1 /*
   2  * Copyright (c) 2009, 2013, 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_STRINGOPTS_HPP
  26 #define SHARE_VM_OPTO_STRINGOPTS_HPP
  27 
  28 #include "opto/node.hpp"
  29 #include "opto/phaseX.hpp"
  30 
  31 class StringConcat;
  32 
  33 class PhaseStringOpts : public Phase {
  34   friend class StringConcat;
  35 
  36  private:
  37   PhaseGVN* _gvn;
  38 
  39   // List of dead nodes to clean up aggressively at the end
  40   Unique_Node_List dead_worklist;
  41 
  42   // Memory slices needed for code gen
  43   int char_adr_idx;
  44 
  45   // Integer.sizeTable - used for int to String conversion
  46   ciField* size_table_field;
  47 
  48   // A set for use by various stages
  49   VectorSet _visited;
  50 
  51   // Stack for doing DFS in memory flow analysis
  52   Node_Stack _path;
  53 
  54   // Collect a list of all SB.toString calls
  55   Node_List collect_toString_calls();
  56 
  57   // Examine the use of the SB alloc to see if it can be replace with
  58   // a single string construction.
  59   StringConcat* build_candidate(CallStaticJavaNode* call);
  60 
  61   // Replace all the SB calls in concat with an optimization String allocation
  62   void replace_string_concat(StringConcat* concat);
  63 
  64   // Load the value of a static field, performing any constant folding.
  65   Node* fetch_static_field(GraphKit& kit, ciField* field);
  66 
  67   // Compute the number of characters required to represent the int value
  68   Node* int_stringSize(GraphKit& kit, Node* value);
  69 
  70   // Copy the characters representing value into char_array starting at start
  71   void int_getChars(GraphKit& kit, Node* value, Node* char_array, Node* start, Node* end);
  72 
  73   // Copy of the contents of the String str into char_array starting at index start.
  74   Node* copy_string(GraphKit& kit, Node* str, Node* char_array, Node* start);
  75 
  76   // Clean up any leftover nodes
  77   void record_dead_node(Node* node);
  78   void remove_dead_nodes();
  79 
  80   PhaseGVN* gvn() { return _gvn; }
  81 
  82   enum {
  83     // max length of constant string copy unrolling in copy_string
  84     unroll_string_copy_length = 6,
  85     memory_flow_iteration_limit = 99
  86   };
  87 
  88  public:
  89   PhaseStringOpts(PhaseGVN* gvn, Unique_Node_List* worklist);
  90 };
  91 
  92 #endif // SHARE_VM_OPTO_STRINGOPTS_HPP