RFR: 8347405: MergeStores with reverse bytes order value [v5]

[Emanuel Peter]

On Fri, 10 Jan 2025 11:16:29 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> kuaiwei 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:
>> 
>>  - Fix build failure after merging
>>  - Merge remote-tracking branch 'origin/master' into pr/merge_stores_reverse
>>  - Exclude RISCV for Reverse nodes
>>  - Fix ppc64le
>>  - Update enum ValueOrder type
>>  - Fix as review comments
>>  - Remove unused test option
>>  - 8347405: MergeStores with reverse bytes order value
>
> src/hotspot/share/opto/memnode.cpp line 3276:
> 
>> 3274:       merged_input_value = _phase->transform(new ReverseBytesINode(nullptr, merged_input_value));
>> 3275:     } else {
>> 3276:       return nullptr;
> 
> Suggestion:
> 
>       // <say why we cannot do anything for 2-element byte case>.
>       return nullptr;

Can you please put a comment here about the limitations?

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PR Review Comment: https://git.openjdk.org/jdk/pull/23030#discussion_r1921901952