src/share/vm/opto/node.hpp

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

*** 1,7 ****
  /*
!  * Copyright (c) 1997, 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) 1997, 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.
*** 421,430 ****
--- 421,440 ----
      if (n != NULL)      n->add_out((Node *)this);
      Compile::current()->record_modified_node(this);
    }
    // Find first occurrence of n among my edges:
    int find_edge(Node* n);
+   int find_prec_edge(Node* n) {
+     for (uint i = req(); i < len(); i++) {
+       if (_in[i] == n) return i;
+       if (_in[i] == NULL) {
+         DEBUG_ONLY( while ((++i) < len()) assert(_in[i] == NULL, "Gap in prec edges!"); )
+         break;
+       }
+     }
+     return -1;
+   }
    int replace_edge(Node* old, Node* neww);
    int replace_edges_in_range(Node* old, Node* neww, int start, int end);
    // NULL out all inputs to eliminate incoming Def-Use edges.
    // Return the number of edges between 'n' and 'this'
    int  disconnect_inputs(Node *n, Compile *c);
*** 474,483 ****
--- 484,506 ----
      // Record that a change happened here.
      #if OPTO_DU_ITERATOR_ASSERT
      debug_only(_last_del = n; ++_del_tick);
      #endif
    }
+   // Close gap after removing edge.
+   void close_prec_gap_at(uint gap) {
+     assert(_cnt <= gap && gap < _max, "no valid prec edge");
+     uint i = gap;
+     Node *last = NULL;
+     for (; i < _max-1; ++i) {
+       Node *next = _in[i+1];
+       if (next == NULL) break;
+       last = next;
+     }
+     _in[gap] = last; // Move last slot to empty one.
+     _in[i] = NULL;   // NULL out last slot.
+   }
  
  public:
    // Globally replace this node by a given new node, updating all uses.
    void replace_by(Node* new_node);
    // Globally replace this node by a given new node, updating all uses
*** 490,506 ****
    // Find the one non-null required input.  RegionNode only
    Node *nonnull_req() const;
    // Add or remove precedence edges
    void add_prec( Node *n );
    void rm_prec( uint i );
    void set_prec( uint i, Node *n ) {
!     assert( is_not_dead(n), "can not use dead node");
!     assert( i >= _cnt, "not a precedence edge");
      if (_in[i] != NULL) _in[i]->del_out((Node *)this);
      _in[i] = n;
      if (n != NULL) n->add_out((Node *)this);
    }
    // Set this node's index, used by cisc_version to replace current node
    void set_idx(uint new_idx) {
      const node_idx_t* ref = &_idx;
      *(node_idx_t*)ref = new_idx;
    }
--- 513,539 ----
    // Find the one non-null required input.  RegionNode only
    Node *nonnull_req() const;
    // Add or remove precedence edges
    void add_prec( Node *n );
    void rm_prec( uint i );
+ 
+   // Note: prec(i) will not necessarily point to n if edge already exists.
    void set_prec( uint i, Node *n ) {
!     assert(i < _max, "oob: i=%d, _max=%d", i, _max);
!     assert(is_not_dead(n), "can not use dead node");
!     assert(i >= _cnt, "not a precedence edge");
!     // Avoid spec violation: duplicated prec edge.
!     if (_in[i] == n) return;
!     if (n == NULL || find_prec_edge(n) != -1) {
!       rm_prec(i);
!       return;
!     }
      if (_in[i] != NULL) _in[i]->del_out((Node *)this);
      _in[i] = n;
      if (n != NULL) n->add_out((Node *)this);
    }
+ 
    // Set this node's index, used by cisc_version to replace current node
    void set_idx(uint new_idx) {
      const node_idx_t* ref = &_idx;
      *(node_idx_t*)ref = new_idx;
    }