content: /*
   * Copyright (C) 2008 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.taobao.android.dx.ssa;
  
  import com.taobao.android.dx.util.BitIntSet;
  import com.taobao.android.dx.util.IntSet;
  import com.taobao.android.dx.util.ListIntSet;
  
  
  /**
   * Makes int sets for various parts of the optimizer.
   */
  public final class SetFactory {
  
      /**
       * BitIntSet/ListIntSet threshold for dominance frontier sets. These
       * sets are kept per basic block until phi placement and tend to be,
       * like the CFG itself, very sparse at large sizes.
       *
       * A value of 3072 here is somewhere around 1.125mb of total bitset size.
       */
      private static final int DOMFRONT_SET_THRESHOLD_SIZE = 3072;
  
      /**
       * BitIntSet/ListIntSet threshold for interference graph sets. These
       * sets are kept per register until register allocation is done.
       *
       * A value of 3072 here is somewhere around 1.125mb of total bitset size.
       */
      private static final int INTERFERENCE_SET_THRESHOLD_SIZE = 3072;
  
      /**
       * BitIntSet/ListIntSet threshold for the live in/out sets kept by
       * {@link SsaBasicBlock}. These are sets of SSA registers kept per basic
       * block during register allocation.
       *
       * The total size of a bitset for this would be the count of blocks
       * times the size of registers. The threshold value here is merely
       * the register count, which is typically on the order of the block
       * count as well.
       */
      private static final int LIVENESS_SET_THRESHOLD_SIZE = 3072;
  
  
      /**
       * Make IntSet for the dominance-frontier sets.
       *
       * @param szBlocks {@code >=0;} count of basic blocks in method
       * @return {@code non-null;} appropriate set
       */
      /*package*/ static IntSet makeDomFrontSet(int szBlocks) {
          return szBlocks <= DOMFRONT_SET_THRESHOLD_SIZE
                  ? new BitIntSet(szBlocks)
                  : new ListIntSet();
      }
  
      /**
       * Make IntSet for the interference graph sets. Public because
       * InterferenceGraph is in another package.
       *
       * @param countRegs {@code >=0;} count of SSA registers used in method
       * @return {@code non-null;} appropriate set
       */
      public static IntSet makeInterferenceSet(int countRegs) {
          return countRegs <= INTERFERENCE_SET_THRESHOLD_SIZE
                  ? new BitIntSet(countRegs)
                  : new ListIntSet();
      }
  
      /**
       * Make IntSet for register live in/out sets.
       *
       * @param countRegs {@code >=0;} count of SSA registers used in method
       * @return {@code non-null;} appropriate set
       */
      /*package*/ static IntSet makeLivenessSet(int countRegs) {
          return countRegs <= LIVENESS_SET_THRESHOLD_SIZE
                  ? new BitIntSet(countRegs)
                  : new ListIntSet();
      }
  }
  