RFR: 8359412: Template-Framework Library: Operations and Expressions [v6]

[Galder Zamarreño]

On Thu, 18 Sep 2025 08:12:50 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Impliementing ideas from original draft PR: https://github.com/openjdk/jdk/pull/23418 ([Exceptions](https://github.com/openjdk/jdk/pull/23418/files#diff-77e7db8cc0c5e02786e1c993362f98fabe219042eb342fdaffc09fd11380259dR41), [ExpressionFuzzer](https://github.com/openjdk/jdk/pull/23418/files#diff-01844ca5cb007f5eab5fa4195f2f1378d4e7c64ba477fba64626c98ff4054038R66)).
>> 
>> Specifically, I'm extending the Template Library with `Expression`s, and lists of `Operations` (some basic Expressions). These Expressions can easily be nested and then filled with arguments, and applied in a `Template`.
>> 
>> Details, in **order you should review**:
>> - `Operations.java`: maps lots of primitive operators as Expressions.
>> - `Expression.java`: the fundamental engine behind Expressions.
>> - `examples/TestExpressions.java`: basic example using Expressions, filling them with random constants.
>> - `tests/TestExpression.java`: correctness test of Expression machinery.
>> - `compiler/igvn/ExpressionFuzzer.java`: expression fuzzer for primitive type expressions, including input range/bits constraints and output range/bits verification.
>> - `PrimitiveType.java`: added `LibraryRNG` facility. We already had `type.con()` which gave us random constants. But we also want to have `type.callLibraryRNG()` so that we can insert a call to a random number generator of the corresponding primitive type. I use this facility in the `ExpressionFuzzer.java` to generate random arguments for the expressions.
>> - `examples/TestPrimitiveTypes.java`: added a `LibraryRNG` example, that tests that has a weak test for randomness: we should have at least 2 different value in 1000 calls.
>> 
>> If the reviewers absolutely insist, I could split out `LibraryRNG` into a separate RFE. But it's really not that much code, and has direct use in the `Expression` examples.
>> 
>> **Future Work**:
>> - Use `Expression`s in a loop over arrays / MemorySegment: fuzz auto-vectorization.
>> - Use `Expression`s to model more operations:
>>   - `Vector API`, more arithmetic operations like from `Math` classes etc.
>> - Ensure that the constraints / checksum mechanic in `compiler/igvn/ExpressionFuzzer.java` work, using IR rules. We may even need to add new IGVN optimizations. Add unsigned constraints.
>> - Find a way to delay IGVN optimizations to test worklist notification: For example, we could add a new testing operator call `TestUtils.delay(x) -> x`, which is intrinsified as some new `DelayNode` that in normal circumstances just fol...
>
> Emanuel Peter has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - more comments
>  - add othervm to test

Nice additions @eme64!

I would have liked to see an example of real use case of this in action included in the PR, e.g. some kind of IR test that takes advantage of this. E.g. a companion version (and/or replacement) for `VectorReduction2`? A follow up RFE would of course be fine for this.

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Marked as reviewed by galder (Author).

PR Review: https://git.openjdk.org/jdk/pull/26885#pullrequestreview-3241161843