RFR: 8304928: Optimize ClassDesc.resolveConstantDesc

[Mandy Chung]

On Thu, 30 Mar 2023 20:06:02 GMT, Chen Liang <liach at openjdk.org> wrote:

> This patch optimizes ClassDesc.resolveConstantDesc for array classes. Otherwise, the performance of reference class resolution remain unchanged. https://jmh.morethan.io/?gist=111095eecf7a735fe8c96e4b952b58c1 It also includes a benchmark for MethodTypeDesc resolution, which currently does not yet depend on class desc resolution but can be later optimized if it does switch.

src/java.base/share/classes/java/lang/constant/ConstantUtils.java line 130:

> 128: 
> 129:     static boolean isPrimitiveArray(String referenceTypeDescriptorString) {
> 130:         return referenceTypeDescriptorString.charAt(referenceTypeDescriptorString.length() - 1) != ';';

it also needs to check if it starts with `[`


Suggestion:

        return referenceTypeDescriptorString.startsWith("[") &&  
                  referenceTypeDescriptorString.charAt(referenceTypeDescriptorString.length() - 1) != ';';

test/micro/org/openjdk/bench/java/lang/constant/MethodTypeDescResolve.java line 53:

> 51: @Fork(1)
> 52: @State(Scope.Benchmark)
> 53: public class MethodTypeDescResolve {

Better to separate this benchmark from this PR.   Probably the optimization done in [PR 10991](https://github.com/openjdk/jdk/pull/10991) should be a separate patch from JDK-8294961 and this benchmark could be included there.

test/micro/org/openjdk/bench/java/lang/constant/ReferenceClassDescResolve.java line 120:

> 118:                 return resolveReference(lookup, cd);
> 119:             }
> 120:         },

I think this benchmark doesn't need this case as that's the implementation of `resolveConstantDesc`.   Was it there when you developed this fix?   Same for MethodTypeDesc benchmark.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13252#discussion_r1153874210
PR Review Comment: https://git.openjdk.org/jdk/pull/13252#discussion_r1153877556
PR Review Comment: https://git.openjdk.org/jdk/pull/13252#discussion_r1153876110