The used dominator intersection algorithm assumes a postorder
numbering of the CFG. The reversal of our natural numbering is
quite similar to postorder, but not the same.
In the future we should precompute both preorder/postorder
numberings and orderings, as these are useful in many places.
We must not split at live range boundaries for SSA constructions,
otherwise an OP_DATA instruction may be separated into new block
and not picked up during renaming.
It's also unnecessary for this use case and only blows up the CFG.
This opcodes inserts a local CV into the closure static variable
table. This replaces the previous mechanism of having static
variables marked as LEXICAL, which perform a symtable lookup
during copying.
This means a) functions which contain closures no longer have to
rebuild their symtable (better performance) and b) we can now track
used variables in SSA.
The DECLARE_(ANON_)INHERITED_CLASS(_DELAYED) opcodes were
referencing the parent ce VAR through extended_value. This is
hacky and we can't track the def-use chain in SSA.
To avoid this, the layout of declaration opcodes is changed
as follows: op1 points to the lcname and rtd_key literals, in
that order. (For anon/lambda declarations only one of lcname or
rtd_key is present.) This frees up op2, which is now used to
reference the parent ce VAR in inheriting declarations. The
jmp offset for anon class declarations is moved frop op2 to
extended_value.
The changes were applied both to class and function declarations
to keep everything symmetric.
