This PR makes ClassDesc.ofDescriptor return the shared constant for primitive descriptor strings ("I" etc..), and leverages this further by refactoring `MethodTypeDescImpl.ofDescriptor` to avoid the intermediate substring for primitives.
Microbenchmarks results look good with expected speedups and allocation reductions any time a primitive is part of the descriptor string, and a non-significant cost otherwise: Name (descString) Cnt Base Error Test Error Unit Change ClassDescFactories.ofDescriptor Ljava/lang/Object; 6 13,941 ± 1,643 14,071 ± 1,333 ns/op 0,99x (p = 0,681 ) :gc.alloc.rate.norm 16,000 ± 0,000 16,000 ± 0,000 B/op 1,00x (p = 0,617 ) ClassDescFactories.ofDescriptor V 6 9,212 ± 1,045 1,405 ± 0,049 ns/op 6,55x (p = 0,000*) :gc.alloc.rate.norm 48,000 ± 0,000 0,000 ± 0,000 B/op 0,00x (p = 0,000*) ClassDescFactories.ofDescriptor I 6 9,009 ± 0,035 1,431 ± 0,192 ns/op 6,30x (p = 0,000*) :gc.alloc.rate.norm 48,000 ± 0,000 0,000 ± 0,000 B/op 0,00x (p = 0,000*) MethodTypeDescFactories.ofDescriptor (Ljava/lang/Object;Ljava/lang/String;)I 6 182,050 ± 4,333 141,644 ± 2,685 ns/op 1,29x (p = 0,000*) :gc.alloc.rate.norm 360,001 ± 0,000 264,001 ± 0,000 B/op 0,73x (p = 0,000*) MethodTypeDescFactories.ofDescriptor ()V 6 17,169 ± 2,008 9,915 ± 0,018 ns/op 1,73x (p = 0,000*) :gc.alloc.rate.norm 120,000 ± 0,000 104,000 ± 0,000 B/op 0,87x (p = 0,000*) MethodTypeDescFactories.ofDescriptor ([IJLjava/lang/String;Z)Ljava/util/List; 6 270,372 ± 3,624 217,050 ± 3,170 ns/op 1,25x (p = 0,000*) :gc.alloc.rate.norm 520,002 ± 0,000 328,001 ± 0,000 B/op 0,63x (p = 0,000*) MethodTypeDescFactories.ofDescriptor ()[Ljava/lang/String; 6 35,036 ± 0,351 36,010 ± 3,882 ns/op 0,97x (p = 0,146 ) :gc.alloc.rate.norm 104,000 ± 0,000 104,000 ± 0,000 B/op 1,00x (p = 0,140 ) * = significant ------------- Commit messages: - Restructure micros - Update ConstantUtils.parseMethodDescriptor - Merge in ClassDescriptor micro Changes: https://git.openjdk.org/jdk/pull/18971/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18971&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8331187 Stats: 126 lines in 6 files changed: 88 ins; 9 del; 29 mod Patch: https://git.openjdk.org/jdk/pull/18971.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/18971/head:pull/18971 PR: https://git.openjdk.org/jdk/pull/18971