On Mon, 20 May 2024 21:29:20 GMT, Vladimir Ivanov <vliva...@openjdk.org> wrote:
> JVM routinely installs loader constraints for unloaded signature classes when > method resolution takes place. MethodHandle resolution took a different route > and eagerly resolves signature classes instead (see > `java.lang.invoke.MemberName$Factory::resolve` and > `sun.invoke.util.VerifyAccess::isTypeVisible` for details). > > There's a micro-optimization which bypasses eager resolution for `java.*` > classes. The downside is that `java.*` signature classes can show up as > unloaded. It manifests as inlining failures during JIT-compilation and may > cause severe performance issues. > > Proposed fix removes the aforementioned special case logic during > `MethodHandle` resolution. > > In some cases it may slow down `MethodHandle` construction a bit (e.g., when > repeatedly constructing `DirectMethodHandle`s with lots of arguments), but > `MethodHandle` construction step is not performance critical. > > Testing: hs-tier1 - hs-tier4 src/java.base/share/classes/sun/invoke/util/VerifyAccess.java line 291: > 289: // guarantees that classes with names beginning "java." cannot > be aliased, > 290: // because class loaders cannot load them directly. However, it > is beneficial > 291: // for JIT-compilers to ensure all signature classes are loaded. Since we anticipate this method to perform side effects, can we rename all of these non-pure `isTypeVisible` to `seeType`/`accessType` to indicate this desired side effect? ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/19319#discussion_r1607426203
