[10] RFR(M): 8185976: PPC64: Implement MulAdd and SquareToLen intrinsics
Gustavo Serra Scalet
gustavo.scalet at eldorado.org.br
Fri Sep 29 21:25:41 UTC 2017
Hi Martin and Goetz,
A new webrev updated to the new repo structure was requested and can be viewed below:
https://gut.github.io/openjdk/webrev/JDK-8185976/webrev.05/
PS: changes applied cleanly from old hotspot to new one.
Can it be sponsored now?
Thanks.
> -----Original Message-----
> From: hotspot-compiler-dev [mailto:hotspot-compiler-dev-
> bounces at openjdk.java.net] On Behalf Of Gustavo Serra Scalet
> Sent: quarta-feira, 6 de setembro de 2017 09:45
> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>; Doerr, Martin
> <martin.doerr at sap.com>; 'hotspot-compiler-dev at openjdk.java.net'
> <hotspot-compiler-dev at openjdk.java.net>
> Subject: RE: [10] RFR(M): 8185976: PPC64: Implement MulAdd and
> SquareToLen intrinsics
>
> Alright, thanks for the instructions. I'll keep that in mind.
>
> > -----Original Message-----
> > From: Lindenmaier, Goetz [mailto:goetz.lindenmaier at sap.com]
> > Sent: quarta-feira, 6 de setembro de 2017 09:44
> > To: Gustavo Serra Scalet <gustavo.scalet at eldorado.org.br>; Doerr,
> > Martin <martin.doerr at sap.com>; 'hotspot-compiler-dev at openjdk.java.net'
> > <hotspot-compiler-dev at openjdk.java.net>
> > Subject: RE: [10] RFR(M): 8185976: PPC64: Implement MulAdd and
> > SquareToLen intrinsics
> >
> > Hi Gustavo,
> >
> > the repos are all closed. Once they are opened again, you will have to
> > merge your change into the new repo structure, post a new webrev and
> > only then it can be sponsored. Me or Martin will sponsor it then.
> >
> > Best regards,
> > Goetz.
> >
> > > -----Original Message-----
> > > From: Gustavo Serra Scalet [mailto:gustavo.scalet at eldorado.org.br]
> > > Sent: Mittwoch, 6. September 2017 14:32
> > > To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>; Doerr, Martin
> > > <martin.doerr at sap.com>; 'hotspot-compiler-dev at openjdk.java.net'
> > > <hotspot-compiler-dev at openjdk.java.net>
> > > Subject: RE: [10] RFR(M): 8185976: PPC64: Implement MulAdd and
> > > SquareToLen intrinsics
> > >
> > > Thanks Goetz.
> > >
> > > Could somebody sponsor this change?
> > >
> > > THanks
> > >
> > > > -----Original Message-----
> > > > From: Lindenmaier, Goetz [mailto:goetz.lindenmaier at sap.com]
> > > > Sent: quarta-feira, 6 de setembro de 2017 03:30
> > > > To: Gustavo Serra Scalet <gustavo.scalet at eldorado.org.br>; Doerr,
> > > > Martin <martin.doerr at sap.com>; 'hotspot-compiler-
> > dev at openjdk.java.net'
> > > > <hotspot-compiler-dev at openjdk.java.net>
> > > > Subject: RE: [10] RFR(M): 8185976: PPC64: Implement MulAdd and
> > > > SquareToLen intrinsics
> > > >
> > > > Hi,
> > > >
> > > > I had a look at this change and tested it. Reviewed.
> > > >
> > > > Best regards,
> > > > Goetz.
