This option has no effect on the production code. But in a custom
scenario of a local bootstrap, where the compiler is replaced with the
one where JVM IR backend is enabled by default, this option allows to
switch back to the old backend.
All of these arguments (except the one for compiling experimental
coroutines) are supposed to go away as soon as we fix related problems
in the JVM IR backend.
Dmitriy Novozhilov