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1351 lines
48 KiB
1351 lines
48 KiB
/*
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* FlowBlock (c) 1998 Jochen Hoenicke
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*
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* You may distribute under the terms of the GNU General Public License.
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*
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* IN NO EVENT SHALL JOCHEN HOENICKE BE LIABLE TO ANY PARTY FOR DIRECT,
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* INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF
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* THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF JOCHEN HOENICKE
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* HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* JOCHEN HOENICKE SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS"
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* BASIS, AND JOCHEN HOENICKE HAS NO OBLIGATION TO PROVIDE MAINTENANCE,
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* SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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* $Id$
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*/
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package jode.flow;
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import java.util.*;
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import jode.TabbedPrintWriter;
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import jode.Expression;
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import jode.CodeAnalyzer;
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import jode.Decompiler;
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/**
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* A flow block is the structure of which the flow graph consists. A
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* flow block contains structured code together with some conditional
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* or unconditional jumps to the head of other flow blocks.
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*
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* We do a T1/T2 analysis to combine all flow blocks to a single. If
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* the graph isn't reducible that doesn't work, but java can only
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* produce reducible flow graphs.
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*/
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public class FlowBlock {
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static FlowBlock END_OF_METHOD =
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new FlowBlock(null, Integer.MAX_VALUE, 0, new EmptyBlock());
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static {
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END_OF_METHOD.label = "END_OF_METHOD";
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}
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/**
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* The code analyzer. This is used to pretty printing the
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* Types and to get information about all locals in this code.
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*/
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CodeAnalyzer code;
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/**
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* The in locals. This are the locals, which are used in this
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* flow block and whose values may be the result of a assignment
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* outside of this flow block. That means, that there is a
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* path from the start of the flow block to the instruction that
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* uses that variable, on which it is never assigned
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*/
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VariableSet in = new VariableSet();
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/**
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* The starting address of this flow block. This is mainly used
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* to produce the source code in code order.
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*/
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int addr;
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/**
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* The length of the structured block, only needed at the beginning.
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*/
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int length;
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/**
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* The outermost structructed block in this flow block.
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*/
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StructuredBlock block;
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/**
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* The last modified structured block.
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*/
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StructuredBlock lastModified;
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/**
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* All Jumps that this flow block contains. The objects may be
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* null, if they were marked as deleted. */
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Vector successors;
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/**
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* This is a vector of flow blocks, which reference this block.
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* Only if this vector contains exactly one element, it can be
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* moved into the preceding flow block.
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*
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* If this vectors contains the null element, this is the first
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* flow block in a method.
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*/
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Vector predecessors;
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/**
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* The default constructor. Creates a new flowblock containing
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* only the given structured block.
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*/
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public FlowBlock(CodeAnalyzer code, int addr, int length,
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StructuredBlock block) {
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this.code = code;
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this.addr = addr;
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this.length = length;
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this.block = block;
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lastModified = block;
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predecessors = new Vector(); // filled in later
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successors = new Vector();
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block.setFlowBlock(this);
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block.fillInSet(in);
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block.fillSuccessors(successors);
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}
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public int getNextAddr() {
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return addr+length;
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}
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/**
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* Create a Catch- resp. FinallyBlock (maybe even SynchronizedBlock)
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* @param sequBlock a SequentialBlock whose first sub block is a
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* RawTryCatchBlock.
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*/
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public StructuredBlock createCatchBlock(SequentialBlock sequBlock) {
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RawTryCatchBlock tryBlock = (RawTryCatchBlock) sequBlock.subBlocks[0];
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StructuredBlock catchBlock = sequBlock.subBlocks[1];
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if (tryBlock.type != null) {
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/*XXX crude hack */
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catchBlock.replace(sequBlock, tryBlock);
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CatchBlock newBlock = new CatchBlock(tryBlock);
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newBlock.replace(catchBlock, catchBlock);
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newBlock.setCatchBlock(catchBlock);
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if (sequBlock.jump != null) {
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if (newBlock.catchBlock.jump == null)
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newBlock.catchBlock.moveJump(sequBlock.jump);
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else
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sequBlock.removeJump();
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}
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return newBlock;
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} else {
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/* XXX implement finally */
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return sequBlock;
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}
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}
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/**
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* This method optimizes the jumps to successor.
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* @param successor The successing flow block
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* @param appendBlock the block where the successor is appended to.
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* @return the new appendBlock, it may have changed.
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*/
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public StructuredBlock optimizeJumps(FlowBlock successor,
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StructuredBlock appendBlock) {
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Enumeration enum = successors.elements();
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next_jump:
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while (enum.hasMoreElements()) {
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Jump jump = (Jump) enum.nextElement();
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if (jump == null || jump.destination != successor)
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continue next_jump;
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while(jump != null) {
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if (jump.prev instanceof EmptyBlock
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&& jump.prev.outer != null
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&& jump.prev.outer instanceof ConditionalBlock
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&& jump.prev.outer.jump != null) {
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if (jump.prev.outer.jump.destination == jump.destination) {
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/* This is a weired "if (cond) empty"-block. We
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* transform it by hand.
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*/
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jump.prev.removeJump();
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continue next_jump;
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}
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/* Swap conditional blocks, that have two jumps, and where
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* this jump is the inner jump.
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*/
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StructuredBlock prev = jump.prev;
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ConditionalBlock cb = (ConditionalBlock) prev.outer;
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jode.Instruction instr = cb.getInstruction();
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/* XXX Expression clean up is necessary. Otherwise
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* this may lead to a ClassCastException.
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*
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* Our code below _depends_ on the fact that this
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* transformation is done.
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*/
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cb.setInstruction(((jode.Expression)instr).negate());
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cb.swapJump(jump.prev);
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}
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/* Now move the jump as far to the outer as possible,
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* without leaving appendBlock.
