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

[Vladimir Kozlov]

On Wed, 21 Feb 2024 03:20:38 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> stackSlot* are used in output_h.cpp and formssel.cpp . I assume they are all useful.
>> 
>> Generic vector operands are not used in instruction forms. But they are used in c++ code snippet Matcher::pd_specialize_generic_vector_operand(). The special vector operands only exists in x86_64 and aarch64 platform.
>
> 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.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17910#discussion_r1496841507