content: /*
   * Copyright (C) 2007 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.rop.code;
  
  import com.taobao.android.dx.rop.type.TypeBearer;
  import com.taobao.android.dx.util.MutabilityControl;
  import java.util.HashMap;
  
  /**
   * Container for local variable information for a particular {@link
   * RopMethod}.
   */
  public final class LocalVariableInfo
          extends MutabilityControl {
      /** {@code >= 0;} the register count for the method */
      private final int regCount;
  
      /**
       * {@code non-null;} {@link RegisterSpecSet} to use when indicating a block
       * that has no locals; it is empty and immutable but has an appropriate
       * max size for the method
       */
      private final RegisterSpecSet emptySet;
  
      /**
       * {@code non-null;} array consisting of register sets representing the
       * sets of variables already assigned upon entry to each block,
       * where array indices correspond to block labels
       */
      private final RegisterSpecSet[] blockStarts;
  
      /** {@code non-null;} map from instructions to the variable each assigns */
      private final HashMap<Insn, RegisterSpec> insnAssignments;
  
      /**
       * Constructs an instance.
       *
       * @param method {@code non-null;} the method being represented by this instance
       */
      public LocalVariableInfo(RopMethod method) {
          if (method == null) {
              throw new NullPointerException("method == null");
          }
  
          BasicBlockList blocks = method.getBlocks();
          int maxLabel = blocks.getMaxLabel();
  
          this.regCount = blocks.getRegCount();
          this.emptySet = new RegisterSpecSet(regCount);
          this.blockStarts = new RegisterSpecSet[maxLabel];
          this.insnAssignments =
              new HashMap<Insn, RegisterSpec>(blocks.getInstructionCount());
  
          emptySet.setImmutable();
      }
  
      /**
       * Sets the register set associated with the start of the block with
       * the given label.
       *
       * @param label {@code >= 0;} the block label
       * @param specs {@code non-null;} the register set to associate with the block
       */
      public void setStarts(int label, RegisterSpecSet specs) {
          throwIfImmutable();
  
          if (specs == null) {
              throw new NullPointerException("specs == null");
          }
  
          try {
              blockStarts[label] = specs;
          } catch (ArrayIndexOutOfBoundsException ex) {
              // Translate the exception.
              throw new IllegalArgumentException("bogus label");
          }
      }
  
      /**
       * Merges the given register set into the set for the block with the
       * given label. If there was not already an associated set, then this
       * is the same as calling {@link #setStarts}. Otherwise, this will
       * merge the two sets and call {@link #setStarts} on the result of the
       * merge.
       *
       * @param label {@code >= 0;} the block label
       * @param specs {@code non-null;} the register set to merge into the start set
       * for the block
       * @return {@code true} if the merge resulted in an actual change
       * to the associated set (including storing one for the first time) or
       * {@code false} if there was no change
       */
      public boolean mergeStarts(int label, RegisterSpecSet specs) {
          RegisterSpecSet start = getStarts0(label);
          boolean changed = false;
  
          if (start == null) {
              setStarts(label, specs);
              return true;
          }
  
          RegisterSpecSet newStart = start.mutableCopy();
          if (start.size() != 0) {
              newStart.intersect(specs, true);
          } else {
              newStart = specs.mutableCopy();
          }
  
          if (start.equals(newStart)) {
              return false;
          }
  
          newStart.setImmutable();
          setStarts(label, newStart);
  
          return true;
      }
  
      /**
       * Gets the register set associated with the start of the block
       * with the given label. This returns an empty set with the appropriate
       * max size if no set was associated with the block in question.
       *
       * @param label {@code >= 0;} the block label
       * @return {@code non-null;} the associated register set
       */
      public RegisterSpecSet getStarts(int label) {
          RegisterSpecSet result = getStarts0(label);
  
          return (result != null) ? result : emptySet;
      }
  
      /**
       * Gets the register set associated with the start of the given
       * block. This is just convenient shorthand for
       * {@code getStarts(block.getLabel())}.
       *
       * @param block {@code non-null;} the block in question
       * @return {@code non-null;} the associated register set
       */
      public RegisterSpecSet getStarts(BasicBlock block) {
          return getStarts(block.getLabel());
      }
  
      /**
       * Gets a mutable copy of the register set associated with the
       * start of the block with the given label. This returns a
       * newly-allocated empty {@link RegisterSpecSet} of appropriate
       * max size if there is not yet any set associated with the block.
       *
       * @param label {@code >= 0;} the block label
       * @return {@code non-null;} the associated register set
       */
      public RegisterSpecSet mutableCopyOfStarts(int label) {
          RegisterSpecSet result = getStarts0(label);
  
          return (result != null) ?
              result.mutableCopy() : new RegisterSpecSet(regCount);
      }
  
      /**
       * Adds an assignment association for the given instruction and
       * register spec. This throws an exception if the instruction
       * doesn't actually perform a named variable assignment.
       *
       * <b>Note:</b> Although the instruction contains its own spec for
       * the result, it still needs to be passed in explicitly to this
       * method, since the spec that is stored here should always have a
       * simple type and the one in the instruction can be an arbitrary
       * {@link TypeBearer} (such as a constant value).
       *
       * @param insn {@code non-null;} the instruction in question
       * @param spec {@code non-null;} the associated register spec
       */
      public void addAssignment(Insn insn, RegisterSpec spec) {
          throwIfImmutable();
  
          if (insn == null) {
              throw new NullPointerException("insn == null");
          }
  
          if (spec == null) {
              throw new NullPointerException("spec == null");
          }
  
          insnAssignments.put(insn, spec);
      }
  
      /**
       * Gets the named register being assigned by the given instruction, if
       * previously stored in this instance.
       *
       * @param insn {@code non-null;} instruction in question
       * @return {@code null-ok;} the named register being assigned, if any
       */
      public RegisterSpec getAssignment(Insn insn) {
          return insnAssignments.get(insn);
      }
  
      /**
       * Gets the number of assignments recorded by this instance.
       *
       * @return {@code >= 0;} the number of assignments
       */
      public int getAssignmentCount() {
          return insnAssignments.size();
      }
  
      public void debugDump() {
          for (int label = 0 ; label < blockStarts.length; label++) {
              if (blockStarts[label] == null) {
                  continue;
              }
  
              if (blockStarts[label] == emptySet) {
                  System.out.printf("%04x: empty set\n", label);
              } else {
                  System.out.printf("%04x: %s\n", label, blockStarts[label]);
              }
          }
      }
  
      /**
       * Helper method, to get the starts for a label, throwing the
       * right exception for range problems.
       *
       * @param label {@code >= 0;} the block label
       * @return {@code null-ok;} associated register set or {@code null} if there
       * is none
       */
      private RegisterSpecSet getStarts0(int label) {
          try {
              return blockStarts[label];
          } catch (ArrayIndexOutOfBoundsException ex) {
              // Translate the exception.
              throw new IllegalArgumentException("bogus label");
          }
      }
  }
  