Instrument invokedynamic-based Groovy bytecode for configuration cache input detection

[mlopatkin]

The configuration cache relies on instrumenting the user-provided bytecode to detect implicit build inputs like system properties or environment variables. By its nature, the instrumentation is tied to the calling conventions of the language used to produce the bytecode. The dynamic Groovy has two non-trivial conventions. One is "old" and is based on Groovy's own "CallSite" class; it is used by default in Groovy before 4. This convention is currently supported. Another one is new and employs Java 7's new invokedynamic instruction. It is the only option for Groovy 4 but can be enabled in earlier versions too. The bytecode produced is completely different, so the configuration cache instrumentation has to be updated to support both conventions.

Gradle is using Groovy 3 with older conventions (at the time of writing, around 7.5) to compile build scripts and plugins, however nothing prevents users from depending on indified libraries, so it is necessary to instrument these properly even now. The invokedynamic instrumentation is also essential to the migration to Groovy 4 within Gradle build scripts.

Note that this only applies to the code used in buildscripts and Gradle plugins and has nothing to do with compiling Groovy code per se.