RFR: 8323116: [REDO] Computational test more than 2x slower when AVX instructions are used [v4]

[Srinivas Vamsi Parasa]

On Fri, 5 Apr 2024 06:55:47 GMT, Quan Anh Mai <qamai at openjdk.org> wrote:

>> Its a cleaver trick to dodge false dependency without compromising on correctness.
>
> @jatin-bhateja I get it but IMO it shouldn't be the responsibility of the assembler to do that, the assembler should emit machine code in a manner that respects what is being written.

> This is a downcast from double precision to single precision value, thus only lower 32 bits of destination hold the actual results for conversion, upper 127:32 bits are copied from non destructive source operand for vex encoded instruction.

Please see the updated description incorporating the correction dst[63:0] -> dst[31,0] for `cvtss2sd`

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PR Review Comment: https://git.openjdk.org/jdk/pull/18503#discussion_r1553927611