RFR: 8365991: AArch64: Ignore BlockZeroingLowLimit when UseBlockZeroing is false [v7]

[Andrew Haley]

On Mon, 24 Nov 2025 07:40:19 GMT, Patrick Zhang <qpzhang at openjdk.org> wrote:

> I wondered why `MacroAssembler::zero_words` uses 16 words to do `stp` unrolling, while `generate_zero_blocks()` 8 words (`const int MacroAssembler::zero_words_block_size = 8;`), so defined this variable to compare `8 vs 16` but did not find obvious performance difference.
> 
> Regarding the var name `block_size`, could `unroll` or `unroll_words` be better?

What's wrong with 16? I'm asking not from a "my teachers said always name constants" point of view, but from a reader's understanding point of view. Named constants are all well and good if the constant has some meaning, but this one is just two words. Perhaps `2 * WordSize` would do.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26917#discussion_r2560000825