> > > >
> > > > > -----Original Message-----
> > > > > From: hotspot-compiler-dev [mailto:hotspot-compiler-dev-
> > > > > bounces at openjdk.java.net] On Behalf Of Gustavo Serra Scalet
> > > > > Sent: Freitag, 1. September 2017 19:12
> > > > > To: Doerr, Martin <martin.doerr at sap.com>; 'hotspot-compiler-
> > > > > dev at openjdk.java.net' <hotspot-compiler-dev at openjdk.java.net>
> > > > > Subject: RE: [10] RFR(M): 8185976: PPC64: Implement MulAdd and
> > > > > SquareToLen intrinsics
> > > > >
> > > > > Hi Martin,
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Doerr, Martin
> > > > > > your first webrev already works on Big Endian. So the only
> > > > > > required change is to fix your new code by this trivial patch:
> > > > > > --- a/src/cpu/ppc/vm/stubGenerator_ppc.cpp Fri Sep 01
> > 17:47:45
> > > > 2017
> > > > > > +0200
> > > > > > +++ b/src/cpu/ppc/vm/stubGenerator_ppc.cpp Fri Sep 01
> > 17:55:08
> > > > 2017
> > > > > > +0200
> > > > > > @@ -3426,7 +3426,9 @@
> > > > > > __ srdi (product, product, 1);
> > > > > > // join them to the same register and store it as Little
> > Endian
> > > > > > __ orr (product, lplw_s, product);
> > > > > > +#ifdef VM_LITTLE_ENDIAN
> > > > > > __ rldicl (product, product, 32, 0);
> > > > > > +#endif
> > > > > > __ stdu (product, 8, out_aux);
> > > > > > __ bdnz (LOOP_SQUARE);
> > > > > >
> > > > > > So please enable it again for Big Endian in vm_version_ppc.
> > > > > > Besides that, it looks good to me. We also need a 2nd review.
> > > > >
> > > > > Great! Thanks for checking it and suggesting the diff.
> > > > >
> > > > > I changed these things. You can find it below:
> > > > > https://gut.github.io/openjdk/webrev/JDK-8185976/webrev.04/
> > > > >
> > > > > I wonder who could be a 2nd reviewer... Anybody in mind that we
> > > > > may
> > > > ping?
> > > > > Maybe Goetz Lindenmaier?
> > > > >
> > > > > Best Regards,
> > > > > Gustavo Serra Scalet
> > > > >
> > > > > >
> > > > > > Best regards,
> > > > > > Martin
> > > > > >
> > > > > >
> > > > > > -----Original Message-----
> > > > > > From: Gustavo Serra Scalet
> > > > > > [mailto:gustavo.scalet at eldorado.org.br]
> > > > > > Sent: Mittwoch, 30. August 2017 19:03
> > > > > > To: Doerr, Martin <martin.doerr at sap.com>; 'hotspot-compiler-
> > > > > > dev at openjdk.java.net' <hotspot-compiler-dev at openjdk.java.net>
> > > > > > Subject: RE: [10] RFR(M): 8185976: PPC64: Implement MulAdd and
> > > > > > SquareToLen intrinsics
> > > > > >
> > > > > > Hi Martin,
> > > > > >
> > > > > > (webrev at the end)
> > > > > >
> > > > > > > -----Original Message-----
> > > > > > > From: Doerr, Martin
> > > > > > >
> > > > > > > > The s/rldicl/rldic/ was fixed for "offset", but "len"
> > > > > > > > doesn't seem to need further changes as it's being cleared
> > > > > > > > with clrldi, which is the same as rldic with no shift.
> > > > > > > > Therefore it's treated appropriately as requested for
> > "offset" parameter. Do you agree?
> > > > > > >
> > > > > > > No, I didn't find clrldi for len in generate_mulAdd(). Only
> > for k.
> > > > > >
> > > > > > I'm sorry. I was thinking about "offset" and "k", which are
> > > > > > both cleaned on generate_mulAdd(). "len" was not cleaned and
> > > > > > it was being used on
> > > > > > muladd() directly with cmpdi, which could lead to problems.
> > > > > >
> > > > > > That is being changed.
> > > > > >
> > > > > > > Where are in_len and out_len fixed up in
> > generate_squareToLen()?
> > > > > >
> > > > > > They are not. According to your suggestions, I agree it also
> > > > > > needs to be done for the same reason.
> > > > > >
> > > > > > > > You are right. The way I'm building the 64 bits of the
> > > > > > > > register depends on which kind of endianness it is run.
> > > > > > > > For now it works only on little endian so I'm adding a
> > > > > > > > switch (just like I did for SHA) to make it available only
> > > > > > > > on
> > little endian systems.
