On Fri, 30 Aug 2024 01:21:14 GMT, Shaojin Wen <s...@openjdk.org> wrote:
>> src/java.base/share/classes/java/lang/classfile/TypeKind.java line 176:
>>
>>> 174: if (cl == double.class ) return DoubleType;
>>> 175: if (cl == void.class ) return VoidType;
>>> 176: else return ReferenceType;
>>
>> This can call `Class::isPrimitive()` to perform an implicit null check and
>> short‑circuit for reference types:
>> Suggestion:
>>
>> if (cl.isPrimitive()) { // implicit null check
>> if (cl == boolean.class) return BooleanType;
>> if (cl == byte.class ) return ByteType;
>> if (cl == char.class ) return CharType;
>> if (cl == int.class ) return IntType;
>> if (cl == long.class ) return LongType;
>> if (cl == short.class ) return ShortType;
>> if (cl == float.class ) return FloatType;
>> if (cl == double.class ) return DoubleType;
>> if (cl == void.class ) return VoidType;
>> }
>> return ReferenceType;
>
> https://github.com/openjdk/jdk/pull/20759#issuecomment-2317655533
> Refer to @cl4es 's comment, isPrimitive is a native method and will be slow
I said it can be relatively slow in the interpreter. This was an invitation to
measure carefully (with and without `-Xint`), not an authoritative statement
that we should avoid `Class::isPrimitive` everywhere. I think you need to
provide supporting evidence that these kinds of optimizations are worthwhile.
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PR Review Comment: https://git.openjdk.org/jdk/pull/20762#discussion_r1738583597
