RFR: 8308869: C2: use profile data in subtype checks when profile has more than one class [v7]

[Roland Westrelin]

On Fri, 30 Jun 2023 17:30:42 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> Roland Westrelin 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 11 additional commits since the last revision:
>> 
>>  - whitespace
>>  - reworked change
>>  - Merge branch 'master' into JDK-8308869
>>  - more test failures
>>  - Merge branch 'master' into JDK-8308869
>>  - whitespaces
>>  - test failures
>>  - review
>>  - 32 bit fix
>>  - white spaces
>>  - ... and 1 more: https://git.openjdk.org/jdk/compare/67d6bdee...101399eb
>
> test/hotspot/jtreg/compiler/c2/irTests/ProfileAtTypeCheck.java line 44:
> 
>> 42:         flags.add("-XX:TypeProfileSubTypeCheckCommonThreshold=90");
>> 43:         if (!Platform.is32bit()) {
>> 44:             flags.add("-XX:-UseCompressedClassPointers");
> 
> What's the purpose of `-XX:-UseCompressedClassPointers` on 64-bit platforms? Make it easier to match the IR?

It is to make it easier to match the IR. I could update the rules so it's not required.

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PR Review Comment: https://git.openjdk.org/jdk/pull/14375#discussion_r1259796098