RFR: 8326135: Enhance adlc to report unused operands [v2]

[kuaiwei]

On Wed, 21 Feb 2024 03:24:14 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> I actually asked why `callback.do_form(instr)` calls in loop are not marking them as used? Why you need to call `do_form_by_name()` for them?
>
> I see that vector operand are not used directly so you are correct about them. But I see `stackSlot*` are used.

For example, stackSlotP in aarch64 is not used. If not do_form_by_name, it will be reported as unused.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17910#discussion_r1496953519