RFR: JDK-8287061: Support for rematerializing scalar replaced objects participating in allocation merges [v7]

[Cesar Soares Lucas]

On Thu, 6 Apr 2023 03:25:31 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Cesar Soares Lucas has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains seven commits:
>> 
>>  - Merge with Master
>>  - Addressing PR review 2: refactor & reuse MacroExpand::scalar_replacement method.
>>  - Address PR feeedback 1: make ObjectMergeValue subclass of ObjectValue & create new IR class to represent scalarized merges.
>>  - Add support for SR'ing some inputs of merges used for field loads
>>  - Fix some typos and do some small refactorings.
>>  - Merge master
>>  - Add support for rematerializing scalar replaced objects participating in allocation merges
>
> src/hotspot/share/opto/escape.cpp line 633:
> 
>> 631: 
>> 632:     SafePointScalarMergeNode* smerge = new SafePointScalarMergeNode(merge_t, merge_idx);
>> 633:     smerge->init_req(0, _compile->root());
> 
> May be use ophi's control here, it should stay bellow merge point. Was there a reason you use `root`?

To be honest, for this Node, I thought it didn't matter. I actually just used the same pattern as in PhaseMacroExpand.
I'll adjust the patch as you suggested, though.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/12897#discussion_r1163448361