On Thu, 29 Aug 2024 05:34:37 GMT, Shaojin Wen <s...@openjdk.org> wrote:
> TypeKind.from(Class) is a frequently called method, which provides a
> specialized method to improve performance.
>
> The following Compiler log shows that the call stack level is reduced and two
> reference accesses (descriptorString() -> String.value) are reduced, which
> can reduce the performance degradation caused by cache misses.
>
> * baseline
>
> @ 48 java.lang.classfile.TypeKind::from (25 bytes) inline
> @ 1 java.lang.Class::isPrimitive (0 bytes) intrinsic
> @ 10 java.lang.Class::descriptorString (170 bytes) failed to inline:
> callee is too large
> @ 15 java.lang.classfile.TypeKind::fromDescriptor (232 bytes) failed to
> inline: callee is too large
>
>
> * current
>
> @ 52 java.lang.classfile.TypeKind::from (103 bytes) failed to inline:
> callee is too large
src/java.base/share/classes/java/lang/classfile/TypeKind.java line 35:
> 33: import jdk.internal.vm.annotation.Stable;
> 34:
> 35: import static java.lang.constant.ConstantDescs.*;
Maybe import the primitive class descriptors from `PrimitiveClassDescImpl` in
order to avoid unnecessary initialisation of unrelated `ConstantDesc`s:
Suggestion:
import static jdk.internal.constant.PrimitiveClassDescImpl.*;
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;
src/java.base/share/classes/java/lang/classfile/TypeKind.java line 258:
> 256: if (desc == CD_double ) return DOUBLE;
> 257: if (desc == CD_void ) return VOID;
> 258: else return REFERENCE;
This can short‑circuit when `desc` is not a `PrimitiveClassDescImpl`:
Suggestion:
if (desc instanceof PrimitiveClassDescImpl) {
if (desc == CD_boolean) return BOOLEAN;
if (desc == CD_byte ) return BYTE;
if (desc == CD_char ) return CHAR;
if (desc == CD_int ) return INT;
if (desc == CD_long ) return LONG;
if (desc == CD_short ) return SHORT;
if (desc == CD_float ) return FLOAT;
if (desc == CD_double ) return DOUBLE;
if (desc == CD_void ) return VOID;
}
return REFERENCE;
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/20762#discussion_r1739629316
PR Review Comment: https://git.openjdk.org/jdk/pull/20762#discussion_r1737538239
PR Review Comment: https://git.openjdk.org/jdk/pull/20762#discussion_r1739630850