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*
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* Note: jump.prev != appendblock implies
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* jump.prev.outer != null, since appendBlock is an outer
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* block of jump.prev
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*/
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while (jump.prev != appendBlock
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&& jump.prev.outer.isSingleExit(jump.prev)) {
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jump.prev.outer.moveJump(jump);
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}
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/* if the jump is the jump of the appendBlock, skip it.
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*/
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if (jump.prev == appendBlock)
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continue next_jump;
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/* remove this jump if it jumps to the getNextFlowBlock().
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*/
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if (jump.prev.outer.getNextFlowBlock(jump.prev) == successor) {
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jump.prev.removeJump();
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continue next_jump;
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}
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if (jump.prev instanceof EmptyBlock &&
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jump.prev.outer instanceof ConditionalBlock) {
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StructuredBlock prev = jump.prev;
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ConditionalBlock cb = (ConditionalBlock) prev.outer;
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jode.Instruction instr = cb.getInstruction();
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/* cb.jump is null (see above), so cb must have a *
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* successor in this block, that means cb.outer is not
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* null.
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*/
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/* If this is the first instruction of a while and the
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* condition of the while is true, use the condition
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* as while condition.
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*/
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/* This is the first instruction in a while block */
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if (cb.outer instanceof SequentialBlock &&
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cb.outer.getSubBlocks()[0] == cb &&
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cb.outer.outer instanceof LoopBlock) {
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LoopBlock loopBlock = (LoopBlock) cb.outer.outer;
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if (loopBlock.getCondition() == LoopBlock.TRUE &&
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loopBlock.getType() != LoopBlock.DOWHILE &&
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loopBlock.getNextFlowBlock() == successor &&
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instr instanceof Expression) {
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prev.removeJump();
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loopBlock.setCondition(((Expression)instr).negate());
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if (cb.outer.jump != null) {
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/* XXX can this happen */
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if (cb.outer.getSubBlocks()[1].jump != null) {
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/* XXX if above can happen,
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* can this happen at all??? */
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cb.outer.removeJump();
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} else
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cb.outer.getSubBlocks()[1].
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moveJump(cb.outer.jump);
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}
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cb.outer.getSubBlocks()[1].replace
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(cb.outer, cb.outer.getSubBlocks()[1]);
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/* cb and cb.outer are not used any more */
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/* Note that cb.outer != appendBlock because
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* appendBlock contains loopBlock
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*/
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continue next_jump;
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}
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}
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/* Now the same for the empty loop. In this case there is
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* no sequential block.
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*/
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if (cb.outer instanceof LoopBlock) {
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LoopBlock loopBlock = (LoopBlock) cb.outer;
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if (loopBlock.getCondition() == LoopBlock.TRUE &&
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loopBlock.getType() != LoopBlock.DOWHILE &&
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loopBlock.getNextFlowBlock() == successor &&
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instr instanceof Expression) {
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prev.removeJump();
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loopBlock.setCondition(((Expression)instr).negate());
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EmptyBlock empty = new EmptyBlock();
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empty.replace(cb, null);
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/* cb is not used any more */
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continue next_jump;
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}
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}
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/* replace all conditional jumps to the successor, which
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* are followed by a block which has the end of the block
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* as normal successor, with "if (not condition) block".
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*/
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if (cb.outer instanceof SequentialBlock &&
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cb.outer.getSubBlocks()[0] == cb &&
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(cb.outer.getNextFlowBlock() == successor ||
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cb.outer.jumpMayBeChanged()) &&
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instr instanceof jode.Expression) {
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SequentialBlock sequBlock =
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(SequentialBlock) cb.outer;
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IfThenElseBlock newIfBlock =
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new IfThenElseBlock(((jode.Expression)instr).negate());
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newIfBlock.replace(sequBlock, sequBlock.getSubBlocks()[1]);
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newIfBlock.setThenBlock(sequBlock.getSubBlocks()[1]);
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newIfBlock.moveJump(sequBlock.jump);
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if (appendBlock == sequBlock)
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appendBlock = newIfBlock;
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if (newIfBlock.getNextFlowBlock() != successor &&
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newIfBlock != appendBlock) {
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newIfBlock.moveJump(jump);
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continue;
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} else {
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prev.removeJump();
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continue next_jump;
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}
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}
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}
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/* if this is a jumps at the end of a then block belonging
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* to a if-then block without else part, and the if-then
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* block is followed by a single block, then replace the
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* if-then block with a if-then-else block and remove the
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* unconditional jump.
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*/
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else if (jump.prev.outer instanceof IfThenElseBlock) {
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IfThenElseBlock ifBlock =
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(IfThenElseBlock)jump.prev.outer;
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if (ifBlock.elseBlock == null
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&& ifBlock.jump == null
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&& ifBlock.outer instanceof SequentialBlock
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&& ifBlock.outer.getSubBlocks()[0] == ifBlock
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&& (ifBlock.outer.getNextFlowBlock() == successor
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|| ifBlock.outer.jumpMayBeChanged())) {
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StructuredBlock elseBlock =
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ifBlock.outer.getSubBlocks()[1];
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ifBlock.outer.removeJump();
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ifBlock.replace(ifBlock.outer, elseBlock);
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if (appendBlock == elseBlock.outer)
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appendBlock = ifBlock;
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ifBlock.moveJump(jump);
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ifBlock.setElseBlock(elseBlock);
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continue;
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}
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}
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/* if this is a jump in a breakable block, and that block
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* has not yet a next block, then create a new jump to that
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* successor.
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*
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* The break to the block will be generated later.
