RFR: 8343689: AArch64: Optimize MulReduction implementation [v8]

[Andrew Haley]

On Fri, 8 Aug 2025 15:13:40 GMT, Mikhail Ablakatov <mablakatov at openjdk.org> wrote:

>> Sorry, the unpredicated version should be in the _SVE Integer Misc - Unpredicated_ section.
>
> Are you asking to move it to another existing section in the file or create a new one? If it's the former, could you point me to the section in the file - I can see neither `sve_ftssel` nor `sve_fexpa` defined. If the latter, in Arm ARM *C4.1.41 SVE Integer Misc - Unpredicated* is followed by *C4.1.42 SVE Element Count*, so the patch places `sve_movprfx` definition right before `sve_cnt*`; I also don't see an opportunity to define an `INSN` for this section as encodings of the instructions within the section do not follow a single pattern.
> 
> If it's something else completely, please elaborate.

Please try to organize things the same way as the Decode section of the ARM.

Insert a new section called _SVE Integer Misc - Unpredicated_ after _SVE bitwise shift by immediate (predicated)_ and put this pattern there.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/23181#discussion_r2264572038