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  1. JDK
  2. JDK-8219881

[vector] Optimized 32-to-64 bit vectorized multiply

    Details

    • Type: Enhancement
    • Status: Open
    • Priority: P4
    • Resolution: Unresolved
    • Affects Version/s: repo-panama
    • Fix Version/s: repo-panama
    • Component/s: hotspot

      Description

      In bignum arithmetic, it is common to implement multiplication by splitting the number up into k-bit limbs, and then using a k-to-2k bit multiply operation. Typical values for k are 32 and 64. Many modern implementations of crypto algorithms make use of parallelism by performing several 32-to-64 bit multiply operations in parallel. Some processors have instructions for a 32-to-64 bit multiply, but not for a 64-to-64 bit multiply low. These processors will benefit from an optimization that computes this multiplication without bothering to compute the high part of the result (which is always 0).

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              • Assignee:
                vlivanov Vladimir Ivanov
                Reporter:
                apetcher Adam Petcher (Inactive)
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                • Created:
                  Updated: