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404 lines
12 KiB
404 lines
12 KiB
/* BasicBlocks Copyright (C) 2000-2002 Jochen Hoenicke.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; see the file COPYING.LESSER. If not, write to
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* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Id$
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*/
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package net.sf.jode.bytecode;
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import net.sf.jode.GlobalOptions;
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import java.io.DataInputStream;
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import java.io.DataOutputStream;
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import java.io.IOException;
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import java.io.PrintWriter;
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import java.util.BitSet;
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import java.util.Stack;
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///#def COLLECTIONS java.util
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Iterator;
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///#enddef
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/**
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* <p>Represents the byte code of a method in form of basic blocks. A
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* basic block is a bunch of instructions, that must always execute in
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* sequential order. Every basic block is represented by an Block
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* object.</p>
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*
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* <p>All jump instructions must be at the end of the block, and the
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* jump instructions doesn't have to remember where they jump to.
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* Instead this information is stored inside the blocks. See
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* <code>Block</code> for details.</p>
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*
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* <p>Exception Handlers are represented by the Handler class. Their
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* start/end range must span over some consecutive BasicBlocks and
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* there handler must be another basic block.</p>
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*
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* <!-- <p>Future work: A subroutine block, i.e. a block where some jsr
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* instructions may jump to, must store its return address in a local
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* variable immediately. There must be exactly one block with the
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* corresponding <code>opc_ret</code> instruction and all blocks that
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* belong to this subroutine must point to the ret block. Bytecode
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* that doesn't have this condition is automatically transformed on
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* reading.</p> -->
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*
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* <p>When the code is written to a class file, the blocks are written
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* in the given order. Goto and return instructions are inserted as
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* necessary, you don't need to care about that.</p>
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*
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* <h3>Creating new BasicBlocks</h3>
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*
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* <p>If you want to create a new BasicBlocks object, first create the
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* Block objects, then initialize them (you need to have all successor
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* blocks created for this). Afterwards create a new BasicBlock and
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* fill its sub blocks: </p>
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*
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* <pre>
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* MethodInfo myMethod = new MethodInfo("foo", "()V", PUBLIC);
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* Block blocks = new Block[10];
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* for (int i = 0; i < 10; i++) blocks[i] = new Block();
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* blocks[0].setCode(new Instruction[] {...},
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* new Block[] {blocks[3], blocks[1]});
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* ...
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* Handler[] excHandlers = new Handler[1];
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* excHandlers[0] = new Handler(blocks[2], blocks[5], blocks[6],
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* "java.lang.NullPointerException");
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* BasicBlocks bb = new BasicBlocks(myMethod);
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* bb.setCode(blocks, blocks[0], excHandlers);
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* classInfo.setMethods(new MethodInfo[] { myMethod });
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* </pre>
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*
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* @see net.sf.jode.bytecode.Block
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* @see net.sf.jode.bytecode.Instruction
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*/
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public class BasicBlocks extends BinaryInfo implements Opcodes {
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/**
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* The method info which contains the basic blocks.
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*/
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private MethodInfo methodInfo;
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/**
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* The maximal number of stack entries, that may be used in this
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* method.
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*/
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int maxStack;
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/**
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* The maximal number of local slots, that may be used in this
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* method.
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*/
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int maxLocals;
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/**
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* This is an array of blocks, which are arrays
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* of Instructions.
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*/
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private Block[] blocks;
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/**
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* The start block. Normally the first block, but differs if method start
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* with a goto, e.g a while. This may be null, if this method is empty.
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*/
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private Block startBlock;
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/**
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* The local variable infos for the method parameters.
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*/
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private LocalVariableInfo[] paramInfos;
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/**
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* The array of exception handlers.
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*/
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private Handler[] exceptionHandlers;
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public BasicBlocks(MethodInfo mi) {
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methodInfo = mi;
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int paramSize = (mi.isStatic() ? 0 : 1)
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+ TypeSignature.getParameterSize(mi.getType());
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paramInfos = new LocalVariableInfo[paramSize];
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for (int i=0; i< paramSize; i++)
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paramInfos[i] = LocalVariableInfo.getInfo(i);
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}
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public int getMaxStack() {
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return maxStack;
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}
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public int getMaxLocals() {
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return maxLocals;
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}
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public MethodInfo getMethodInfo() {
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return methodInfo;
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}
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public Block getStartBlock() {
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return startBlock;
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}
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public Block[] getBlocks() {
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return blocks;
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}
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/**
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* @return the exception handlers, or null if the method has no
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* exception handlers.