> > > > > > >
> > > > > > > It shouldn't be that hard to get it working on big endian
> > > > > > > ;-) Btw., my point was not to replace the 2 4-byte store
> > > > > > > instructions by an 8-byte one (though I'm also ok with
> that).
> > > > > > > It was that 2 stwu which update the same pointer doesn't
> > > > > > > make sense from
> > > > performance point of view.
> > > > > > > Please keep something which works on big endian, too.
> > > > > >
> > > > > > I see. The 2x stwu was being used like that because it was the
> > > > > > trivial approach when considering the original java update:
> > > > > > z[i++] = (lastProductLowWord << 31) | (int)(product >>> 33);
> > > > > > z[i++] = (int)(product >>> 1);
> > > > > >
> > > > > > As you pointed out, that might cause some stall on the
> > > > > > pipeline so I made it with 1s stdu (and could improve code by
> > > > > > reducing 1
> > > > > > instruction)
> > > > > >
> > > > > > Now about having a big endian version: I'm not confident in
> > > > > > doing so as I don't have access to such a machine at the
> moment.
> > > > > > You were kind on offering test support but I don't know if
> > > > > > it'd work like that. I may support you in checking out which
> > > > > > places are endianness-related but I'm not comfortable in
> > > > > > sending you untested
> > > > code.
> > > > > >
> > > > > > Would you be interested in doing such a changes for making it
> > > > > > work on Big Endian? For this patch, I provided an interesting
> > > > > > test that might help you to verify if it worked.
> > > > > >
> > > > > > > > No, I used the jdk8u152-b01 (State of repository at Thu
> > > > > > > > Apr
> > > > > > > > 6
> > > > > > > > 14:15:31 2017). The reported performance speedup was
> > > > > > > > calculated by running the following test
> > (TestSquareToLen.java):
> > > > > > >
> > > > > > > Seems like JDK-8145913 has not been backported, yet. Sorry
> > > > > > > for not checking this earlier. So if you want to make RSA
> > > > > > > really fast, it should be so much better to backport that
> > > > > > > one. But I can still sponsor this change as it may be used
> elsewhere.
> > > > > >
> > > > > > No problem. It's nice to know that I may not need to request a
> > > > > > backport of this patch for performance reasons.
> > > > > >
> > > > > > And at last, but not least, the new webrev with these clrldi
> > > > changes:
> > > > > > https://gut.github.io/openjdk/webrev/JDK-
> > > > > 8185976/webrev.03/index.html
> > > > > >
> > > > > > Thank you once again,
> > > > > > Gustavo Serra Scalet
> > > > > >
> > > > > > > Best regards,
> > > > > > > Martin
> > > > > > >
> > > > > > >
> > > > > > > -----Original Message-----
> > > > > > > From: Gustavo Serra Scalet
> > > > > > > [mailto:gustavo.scalet at eldorado.org.br]
> > > > > > > Sent: Dienstag, 29. August 2017 22:37
> > > > > > > To: Doerr, Martin <martin.doerr at sap.com>; 'hotspot-compiler-
> > > > > > > dev at openjdk.java.net'
> > > > > > > <hotspot-compiler-dev at openjdk.java.net>
> > > > > > > Subject: RE: [10] RFR(M): 8185976: PPC64: Implement MulAdd
> > > > > > > and SquareToLen intrinsics
> > > > > > >
> > > > > > > Hi Martin,
> > > > > > >
> > > > > > > New changes:
> > > > > > > https://gut.github.io/openjdk/webrev/JDK-8185976/webrev.02/
> > > > > > >
> > > > > > > Check comments below, please.
> > > > > > >
> > > > > > > > -----Original Message-----
> > > > > > > > From: Doerr, Martin
> > > > > > > >
> > > > > > > > 1. Sign extending offset and len Right, sign and zero
> > > > > > > > extending is equivalent for offset and len because they
> > > > > > > > are guaranteed to be >=0 (by checks in Java). But you can
> > > > > > > > only rely on bit 32 (IBM
> > > > > > > > notation) to be 0. Bit 0-31 may contain
> > > > > > > garbage.