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*/
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for (StructuredBlock surrounder = jump.prev.outer;
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surrounder != null && surrounder != appendBlock.outer;
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surrounder = surrounder.outer) {
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if (surrounder instanceof BreakableBlock) {
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if (surrounder.getNextFlowBlock() != successor
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&& surrounder.jumpMayBeChanged()) {
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surrounder.setJump(new Jump(successor));
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successors.addElement(surrounder.jump);
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}
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}
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}
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continue next_jump;
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}
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}
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return appendBlock;
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}
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/**
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* Move the successors of the given flow block to this flow block.
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* @param succ the other flow block
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*/
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void mergeSuccessors(FlowBlock succ) {
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/* Merge the sucessors from the successing flow block
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*/
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Enumeration enum = succ.successors.elements();
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while (enum.hasMoreElements()) {
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Jump jump = (Jump) enum.nextElement();
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if (jump == null)
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continue;
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successors.addElement(jump);
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if (jump.destination.predecessors.contains(succ)) {
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/*XXX comment and make clearer, better etc.*/
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jump.destination.predecessors.removeElement(succ);
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if (!jump.destination.predecessors.contains(this))
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jump.destination.predecessors.addElement(this);
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}
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}
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}
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/**
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* Resolve remaining jumps to the successor by generating break
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* instructions. As last resort generate a do while(false) block.
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* @param successor The successing flow block
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* @param appendBlock the block where the successor is appended to.
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* @return the new appendBlock, it may have changed.
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*/
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StructuredBlock resolveRemaining(FlowBlock succ,
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StructuredBlock appendBlock) {
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LoopBlock doWhileFalse = null;
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Enumeration enum = successors.elements();
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next_jump:
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while (enum.hasMoreElements()) {
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Jump jump = (Jump) enum.nextElement();
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if (jump == null || jump.destination != succ
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|| jump.prev == appendBlock)
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continue;
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int breaklevel = 0;
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BreakableBlock breakToBlock = null;
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for (StructuredBlock surrounder = jump.prev.outer;
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surrounder != null && surrounder != appendBlock.outer;
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surrounder = surrounder.outer) {
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if (surrounder instanceof BreakableBlock) {
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breaklevel++;
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if (surrounder.getNextFlowBlock() == succ) {
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breakToBlock = (BreakableBlock) surrounder;
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break;
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}
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}
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}
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StructuredBlock prevBlock = jump.prev;
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prevBlock.removeJump();
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if (breakToBlock == null) {
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/* Nothing else helped, so put a do/while(0)
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* block around appendBlock and break to that
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* block.
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*/
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if (doWhileFalse == null) {
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doWhileFalse = new LoopBlock(LoopBlock.DOWHILE,
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LoopBlock.FALSE);
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doWhileFalse.setJump(new Jump(succ));
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}
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prevBlock.appendBlock
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(new BreakBlock(doWhileFalse, breaklevel > 0));
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} else
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prevBlock.appendBlock
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(new BreakBlock(breakToBlock, breaklevel > 1));
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}
|
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if (doWhileFalse != null) {
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doWhileFalse.replace(appendBlock, appendBlock);
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doWhileFalse.setBody(appendBlock);
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doWhileFalse.jump = null;
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}
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|
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/* Now remove the jump of the appendBlock if it points to
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* successor.
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*/
|
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if (appendBlock.jump != null
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&& appendBlock.jump.destination == succ)
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appendBlock.removeJump();
|
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return appendBlock;
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}
|
|
|
|
/**
|
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* Updates the in/out-Vectors of the structured block of the
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* successing flow block simultanous to a T1 transformation.
|
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* @param successor The flow block which is unified with this flow
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* block.
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|
* @return The variables that must be defined in this block.
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|
*/
|
|
void updateInOut (FlowBlock successor, boolean t1Transformation) {
|
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/* First get the out vectors of all jumps to successor and
|
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* calculate the intersection.
|
|
*/
|
|
VariableSet gens = new VariableSet();
|
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VariableSet kills = null;
|
|
Enumeration enum = successors.elements();
|
|
while (enum.hasMoreElements()) {
|
|
Jump jump = (Jump) enum.nextElement();
|
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if (jump == null || jump.destination != successor)
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continue;
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gens.unionExact(jump.gen);
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if (kills == null)
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kills = jump.kill;
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else
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kills = kills.intersect(jump.kill);
|
|
}
|
|
|
|
/* Merge the locals used in successing block with those written
|
|
* by this blocks
|
|
*/
|
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successor.in.merge(gens);
|
|
|
|
/* Now update in and out set of successing block */
|
|
|
|
if (t1Transformation)
|
|
successor.in.subtract(kills);
|
|
/* The gen/kill sets must be updated for every jump in the block */
|
|
enum = successor.successors.elements();
|
|
while (enum.hasMoreElements()) {
|
|
Jump jump = (Jump) enum.nextElement();
|
|
if (jump != null) {
|
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jump.gen.mergeGenKill(gens, jump.kill);
|
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if (t1Transformation)
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jump.kill.add(kills);
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}
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}
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in.unionExact(successor.in);
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|
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if (Decompiler.debugInOut) {
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System.err.println("UpdateInOut: gens : "+gens);
|
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System.err.println(" kills: "+kills);
|
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System.err.println(" s.in : "+successor.in);
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System.err.println(" in : "+in);
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}
|
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}
|
|
|
|
|
|
/* Special cases:
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|
*
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|
* try-header
|
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* |- first instruction
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|
* | ...
