| /* |
| * 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.dx.rop.code; |
| |
| import com.android.dx.util.Bits; |
| import com.android.dx.util.Hex; |
| import com.android.dx.util.IntList; |
| |
| /** |
| * All of the parts that make up a method at the rop layer. |
| */ |
| public final class RopMethod { |
| /** {@code non-null;} basic block list of the method */ |
| private final BasicBlockList blocks; |
| |
| /** {@code >= 0;} label for the block which starts the method */ |
| private final int firstLabel; |
| |
| /** |
| * {@code null-ok;} array of predecessors for each block, indexed by block |
| * label |
| */ |
| private IntList[] predecessors; |
| |
| /** |
| * {@code null-ok;} the predecessors for the implicit "exit" block, that is |
| * the labels for the blocks that return, if calculated |
| */ |
| private IntList exitPredecessors; |
| |
| /** |
| * Constructs an instance. |
| * |
| * @param blocks {@code non-null;} basic block list of the method |
| * @param firstLabel {@code >= 0;} the label of the first block to execute |
| */ |
| public RopMethod(BasicBlockList blocks, int firstLabel) { |
| if (blocks == null) { |
| throw new NullPointerException("blocks == null"); |
| } |
| |
| if (firstLabel < 0) { |
| throw new IllegalArgumentException("firstLabel < 0"); |
| } |
| |
| this.blocks = blocks; |
| this.firstLabel = firstLabel; |
| |
| this.predecessors = null; |
| this.exitPredecessors = null; |
| } |
| |
| /** |
| * Gets the basic block list for this method. |
| * |
| * @return {@code non-null;} the list |
| */ |
| public BasicBlockList getBlocks() { |
| return blocks; |
| } |
| |
| /** |
| * Gets the label for the first block in the method that this list |
| * represents. |
| * |
| * @return {@code >= 0;} the first-block label |
| */ |
| public int getFirstLabel() { |
| return firstLabel; |
| } |
| |
| /** |
| * Gets the predecessors associated with the given block. This throws |
| * an exception if there is no block with the given label. |
| * |
| * @param label {@code >= 0;} the label of the block in question |
| * @return {@code non-null;} the predecessors of that block |
| */ |
| public IntList labelToPredecessors(int label) { |
| if (exitPredecessors == null) { |
| calcPredecessors(); |
| } |
| |
| IntList result = predecessors[label]; |
| |
| if (result == null) { |
| throw new RuntimeException("no such block: " + Hex.u2(label)); |
| } |
| |
| return result; |
| } |
| |
| /** |
| * Gets the exit predecessors for this instance. |
| * |
| * @return {@code non-null;} the exit predecessors |
| */ |
| public IntList getExitPredecessors() { |
| if (exitPredecessors == null) { |
| calcPredecessors(); |
| } |
| |
| return exitPredecessors; |
| } |
| |
| |
| /** |
| * Returns an instance that is identical to this one, except that |
| * the registers in each instruction are offset by the given |
| * amount. |
| * |
| * @param delta the amount to offset register numbers by |
| * @return {@code non-null;} an appropriately-constructed instance |
| */ |
| public RopMethod withRegisterOffset(int delta) { |
| RopMethod result = new RopMethod(blocks.withRegisterOffset(delta), |
| firstLabel); |
| |
| if (exitPredecessors != null) { |
| /* |
| * The predecessors have been calculated. It's safe to |
| * inject these into the new instance, since the |
| * transformation being applied doesn't affect the |
| * predecessors. |
| */ |
| result.exitPredecessors = exitPredecessors; |
| result.predecessors = predecessors; |
| } |
| |
| return result; |
| } |
| |
| /** |
| * Calculates the predecessor sets for each block as well as for the |
| * exit. |
| */ |
| private void calcPredecessors() { |
| int maxLabel = blocks.getMaxLabel(); |
| IntList[] predecessors = new IntList[maxLabel]; |
| IntList exitPredecessors = new IntList(10); |
| int sz = blocks.size(); |
| |
| /* |
| * For each block, find its successors, and add the block's label to |
| * the successor's predecessors. |
| */ |
| for (int i = 0; i < sz; i++) { |
| BasicBlock one = blocks.get(i); |
| int label = one.getLabel(); |
| IntList successors = one.getSuccessors(); |
| int ssz = successors.size(); |
| if (ssz == 0) { |
| // This block exits. |
| exitPredecessors.add(label); |
| } else { |
| for (int j = 0; j < ssz; j++) { |
| int succLabel = successors.get(j); |
| IntList succPreds = predecessors[succLabel]; |
| if (succPreds == null) { |
| succPreds = new IntList(10); |
| predecessors[succLabel] = succPreds; |
| } |
| succPreds.add(label); |
| } |
| } |
| } |
| |
| // Sort and immutablize all the predecessor lists. |
| for (int i = 0; i < maxLabel; i++) { |
| IntList preds = predecessors[i]; |
| if (preds != null) { |
| preds.sort(); |
| preds.setImmutable(); |
| } |
| } |
| |
| exitPredecessors.sort(); |
| exitPredecessors.setImmutable(); |
| |
| /* |
| * The start label might not ever have had any predecessors |
| * added to it (probably doesn't, because of how Java gets |
| * translated into rop form). So, check for this and rectify |
| * the situation if required. |
| */ |
| if (predecessors[firstLabel] == null) { |
| predecessors[firstLabel] = IntList.EMPTY; |
| } |
| |
| this.predecessors = predecessors; |
| this.exitPredecessors = exitPredecessors; |
| } |
| } |