RFR: 8046943: RSA Acceleration (original) (raw)

Anthony Scarpino anthony.scarpino at oracle.com
Mon Jun 15 17:06:47 UTC 2015

On 06/15/2015 09:58 AM, Andrew Haley wrote:

On 06/15/2015 05:38 PM, Anthony Scarpino wrote:

On 06/12/2015 04:06 AM, Andrew Haley wrote:

http://cr.openjdk.java.net/~aph/8046943-hs-1/ http://cr.openjdk.java.net/~aph/8046943-jdk-1/

Please don't use the JEP 246 in the comments when you push. There are a number of changesets related to 246 and I'd rather not have one associated with it. We can link the a separate bug id to the JEP. Right. 3. I fused squaring and multiplication into a single montgomeryMultiply method. This has two advantages. Firstly, we only need a single intrinsic, and secondly the decision whether to use multiply or squaring can be made in the runtime library. If the target does not support the montgomeryMultiply intrinsic there is no slowdown when using C2 because it removes the if (a == b) test in

if (a == b) { product = squareToLen(a, len, product); } else { product = multiplyToLen(a, len, b, len, product); } I don't agree with fusing them together. I think there should two separate intrinsics. For one, SPARC has a montsqr and montmul instructions. Additionally if someone wants to call montgomerySquare, they should be able to call it directly with it's needed number of arguments and not pass 'a' twice to satisfy an internal if(). OK, fair enough. I'll think a little more about the best way to do this. Out of curiosity I just had a look at the SPARC instruction specifications, and happily (it certainly surprised me!) they are almost exactly the same as what I've done, so using those instructions should be a trivial change after this patch. The SPARC instruction seems to be limited to 32 words (2048 bits) but I guess you'd just use the software for larger sizes. Andrew.

Correct, I was prototyping a SPARC intrinsic in May and we independently had similar methods in BigInteger. At least I believe you had a montgomerySqr and montgomeryMul method in BigInteger back in April/May.

The instruction gets tedious getting the data to the instruction and the limitation hurts.

Tony

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