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* | last instruction
|
|
* |- optional jump (last+1)
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|
* | ...
|
|
* `- catch block
|
|
*
|
|
* A try block may have many try-headers with different catch blocks
|
|
* and there may be a finally block:
|
|
*
|
|
* try-header any
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|
* | try-header
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|
* |--|- first instruction
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|
* | | ...
|
|
* | | every jump to outside is preceded by jsr finally
|
|
* | | ...
|
|
* | | last instruction
|
|
* | |- optional jump after catch block (last+1)
|
|
* | | ... |
|
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* | `- catch block |
|
|
* | ... |
|
|
* | ,-----------------'
|
|
* | |-jump after all catch blocks
|
|
* | v
|
|
* | jsr finally -----------------,
|
|
* |- jump after finally |
|
|
* `- catch any (local_n) v
|
|
* jsr finally ---------------->|
|
|
* throw local_n; |
|
|
* finally: <-----------------------'
|
|
* astore_n
|
|
* ...
|
|
* return_n
|
|
*
|
|
*
|
|
* flow-block
|
|
* finally-block
|
|
* ---> try-header
|
|
* finally {
|
|
* ---> first-finally-instruction
|
|
*
|
|
* A synchronized block uses a similar technique:
|
|
*
|
|
* local_x = monitor object;
|
|
* monitorenter local_x
|
|
* try-header any
|
|
* |- syncronized block
|
|
* | ...
|
|
* | every jump to outside is preceded by jsr monexit ---,
|
|
* | ... |
|
|
* |- monitorexit local_x |
|
|
* | jump after this block (without jsr monexit) |
|
|
* `- catch any (local_n) |
|
|
* monitorexit local_x |
|
|
* throw local_n |
|
|
* monexit: <-----------------------------------------------'
|
|
* astore_n
|
|
* monitorexit local_x
|
|
* return_n
|
|
*/
|
|
|
|
public void checkConsistent() {
|
|
if (!Decompiler.doChecks)
|
|
return;
|
|
// try {
|
|
if (block.outer != null || block.flowBlock != this) {
|
|
throw new RuntimeException("Inconsistency");
|
|
}
|
|
block.checkConsistent();
|
|
Enumeration enum = successors.elements();
|
|
while (enum.hasMoreElements()) {
|
|
Jump jump = (Jump) enum.nextElement();
|
|
if (jump == null)
|
|
continue;
|
|
|
|
if (jump.prev.flowBlock != this ||
|
|
jump.prev.jump != jump)
|
|
throw new RuntimeException("Inconsistency");
|
|
|
|
StructuredBlock sb = jump.prev;
|
|
while (sb != block) {
|
|
if (sb.outer == null)
|
|
throw new RuntimeException("Inconsistency");
|
|
StructuredBlock[] blocks = sb.outer.getSubBlocks();
|
|
int i;
|
|
for (i=0; i<blocks.length; i++)
|
|
if (blocks[i] == sb)
|
|
break;
|
|
if (i == blocks.length)
|
|
throw new RuntimeException("Inconsistency");
|
|
sb = sb.outer;
|
|
}
|
|
}
|
|
// } catch (RuntimeException ex) {
|
|
// ex.printStackTrace();
|
|
// try {
|
|
// jode.TabbedPrintWriter writer =
|
|
// new jode.TabbedPrintWriter(System.err, " ");
|
|
// writer.tab();
|
|
// block.dumpSource(writer);
|
|
// } catch (java.io.IOException ioex) {
|
|
// }
|
|
// }
|
|
}
|
|
|
|
/**
|
|
* Do a T1 transformation with succ if possible. It is possible,
|
|
* iff succ has exactly this block as predecessor.
|
|
* @param succ the successor block, must be a valid successor of this
|
|
* block, i.e. not null
|
|
*/
|
|
public boolean doT1(FlowBlock succ) {
|
|
/* check if this successor has only this block as predecessor.
|
|
* if the predecessor is not unique, return false. */
|
|
if (succ.predecessors.size() != 1 ||
|
|
succ.predecessors.elementAt(0) != this)
|
|
return false;
|
|
|
|
checkConsistent();
|
|
succ.checkConsistent();
|
|
|
|
/* First find the innermost block that contains all jumps to this
|
|
* successor and the last modified block.
|
|
*/
|
|
Enumeration enum = successors.elements();
|
|
StructuredBlock appendBlock = lastModified;
|
|
while(enum.hasMoreElements()) {
|
|
Jump jump = (Jump) enum.nextElement();
|
|
if (jump == null || jump.destination != succ)
|
|
continue;
|
|
|
|
while (!appendBlock.contains(jump.prev)) {
|
|
appendBlock = appendBlock.outer;
|
|
if (appendBlock instanceof SequentialBlock
|
|
&& appendBlock.getSubBlocks()[0]
|
|
instanceof RawTryCatchBlock) {
|
|
|
|
/* We leave the catch block of a raw-try-catch-block.
|
|
* We shall now create the Catch- resp. FinallyBlock.
|
|
*/
|
|
appendBlock =
|
|
createCatchBlock((SequentialBlock)appendBlock);
|
|
}
|
|
}
|
|
/* appendBlock can't be null now, because the
|
|
* outermost block contains every structured block.
|
|
*/
|
|
}
|
|
|
|
/* Update the in/out-Vectors now */
|
|
updateInOut(succ, true);
|
|
|
|
/* The switch "fall through" case: if the appendBlock is a
|
|
* switch, and the successor is the address of a case, and all
|
|
* other successors are inside the block preceding that case.
|
|
*/
|
|
StructuredBlock precedingcase = null;
|
|
StructuredBlock nextcase = null;
|
|
if (appendBlock instanceof SwitchBlock) {
|
|
nextcase = ((SwitchBlock) appendBlock).findCase(succ);
|
|
precedingcase =
|
|
((SwitchBlock) appendBlock).prevCase(nextcase);
|
|
|
|
enum = successors.elements();
|
|
while (nextcase != null && enum.hasMoreElements()) {
|
|
Jump jump = (Jump) enum.nextElement();
|
|
if (jump == null
|
|
|| jump.destination != succ
|
|
|| jump.prev == nextcase
|
|
|| (precedingcase != null
|
|
&& precedingcase.contains(jump.prev)))
|
|
continue;
|
|
nextcase = null;
|
|
}
|
|
}
|
|
if (nextcase != null) {
|
|
SwitchBlock switchBlock = (SwitchBlock) appendBlock;
|
|
|
|
/* Now put the succ.block into the next case.
