--- old/src/share/vm/opto/split_if.cpp	2015-10-14 13:54:29.977508412 +0200
+++ new/src/share/vm/opto/split_if.cpp	2015-10-14 13:54:29.888510564 +0200
@@ -73,7 +73,8 @@
   if( n->is_Phi() ) return false; // Local PHIs are expected
 
   // Recursively split-up inputs
-  for (uint i = 1; i < n->req(); i++) {
+  uint first_input = n->Opcode() == Op_ShenandoahWBMemProj ? 0 : 1;
+  for (uint i = first_input; i < n->req(); i++) {
     if( split_up( n->in(i), blk1, blk2 ) ) {
       // Got split recursively and self went dead?
       if (n->outcnt() == 0)
@@ -216,6 +217,7 @@
   register_new_node(phi, blk1);
 
   // Remove cloned-up value from optimizer; use phi instead
+  split_mem_thru_phi(n, blk1, phi);
   _igvn.replace_node( n, phi );
 
   // (There used to be a self-recursive call to split_up() here,