> > > > > > > > rldicl was incorrect. My mistake, sorry for that. Correct
> > > > > > > > would be rldic which also clears the least significant
> bits.
> > > > > > > > len should also get fixed e.g. by replacing cmpdi by
> > > > > > > > extsw_ in
> > > > > > muladd.
> > > > > > >
> > > > > > > The s/rldicl/rldic/ was fixed for "offset", but "len"
> > > > > > > doesn't seem to need further changes as it's being cleared
> > > > > > > with clrldi, which is the same as rldic with no shift.
> > > > > > > Therefore it's treated appropriately as requested for
> "offset"
> > parameter. Do you agree?
> > > > > > >
> > > > > > > > 2. Using 8 byte instructions for int The code which feeds
> > > > > > > > stdu is endianess specific. Doesn't work on all
> > > > > > > > PPC64 platforms.
> > > > > > >
> > > > > > > You are right. The way I'm building the 64 bits of the
> > > > > > > register depends on which kind of endianness it is run. For
> > > > > > > now it works only on little endian so I'm adding a switch
> > > > > > > (just like I did for
> > > > > > > SHA) to make it available only on little endian systems.
> > > > > > >
> > > > > > > > 3.Regarding Andrew's point: Superseded by Montgomery?
> > > > > > > > The Montgomery change got backported to jdk8u (JDK-8150152
> > > > > > > > in
> > > > > > 8u102).
> > > > > > > > I'd expect the performance improvement of these intrinsics
> > > > > > > > to be irrelevant for crypto.rsa. Did you measure with an
> > > > > > > > older jdk8
> > > > > > release?
> > > > > > >
> > > > > > > No, I used the jdk8u152-b01 (State of repository at Thu Apr
> > > > > > > 6
> > > > > > > 14:15:31 2017). The reported performance speedup was
> > > > > > > calculated by running the following test
> > (TestSquareToLen.java):
> > > > > > > import java.math.BigInteger;
> > > > > > >
> > > > > > > public class TestSquareToLen {
> > > > > > >
> > > > > > > public static void main(String args[]) throws Exception
> > > > > > > {
> > > > > > >
> > > > > > > int n = 10000000;
> > > > > > > if (args.length >=1) {
> > > > > > > n = Integer.parseInt(args[0]);
> > > > > > > }
> > > > > > >
> > > > > > > BigInteger b1 = new
> > > > > > >
> > > > >
> > > BigInteger("34893980923557359086350514982082503920002298311877320859
> > > > > 99
> > > > > > > 36
> > > > > > >
> > > > >
> > > 7395594183801021468843071391756049207873137016631559837931214754926
> > > > > 092
> > > > > > > 22
> > > > > > >
> > > > >
> > > 3780292110207609223272184808289336630057735969423726808520641030118
> > > > > 116
> > > > > > > 51
> > > > > > >
> > > > >
> > > 6440180488338234823908199478965242076358579845520899779963131131540
> > > > > 166
> > > > > > > 68 718795349783157384006672542605760392289645528307");
> > > > > > > BigInteger b2 = BigInteger.valueOf(0);
> > > > > > > BigInteger check = BigInteger.valueOf(1);
> > > > > > > for (int i = 0; i < n; i++) {
> > > > > > > b2 = b1.multiply(b1);
> > > > > > > if (i == 0)
> > > > > > > // Didn't JIT yet. Comparing against interpreted
> > mode
> > > > > > > check = b2;
> > > > > > > }
> > > > > > > if (b2.compareTo(check) == 0)
> > > > > > > System.out.println("Check ok!");
> > > > > > > else
> > > > > > > System.out.println("Check failed!");
> > > > > > > }
> > > > > > > }
> > > > > > >
> > > > > > >
> > > > > > > I got these results on JDK8 on my POWER8 machine:
> > > > > > > $ ./javac TestSquareToLen.java $ sudo perf stat -r 5 ./java
> > > > > > > -XX:-UseMulAddIntrinsic -XX:- UseSquareToLenIntrinsic
> > > > > > > TestSquareToLen Check ok!
> > > > > > > Check ok!
> > > > > > > Check ok!
