RFR: 8332442: C2: refactor Mod cases in Compile::final_graph_reshaping_main_switch() [v6]

[Kangcheng Xu]

On Wed, 11 Sep 2024 18:57:17 GMT, Jasmine Karthikeyan <jkarthikeyan at openjdk.org> wrote:

>> 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 12 additional commits since the last revision:
>> 
>>  - Merge branch 'openjdk:master' into refactor-mod-cases
>>  - improve formatting, nullptr comparison, update test flags, use custom @Run tests
>>  - allow one div on platforms without hardware divmod
>>  - remove platform restriction
>>  - 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
>>  - ... and 2 more: https://git.openjdk.org/jdk/compare/d6ffaaff...fe7b82ef
>
> test/hotspot/jtreg/compiler/c2/TestDivModNodes.java line 33:
> 
>> 31: /*
>> 32:  * @test
>> 33:  * @summary Test that DIV and MOD nodes are converted into DIVMOD where possible
> 
> I think you're missing `@bug 8332442` here.

Good catch. Thanks!

> test/hotspot/jtreg/compiler/c2/TestDivModNodes.java line 68:
> 
>> 66:     private static void runSignedIntDivMod() {
>> 67:         int dividend = RANDOM.nextInt();
>> 68:         int divisor = RANDOM.nextInt();
> 
> Since `nextInt()` can return 0, this might lead to a very rare test failure since div/mod by 0 results in an `ArithmeticException`. You could do `divisor = (divisor == 0) ? 1 : divisor` to avoid that, like we do in the other division idealization tests:
> https://github.com/openjdk/jdk/blob/51b85a1f692fed7a66bdc0fae21438a60aafe7c2/test/hotspot/jtreg/compiler/c2/irTests/DivINodeIdealizationTests.java#L45-L46

changed to `nextNonZeroInt()` and `nextNonZeroLong()`

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PR Review Comment: https://git.openjdk.org/jdk/pull/20877#discussion_r1755537089
PR Review Comment: https://git.openjdk.org/jdk/pull/20877#discussion_r1755539364