RFR: 8345485: C2 MergeLoads: merge adjacent array/native memory loads into larger load [v4]

[kuaiwei]

On Tue, 18 Mar 2025 08:19:47 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> kuaiwei has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Revert extract value and add more tests
>
> test/hotspot/jtreg/compiler/c2/TestMergeLoads.java line 55:
> 
>> 53:     byte[] aB = new byte[RANGE];
>> 54:     char[] aC = new char[RANGE];
>> 55:     short[] aS = new short[RANGE];
> 
> What about merging loads on `int[]`?

Now there's limit to merge 2 LoadI as LoadL. 
For byte and short, there's already unsigned load for them in C2, so they can extend safely. But there's no unsigned load for integer, so I stop merging 2 integer load in this patch. I will check if it can be done in other way.

> test/hotspot/jtreg/compiler/c2/TestMergeLoads.java line 145:
> 
>> 143:             a[i] = (short)RANDOM.nextInt();
>> 144:         }
>> 145:     }
> 
> Suggestion:
> 
>     }
> 
> 
> Please put a space between methods ;)

Ok

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PR Review Comment: https://git.openjdk.org/jdk/pull/24023#discussion_r2000516075
PR Review Comment: https://git.openjdk.org/jdk/pull/24023#discussion_r2000518140