RFR: 8306842: Classfile API performance improvements [v3]

[Claes Redestad]

On Tue, 9 May 2023 16:09:14 GMT, Adam Sotona <asotona at openjdk.org> wrote:

>> Following improvements implemented:
>> - Switch over `String` replaced with switch single char
>> - Binary search for frames in `StackMapGenerator`
>> - `StackMapGenerator.rawHandlers` with pre-calculated offsets
>> - `ClassEntry` is caching `ClassDesc` symbol
>> - Caching of type symbols in `NameAndTypeEntry` and `MethodTypeEntry`
>> - Caching `MethodTypeDesc` in `MethodInfo` implementations
>> - `StackMapGenerator` and `Utils` delegating to cached `MethodTypeDesc` instead of custom parsing
>> 
>> No API change.
>> 
>> Benchmarks show stack map generation improved by 21% and code generation from symbols improved by 30%.
>> 
>> 
>> Benchmark                     Mode  Cnt       Score       Error  Units
>> GenerateStackMaps.benchmark  thrpt   10  407931.202 ± 13101.023  ops/s
>> RebuildMethodBodies.shared   thrpt    4   10258.597 ±   383.699  ops/s
>> RebuildMethodBodies.unshared thrpt    4    7224.543 ±   256.800  ops/s
>> 
>> 
>> 
>> Benchmark                     Mode  Cnt       Score      Error  Units
>> GenerateStackMaps.benchmark  thrpt   10  495101.110 ± 2389.628  ops/s
>> RebuildMethodBodies.shared    thrpt   4   13380.272 ±  810.113  ops/s
>> RebuildMethodBodies.unshared  thrpt   4    9399.863 ±  557.060  ops/s
>
> Adam Sotona has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fixed StackMapGenerator

I'm having a look, but hit an early hurdle in that the microbenchmarks under org/openjdk/bench/jdk/classfile all seem to be missing necessary `--add-opens` flags. Micros should be runnable without any extra flags on the command line.

test/micro/org/openjdk/bench/jdk/classfile/RebuildMethodBodies.java line 42:

> 40: @BenchmarkMode(Mode.Throughput)
> 41: @State(Scope.Benchmark)
> 42: @Fork(value = 1, jvmArgsAppend = {"--enable-preview"})

Suggestion:

@Fork(value = 1, jvmArgsAppend = {"--enable-preview",
                                  "--add-opens", "java.base/jdk.internal.classfile=ALL-UNNAMED",
                                  "--add-opens", "java.base/jdk.internal.classfile.constantpool=ALL-UNNAMED",
                                  "--add-opens", "java.base/jdk.internal.classfile.instruction=ALL-UNNAMED"})

-------------

PR Review: https://git.openjdk.org/jdk/pull/13671#pullrequestreview-1418960199
PR Review Comment: https://git.openjdk.org/jdk/pull/13671#discussion_r1188810244