|
|
*/
|
|
nextcase.removeJump();
|
|
succ.block.replace(nextcase, succ.block);
|
|
/* nextcase is not referenced any more */
|
|
|
|
/* Do the following modifications on the struct block. */
|
|
appendBlock = precedingcase;
|
|
|
|
} else {
|
|
|
|
/* Prepare the unification of the blocks: Make sure if
|
|
* possible that appendBlock has a successor outside of
|
|
* this block.
|
|
*
|
|
* This doesn't change the semantics, since appendBlock
|
|
* is the last block that could be modified.
|
|
* XXX (is this true for switches)*/
|
|
if (appendBlock.jump == null) {
|
|
Jump jump = new Jump(succ);
|
|
appendBlock.setJump(jump);
|
|
successors.addElement(jump);
|
|
}
|
|
|
|
/* Now unify the blocks: Create a new SequentialBlock
|
|
* containing appendBlock and successor.block. Then replace
|
|
* appendBlock with the new sequential block.
|
|
*/
|
|
SequentialBlock sequBlock =
|
|
new SequentialBlock();
|
|
sequBlock.replace(appendBlock, appendBlock);
|
|
sequBlock.setFirst(appendBlock);
|
|
sequBlock.setSecond(succ.block);
|
|
}
|
|
|
|
mergeSuccessors(succ);
|
|
|
|
checkConsistent();
|
|
|
|
/* Try to eliminate as many jumps as possible.
|
|
*/
|
|
|
|
/* appendBlock may be zero, if this is the switchcase with
|
|
* precedingcase = null. But in this case, there can't be
|
|
* any jumps.
|
|
*/
|
|
if (appendBlock != null) {
|
|
|
|
appendBlock = optimizeJumps(succ, appendBlock);
|
|
|
|
checkConsistent();
|
|
|
|
// TabbedPrintWriter writer = new jode.TabbedPrintWriter(System.err, " ");
|
|
// try {
|
|
// writer.println("XXXXXXXXXXXXXXXX");
|
|
// writer.tab();
|
|
// dumpSource(writer);
|
|
// } catch(java.io.IOException ex) {}
|
|
|
|
appendBlock = resolveRemaining(succ, appendBlock);
|
|
}
|
|
|
|
/* Believe it or not: Now the rule, that the first part of a
|
|
* SequentialBlock shouldn't be another SequentialBlock is
|
|
* fulfilled. <p>
|
|
*
|
|
* This isn't easy to prove, it has a lot to do with the
|
|
* transformation in optimizeJump and the fact that
|
|
* appendBlock was the innermost Block containing all jumps
|
|
* and lastModified.
|
|
*/
|
|
|
|
/* Set last modified to correct value. */
|
|
lastModified = succ.lastModified;
|
|
|
|
/* Set addr+length to (semi-)correct value */
|
|
if (succ.addr < addr)
|
|
addr = succ.addr;
|
|
length += succ.length;
|
|
|
|
/* T1 transformation succeeded */
|
|
checkConsistent();
|
|
return true;
|
|
}
|
|
|
|
|
|
public boolean doT2(int start, int end) {
|
|
/* If there are no jumps to the beginning of this flow block
|
|
* or if this block has other predecessors with a higher
|
|
* address, return false. The second condition make sure that
|
|
* the while isn't created up to the first continue. */
|
|
if (!predecessors.contains(this))
|
|
return false;
|
|
|
|
Enumeration preds = predecessors.elements();
|
|
while (preds.hasMoreElements()) {
|
|
FlowBlock predFlow = (FlowBlock) preds.nextElement();
|
|
if (predFlow != null && predFlow != this
|
|
&& predFlow.addr >= start && predFlow.addr < end) {
|
|
return false;
|
|
}
|
|
}
|
|
|
|
checkConsistent();
|
|
|
|
/* Update the in/out-Vectors now */
|
|
updateInOut(this, false);
|
|
|
|
|
|
while (lastModified != block) {
|
|
lastModified = lastModified.outer;
|
|
if (lastModified instanceof SequentialBlock
|
|
&& lastModified.getSubBlocks()[0]
|
|
instanceof RawTryCatchBlock) {
|
|
|
|
/* We leave the catch block of a raw-try-catch-block.
|
|
* We shall now create the Catch- resp. FinallyBlock.
|
|
*/
|
|
lastModified =
|
|
createCatchBlock((SequentialBlock)lastModified);
|
|
}
|
|
}
|
|
|
|
/* If there is only one jump to the beginning and it is the
|
|
* last jump and (there is a do/while(0) block surrounding
|
|
* everything but the last instruction, or the last
|
|
* instruction is a increase/decrease statement), replace the
|
|
* do/while(0) with a for(;;last_instr) resp. create a new one
|
|
* and replace breaks to do/while with continue to for.
|
|
*/
|
|
/* XXX implement above */
|
|
/* XXX condition for do/while(cond) blocks */
|
|
{
|
|
/* Otherwise: */
|
|
|
|
/* create a new while(true) block.
