RFR: 8315066: Add unsigned bounds and known bits to TypeInt/Long [v57]

[Emanuel Peter]

On Fri, 2 May 2025 08:55:45 GMT, Quan Anh Mai <qamai at openjdk.org> wrote:

>> Hi,
>> 
>> This patch adds unsigned bounds and known bits constraints to TypeInt and TypeLong. This opens more transformation opportunities in an elegant manner as well as helps avoid some ad-hoc rules in Hotspot.
>> 
>> In general, a `TypeInt/Long` represents a set of values `x` that satisfies: `x s>= lo && x s<= hi && x u>= ulo && x u<= uhi && (x & zeros) == 0 && (x & ones) == ones`. These constraints are not independent, e.g. an int that lies in [0, 3] in signed domain must also lie in [0, 3] in unsigned domain and have all bits but the last 2 being unset. As a result, we must canonicalize the constraints (tighten the constraints so that they are optimal) before constructing a `TypeInt/Long` instance.
>> 
>> This is extracted from #15440 , node value transformations are left for later PRs. I have also added unit tests to verify the soundness of constraint normalization.
>> 
>> Please kindly review, thanks a lot.
>> 
>> Testing
>> 
>> - [x] GHA
>> - [x] Linux x64, tier 1-4
>
> Quan Anh Mai has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Emanuel's reviews

And a few comments about the gtests :)

test/hotspot/gtest/opto/test_rangeinference.cpp line 113:

> 111:   for (int i = 0; i < parameters; i++) {
> 112:     S a = uniform_random<U>();
> 113:     S b = uniform_random<U>();

How expensive would it be to run a few more here?

test/hotspot/gtest/utilities/test_intn_t.cpp line 38:

> 36:     if (i < intn_t<n>::max) {
> 37:       ASSERT_TRUE(intn_t<n>(i) < intn_t<n>(i + 1));
> 38:     }

How about a check for the overflow case?

test/hotspot/gtest/utilities/test_intn_t.cpp line 51:

> 49:   test_intn_t<7>();
> 50:   test_intn_t<8>();
> 51: }

And how about some tests for `uintn_t`?

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PR Review: https://git.openjdk.org/jdk/pull/17508#pullrequestreview-2811578117
PR Review Comment: https://git.openjdk.org/jdk/pull/17508#discussion_r2071352975
PR Review Comment: https://git.openjdk.org/jdk/pull/17508#discussion_r2071360729
PR Review Comment: https://git.openjdk.org/jdk/pull/17508#discussion_r2071361519