RFR: 8287139: aarch64 intrinsic for unsignedMultiplyHigh

[Bhavana-Kilambi]

On Mon, 23 May 2022 13:10:52 GMT, Raffaello Giulietti <duke at openjdk.java.net> wrote:

>> src/hotspot/cpu/aarch64/aarch64.ad line 11151:
>> 
>>> 11149: 
>>> 11150:   ins_cost(INSN_COST * 7);
>>> 11151:   format %{ "umulh   $dst, $src1, $src2, \t# umulhi" %}
>> 
>> There's an unnecessary trailing comma here and in the `smulh` pattern above.
>
> I didn't run the benchmark.
> Isn't a single instruction supposed to be faster anyway, as opposed to the java method?

Hi, I tried the JMH benchmark with this patch, it does generate the "umulh" instruction instead of smulh.

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PR: https://git.openjdk.java.net/jdk/pull/8840