On Thu, 12 Sep 2024 12:01:47 GMT, Raffaello Giulietti <rgiulie...@openjdk.org>
wrote:
>> Yes, it could, but the problem is that in this way the precondition `(resPos
>> <= offset || resPos >= offset + intLen)` would be no longer correct, and in
>> particular `resPos <= offset` is used by `MBI.leftShift()` if `result ==
>> value`.
>
> I mean something like
>
> private void primitiveRightShift(int n, int[] result, int resPos) {
> int[] val = value;
> int n2 = 32 - n;
> int c = 0;
> for (int i = 0; i < intLen; i++) {
> int b = val[offset + i];
> result[resPos + i] = c << n2 | b >>> n;
> c = b;
> }
> }
>
> and
>
> private void primitiveLeftShift(int n, int[] result, int resPos) {
> int[] val = value;
> int n2 = 32 - n;
> int c = 0;
> for (int i = intLen - 1; i >= 0; i--) {
> int b = val[offset + i];
> result[resPos + i] = c >>> n2 | b << n;
> c = b;
> }
>
> They are compatible with the precondition, right?
But in the second version, the precondition must be `resPos <= offset - intLen
|| resPos >= offset` to make sure that the result is correct whether `result ==
value`, and the condition `resPos <= offset - intLen` is stronger than `resPos
<= offset`.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/20008#discussion_r1756759551
