src/share/vm/opto/ifnode.cpp

rev 12674 : 8164954: split_if creates empty phi and region nodes
Summary: Don't split if all edges will be moved to new phi
Reviewed-by:

*** 247,256 ****
--- 247,263 ----
      if (proj != NULL) {
        nb_predicate_proj++;
        predicate_proj = proj;
      }
    }
+ 
+   // If all the defs of the phi are the same constant, we already have the desired end state.
+   // Skip the split that would create empty phi and region nodes.
+   if((r->req() - req_c) == 1) {
+     return NULL;
+   }
+ 
    if (nb_predicate_proj > 1) {
      // Can happen in case of loop unswitching and when the loop is
      // optimized out: it's not a loop anymore so we don't care about
      // predicates.
      assert(!r->is_Loop(), "this must not be a loop anymore");