dexgen/src/com/android/dexgen/dex/code/BlockAddresses.java

/*
 * 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.android.dexgen.dex.code;

import com.android.dexgen.rop.code.BasicBlock;
import com.android.dexgen.rop.code.BasicBlockList;
import com.android.dexgen.rop.code.Insn;
import com.android.dexgen.rop.code.RopMethod;
import com.android.dexgen.rop.code.SourcePosition;

/**
 * Container for the set of {@link CodeAddress} instances associated with
 * the blocks of a particular method. Each block has a corresponding
 * start address, end address, and last instruction address.
 */
public final class BlockAddresses {
    /** {@code non-null;} array containing addresses for the start of each basic
     * block (indexed by basic block label) */
    private final CodeAddress[] starts;

    /** {@code non-null;} array containing addresses for the final instruction
     * of each basic block (indexed by basic block label) */
    private final CodeAddress[] lasts;

    /** {@code non-null;} array containing addresses for the end (just past the
     * final instruction) of each basic block (indexed by basic block
     * label) */
    private final CodeAddress[] ends;

    /**
     * Constructs an instance.
     *
     * @param method {@code non-null;} the method to have block addresses for
     */
    public BlockAddresses(RopMethod method) {
        BasicBlockList blocks = method.getBlocks();
        int maxLabel = blocks.getMaxLabel();

        this.starts = new CodeAddress[maxLabel];
        this.lasts = new CodeAddress[maxLabel];
        this.ends = new CodeAddress[maxLabel];

        setupArrays(method);
    }

    /**
     * Gets the instance for the start of the given block.
     *
     * @param block {@code non-null;} the block in question
     * @return {@code non-null;} the appropriate instance
     */
    public CodeAddress getStart(BasicBlock block) {
        return starts[block.getLabel()];
    }

    /**
     * Gets the instance for the start of the block with the given label.
     *
     * @param label {@code non-null;} the label of the block in question
     * @return {@code non-null;} the appropriate instance
     */
    public CodeAddress getStart(int label) {
        return starts[label];
    }

    /**
     * Gets the instance for the final instruction of the given block.
     *
     * @param block {@code non-null;} the block in question
     * @return {@code non-null;} the appropriate instance
     */
    public CodeAddress getLast(BasicBlock block) {
        return lasts[block.getLabel()];
    }

    /**
     * Gets the instance for the final instruction of the block with
     * the given label.
     *
     * @param label {@code non-null;} the label of the block in question
     * @return {@code non-null;} the appropriate instance
     */
    public CodeAddress getLast(int label) {
        return lasts[label];
    }

    /**
     * Gets the instance for the end (address after the final instruction)
     * of the given block.
     *
     * @param block {@code non-null;} the block in question
     * @return {@code non-null;} the appropriate instance
     */
    public CodeAddress getEnd(BasicBlock block) {
        return ends[block.getLabel()];
    }

    /**
     * Gets the instance for the end (address after the final instruction)
     * of the block with the given label.
     *
     * @param label {@code non-null;} the label of the block in question
     * @return {@code non-null;} the appropriate instance
     */
    public CodeAddress getEnd(int label) {
        return ends[label];
    }

    /**
     * Sets up the address arrays.
     */
    private void setupArrays(RopMethod method) {
        BasicBlockList blocks = method.getBlocks();
        int sz = blocks.size();

        for (int i = 0; i < sz; i++) {
            BasicBlock one = blocks.get(i);
            int label = one.getLabel();
            Insn insn = one.getInsns().get(0);

            starts[label] = new CodeAddress(insn.getPosition());

            SourcePosition pos = one.getLastInsn().getPosition();

            lasts[label] = new CodeAddress(pos);
            ends[label] = new CodeAddress(pos);
        }
    }
}