RFR: 8373722: [TESTBUG] compiler/vectorapi/TestVectorOperationsWithPartialSize.java fails intermittently

[Jie Fu]

On Wed, 24 Dec 2025 14:38:37 GMT, Jie Fu <jiefu at openjdk.org> wrote:

>> Yeah, I'm trying to extend the value range to `1~3000`. The tests are still running... Since the result largely depends on the random values,  I run this test `500` times on SVE/NEON/X86 machines respectively (**1500** times totally), and have not observed failure now. Is that fine to you? I will update the test once all tests pass. Thanks for looking at this change!
>
>> Yeah, I'm trying to extend the value range to `1~3000`. The tests are still running... Since the result largely depends on the random values, I run this test `500` times on SVE/NEON/X86 machines respectively (**1500** times totally), and have not observed failure now. Is that fine to you? I will update the test once all tests pass. Thanks for looking at this change!
> 
> As with range `1~3000`, we may still see failures even with 1000ULP according to the following program, right?
> 
> 
> class T {
>   public static void main(String[] args) {
> 
>     float ROUNDING_ERROR_FACTOR_ADD = 1000.0f;
> 
>     Float a = 1.0f + (ROUNDING_ERROR_FACTOR_ADD + 1) * Math.ulp(1.0f);
>     Float b = 3000.0f;
> 
>     Float expected = a + b - b;
>     Float actual   = a + (b - b);
> 
>     float tolerance = Math.ulp(expected) * ROUNDING_ERROR_FACTOR_ADD;
>     if (Math.abs(expected - actual) > tolerance) {
>       System.out.println("Error: Out of tolerance!");
>     }
>   }
> }

> > Yeah, I'm trying to extend the value range to `1~3000`. The tests are still running... Since the result largely depends on the random values, I run this test `500` times on SVE/NEON/X86 machines respectively (**1500** times totally), and have not observed failure now. Is that fine to you? I will update the test once all tests pass. Thanks for looking at this change!
> 
> As with range `1~3000`, we may still see failures even with 1000ULP according to the following program, right?
> 
> ```java
> class T {
>   public static void main(String[] args) {
> 
>     float ROUNDING_ERROR_FACTOR_ADD = 1000.0f;
> 
>     Float a = 1.0f + (ROUNDING_ERROR_FACTOR_ADD + 1) * Math.ulp(1.0f);
>     Float b = 3000.0f;
> 
>     Float expected = a + b - b;
>     Float actual   = a + (b - b);
> 
>     float tolerance = Math.ulp(expected) * ROUNDING_ERROR_FACTOR_ADD;
>     if (Math.abs(expected - actual) > tolerance) {
>       System.out.println("Error: Out of tolerance!");
>     }
>   }
> }
> ```

Oops, if the range is `1~3000`, there is no negative float, so the above program should not happen.
Just ignore it.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/28960#discussion_r2645879485