Re: Eager vs Lazy resolution of classes

[Andrew Haley <aph at redhat dot com>]

This issue has a bearing on split verification.

We need to be able to verify a class without doing full class
initialization of the classes it refers to.  The verifier in the
runtime library does this (see ref_intersection::compatible()).  This is
OK.

However, _Jv_IsAssignableFrom() uses klass->ancestors, and this field
is initialized until _Jv_PrepareConstantTimeTables().

For split verification to work, we need a way to test assignability
without fully preparing the target classes.  This should be easy
enough: we only need to load ancestors and superinterfaces to
determine assignability.
_Jv_BytecodeVerifier::is_assignable_from_slow() looks like it will do
the trick, but it's buried inside the verifier.

Tom, can you see a good way to expose this useful functionality?  I
think something like a version of _Jv_IsAssignableFrom() that checks
to see if we can do a check the fast way but falls back to the slow
way would be fine.

Andrew.