RFR: 8347645: C2: XOR bounded value handling blocks constant folding [v42]

[Emanuel Peter]

On Mon, 24 Mar 2025 15:39:31 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Johannes Graham has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 57 commits:
>> 
>>  - Merge branch 'openjdk:master' into xor_const
>>  - Merge branch 'openjdk:master' into xor_const
>>  - invert comparison in tests
>>  - update bug numbers and summary
>>  - add test of random ranges
>>  - consistency
>>  - Merge branch 'openjdk:master' into xor_const
>>  - widen range of test values; add missing comment
>>  - a few more tests
>>  - add comments
>>    
>>    Co-authored-by: Emanuel Peter <emanuel.peter at oracle.com>
>>  - ... and 47 more: https://git.openjdk.org/jdk/compare/02a4ce23...06537f21
>
> test/hotspot/jtreg/compiler/c2/irTests/XorINodeIdealizationTests.java line 385:
> 
>> 383:     public int testRandomLimits(int x, int y) {
>> 384:         x = RANGE_1.clamp(x);
>> 385:         y = RANGE_2.clamp(y);
> 
> Question:
> did you verify that this `RANGE_1` with its clamp values are really detected as constants by C2, and not seen as loads? Maybe that works, but I've never tried it myself.

I  just hope that the abstraction here does not invalidate our intent to have constant min/max bounds for the clamping ;)

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PR Review Comment: https://git.openjdk.org/jdk/pull/23089#discussion_r2010435990