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*/
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public Handler[] getExceptionHandlers() {
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return exceptionHandlers;
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}
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public LocalVariableInfo getParamInfo(int i) {
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return paramInfos[i];
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}
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public int getParamCount() {
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return paramInfos.length;
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}
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/**
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* Updates the maxStack and maxLocals according to the current code.
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* Call this every time you change the code.
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*/
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public void updateMaxStackLocals() {
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maxLocals = getParamCount();
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maxStack = 0;
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if (startBlock == null)
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return;
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BitSet visited = new BitSet();
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Stack todo = new Stack();
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startBlock.stackHeight = 0;
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todo.push(startBlock);
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while (!todo.isEmpty()) {
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Block block = (Block) todo.pop();
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int stackHeight = block.stackHeight;
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if (stackHeight + block.maxpush > maxStack)
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maxStack = stackHeight + block.maxpush;
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stackHeight += block.delta;
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Block[] succs = block.getSuccs();
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Instruction[] instr = block.getInstructions();
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for (int i = 0; i < instr.length; i++) {
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if (instr[i].hasLocal()) {
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int slotlimit = instr[i].getLocalSlot() + 1;
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int opcode = instr[i].getOpcode();
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if (opcode == opc_lstore || opcode == opc_dstore
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|| opcode == opc_lload || opcode == opc_dload)
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slotlimit++;
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if (slotlimit > maxLocals)
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maxLocals = slotlimit;
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}
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}
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if (instr.length > 0
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&& instr[instr.length-1].getOpcode() == opc_jsr) {
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if (!visited.get(succs[0].blockNr)) {
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succs[0].stackHeight = stackHeight + 1;
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todo.push(succs[0]);
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visited.set(succs[0].blockNr);
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} else if (succs[0].stackHeight != stackHeight + 1)
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throw new IllegalArgumentException
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("Block has two different stack heights.");
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if (succs[1] != null && !visited.get(succs[1].blockNr)) {
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succs[1].stackHeight = stackHeight;
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todo.push(succs[1]);
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visited.set(succs[1].blockNr);
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} else if ((succs[1] == null ? 0 : succs[1].stackHeight)
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!= stackHeight)
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throw new IllegalArgumentException
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("Block has two different stack heights.");
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} else {
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for (int i = 0; i < succs.length; i++) {
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if (succs[i] != null && !visited.get(succs[i].blockNr)) {
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succs[i].stackHeight = stackHeight;
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todo.push(succs[i]);
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visited.set(succs[i].blockNr);
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} else if ((succs[i] == null ? 0 : succs[i].stackHeight)
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!= stackHeight)
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throw new IllegalArgumentException
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("Block has two different stack heights.");
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}
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}
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Handler[] handler = block.getHandlers();
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for (int i = 0; i < handler.length; i++) {
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if (!visited.get(handler[i].getCatcher().blockNr)) {
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handler[i].getCatcher().stackHeight = 1;
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todo.push(handler[i].getCatcher());
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visited.set(handler[i].getCatcher().blockNr);
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} else if (handler[i].getCatcher().stackHeight != 1)
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throw new IllegalArgumentException
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("Block has two different stack heights.");
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}
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}
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}
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public void setBlocks(Block[] blocks, Block startBlock,
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Handler[] handlers) {
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this.blocks = blocks;
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this.startBlock = startBlock;
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exceptionHandlers = handlers.length == 0 ? Handler.EMPTY : handlers;
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ArrayList activeHandlers = new ArrayList();
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for (int i = 0; i < blocks.length; i++) {
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blocks[i].blockNr = i;
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for (int j = 0; j < handlers.length; j++) {
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if (handlers[j].getStart() == blocks[i])
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activeHandlers.add(handlers[j]);
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}
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if (activeHandlers.size() == 0)
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blocks[i].catchers = Handler.EMPTY;
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else
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blocks[i].catchers =
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(Handler[]) activeHandlers.toArray(Handler.EMPTY);
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for (int j = 0; j < handlers.length; j++) {
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if (handlers[j].getEnd() == blocks[i])
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activeHandlers.remove(handlers[j]);
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}
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}
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/* Check if all successor blocks are in this basic block */
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for (int i = 0; i < blocks.length; i++) {
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Block[] succs = blocks[i].getSuccs();
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for (int j = 0; j < succs.length; j++) {
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if (succs[j] != null
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&& succs[j] != blocks[succs[j].blockNr])
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throw new IllegalArgumentException
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("Succ " + j + " of block " + i
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+ " not in basicblocks");
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}
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}
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updateMaxStackLocals();
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// TransformSubroutine.createSubroutineInfo(this);
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}
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/**
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* Sets the name and type of a method parameter. This overwrites
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* any previously set parameter info for this slot.
