RFR: 8348411: C2: Remove the control input of LoadKlassNode and LoadNKlassNode [v5]

[Emanuel Peter]

On Thu, 6 Feb 2025 19:11:58 GMT, Quan Anh Mai <qamai at openjdk.org> wrote:

>> Hi,
>> 
>> This patch removes the control input of `LoadKlassNode` and `LoadNKlassNode`. They can only have a control input if created inside `Parse::array_store_check()`, the reason given is:
>> 
>>     // We are allowed to use the constant type only if cast succeeded
>> 
>> But this seems incorrect, the load from the constant type can be done regardless, and it will be constant-folded. This patch only makes that more formal and cleanup `LoadKlassNode::can_remove_control`.
>> 
>> Please take a look and leave your reviews, thanks a lot.
>
> Quan Anh Mai 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 five additional commits since the last revision:
> 
>  - Merge branch 'master' into loadklassctrl
>  - format
>  - clearer intention, revert formatting, add assert
>  - remove always_see_exact_class
>  - remove control input of LoadKlassNode

Marked as reviewed by epeter (Reviewer).

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

PR Review: https://git.openjdk.org/jdk/pull/23274#pullrequestreview-2600950916