RFR: 8287087: C2: perform SLP reduction analysis on-demand [v3]

[Roberto Castañeda Lozano]

On Mon, 24 Apr 2023 09:09:54 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

>> Roberto Castañeda Lozano has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 31 commits:
>> 
>>  - Use is_marked_reduction() in new SLP code
>>  - Merge master
>>  - Emit Node::Flag_has_swapped_edges in IGV graphs
>>  - Merge master
>>  - Relax the reduction cycle search bound
>>  - Remove redundant IR check precondition
>>  - Use SuperWord members in reduction marking
>>  - Remove redundant opcode checks
>>  - Do not run test in x86-32
>>  - Update existing test instead of removing it
>>  - ... and 21 more: https://git.openjdk.org/jdk/compare/a3137c75...d9fc7b22
>
> Hi @jatin-bhateja, I have written a qualitative comparison between this PR and the generic search approach proposed by @eme64 and you (see **Alternative approaches** section in the updated PR description). I hope the comparison clarifies and motivates the plan outlined in https://github.com/openjdk/jdk/pull/13120#discussion_r1166778814. Please let me know whether you agree with that plan so that we can move forward with this RFE, [JDK-8302673](https://bugs.openjdk.org/browse/JDK-8302673), and also [JDK-8302652](https://bugs.openjdk.org/browse/JDK-8302652).

> Hi @robcasloz , Apart from some earlier shared concerns on path detection traversal which are not blocking issues, patch looks good to me. Best Regards, Jatin

Thanks for reviewing, Jatin!

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PR Comment: https://git.openjdk.org/jdk/pull/13120#issuecomment-1521757717