RFR: 8360179: RISC-V: Only enable BigInteger intrinsics when AvoidUnalignedAccess == false [v2]

[Fei Yang]

On Mon, 23 Jun 2025 03:28:20 GMT, Anjian Wen <wenanjian at openjdk.org> wrote:

>> This disables BigInteger.multiplyToLen(), BigInteger.squareToLen(), BigInteger.montgomeryMultiply()
>> and BigInteger.montgomerySquare() on linux-riscv64 platforms where misaligned memory accesses is slow.
>> The reason is that these four BigInteger intrinsics do 8-byte misaligned memory accesses to int arrays
>> under -XX:+UseCompactObjectHeaders. And this will have a negative impact on SPECJvm2008 crypto tests.
>> 
>> Testing:
>> - [x] Tier1-3 tests.
>> - [x] SPECJvm2008 crypto performance tests.
>> [score.txt](https://github.com/user-attachments/files/20846531/score.txt)
>
> Anjian Wen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove useless func multiply_32_x_32_loop which only used in AvoidUnalignedAccesses case!

Thanks!

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

Marked as reviewed by fyang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/25923#pullrequestreview-2948897930