On Sun, 22 Sep 2024 13:37:38 GMT, Chen Liang <li...@openjdk.org> wrote:
>> Optimize checkAssignableTo to avoid clone when stackSize is 0, and use clone
>> instead of Array.copyOf to avoid compression and then expansion
>
> src/java.base/share/classes/jdk/internal/classfile/impl/StackMapGenerator.java
> line 1102:
>
>> 1100: target.localsSize = localsSize;
>> 1101: if (stackSize > 0) {
>> 1102: target.stack = Arrays.copyOf(stack, stackSize);
>
> Do you think we should use `.clone()` to avoid `getClass` checks and to avoid
> extra array growing in case the new stack/local immediately grows due to
> instructions after target?
>
> Also I think you can do `localsSize > 0` check for locals assignment too.
stack.length may be larger than stackSize. In this case, the length of the
array copied by clone will be longer than Arrays.copyOf. However, I have no
evidence that Arrays.copyOf is faster than clone.
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PR Review Comment: https://git.openjdk.org/jdk/pull/21121#discussion_r1770563199
