Request for review (S): C2 should recognize "obj.getClass() == A.class" code pattern

[Krystal Mok]

Hi all,

I've made a few improvements over the last patch, per John's suggestion,
posted here: https://gist.github.com/2481025#file_class_eq_ver_2.patch
Could I get some reviews for the new version, please?

The new patch normalizes "x.getClass() == y.getClass()" in addition to the
old version.
It also sharpens the type of obj to Foo:NotNull:exact in the IfTrue branch
of "if (x._klass == Foo.klass)".

Tested with the experiment that still had redundant checks with the old
patch (https://gist.github.com/2485414), and now the redundant check is
gone. Thanks a lot, John!

I'm re-running SPECjvm2008 to see if it runs all right.

There are still two doubts, though:
1. In Parse::adjust_map_after_if(), should I delay the transform of
CheckCastPP node, or should I follow the example in
GraphKit::type_check_receiver()?
2. The receiver of getClass() is casted to not_null with a CastPP when
parsing the invokevirtual instruction. Should I sharpen the uncast obj, or
is it okay to just sharpen the CastPP as I'm doing now?

Regards,
Kris
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