| /* |
| * |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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 org.apache.royale.abc.semantics; |
| |
| import java.util.ArrayList; |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.Set; |
| |
| import org.apache.royale.abc.ABCConstants; |
| import org.apache.royale.abc.graph.IBasicBlock; |
| |
| /** |
| * Block implements {@link IBasicBlock} and is |
| * the normal representation of a vertex in a |
| * method's flowgraph. |
| */ |
| public class Block implements IBasicBlock |
| { |
| /** |
| * Instructions in this block. A Block created by a ControlFlowGraph has one |
| * targetable instruction as its last instruction. A Block that has been |
| * modified to have a targetable instruction in its interior will have |
| * unpredictable results until it's serialized into a new InstructionList |
| * and the ControlFlowGraph rebuilt. |
| */ |
| private ArrayList<Instruction> instructions = new ArrayList<Instruction>(); |
| |
| /** |
| * Successors to this block. |
| */ |
| private Collection<IBasicBlock> successors = Collections.emptySet(); |
| |
| /** |
| * @return successors of this block. |
| */ |
| public Collection<IBasicBlock> getSuccessors() |
| { |
| return this.successors; |
| } |
| |
| /** |
| * block number assigned by ControlFlowGraph. So far, |
| * only used to try to guarantee order in lists/collections |
| */ |
| public int blocknum; |
| |
| /** |
| * Add a successor to this block. |
| * |
| * @param succ - the successor block. |
| */ |
| void addSuccessor(IBasicBlock succ) |
| { |
| if (this.successors.size() == 0) |
| this.successors = new ArrayList<IBasicBlock>(); |
| |
| this.successors.add(succ); |
| } |
| |
| void add(Instruction insn) |
| { |
| this.instructions.add(insn); |
| } |
| |
| /** |
| * @return this Block's instructions' size. |
| */ |
| public int size() |
| { |
| return this.instructions.size(); |
| } |
| |
| /** |
| * @return the Instruction at the specified index. |
| */ |
| public Instruction get(int idx) |
| { |
| return this.instructions.get(idx); |
| } |
| |
| /** |
| * @return this Block's instructions as a mutable list. |
| */ |
| public List<Instruction> getInstructions() |
| { |
| return this.instructions; |
| } |
| |
| /** |
| * Determines if control can fall through the end of the Block. |
| * This will look back through the Block's instructions, |
| * skipping any non-exectuable instructions such as debug instructions. |
| * Returns, throws, and unconditional branches will not fall through, but |
| * conditional branches and all other instructions will fall through. |
| * |
| * @return true if control can fall through this Block. |
| */ |
| public boolean canFallThrough() |
| { |
| // Look for the last executable instruction; |
| // skip non-executable instructions, e.g., debug |
| for ( int i = this.instructions.size() -1; i >= 0; i-- ) |
| { |
| Instruction insn = this.instructions.get(i); |
| |
| if (insn.isExecutable()) |
| { |
| int prev_op = insn.getOpcode(); |
| if ( |
| prev_op == ABCConstants.OP_jump || |
| prev_op == ABCConstants.OP_throw || |
| insn.isReturn()) |
| { |
| return false; |
| } |
| else |
| { |
| return true; |
| } |
| } |
| } |
| |
| // No executable instructions in this block. |
| return true; |
| } |
| } |