On Sun, 7 Jan 2024 18:16:05 GMT, Chen Liang <li...@openjdk.org> wrote:
>> Original code has been significant in profiler. >> >> >> MethodTypeDesc desc = MethodTypeDesc.of(toClassDesc(returnType), >> >> Arrays.stream(parameterTypes).map(ProxyGenerator::toClassDesc).toArray(ClassDesc[]::new)); >> >> >> 1. each `toClassDesc` builds `descriptorString` and parses/validates it >> while constructing `ClassDesc` >> 2. `Arrays.stream(...).map(...).toArray(...)` allocates an array >> 3. `MethodTypeDesc.of(...)` clones the array and iterates params to check >> for void >> 4. `desc.descriptorString()` then finally use the `StringJoiner` >> >> Optimized code only joins `descriptorString`, no validations, no streaming, >> no arrays, no cloning. >> >> >> I suggest this patch as this code is considered as performance critical. >> However we can go through `ClassDesc` and `MethodTypeDesc` if not >> performance critical or if the conversions would be optimized. >> >> For example better (trusted) paths from `MethodType` to >> `MethodTypeDescriptor` and from `Class` to `ClassDesc`, avoiding at least >> validations. > > Turns out your approach to avoid MTD here is apparently useless; > `MethodTypeDesc` is still created for initializing the local tracker > `topLocal` in `DirectCodeBuilder`. In addition, `StackMapDecoder` also uses > `methodTypeSymbol` to compute the initial frame. > > IMO we should just stay with MTD; the descriptor breakdown happens too often > and, from previous benchmarks, descriptor breakdown is actually slow (which > gives CF API a small edge over ASM here). But we can still replace the > `parameterList()` iteration with index-based iteration to avoid array copies. Right, there are still so many conversions. I'll revert the custom code to simplify further optimizations. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/17121#discussion_r1444690465