|
|
*/
|
|
StructuredBlock bodyBlock = block;
|
|
|
|
/* Prepare the unification of the blocks: Make sure that
|
|
* bodyBlock has a jump. */
|
|
if (bodyBlock.jump == null) {
|
|
Jump jump = new Jump(this);
|
|
bodyBlock.setJump(jump);
|
|
successors.addElement(jump);
|
|
}
|
|
|
|
LoopBlock whileBlock =
|
|
new LoopBlock(LoopBlock.WHILE, LoopBlock.TRUE);
|
|
|
|
whileBlock.replace(bodyBlock, bodyBlock);
|
|
whileBlock.setBody(bodyBlock);
|
|
|
|
/* Try to eliminate as many jumps as possible.
|
|
*/
|
|
bodyBlock = optimizeJumps(this, bodyBlock);
|
|
|
|
/* if there are further jumps to this, replace every jump with a
|
|
* continue to while block and return true.
|
|
*/
|
|
Enumeration enum = successors.elements();
|
|
while (enum.hasMoreElements()) {
|
|
Jump jump = (Jump) enum.nextElement();
|
|
|
|
if (jump == null || jump.destination != this
|
|
|| jump.prev == bodyBlock)
|
|
continue;
|
|
|
|
int breaklevel = 0, continuelevel = 0;
|
|
BreakableBlock breakToBlock = null;
|
|
for (StructuredBlock surrounder = jump.prev.outer;
|
|
surrounder != whileBlock;
|
|
surrounder = surrounder.outer) {
|
|
if (surrounder instanceof BreakableBlock) {
|
|
if (surrounder instanceof LoopBlock)
|
|
continuelevel++;
|
|
breaklevel++;
|
|
if (surrounder.getNextFlowBlock() == this) {
|
|
breakToBlock = (BreakableBlock) surrounder;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
StructuredBlock prevBlock = jump.prev;
|
|
prevBlock.removeJump();
|
|
if (breakToBlock == null)
|
|
prevBlock.appendBlock
|
|
(new ContinueBlock(whileBlock, continuelevel > 0));
|
|
else
|
|
prevBlock.appendBlock
|
|
(new BreakBlock(breakToBlock, breaklevel > 1));
|
|
|
|
}
|
|
|
|
/* Now remove the jump of block if it points to this.
|
|
*/
|
|
if (bodyBlock.jump != null &&
|
|
bodyBlock.jump.destination == this)
|
|
bodyBlock.removeJump();
|
|
|
|
lastModified = whileBlock;
|
|
}
|
|
|
|
/* remove ourself from the predecessor list.
|
|
*/
|
|
predecessors.removeElement(this);
|
|
|
|
/* T2 analysis succeeded */
|
|
checkConsistent();
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
/**
|
|
* Do a T1 transformation with the end_of_method block.
|
|
*/
|
|
public void mergeEndBlock() {
|
|
checkConsistent();
|
|
|
|
/* First find the innermost block that contains all jumps to the
|
|
* END_OF_METHOD block.
|
|
*/
|
|
Enumeration enum = successors.elements();
|
|
StructuredBlock appendBlock = lastModified;
|
|
while(enum.hasMoreElements()) {
|
|
Jump jump = (Jump) enum.nextElement();
|
|
if (jump == null || jump.destination != END_OF_METHOD)
|
|
continue;
|
|
|
|
while (!appendBlock.contains(jump.prev)) {
|
|
appendBlock = appendBlock.outer;
|
|
if (appendBlock instanceof SequentialBlock
|
|
&& appendBlock.getSubBlocks()[0]
|
|
instanceof RawTryCatchBlock) {
|
|
|
|
/* We leave the catch block of a raw-try-catch-block.
|
|
* We shall now create the Catch- resp. FinallyBlock.
|
|
*/
|
|
appendBlock =
|
|
createCatchBlock((SequentialBlock)appendBlock);
|
|
}
|
|
}
|
|
/* appendBlock can't be null now, because the
|
|
* outermost block contains every structured block.
|
|
*/
|
|
}
|
|
|
|
/* Try to eliminate as many jumps as possible.
|
|
*/
|
|
|
|
appendBlock = optimizeJumps(END_OF_METHOD, appendBlock);
|
|
|
|
enum = successors.elements();
|
|
next_jump:
|
|
while (enum.hasMoreElements()) {
|
|
Jump jump = (Jump) enum.nextElement();
|
|
|
|
if (jump == null || jump.destination != END_OF_METHOD ||
|
|
jump.prev == appendBlock)
|
|
continue;
|
|
|
|
BreakableBlock breakToBlock = null;
|
|
for (StructuredBlock surrounder = jump.prev.outer;
|
|
surrounder != null && surrounder != appendBlock.outer;
|
|
surrounder = surrounder.outer) {
|
|
if (surrounder instanceof BreakableBlock) {
|
|
if (surrounder.getNextFlowBlock() == END_OF_METHOD)
|
|
breakToBlock = (BreakableBlock) surrounder;
|
|
|
|
/* We don't want labeled breaks, because we can
|
|
* simply return. */
|
|
break;
|
|
}
|
|
}
|
|
StructuredBlock prevBlock = jump.prev;
|
|
prevBlock.removeJump();
|
|
|
|
if (breakToBlock == null)
|
|
/* The successor is the dummy return instruction, so
|
|
* replace the jump with a return.
|
|
*/
|
|
prevBlock.appendBlock(new ReturnBlock());
|
|
else
|
|
prevBlock.appendBlock
|
|
(new BreakBlock(breakToBlock, false));
|
|
}
|
|
|
|
/* Now remove the jump of the appendBlock if it points to
|
|
* successor.
|
|
*/
|
|
if (appendBlock.jump != null
|
|
&& appendBlock.jump.destination == END_OF_METHOD)
|
|
appendBlock.removeJump();
|
|
|
|
/* transformation succeeded */
|
|
checkConsistent();
|
|
}
|
|
|
|
|
|
static Transformation[] exprTrafos = {
|
|
new RemoveEmpty(),
|
|
new CreateExpression(),
|
|
new CreatePostIncExpression(),
|
|
new CreateAssignExpression(),
|
|
new CreateNewConstructor(),
|
|
new CombineIfGotoExpressions(),
|
|
new CreateIfThenElseOperator(),
|
|
new CreateConstantArray(),
|
|
new SimplifyExpression()
|
|
};
|
|
|
|
|
|
/**
|
|
* Search for an apropriate successor.
