RFR: 8335392: C2 MergeStores: enhanced pointer parsing [v6]

[Emanuel Peter]

On Mon, 28 Oct 2024 13:29:51 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> Emanuel Peter has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   changes to NoOverflowInt for Dean
>
> src/hotspot/share/opto/mempointer.hpp line 110:
> 
>> 108: //
>> 109: //     pointer = ms.heapBase() +           ms.address() +           i
>> 110: //             = 0             + 1       * ms.address() + 1       * i
> 
> For variation, do you want to change this to `short` to also have an example with a `scale` other than 1 for `MemorySegment`?

good idea!

> src/hotspot/share/opto/mempointer.hpp line 365:
> 
>> 363:   {
>> 364:     const jint max_distance = 1 << 30;
>> 365:     assert(_distance < max_distance && _distance > -max_distance, "safe distance");
> 
> The variable name "max_distance" suggests that the assert should use `>=` and `<=`. Would that still be correct? Maybe you should add a comment about the max distance and why it has this value.

Good point. I'll try to remember the reason and add better comments.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19970#discussion_r1820915837
PR Review Comment: https://git.openjdk.org/jdk/pull/19970#discussion_r1820918265