src/share/vm/opto/lcm.cpp

rev 9822 : 8146612: C2: Precedence edges specification violated
Reviewed-by: kvn

*** 1,7 ****
  /*
!  * Copyright (c) 1998, 2015, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
--- 1,7 ----
  /*
!  * Copyright (c) 1998, 2016, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
*** 947,956 ****
--- 947,963 ----
          // and then removes the last edge. If the specified edge > number of
          // edges the last edge will be moved outside of the input edges array
          // and the edge will be lost. This is why this code should be
          // executed only when Precedent (== TypeFunc::Parms) edge is present.
          Node *x = n->in(TypeFunc::Parms);
+         if (x != NULL && get_block_for_node(x) == block && n->find_prec_edge(x) != -1) {
+           // Old edge to node within same block will get removed, but no precedence
+           // edge will get added because it already exists. Update ready count.
+           int cnt = ready_cnt.at(n->_idx);
+           assert(cnt > 1, "MemBar node %d must not get ready here", n->_idx);
+           ready_cnt.at_put(n->_idx, cnt-1);
+         }
          n->del_req(TypeFunc::Parms);
          n->add_prec(x);
        }
      }
    }