On Tue, 4 Jul 2023 22:03:58 GMT, John R Rose <jr...@openjdk.org> wrote:
>>> Hmm, I think that issue refers to code that have explicit non-Object >>> parameter types (like `X::equals(Object)boolean` in the issue's sample). >>> This method already have both arguments as `Object`, so I don't think >>> there's any type-specific inlining opportunities. >> >> If that's true, then perhaps those (and some other) locations got that idea >> wrong: >> * >> https://github.com/openjdk/jdk/blob/faf1b822d03b726413d77a2b247dfbbf4db7d57e/src/java.base/share/classes/java/util/Collections.java#L5712-L5719 >> * >> https://github.com/openjdk/jdk/blob/faf1b822d03b726413d77a2b247dfbbf4db7d57e/src/java.base/share/classes/java/util/AbstractMap.java#L577-L585 >> >> Maybe @rose00 could clarify that? >> >> FWIW, I also note that `HashMap` does not use similar private static >> methods; it uses `Objects.equals(Object, Object)` and `Objects.hashCode` >> overloads that take parameters. > > I wrote a little case study on `Objects::equals` that talks about how it > should optimize, when it does, why it doesn’t, and how (maybe) to fix that. > > https://cr.openjdk.org/~jrose/jvm/equals-profile.html > https://cr.openjdk.org/~jrose/jvm/equals-profile.md > > This is also attached to the JBS bug. > > The work on [JDK-8026251](https://bugs.openjdk.org/browse/JDK-8026251) with > the `TypeProfileLevel` switch bring us closer to correctly optimizing > `Objects::equals` in more cases. Sadly, JDK refactoring by itself will not > get all the way to where we want to go. The JVM’s profiling logic needs > tweaking. I'd suggest replacing the calls to `valuesMatch` with `Objects.equals` and remove the `valuesMatch` method as unnecessary. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/14752#discussion_r1253289975
