review (S) for 6930398: fix for return address locals in OSR entries uses wrong test

[Vladimir Kozlov]

Looks good.

Vladimir

Tom Rodriguez wrote:
> http://cr.openjdk.java.net/~never/6930398
> 
> 6930398: fix for return address locals in OSR entries uses wrong test
> Reviewed-by:
> 
> The fix for 6915557 is attempting to handle locals containing return
> address specially but the test it's using is wrong.  C2's type system
> smears together T_ADDRESS with raw pointer types, so
> TypePtr::NULL_PTr->basic_type() == T_ADDRESS so the logic will trigger
> for locals which are provably null resulting in asserts later.  The
> correct fix is to test the ciType of the local which correctly
> distinguishes these cases.  Tested with failing tests from nightly.
> 
> src/share/vm/opto/parse1.cpp