RFR: 8069539: RSA acceleration (original) (raw)

Vladimir Kozlov vladimir.kozlov at oracle.com
Tue Apr 14 17:58:07 UTC 2015

Thank you, Andrew, for suggestions.

Vladimir

On 4/14/15 10:41 AM, Andrew Haley wrote:

On 04/14/2015 06:22 PM, Vladimir Kozlov wrote:

We are discussing how and which checks to add into java code which calls intrinsified methods to keep intrinsic simple. Yes, good idea. While you're in there, there's a couple of thoughts I'd like to draw your attention to. Montgomery multiplication and squaring are implemented as separate steps, like so: a = multiplyToLen(t, modLen, mult, modLen, a); a = montReduce(a, mod, modLen, inv); a = squareToLen(t, modLen, a); a = montReduce(a, mod, modLen, inv); It is possible to interleave the multiplication and Montgomery reduction, and this can lead to a useful speedup on some architectures. It would be nice if Montgomery multiplication and squaring were factored into separate methods, and then they could be replaced by intrinsics. Also, all these word-reversal and misaligned long stores / loads in the multiplyToLen intrinsic code are a real PITA. If we word-reversed the arrays so that they were in little-endian form we'd have neither misaligned long stores / loads nor repeated word-reversals. We could do the word reversal on the stack: AFAICS it's unusual for multiplyToLen to be called for huge bignums, and I suppose if it did happen for a bignum larger than some threshold we could do the word reversal on the heap. Andrew.

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