On Fri, 19 Apr 2024 13:23:53 GMT, Claes Redestad <redes...@openjdk.org> wrote:
> We can reduce overhead of first use of a switch bootstrap by moving
> `typePairToName` into `TypePairs` and by explicitly overriding `hashCode` and
> `equals`. The first change avoids loading and initializing the `TypePairs`
> class in actual cases, the second remove some excess code generation from
> happening on first use.
src/java.base/share/classes/java/lang/runtime/SwitchBootstraps.java line 685:
> 683: record TypePairs(Class<?> from, Class<?> to) {
> 684:
> 685: private static final Map<TypePairs, String> typePairToName =
> initialize();
If `TypePairs.typePairToName` is never modified after initialisation, then it
should probably be made immutable:
Suggestion:
private static final Map<TypePairs, String> typePairToName =
Map.copyOf(initialize());
src/java.base/share/classes/java/lang/runtime/SwitchBootstraps.java line 699:
> 697:
> 698: public boolean equals(Object other) {
> 699: if (other instanceof TypePairs otherPair) {
To match the behaviour of the `equals` method body generated by
`java.lang.runtime.ObjectMethods::bootstrap`, this should include a fast
path check for `this == other`:
Suggestion:
if (this == other) {
return true;
}
if (other instanceof TypePairs otherPair) {
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/18865#discussion_r1573061423
PR Review Comment: https://git.openjdk.org/jdk/pull/18865#discussion_r1573059594
