This is agnostic now that it isnt using a descriptor.

This trivial sorting helps speed up bad cases (like in CTS significantly).

These are required ...

Without this stitch_blocks complains about ending in a jump with a
non-empty block after the inserted body.

Since we do no repacking yet, just use invocation.

cleanup.

And lower vtn generated constant loads early, so that the later
large_constant pass can use the normal offset based scheme.