diff -r 1faa170a7597 -r 77222140e9ad hotspot/src/share/vm/opto/c2_globals.hpp
--- a/hotspot/src/share/vm/opto/c2_globals.hpp	Fri Oct 21 00:58:30 2011 -0700
+++ b/hotspot/src/share/vm/opto/c2_globals.hpp	Sun Oct 23 20:23:14 2011 -0700
@@ -201,7 +201,7 @@
   diagnostic(bool, UnrollLimitCheck, true,                                  \
           "Additional overflow checks during loop unroll")                  \
                                                                             \
-  product(bool, OptimizeFill, false,                                        \
+  product(bool, OptimizeFill, true,                                         \
           "convert fill/copy loops into intrinsic")                         \
                                                                             \
   develop(bool, TraceOptimizeFill, false,                                   \
@@ -459,7 +459,7 @@
   product(bool, UseOptoBiasInlining, true,                                  \
           "Generate biased locking code in C2 ideal graph")                 \
                                                                             \
-  product(bool, OptimizeStringConcat, false,                                \
+  product(bool, OptimizeStringConcat, true,                                 \
           "Optimize the construction of Strings by StringBuilder")          \
                                                                             \
   notproduct(bool, PrintOptimizeStringConcat, false,                        \