review (S) for 6984979: OptimizeFill misses some cases with an odd memory graph

[Tom Rodriguez]

http://cr.openjdk.java.net/~never/6984979

6984979: OptimizeFill misses some cases with an odd memory graph
Reviewed-by:

The logic for the new OptimizeFill code misses a case where the Phi
usage is different than expected.  Sometimes during transformation of
the loop there are uses of the memory phi outside the loop.  This
appears to be a valid though slightly surprising structure but it
interferes with the fill matching logic that assumes the store in the
loop should be the only outgoing state.  The fix is to allow the phi
to be used outside the loop and replace it with the outgoing memory of
the call to the fill.  Tested with jbb, runthere and ctw.