RFR: 8347405: MergeStores with reverse bytes order value [v4]

[Emanuel Peter]

On Wed, 22 Jan 2025 08:17:08 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>>> My testing with TestMergeStores.java succeeded. I wanted to put the change through our ci testing but the builds failed because of incompatible changes in master. May I ask you to merge master so I can do the additional testing?
>> 
>> It's fixed.
>
> @kuaiwei Feel free to ping me again here whenever this is ready for a re-review :)

> @eme64 , I made new change to merge more stores. It could merge pattern like
> 
> ```c++
> a[0] = vL <<  8;
> a[1] = vL << 16;
> a[2] = vL << 24;
> a[3] = vL << 32;
> ```
> 
> It passed tier1 tests in x86 and aarch64 platform. May I ask you to review it again? Thanks.

@kuaiwei That is a nice idea / generalization!

However: I think we should really do that in a separate RFE. Because it needs to be thoroughly tested, and that would blow up the size of your PR, and make reviewing much slower. The reverse order is already complex enough for us to review ;)

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PR Comment: https://git.openjdk.org/jdk/pull/23030#issuecomment-2615006538