RFR: 8295102: Always load @lambda-form-invoker lines from default classlist

Ioi Lam iklam at openjdk.org
Tue Oct 11 02:20:17 UTC 2022


The `@lambda-form-invoker` lines in the default classlist (`$JAVA_HOME/lib/classlist`) control what lambda-form invoker methods are added to these classes that are generated during a CDS dump ([see here](https://github.com/iklam/jdk/blob/5aa997b001367141a6a2d2e69649d41b46199ab4/src/hotspot/share/cds/lambdaFormInvokers.cpp#L230)):

- `java.lang.invoke.Invokers$Holder`
- `java.lang.invoke.DirectMethodHandle$Holder`
- `java.lang.invoke.DelegatingMethodHandle$Holder`
- `java.lang.invoke.LambdaForm$Holder`

The list of these invoker methods is generated as part of the [JDK build process](https://github.com/iklam/jdk/blob/1996f649a3a30b7ac4b547a762417f807f5fa414/make/GenerateLinkOptData.gmk#L64). They are used for invoking MethodHandles of commonly-used types, so that we can avoid generating custom LambdaForm classes.

When a CDS archive is created with a non-default classlist, (e.g., `-XX:SharedClassListFile=foo.classlist`), such a classlist may not contain all the `@lambda-form-invoker` lines as in the default classlist. As a result, at runtime, more custom LambdaForm classes may be generated than necessary.

The solution is to always load the `@lambda-form-invoker` lines from the default classlist, to make sure the CDS image has all the commonly-used invoker methods.

-------------

Commit messages:
 - fixed build
 - 8295102: Always load @lambda-form-invoker lines from default classlist

Changes: https://git.openjdk.org/jdk/pull/10639/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10639&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8295102
  Stats: 263 lines in 7 files changed: 224 ins; 34 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/10639.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10639/head:pull/10639

PR: https://git.openjdk.org/jdk/pull/10639


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