1 /*

     2  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #ifndef SHARE_VM_OPTO_REPLACEDNODES_HPP

    26 #define SHARE_VM_OPTO_REPLACEDNODES_HPP

    27 

    28 #include "opto/connode.hpp"

    29 

    30 // During parsing, when a node is "improved",

    31 // GraphKit::replace_in_map() is called to update the current map so

    32 // that the improved node is used from that point

    33 // on. GraphKit::replace_in_map() doesn't operate on the callers maps

    34 // and so some optimization opportunities may be lost. The

    35 // ReplacedNodes class addresses that problem.

    36 //

    37 // A ReplacedNodes object is a list of pair of nodes. Every

    38 // SafePointNode carries a ReplacedNodes object. Every time

    39 // GraphKit::replace_in_map() is called, a new pair of nodes is pushed

    40 // on the list of replaced nodes. When control flow paths merge, their

    41 // replaced nodes are also merged. When parsing exits a method to

    42 // return to a caller, the replaced nodes on the exit path are used to

    43 // update the caller's map.

    44 class ReplacedNodes VALUE_OBJ_CLASS_SPEC {

    45  private:

    46   class ReplacedNode VALUE_OBJ_CLASS_SPEC {

    47   private:

    48     Node* _initial;

    49     Node* _improved;

    50   public:

    51     ReplacedNode() : _initial(NULL), _improved(NULL) {}

    52     ReplacedNode(Node* initial, Node* improved) : _initial(initial), _improved(improved) {}

    53     Node* initial() const  { return _initial; }

    54     Node* improved() const { return _improved; }

    55 

    56     bool operator==(const ReplacedNode& other) {

    57       return _initial == other._initial && _improved == other._improved;

    58     }

    59   };

    60   GrowableArray<ReplacedNode>* _replaced_nodes;

    61 

    62   void allocate_if_necessary();

    63   bool has_node(const ReplacedNode& r) const;

    64   bool has_target_node(Node* n) const;

    65 

    66  public:

    67   ReplacedNodes()

    68     : _replaced_nodes(NULL) {}

    69 

    70   void clone();

    71   void record(Node* initial, Node* improved);

    72   void transfer_from(const ReplacedNodes& other, uint idx);

    73   void reset();

    74   void apply(Node* n);

    75   void merge_with(const ReplacedNodes& other);

    76   bool is_empty() const;

    77   void dump(outputStream *st) const;

    78   void apply(Compile* C, Node* ctl);

    79 };

    80 

    81 #endif // SHARE_VM_OPTO_REPLACEDNODES_HPP