RFR: 8366984: Remove delay slot support

[Emanuel Peter]

On Tue, 9 Sep 2025 09:23:46 GMT, Daniel Jeliński <djelinski at openjdk.org> wrote:

>> src/hotspot/cpu/arm/arm.ad line 3383:
>> 
>>> 3381:     BR     : R;
>>> 3382: %}
>>> 3383: 
>> 
>> Where was this used? Or is it an unrelated cleanup?
>
> Removing the comment alone didn't feel quite right, so I removed the following block as well. The block appears to be unused. It was copy-pasted from [SPARC](https://github.com/openjdk/jdk/blob/8153779ad32d1e8ddd37ced826c76c7aafc61894/hotspot/src/cpu/sparc/vm/sparc.ad#L4984), where it was also unused.

Thanks for the explanation :)

>> src/hotspot/share/adlc/adlparse.cpp line 1394:
>> 
>>> 1392:           parse_err(SYNERR, "Using obsolete token, branch_has_delay_slot");
>>> 1393:           break;
>>> 1394:         }
>> 
>> I'm curious: why do you add that special warning? It would fail later anyway, right? Are we expecting anyone to parse things produced by different versions?
>
> I took my inspiration from earlier work on adlc (see 6e35bcbf038cec0210c38428a8e1c233e102911a or 3f9c8a39201644952c6d07b97695a5a7ef918622), but I don't mind removing these warnings and the related code block entirely.

Sounds good, just keep the "obsolete" error :)

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PR Review Comment: https://git.openjdk.org/jdk/pull/27119#discussion_r2333063403
PR Review Comment: https://git.openjdk.org/jdk/pull/27119#discussion_r2333062954