Add "call data" wrapper IMEMO object so inline cache can be updated
Currently the compactor will invalidate all inline caches. I would like to update references in inline caches so we don't have to invalidate. Most inline caches are reachable from instruction sequences, but one cache is not:
This static variable can't be reached from the GC. I'd like to introduce a new IMEMO object that wraps this cache, then the GC can reach the cache and update the value.
I've attached a patch that implements the new IMEMO object, and also removes the restriction on GCC so that all compilers get the cache hit.
Does this seem OK shyouhei, ko1?