'gvn' - HIR transformation that performs global elimination of expressions
While the Hash value numbering optimization works in a local scope the scope for this optimization is the whole method
header file: http://svn.apache.org/viewvc/harmony/enhanced/drlvm/trunk/vm/jitrino/src/optimizer/globalcodemotion.h
implementation file: http://svn.apache.org/viewvc/harmony/enhanced/drlvm/trunk/vm/jitrino/src/optimizer/globalcodemotion.cpp