On Sun, 26 Mar 2023 20:45:19 GMT, Chen Liang <li...@openjdk.org> wrote:
>> Fixed the bug where if a caller keeps a reference to the array passed into >> `MethodTypeDesc.of`, the caller may mutate the Desc via the array and can >> create invalid MethodTypeDesc. >> >> Unfortunately, since the input array now needs to be copied, the `of` >> factory suffers from a performance drop. But otherwise, this patch has minor >> performance gains on `ofDescriptor` factory, even compared to Adam's patch >> that optimized `ofDescriptor` in #12945. >> >> This patch moves the parameters to an immutable list, to avoid allocations >> on `parameterList` as well. >> >> Benchmark of Oracle JDK 20: >> https://gist.github.com/683c6219e183cbc2b336224fc2c0d50a >> Benchmark of this patch: >> https://gist.github.com/22be9371a2370fb4a7b44f1684750ec4 >> Benchmark of [asotona's >> patch](https://github.com/openjdk/jdk/pull/12945/files#diff-ac8e413d3e13532a2b0d34a90253c6ddd7a4f04082f792b9d076e9b5a33f2078): >> https://gist.github.com/eb98579c3b51cafae481049a95a78f80 >> >> [sotona vs >> this](https://jmh.morethan.io/?gists=eb98579c3b51cafae481049a95a78f80,22be9371a2370fb4a7b44f1684750ec4); >> [20 vs >> this](https://jmh.morethan.io/?gists=683c6219e183cbc2b336224fc2c0d50a,22be9371a2370fb4a7b44f1684750ec4); >> [20 vs >> sotona](https://jmh.morethan.io/?gists=683c6219e183cbc2b336224fc2c0d50a,eb98579c3b51cafae481049a95a78f80), >> for reference > > Chen Liang has updated the pull request incrementally with one additional > commit since the last revision: > > Fix some inconsistencies in the method descriptor derivation methods > Additional comments: > > 1. Maybe it's feasible to add another factory: > > ```java > static MethodTypeDesc of(ClassDesc returnType, List<ClassDesc> > parameterTypes) { > return new MethodTypeDescImpl(returnType, List.copyOf(parameterTypes)); > } > ``` > > which would avoid another copy if `parameterTypes` is already a list from > `List.of` factories. > > 2. Avoiding copies in `parameterList` can speed up its users, such as stack > map generation in the Classfile API. Yes, any improvements avoiding unnecessary arrays copying are welcome. `ClassDesc` and `MethodTypeDesc` are key pieces of the Classfile API with significant performance impact. ------------- PR Comment: https://git.openjdk.org/jdk/pull/13186#issuecomment-1511111107
