RFR: 8350563: C2 compilation fails because PhaseCCP does not reach a fixpoint [v5]

[Christian Hagedorn]

On Wed, 19 Mar 2025 16:11:35 GMT, Liam Miller-Cushon <cushon at openjdk.org> wrote:

>> Hello, please consider this fix for [JDK-8350563](https://bugs.openjdk.org/browse/JDK-8350563) contributed by my colleague Matthias Ernst.
>> 
>> https://github.com/openjdk/jdk/pull/22856 introduced a new `Value()` optimization for the pattern `AndIL(Con, Mask)`.
>> This optimization can look through CastNodes, and therefore requires additional logic in CCP to push these
>> transitive uses to the worklist.
>> 
>> The optimization is closely related to analogous optimizations for SHIFT nodes, and we also extend the existing logic for
>> CCP worklist handling: the current logic is "if the shift input to a SHIFT node changes, push indirect AND node uses to the CCP worklist".
>> We extend it by adding "if the (new) type of a node is an IntegerType that `is_con, ...` to the predicate.
>
> Liam Miller-Cushon has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 10 additional commits since the last revision:
> 
>  - Merge remote-tracking branch 'origin/master' into JDK-8350563
>  - Reformat test and update package to ccp
>  - Review comments
>  - Update test/hotspot/jtreg/compiler/c2/TestAndConZeroCCP.java
>    
>    Co-authored-by: Emanuel Peter <emanuel.peter at oracle.com>
>  - copyright
>  - style
>  - Merge branch 'openjdk:master' into mernst/JDK-8350563
>  - RegTest
>  - Merge branch 'openjdk:master' into mernst/JDK-8350563
>  - push `con->(cast*)->and` uses

test/hotspot/jtreg/compiler/ccp/TestAndConZeroCCP.java line 29:

> 27:  * @summary Test that And nodes are added to the CCP worklist if they have a constant as input.
> 28:  * @run main/othervm -Xbatch -XX:-TieredCompilation compiler.ccp.TestAndConZeroCCP
> 29:  * @run driver compiler.ccp.TestAndConZeroCCP

Forgot the 2nd update in the suggestion:
Suggestion:

 * @run main compiler.ccp.TestAndConZeroCCP

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/23871#discussion_r2003740004