RFR: 8283626: AArch64: Set relocInfo::offset_unit to 4 [v2]

[Volker Simonis]

On Mon, 28 Mar 2022 13:40:14 GMT, Evgeny Astigeevich <duke at openjdk.java.net> wrote:

>> AArch64 instructions size is 4 bytes. Two lowest bits of `relocInfo` offsets can be discarded.
>> Tested with release and fastdebug builds:
>> - `gtest`: Passed.
>> - `tier1`...`tier4`: Passed
>
> Evgeny Astigeevich has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Updated code comments

Looks good to me.

This also fixes the issue that currently `OptoLoopAlignment` can be set to `1` although it should be a *multiple of NOP size* according to `OptoLoopAlignmentConstraintFunc()`.

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Marked as reviewed by simonis (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/7991