+# -O3 helps unroll some loops (especially in copy() with a constant argument).
+# -fno-strict-aliasing is a hack because we often mix StgPtr and StgClosure pointers
+# to the same object, and gcc will assume these don't alias. eg. it happens in
+# copy() with gcc 3.4.3, the upd_evacee() assigments get moved before the object copy.