> > > > > > > Check ok!
> > > > > > > Check ok!
> > > > > > >
> > > > > > > Performance counter stats for './java
> > > > > > > -XX:-UseMulAddIntrinsic
> > > > > > > -XX:- UseSquareToLenIntrinsic TestSquareToLen' (5 runs):
> > > > > > >
> > > > > > > 15148.009557 task-clock (msec) # 1.053
> > CPUs
> > > > > > > utilized ( +- 0.48% )
> > > > > > > 2,425 context-switches # 0.160
> > K/sec
> > > > > > > ( +- 5.84% )
> > > > > > > 356 cpu-migrations # 0.023
> > K/sec
> > > > > > > ( +- 3.01% )
> > > > > > > 5,153 page-faults # 0.340
> > K/sec
> > > > > > > ( +- 5.22% )
> > > > > > > 54,536,889,909 cycles # 3.600
> > GHz
> > > > > > > ( +- 0.56% ) (66.68%)
> > > > > > > 239,554,105 stalled-cycles-frontend # 0.44%
> > > > frontend
> > > > > > > cycles idle ( +- 4.87% ) (49.90%)
> > > > > > > 27,683,316,001 stalled-cycles-backend # 50.76%
> > > > backend
> > > > > > > cycles idle ( +- 0.56% ) (50.17%)
> > > > > > > 102,020,229,733 instructions # 1.87
> > insn
> > > > per
> > > > > > > cycle
> > > > > > > # 0.27
> > > > stalled
> > > > > > > cycles per insn ( +- 0.14% ) (66.94%)
> > > > > > > 7,706,072,218 branches # 508.718
> > M/sec
> > > > > > > ( +- 0.23% ) (50.20%)
> > > > > > > 456,051,162 branch-misses # 5.92%
> > of
> > > > all
> > > > > > > branches ( +- 0.09% ) (50.07%)
> > > > > > >
> > > > > > > 14.390840733 seconds time elapsed ( +- 0.09% )
> > > > > > >
> > > > > > > $ sudo perf stat -r 5 ./java -XX:+UseMulAddIntrinsic -
> > > > > > > XX:+UseSquareToLenIntrinsic TestSquareToLen Check ok!
> > > > > > > Check ok!
> > > > > > > Check ok!
> > > > > > > Check ok!
> > > > > > > Check ok!
> > > > > > >
> > > > > > > Performance counter stats for './java
> > > > > > > -XX:+UseMulAddIntrinsic
> > > > > > > - XX:+UseSquareToLenIntrinsic TestSquareToLen' (5 runs):
> > > > > > >
> > > > > > > 11368.141410 task-clock (msec) # 1.045
> > CPUs
> > > > > > > utilized ( +- 0.64% )
> > > > > > > 1,964 context-switches # 0.173
> > K/sec
> > > > > > > ( +- 8.93% )
> > > > > > > 338 cpu-migrations # 0.030
> > K/sec
> > > > > > > ( +- 7.65% )
> > > > > > > 5,627 page-faults # 0.495
> > K/sec
> > > > > > > ( +- 6.15% )
> > > > > > > 41,100,168,967 cycles # 3.615
> > GHz
> > > > > > > ( +- 0.50% ) (66.36%)
> > > > > > > 309,052,316 stalled-cycles-frontend # 0.75%
> > > > frontend
> > > > > > > cycles idle ( +- 2.84% ) (49.89%)
> > > > > > > 14,188,581,685 stalled-cycles-backend # 34.52%
> > > > backend
> > > > > > > cycles idle ( +- 0.99% ) (50.34%)
> > > > > > > 77,846,029,829 instructions # 1.89
> > insn
> > > > per
> > > > > > > cycle
> > > > > > > # 0.18
> > > > stalled
> > > > > > > cycles per insn ( +- 0.29% ) (66.96%)
> > > > > > > 8,435,216,989 branches # 742.005
> > M/sec
> > > > > > > ( +- 0.28% ) (50.17%)
> > > > > > > 339,903,936 branch-misses # 4.03%
> > of
> > > > all
> > > > > > > branches ( +- 0.27% ) (49.90%)
> > > > > > >
> > > > > > > 10.882357546 seconds time elapsed ( +- 0.24% )
> > > > > > >
> > > > > > >
> > > > > > > (out of curiosity, these numbers are 15.19s (+- 0.32%) and
> > > > > > > 13.42s
> > > > > > > (+-
> > > > > > > 0.53%) on JDK10)
> > > > > > >
> > > > > > > I may run for SpecJVM2008's crypto.rsa if you are
> interested.