|
|
* @param prevSucc The successor, that was previously tried.
|
|
* @param start The minimum address.
|
|
* @param end The maximum address + 1.
|
|
* @return the successor with smallest address greater than prevSucc
|
|
* or null if there isn't any further successor at all.
|
|
*/
|
|
FlowBlock getSuccessor(int start, int end) {
|
|
/* search successor with smallest addr. */
|
|
Enumeration enum = successors.elements();
|
|
FlowBlock succ = null;
|
|
while (enum.hasMoreElements()) {
|
|
Jump jump = (Jump) enum.nextElement();
|
|
if (jump == null)
|
|
continue;
|
|
FlowBlock fb = jump.destination;
|
|
if (fb.addr < start || fb.addr >= end || fb == this)
|
|
continue;
|
|
if (succ == null || fb.addr < succ.addr) {
|
|
succ = fb;
|
|
}
|
|
}
|
|
return succ;
|
|
}
|
|
|
|
/**
|
|
* The main analyzation. This calls doT1 and doT2 on apropriate
|
|
* regions until the whole function is transformed to a single
|
|
* block.
|
|
*/
|
|
public void analyze() {
|
|
analyze(0, Integer.MAX_VALUE);
|
|
mergeEndBlock();
|
|
}
|
|
|
|
/**
|
|
* The main analyzation. This calls doT1 and doT2 on apropriate
|
|
* regions. Only blocks whose address lies in the given address
|
|
* range are considered.
|
|
* @param start the start of the address range.
|
|
* @param end the end of the address range.
|
|
*/
|
|
public boolean analyze(int start, int end) {
|
|
try {
|
|
jode.TabbedPrintWriter writer = null;
|
|
if (Decompiler.isFlowDebugging)
|
|
writer = new jode.TabbedPrintWriter(System.err, " ");
|
|
|
|
boolean changed = false;
|
|
|
|
while (true) {
|
|
|
|
if (Decompiler.isFlowDebugging) {
|
|
writer.println("before Transformation: ");
|
|
writer.tab();
|
|
dumpSource(writer);
|
|
writer.untab();
|
|
}
|
|
|
|
/* First do some non flow transformations. */
|
|
int i=0;
|
|
while (i < exprTrafos.length) {
|
|
if (exprTrafos[i].transform(this))
|
|
i = 0;
|
|
else
|
|
i++;
|
|
}
|
|
|
|
if (Decompiler.isFlowDebugging) {
|
|
writer.println("after Transformation: ");
|
|
writer.tab();
|
|
dumpSource(writer);
|
|
writer.untab();
|
|
}
|
|
|
|
if (doT2(start, end)) {
|
|
|
|
if (Decompiler.isFlowDebugging) {
|
|
writer.println("after T2: ");
|
|
writer.tab();
|
|
dumpSource(writer);
|
|
writer.untab();
|
|
}
|
|
|
|
/* T2 transformation succeeded. This may
|
|
* make another T1 analysis in the previous
|
|
* block possible.
|
|
*/
|
|
if (addr != 0)
|
|
return true;
|
|
}
|
|
|
|
FlowBlock succ = getSuccessor(start, end);
|
|
while (true) {
|
|
if (succ == null) {
|
|
/* the Block has no successor where t1 is applicable.
|
|
* Finish this analyzation.
|
|
*/
|
|
if (Decompiler.isFlowDebugging) {
|
|
writer.println("No more successors applicable: "
|
|
+ start + " - " + end + "; "
|
|
+ addr + " - " + (addr+length));
|
|
}
|
|
return changed;
|
|
} else {
|
|
/* Only do T1 transformation if the blocks are
|
|
* adjacent. */
|
|
if (succ.block instanceof SwitchBlock) {
|
|
/* analyze succ, the new region is the
|
|
* continous region of
|
|
* [start,end) \cap \compl [addr, addr+length)
|
|
* where succ.addr lies in.
|
|
*/
|
|
int newStart = (succ.addr > addr)
|
|
? addr+length : start;
|
|
int newEnd = (succ.addr > addr)
|
|
? end : addr;
|
|
if (succ.analyzeSwitch(newStart, newEnd))
|
|
break;
|
|
|
|
} if ((succ.addr == addr+length
|
|
|| succ.addr+succ.length == addr)
|
|
&& doT1(succ)) {
|
|
/* T1 transformation succeeded. */
|
|
changed = true;
|
|
|
|
if (Decompiler.isFlowDebugging) {
|
|
writer.println("after T1: ");
|
|
writer.tab();
|
|
dumpSource(writer);
|
|
writer.untab();
|
|
}
|
|
break;
|
|
} else {
|
|
/* analyze succ, the new region is the
|
|
* continous region of
|
|
* [start,end) \cap \compl [addr, addr+length)
|
|
* where succ.addr lies in.
|
|
*/
|
|
int newStart = (succ.addr > addr)
|
|
? addr+length : start;
|
|
int newEnd = (succ.addr > addr)
|
|
? end : addr;
|
|
if (succ.analyze(newStart, newEnd))
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* Try the next successor.
|
|
*/
|
|
succ = getSuccessor(succ.addr+1, end);
|
|
}
|
|
}
|
|
} catch (java.io.IOException ioex) {
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* The switch analyzation. This calls doSwitchT1 and doT2 on apropriate
|
|
* regions. Only blocks whose address lies in the given address
|
|
* range are considered and it is taken care of, that the switch
|
|
* is never leaved. <p>
|
|
* The current flow block must contain the switch block as main
|
|
* block.
