--- old/src/share/vm/opto/cfgnode.cpp Thu Oct 8 12:38:43 2009 +++ new/src/share/vm/opto/cfgnode.cpp Thu Oct 8 12:38:43 2009 @@ -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 --- old/src/share/vm/opto/ifnode.cpp Thu Oct 8 12:38:44 2009 +++ new/src/share/vm/opto/ifnode.cpp Thu Oct 8 12:38:43 2009 @@ -240,7 +240,6 @@ // 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. @@ -247,6 +246,7 @@ 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;