> > > > > > >
> > > > > > > Thank you once again for reviewing this.
> > > > > > >
> > > > > > > Best regards,
> > > > > > > Gustavo
> > > > > > >
> > > > > > > > (I think the change is still acceptable as the intrinsics
> > > > > > > > could be used elsewhere and the implementation also exists
> > > > > > > > on other
> > > > > > > > platforms.)
> > > > > > > >
> > > > > > > > Best regards,
> > > > > > > > Martin
> > > > > > > >
> > > > > > > >
> > > > > > > > -----Original Message-----
> > > > > > > > From: Gustavo Serra Scalet
> > > > > > > > [mailto:gustavo.scalet at eldorado.org.br]
> > > > > > > > Sent: Mittwoch, 16. August 2017 18:50
> > > > > > > > To: Doerr, Martin <martin.doerr at sap.com>;
> > > > > > > > 'hotspot-compiler- dev at openjdk.java.net'
> > > > > > > > <hotspot-compiler-dev at openjdk.java.net>
> > > > > > > > Subject: RE: [10] RFR(M): 8185976: PPC64: Implement MulAdd
> > > > > > > > and SquareToLen intrinsics
> > > > > > > >
> > > > > > > > Hi Martin,
> > > > > > > >
> > > > > > > > Thanks for dedicated review. It took me a while to be able
> > > > > > > > to work on this but I hope to have your points solved.
> > > > > > > > Please check below the review as well as my comments
> > > > > > > > quoting
> > your email:
> > > > > > > > https://gut.github.io/openjdk/webrev/JDK-8185976/webrev.01
> > > > > > > > /
> > > > > > > >
> > > > > > > > > -----Original Message----- First of all, C2 does not
> > > > > > > > > perform sign extend when calling
> > > > stubs.
> > > > > > > > > The int parms need to get zero/sign extended. (Could
> > > > > > > > > even be done without extra instructions by replacing
> > > > > > > > > sldi -> rldicl, cmpdi -> extsw_ in some
> > > > > > > > > cases.)
> > > > > > > >
> > > > > > > > Does it make a difference on my case?
> > > > > > > >
> > > > > > > > I guess you are talking about mulAdd preparation code. The
> > > > > > > > only aspect I found about him is to force the cast from 32
> > > > > > > > bits -> 64 bits by cleaning higher bits. Offset is a
> > > > > > > > signed integer but it can't be
> > > > > > > negative anyway.
> > > > > > > >
> > > > > > > > So I changed from:
> > > > > > > > sldi (R5_ARG3, R5_ARG3, 2);
> > > > > > > >
> > > > > > > > to:
> > > > > > > > rldicl (R5_ARG3, R5_ARG3, 2, 32); // always positive
> > > > > > > >
> > > > > > > >
> > > > > > > > > macroAssembler_ppc.cpp:
> > > > > > > > > - Indentation should be 2 spaces.
> > > > > > > >
> > > > > > > > Done
> > > > > > > >
> > > > > > > >
> > > > > > > > > stubGenerator_ppc:cpp:
> > > > > > > > > - or_, addi_ should get replaced by orr, addi when CR0
> > > > > > > > > result is not needed.
> > > > > > > >
> > > > > > > > Done
> > > > > > > >
> > > > > > > > > - Where is lplw initialized?
> > > > > > > >
> > > > > > > > It should be initialized with 0, I missed that...
> > > > > > > >
> > > > > > > > > - I believe that the updating load/store instructions
> e.g.
> > > > > > > > > lwzu don't perform well on some processors. At least
> > > > > > > > > using stwu 2 times in the loop doesn't make sense.