|
|
* @param start the start of the address range.
|
|
* @param end the end of the address range.
|
|
*/
|
|
public boolean analyzeSwitch(int start, int end) {
|
|
SwitchBlock switchBlock = (SwitchBlock) block;
|
|
boolean changed = false;
|
|
StructuredBlock lastBlock = null;
|
|
lastModified = block;
|
|
/* XXX - move to switchBlock??? */
|
|
for (int i=0; i < switchBlock.caseBlocks.length; i++) {
|
|
if (switchBlock.caseBlocks[i].subBlock != null
|
|
&& switchBlock.caseBlocks[i].subBlock.jump != null) {
|
|
FlowBlock next = switchBlock.caseBlocks[i].
|
|
subBlock.jump.destination;
|
|
if (next.addr >= end)
|
|
return changed;
|
|
else if (next.addr >= start) {
|
|
|
|
/* First analyze the next block. It may
|
|
* return early after a T2 trafo so call it
|
|
* until nothing more is possible.
|
|
*/
|
|
while (next.analyze(addr + length, end))
|
|
changed = changed || true;
|
|
|
|
if (next.addr != addr + length)
|
|
return changed;
|
|
|
|
/* Check if next has only the previous case
|
|
* and this case as predecessor. Otherwise
|
|
* break the analysis.
|
|
*/
|
|
if (next.predecessors.size() != 1
|
|
|| next.predecessors.elementAt(0) != this)
|
|
return changed;
|
|
|
|
boolean lastContains = false;
|
|
for (int j=0; j<successors.size(); j++) {
|
|
Jump jump = (Jump) successors.elementAt(j);
|
|
if (jump != null && jump.destination == next
|
|
&& jump !=
|
|
switchBlock.caseBlocks[i].subBlock.jump) {
|
|
if (lastBlock != null
|
|
&& lastBlock.contains(jump.prev))
|
|
lastContains = true;
|
|
else
|
|
return changed;
|
|
}
|
|
}
|
|
checkConsistent();
|
|
|
|
updateInOut(next, true);
|
|
switchBlock.caseBlocks[i].subBlock.removeJump();
|
|
next.block.replace(switchBlock.caseBlocks[i].subBlock,
|
|
null);
|
|
|
|
mergeSuccessors(next);
|
|
if (lastContains) {
|
|
lastBlock = optimizeJumps(next, lastBlock);
|
|
lastBlock = resolveRemaining(next, lastBlock);
|
|
}
|
|
|
|
/* Set length to correct value */
|
|
length += next.length;
|
|
|
|
lastBlock = next.block;
|
|
checkConsistent();
|
|
changed = true;
|
|
}
|
|
}
|
|
}
|
|
return changed;
|
|
}
|
|
|
|
/**
|
|
* Resolves the destinations of all jumps.
|
|
*/
|
|
public void resolveJumps(FlowBlock[] instr) {
|
|
Enumeration enum = successors.elements();
|
|
while (enum.hasMoreElements()) {
|
|
Jump jump = (Jump) enum.nextElement();
|
|
if (jump != null) {
|
|
if (jump.destAddr == -1)
|
|
jump.destination = END_OF_METHOD;
|
|
else
|
|
jump.destination = instr[jump.destAddr];
|
|
if (!jump.destination.predecessors.contains(this))
|
|
jump.destination.predecessors.addElement(this);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Mark the flow block as first flow block in a method.
|
|
*/
|
|
public void makeStartBlock() {
|
|
predecessors.addElement(null);
|
|
}
|
|
|
|
public void addSuccessor(Jump jump) {
|
|
successors.addElement(jump);
|
|
if (!jump.destination.predecessors.contains(this))
|
|
jump.destination.predecessors.addElement(this);
|
|
}
|
|
|
|
public void removeSuccessor(Jump jump) {
|
|
successors.setElementAt(null, successors.indexOf(jump));
|
|
}
|
|
|
|
public void makeDeclaration(VariableSet param) {
|
|
in.merge(param);
|
|
in.subtract(param);
|
|
block.propagateUsage();
|
|
block.makeDeclaration(param);
|
|
}
|
|
|
|
/**
|
|
* Print the source code for this structured block. This handles
|
|
* everything that is unique for all structured blocks and calls
|
|
* dumpInstruction afterwards.
|
|
* @param writer The tabbed print writer, where we print to.
|
|
*/
|
|
public void dumpSource(TabbedPrintWriter writer)
|
|
throws java.io.IOException
|
|
{
|
|
if (predecessors.size() != 1 ||
|
|
predecessors.elementAt(0) != null) {
|
|
writer.untab();
|
|
writer.println(label+":");
|
|
writer.tab();
|
|
}
|
|
|
|
if (Decompiler.debugInOut) {
|
|
writer.println("in: "+in);
|
|
}
|
|
|
|
block.dumpSource(writer);
|
|
}
|
|
|
|
/**
|
|
* The serial number for labels.
|
|
*/
|
|
static int serialno = 0;
|
|
|
|
/**
|
|
* The label of this instruction, or null if it needs no label.
|
|
*/
|
|
String label = null;
|
|
|
|
/**
|
|
* Returns the label of this block and creates a new label, if
|
|
* there wasn't a label previously.
|
|
*/
|
|
public String getLabel() {
|
|
if (label == null)
|
|
label = "flow_"+addr+"_"+(serialno++)+"_";
|
|
return label;
|
|
}
|
|
|
|
/**
|
|
* Returns the structured block, that this flow block contains.
|
|
*/
|
|
public StructuredBlock getBlock() {
|
|
return block;
|
|
}
|
|
}
|
|
|