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/*
 * 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.android.jack.dx.ssa;

import com.android.jack.dx.util.BitIntSet;
import com.android.jack.dx.util.IntSet;
import com.android.jack.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();
  }
}