RFR: 8341260: Add Float16 to jdk.incubator.vector [v6]

[Raffaello Giulietti]

On Tue, 22 Oct 2024 23:47:33 GMT, Joe Darcy <darcy at openjdk.org> wrote:

>> Port of Float16 from java.lang in the lworld+fp16 branch to jdk.incubabor.vector.
>
> Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add equals/hashCode implementation; tests to follow.

src/jdk.incubator.vector/share/classes/jdk/incubator/vector/Float16.java line 708:

> 706:     public static int hashCode(Float16 value) {
> 707:         Float16 f16 = isNaN(value) ? Float16.NaN : value;
> 708:         return (int)float16ToRawShortBits(f16);

What about randomizing the returned value? IIUC, JEP 401 does not speak against.
The purpose would not be to conceal anything, but to ensure that clients cannot rely on specific values.


    private static final int HASH_MASK = RandomGenerator.getDefault().nextInt();
    
    /**
     * Returns a hash code for a {@code Float16} value; compatible with
     * {@code Float16.hashCode()}.
     *
     * @param value the value to hash
     * @return a hash code value for a {@code Float16} value.
     */
    public static int hashCode(Float16 value) {
        Float16 f16 = isNaN(value) ? Float16.NaN : value;
        int bits = float16ToRawShortBits(f16);
        return (bits << 16 | bits & 0xFFFF) ^ HASH_MASK;
    }

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PR Review Comment: https://git.openjdk.org/jdk/pull/21574#discussion_r1812694738