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* @param info a local variable info mapping a slot nr to a name
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* and a type.
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*/
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public void setParamInfo(LocalVariableInfo info) {
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paramInfos[info.getSlot()] = info;
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}
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private BasicBlockReader reader;
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void read(ConstantPool cp,
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DataInputStream input,
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int howMuch) throws IOException {
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if ((GlobalOptions.debuggingFlags
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& GlobalOptions.DEBUG_BYTECODE) != 0)
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GlobalOptions.err.println("Reading "+methodInfo);
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reader = new BasicBlockReader(this);
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reader.readCode(cp, input);
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readAttributes(cp, input, howMuch);
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reader.convert();
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reader = null;
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if ((GlobalOptions.debuggingFlags
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& GlobalOptions.DEBUG_BYTECODE) != 0)
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dumpCode(GlobalOptions.err);
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}
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protected void readAttribute(String name, int length, ConstantPool cp,
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DataInputStream input,
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int howMuch) throws IOException {
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if (howMuch >= ClassInfo.ALMOSTALL
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&& name.equals("LocalVariableTable")) {
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reader.readLVT(length, cp, input);
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} else if (howMuch >= ClassInfo.ALMOSTALL
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&& name.equals("LineNumberTable")) {
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reader.readLNT(length, cp, input);
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} else
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super.readAttribute(name, length, cp, input, howMuch);
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}
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void reserveSmallConstants(GrowableConstantPool gcp) {
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for (int i=0; i < blocks.length; i++) {
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next_instr:
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for (Iterator iter
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= Arrays.asList(blocks[i].getInstructions()).iterator();
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iter.hasNext(); ) {
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Instruction instr = (Instruction) iter.next();
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if (instr.getOpcode() == Opcodes.opc_ldc) {
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Object constant = instr.getConstant();
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if (constant == null)
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continue next_instr;
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for (int j=1; j < Opcodes.constants.length; j++) {
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if (constant.equals(Opcodes.constants[j]))
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continue next_instr;
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}
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if (constant instanceof Integer) {
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int value = ((Integer) constant).intValue();
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if (value >= Short.MIN_VALUE
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&& value <= Short.MAX_VALUE)
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continue next_instr;
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}
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gcp.reserveConstant(constant);
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}
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}
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}
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}
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BasicBlockWriter bbw;
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void prepareWriting(GrowableConstantPool gcp) {
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bbw = new BasicBlockWriter(this, gcp);
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prepareAttributes(gcp);
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}
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protected int getAttributeCount() {
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return super.getAttributeCount() + bbw.getAttributeCount();
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}
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protected void writeAttributes(GrowableConstantPool gcp,
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DataOutputStream output)
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throws IOException {
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super.writeAttributes(gcp, output);
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bbw.writeAttributes(gcp, output);
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}
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void write(GrowableConstantPool gcp,
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DataOutputStream output) throws IOException {
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output.writeInt(bbw.getSize() + getAttributeSize());
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bbw.write(gcp, output);
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writeAttributes(gcp, output);
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bbw = null;
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}
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public void dumpCode(PrintWriter output) {
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output.println(methodInfo.getName()+methodInfo.getType()+":");
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if (startBlock == null)
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output.println("\treturn");
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else if (startBlock != blocks[0])
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output.println("\tgoto "+startBlock);
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for (int i=0; i< blocks.length; i++) {
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blocks[i].dumpCode(output);
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}
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for (int i=0; i< exceptionHandlers.length; i++) {
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output.println("catch " + exceptionHandlers[i].type
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+ " from " + exceptionHandlers[i].start
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+ " to " + exceptionHandlers[i].end
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+ " catcher " + exceptionHandlers[i].catcher);
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}
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}
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public String toString() {
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return "BasicBlocks["+methodInfo+"]";
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}
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}
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