# HG changeset patch
# User neliasso
# Date 1488805732 -3600
#      Mon Mar 06 14:08:52 2017 +0100
# Node ID de086005215433a4c5301d649454f2ce0ba33e14
# Parent  18607b3adc857731753af321fc02ed393c9473c8
8164954: split_if creates empty phi and region nodes
Summary: Don't split if all edges will be moved to new phi
Reviewed-by:

diff --git a/src/share/vm/opto/ifnode.cpp b/src/share/vm/opto/ifnode.cpp
--- a/src/share/vm/opto/ifnode.cpp
+++ b/src/share/vm/opto/ifnode.cpp
@@ -249,6 +249,13 @@
       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