RFR: 8332442: C2: refactor Mod cases in Compile::final_graph_reshaping_main_switch() [v3]

[Emanuel Peter]

On Tue, 10 Sep 2024 15:57:24 GMT, Kangcheng Xu <kxu at openjdk.org> wrote:

>> Hello all. This patch addresses [JDK-8332442](https://bugs.openjdk.org/browse/JDK-8332442) and refactors `Op_ModI`/`Op_ModL`/`Op_UModI`/`Op_UModL` cases in `DIVMOD` transforamtions. The purpose of the transformation to convert adjacent div `/`  and mod `%` operations of the same operands into one should the platform support this feature (e.g., x86-64).
>> 
>> I took the liberty adding _signed_ DIVMOD nodes (i.e., `DIV_MOD_I` and `DIV_MOD_L`) to the `IRNode` class constants as they are previously missing. Please let me know if they were left intentionally and if there are any other concerns. Thanks!
>> 
>> ~This will be a draft PR before GHA tests are confirmed passing.~
>
> Kangcheng Xu 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 eight additional commits since the last revision:
> 
>  - Merge branch 'openjdk:master' into refactor-mod-cases
>  - include aarch64 in tests, add more configuration combinations
>  - remove redundant arguments, test with -XX:-UseDivMod
>  - Merge branch 'master' into refactor-mod-cases
>  - Add test and IRNode for signed int/long divmod
>  - created IR tests
>  - passing tier1 tests
>  - refactor divmod ops to handle_div_mod_op

test/hotspot/jtreg/compiler/c2/TestDivModNodes.java line 38:

> 36:  * @run main/othervm -XX:+UseDivMod compiler.c2.TestDivModNodes
> 37:  * @run main/othervm -XX:-UseDivMod compiler.c2.TestDivModNodes
> 38:  */

Drive by comment: please allow it to run on any platform, and add restrictions on whee the IR rules are run. That allows us to test results on other platforms, which is valuable on its own.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20877#discussion_r1752261217