RFR: 8344213: Cleanup OpaqueLoop*Node verification code for Assertion Predicates [v4]

[Tobias Hartmann]

On Mon, 25 Nov 2024 13:55:53 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> This patch cleans up the `OpaqueLoop*Node` verification code that is called with `PhaseIdeaLoop::assertion_predicate_has_loop_opaque_node()`.
>> 
>> There are some places where the verification code is
>> - missing
>> - called twice in row with different methods
>> - unnecessarily called
>> 
>> This patch cleans this up and moves the verification code inside the `TemplateAssertionPredicate` and the `InitializedAssertionPredicate` class.
>> 
>> #### Details of this Patch
>> - Doing a simpler BFS similar to what `ReplaceOpaqueStrideInput::replace()` is doing.
>> - Noticed that the new code looks very similar, so I decided to create a dedicated `DataNodeBFS` class which could be reused again in the future to perform a BFS on data nodes.
>>   - One can implement the new `BFSActions` interface to define
>>     - Whether a node's input should be further visited.
>>     - Whether a node is a target node for this BFS.
>>     - What action that should be performed with the target node.
>>   - Updated `ReplaceOpaqueStrideInput` to use the new `DataNodeBFS/BFSActions` classes.
>>   - Implemented a new `OpaqueLoopNodesVerifier` class using `DataNodeBFS/BFSActions` which does the `OpaqueLoop*Node` verification previously done with `assertion_predicate_has_loop_opaque_node()`:
>>     - Verify Template Assertion Predicates:
>>       - For init value: Only `OpaqueLoopInit`
>>       - For last value: Both `OpaqueLoop*Nodes`
>>     - Verify Initialized Assertion Predicates:
>>       - No `OpaqueLoop*Nodes`
>> 
>> Thanks,
>> Christian
>
> Christian Hagedorn has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Fix local variable name
>  - Revert "Generalize BFS"
>    
>    This reverts commit fbde591803ada158cacc11bc553e1b5061e59ae7.

Still good.

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Marked as reviewed by thartmann (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22136#pullrequestreview-2458730889