# HG changeset patch
# User kvn
# Date 1255498351 25200
# Node ID ce590301ae2adcfbdc0a5b7b34229c20470db926
# Parent  5f29a958a545e7335038aa3278d24dfcf7b860dd
6889300: assert(i != k || is_new || i->outcnt()  > 0, "don't return dead nodes")
Summary: PhiNode::Ideal() should return TOP for Phi node with no users.
Reviewed-by: never, jrose

diff -r 5f29a958a545 -r ce590301ae2a src/share/vm/opto/cfgnode.cpp
--- a/src/share/vm/opto/cfgnode.cpp	Tue Oct 13 20:54:13 2009 -0700
+++ b/src/share/vm/opto/cfgnode.cpp	Tue Oct 13 22:32:31 2009 -0700
@@ -1531,6 +1531,8 @@
     return NULL;                // No change
 
   Node *top = phase->C->top();
+  bool new_phi = (outcnt() == 0); // transforming new Phi
+  assert(!can_reshape || !new_phi, "for igvn new phi should be hooked");
 
   // The are 2 situations when only one valid phi's input is left
   // (in addition to Region input).
@@ -1550,6 +1552,12 @@
     }
   }
 
+  if (can_reshape && outcnt() == 0) {
+    // set_req() above may kill outputs if Phi is referenced
+    // only by itself on the dead (top) control path.
+    return top;
+  }
+
   Node* uin = unique_input(phase);
   if (uin == top) {             // Simplest case: no alive inputs.
     if (can_reshape)            // IGVN transformation
@@ -1684,8 +1692,7 @@
             // Equivalent code is in MemNode::Ideal_common
             Node *m  = phase->transform(n);
             if (outcnt() == 0) {  // Above transform() may kill us!
-              progress = phase->C->top();
-              break;
+              return top;
             }
             // If transformed to a MergeMem, get the desired slice
             // Otherwise the returned node represents memory for every slice
diff -r 5f29a958a545 -r ce590301ae2a src/share/vm/opto/ifnode.cpp
--- a/src/share/vm/opto/ifnode.cpp	Tue Oct 13 20:54:13 2009 -0700
+++ b/src/share/vm/opto/ifnode.cpp	Tue Oct 13 22:32:31 2009 -0700
@@ -240,13 +240,13 @@
   // as a single huge transform.
   igvn->register_new_node_with_optimizer( region_c );
   igvn->register_new_node_with_optimizer( region_x );
-  phi_x = phase->transform( phi_x );
   // Prevent the untimely death of phi_x.  Currently he has no uses.  He is
   // about to get one.  If this only use goes away, then phi_x will look dead.
   // However, he will be picking up some more uses down below.
   Node *hook = new (igvn->C, 4) Node(4);
   hook->init_req(0, phi_x);
   hook->init_req(1, phi_c);
+  phi_x = phase->transform( phi_x );
 
   // Make the compare
   Node *cmp_c = phase->makecon(t);
@@ -322,6 +322,7 @@
         phi_s = PhiNode::make_blank(region_s,phi);
         phi_s->init_req( 1, phi_c );
         phi_s->init_req( 2, phi_x );
+        hook->add_req(phi_s);
         phi_s = phase->transform(phi_s);
       }
       proj_path_data = phi_s;
@@ -333,6 +334,7 @@
         phi_f = PhiNode::make_blank(region_f,phi);
         phi_f->init_req( 1, phi_c );
         phi_f->init_req( 2, phi_x );
+        hook->add_req(phi_f);
         phi_f = phase->transform(phi_f);
       }
       proj_path_data = phi_f;