> > > > > > > >
> > > > > > > > You are right. I could manipulate the bits differently and
> > > > > > > > ended up with a single stdu in the loop. Neat! Although I
> > > > > > > > could not reduce the total number of instructions.
> > > > > > > >
> > > > > > > > > - Note: It should be possible to use 8 byte instead of 4
> > > > > > > > > byte
> > > > > > > > > instructions: MacroAssembler::multiply64, addc, adde.
> > > > > > > > > But I'm not requesting to change that because I guess it
> > > > > > > > > would make the code very complicated, especially when
> > > > > > > > > supporting both endianess
> > > > > > > versions.
> > > > > > > >
> > > > > > > > Yes, that would require a new analysis on this code. May
> > > > > > > > we consider it next? As you said, I prefer having an
> > > > > > > > initial version that looks as simple as the original java
> code.
> > > > > > > >
> > > > > > > > > - The squareToLen stub implementation is very close the
> > > > > > > > > Java implementation. So it'd be interesting to
> > > > > > > > > understand what C2 doesn't do as well as the hand
> > > > > > > > > written assembly code. Do you know that? (Not absolutely
> > > > > > > > > necessary for accepting this change as long as the stub
> > > > > > > > > is measurably
> > > > > > > > > faster.)
> > > > > > > >
> > > > > > > > I don't know either. Basically I chose doing it because I
> > > > > > > > noticed some performance gain on SpecJVM2008 when
> > > > > > > > analyzing
> > > X64.
> > > > > > > > Then, taking a closer look, I didn't notice any AVX or
> > > > > > > > some special instructions on
> > > > > > > > X64 so I decided to try it on ppc64 by using some basic
> > > > assembly.
> > > > > > > >
> > > > > > > > Thanks
> > > > > > > >
> > > > > > > > >
> > > > > > > > > Best regards,
> > > > > > > > > Martin
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > -----Original Message-----
> > > > > > > > > From: hotspot-compiler-dev [mailto:hotspot-compiler-dev-
> > > > > > > > > bounces at openjdk.java.net] On Behalf Of Gustavo Serra
> > > > > > > > > Scalet
> > > > > > > > > Sent: Donnerstag, 10. August 2017 19:22
> > > > > > > > > To: 'hotspot-compiler-dev at openjdk.java.net'
> > > > > > > > > <hotspot-compiler- dev at openjdk.java.net>
> > > > > > > > > Subject: FW: [10] RFR(M): 8185976: PPC64: Implement
> > > > > > > > > MulAdd
> > > and
> > > > > > > > > SquareToLen intrinsics
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > -----Original Message-----
> > > > > > > > > From: ppc-aix-port-dev [mailto:ppc-aix-port-dev-
> > > > > > > > > bounces at openjdk.java.net] On Behalf Of Gustavo Serra
> > > > > > > > > Scalet
> > > > > > > > > Sent: terça-feira, 8 de agosto de 2017 17:19
> > > > > > > > > To: ppc-aix-port-dev at openjdk.java.net
> > > > > > > > > Subject: [10] RFR(M): 8185976: PPC64: Implement MulAdd
> > > > > > > > > and SquareToLen intrinsics
> > > > > > > > >
> > > > > > > > > Hi,
> > > > > > > > >
> > > > > > > > > Could you please review this specific PPC64 change to
> > hotspot?
> > > > > > > > > By implementing these intrinsics I noticed a small
> > > > > > > > > improvement with microbenchmarks analysis. On
> > > > > > > > > SpecJVM2008's crypto.rsa benchmark, only when
> > > > > > > > > backporting to JDK8 an improvement was
> > > > noticed.
> > > > > > > > >
> > > > > > > > > JBS: https://bugs.openjdk.java.net/browse/JDK-8185976
> > > > > > > > > Webrev: https://gut.github.io/openjdk/webrev/JDK-
> > > > > 8185976/webrev/
> > > > > > > > >
> > > > > > > > > Motivation for this implementation:
> > > > > > > > > https://twitter.com/ijuma/status/698309312498835457
> > > > > > > > >
> > > > > > > > > Best regards,
> > > > > > > > > Gustavo Serra Scalet
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