.4s, v17.4s, v18.4s
> 
>   About 13% performance gain achieved for the test case on my aarch64
> server.
>   Tested with jtreg hotspot & langtools.  Results are the same before and
> after.
>   Is it OK to push?
> 
> Felix,
> Thanks for your help.