RFR: 8188044: We need Math.unsignedMultiplyHigh [v2]

[Andrew Haley]

On Thu, 1 Jul 2021 18:08:22 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

>> Please consider this proposal to add a method `unsignedMultiplyHigh(long,long)` to each of `java.lang.Math` and `java.lang.StrictMath`.
>
> Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8188044: Add @see links between multiplyHigh() and unsignedMultiplyHigh().

src/java.base/share/classes/java/lang/Math.java line 1211:

> 1209:         long z1 = t >>> 32;
> 1210: 
> 1211:         return x1 * y1 + z1 + (z0 >>> 32);

Suggestion:

        long result = Math.multiplyHigh(x, y);
        if (x < 0) result += y;
        if (y < 0) result += x;
        return result;

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PR: https://git.openjdk.java.net/jdk/pull/4644