RFR(M): 8248190: PPC: Enable Power10 system and use new byte-reverse instructions

[joserz at linux.ibm.com]

Hallo Martin!

Thank you very much for your review. Here is the v3:

Webrev: http://cr.openjdk.java.net/~mhorie/8248190/webrev.02/
Bug: https://bugs.openjdk.java.net/browse/JDK-8248190

I run a functional test and it's working as expected. If you try to run it in a system <P10 you will get the following message:

$ java -XX:+UseByteReverseInstructions ReverseBytes
OpenJDK 64-Bit Server VM warning: UseByteReverseInstructions specified, but needs at least Power10.
(continue with existing code)

> Unfortunately, I couldn’t find a Power10 machine in my garage ��
��������

This is the code I use to test:
8<---------------------------------------------------------------
import java.io.IOException;

class ReverseBytes
{
    public static void main(String[] args) throws IOException
    {
        for (int i = 0; i < 1000000; ++i) {
            if (Integer.reverseBytes(0x12345678) != 0x78563412) {
                throw new RuntimeException();
            }

            if (Long.reverseBytes(0x123456789ABCDEF0L) != 0xF0DEBC9A78563412L) {
                throw new RuntimeException();
            }

            if (Short.reverseBytes((short)0x1234) != (short)0x3412) {
                throw new RuntimeException();
            }

            if (Character.reverseBytes((char)0xabcd) != (char)0xcdab) {
                throw new RuntimeException();
            }
        }
        System.out.println("ok");
    }
}
8<---------------------------------------------------------------

Best regards!

Jose

On Tue, Aug 18, 2020 at 09:13:39AM +0000, Doerr, Martin wrote:
> Hi Michihiro and Jose,
> 
> I had only done a quick review during my vacation. Thanks for updating the description of PowerArchitecturePPC64.
> After taking a second look, I have a few minor requests. Sorry for that.
> 
> 
>   *   “UseByteReverseInstructions” (plural) would be more consistent with other names.
>   *   Please add “size” specifications to the ppc.ad file. Otherwise, the compiler has to determine sizes dynamically every time.
>   *   bytes_reverse_short: “format” specification misses “extsh”.
> 
> Unfortunately, I couldn’t find a Power10 machine in my garage ��
> So we rely on your testing.
> 
> Thanks and best regards,
> Martin
> 
> 
> From: Michihiro Horie <HORIE at jp.ibm.com>
> Sent: Dienstag, 18. August 2020 09:28
> To: Doerr, Martin <martin.doerr at sap.com>
> Cc: hotspot-compiler-dev at openjdk.java.net; joserz at linux.ibm.com
> Subject: RE: RFR(M): 8248190: PPC: Enable Power10 system and use new byte-reverse instructions
> 
> 
> Jose,
> Latest change looks good also to me.
> 
> Marin,
> Do you think if I can push the change?
> 
> Best regards,
> Michihiro
> 
> 
> ----- Original message -----
> From: "Doerr, Martin" <martin.doerr at sap.com<mailto:martin.doerr at sap.com>>
> To: "joserz at linux.ibm.com<mailto:joserz at linux.ibm.com>" <joserz at linux.ibm.com<mailto:joserz at linux.ibm.com>>
> Cc: hotspot compiler <hotspot-compiler-dev at openjdk.java.net<mailto:hotspot-compiler-dev at openjdk.java.net>>, "horie at jp.ibm.com<mailto:horie at jp.ibm.com>" <horie at jp.ibm.com<mailto:horie at jp.ibm.com>>
> Subject: [EXTERNAL] Re: RFR(M): 8248190: PPC: Enable Power10 system and use new byte-reverse instructions
> Date: Wed, Jul 1, 2020 4:01 AM
> 
> Thanks for the much better flag description.
> Looks good.
> 
> Best regards,
> Martin
> 
> > Am 30.06.2020 um 02:15 schrieb "joserz at linux.ibm.com<mailto:joserz at linux.ibm.com>" <joserz at linux.ibm.com<mailto:joserz at linux.ibm.com>>:
> >
> > Hello team,
> >
> > Here's the 2nd version, implementing the suggestions asked by Martin.
> >
> > Webrev: https://cr.openjdk.java.net/~mhorie/8248190/webrev.01/
> > Bug: https://bugs.openjdk.java.net/browse/JDK-8248190
> >
> > Thank you!!
> >
> > Jose
> >
> >> On Sat, Jun 27, 2020 at 09:29:32AM +0000, Doerr, Martin wrote:
> >> Hi Jose,
> >>
> >> Can you replace the outdated description of PowerArchitecturePPC64 in globals_poc.hpp by something generic, please?
> >>
> >> Please update the Copyright year in vm_version_poc.hpp.
> >>
> >> I can‘t test the change, but it looks good to me.
> >>
> >> Best regards,
> >> Martin
> >>
> >>>> Am 26.06.2020 um 20:29 schrieb "joserz at linux.ibm.com<mailto:joserz at linux.ibm.com>" <joserz at linux.ibm.com<mailto:joserz at linux.ibm.com>>:
> >>>
> >>> Hello team!
> >>>
> >>> This patch introduces Power10 to OpenJDK and implements three new instructions:
> >>> - brh - byte-reverse halfword
> >>> - brw - byte-reverse word
> >>> - brd - byte-reverse doubleword
> >>>
> >>> Webrev: https://cr.openjdk.java.net/~mhorie/8248190/webrev.00/
> >>> Bug: https://bugs.openjdk.java.net/browse/JDK-8248190
> >>>
> >>> Thanks for your review!
> >>>
> >>> Jose R. Ziviani
>