1 /*
   2  * Copyright (c) 1999, 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 #include "incls/_precompiled.incl"
  26 #include "incls/_ciConstantPoolCache.cpp.incl"
  27 
  28 // ciConstantPoolCache
  29 //
  30 // This class caches indexed constant pool lookups.
  31 
  32 // ------------------------------------------------------------------
  33 // ciConstantPoolCache::ciConstantPoolCache
  34 ciConstantPoolCache::ciConstantPoolCache(Arena* arena,
  35                                  int expected_size) {
  36   _elements =
  37     new (arena) GrowableArray<void*>(arena, expected_size, 0, 0);
  38   _keys = new (arena) GrowableArray<intptr_t>(arena, expected_size, 0, 0);
  39 }
  40 
  41 // ------------------------------------------------------------------
  42 // ciConstantPoolCache::get
  43 //
  44 // Get the entry at some index
  45 void* ciConstantPoolCache::get(int index) {
  46   ASSERT_IN_VM;
  47   int pos = find(index);
  48   if (pos >= _keys->length() ||
  49       _keys->at(pos) != index) {
  50     // This element is not present in the cache.
  51     return NULL;
  52   }
  53   return _elements->at(pos);
  54 }
  55 
  56 // ------------------------------------------------------------------
  57 // ciConstantPoolCache::find
  58 //
  59 // Use binary search to find the position of this index in the cache.
  60 // If there is no entry in the cache corresponding to this oop, return
  61 // the position at which the index would be inserted.
  62 int ciConstantPoolCache::find(int key) {
  63   int min = 0;
  64   int max = _keys->length()-1;
  65 
  66   while (max >= min) {
  67     int mid = (max + min) / 2;
  68     int value = _keys->at(mid);
  69     if (value < key) {
  70       min = mid + 1;
  71     } else if (value > key) {
  72       max = mid - 1;
  73     } else {
  74       return mid;
  75     }
  76   }
  77   return min;
  78 }
  79 
  80 // ------------------------------------------------------------------
  81 // ciConstantPoolCache::insert
  82 //
  83 // Insert a ciObject into the table at some index.
  84 void ciConstantPoolCache::insert(int index, void* elem) {
  85   int i;
  86   int pos = find(index);
  87   for (i = _keys->length()-1; i >= pos; i--) {
  88     _keys->at_put_grow(i+1, _keys->at(i));
  89     _elements->at_put_grow(i+1, _elements->at(i));
  90   }
  91   _keys->at_put_grow(pos, index);
  92   _elements->at_put_grow(pos, elem);
  93 }
  94 
  95 // ------------------------------------------------------------------
  96 // ciConstantPoolCache::print
  97 //
  98 // Print debugging information about the cache.
  99 void ciConstantPoolCache::print() {
 100   Unimplemented();
 101 }