RFR: 8275167: x86 intrinsic for unsignedMultiplyHigh

[Andrew Haley]

On Wed, 13 Oct 2021 18:55:10 GMT, Vamsi Parasa <duke at openjdk.java.net> wrote:

> Optimize the new Math.unsignedMultiplyHigh using the x86 mul instruction. This change show 1.87X improvement on a micro benchmark.

src/hotspot/share/opto/mulnode.cpp line 468:

> 466: }
> 467: 
> 468: //=============================================================================

MulHiLNode::Value() and UMulHiLNode::Value() seem to be identical. Perhaps some refactoring would be in order, maybe make a common shared routine.

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PR: https://git.openjdk.java.net/jdk/pull/5933