Exemplo n.º 1
0
  /** Recursively traverse all blocks from 'block' until block from 'exits' */
  private BlockNode traverse(IRegion r, BlockNode block, RegionStack stack) {
    BlockNode next = null;
    boolean processed = false;

    List<LoopInfo> loops = block.getAll(AType.LOOP);
    int loopCount = loops.size();
    if (loopCount != 0 && block.contains(AFlag.LOOP_START)) {
      if (loopCount == 1) {
        next = processLoop(r, loops.get(0), stack);
        processed = true;
      } else {
        for (LoopInfo loop : loops) {
          if (loop.getStart() == block) {
            next = processLoop(r, loop, stack);
            processed = true;
            break;
          }
        }
      }
    }

    if (!processed && block.getInstructions().size() == 1) {
      InsnNode insn = block.getInstructions().get(0);
      switch (insn.getType()) {
        case IF:
          next = processIf(r, block, (IfNode) insn, stack);
          processed = true;
          break;

        case SWITCH:
          next = processSwitch(r, block, (SwitchNode) insn, stack);
          processed = true;
          break;

        case MONITOR_ENTER:
          next = processMonitorEnter(r, block, insn, stack);
          processed = true;
          break;

        default:
          break;
      }
    }
    if (!processed) {
      r.getSubBlocks().add(block);
      next = getNextBlock(block);
    }
    if (next != null && !stack.containsExit(block) && !stack.containsExit(next)) {
      return next;
    }
    return null;
  }
Exemplo n.º 2
0
 private static void insertContinue(LoopInfo loop) {
   BlockNode loopEnd = loop.getEnd();
   List<BlockNode> predecessors = loopEnd.getPredecessors();
   if (predecessors.size() <= 1) {
     return;
   }
   Set<BlockNode> loopExitNodes = loop.getExitNodes();
   for (BlockNode pred : predecessors) {
     if (canInsertContinue(pred, predecessors, loopEnd, loopExitNodes)) {
       InsnNode cont = new InsnNode(InsnType.CONTINUE, 0);
       pred.getInstructions().add(cont);
     }
   }
 }
Exemplo n.º 3
0
 private void addBreakLabel(Edge exitEdge, BlockNode exit, InsnNode breakInsn) {
   BlockNode outBlock = BlockUtils.getNextBlock(exitEdge.getTarget());
   if (outBlock == null) {
     return;
   }
   List<LoopInfo> exitLoop = mth.getAllLoopsForBlock(outBlock);
   if (!exitLoop.isEmpty()) {
     return;
   }
   List<LoopInfo> inLoops = mth.getAllLoopsForBlock(exitEdge.getSource());
   if (inLoops.size() < 2) {
     return;
   }
   // search for parent loop
   LoopInfo parentLoop = null;
   for (LoopInfo loop : inLoops) {
     if (loop.getParentLoop() == null) {
       parentLoop = loop;
       break;
     }
   }
   if (parentLoop == null) {
     return;
   }
   if (parentLoop.getEnd() != exit && !parentLoop.getExitNodes().contains(exit)) {
     LoopLabelAttr labelAttr = new LoopLabelAttr(parentLoop);
     breakInsn.addAttr(labelAttr);
     parentLoop.getStart().addAttr(labelAttr);
   }
 }
Exemplo n.º 4
0
  private BlockNode makeEndlessLoop(
      IRegion curRegion, RegionStack stack, LoopInfo loop, BlockNode loopStart) {
    LoopRegion loopRegion = new LoopRegion(curRegion, loop, null, false);
    curRegion.getSubBlocks().add(loopRegion);

    loopStart.remove(AType.LOOP);
    stack.push(loopRegion);

    BlockNode loopExit = null;
    // insert 'break' for exits
    List<Edge> exitEdges = loop.getExitEdges();
    for (Edge exitEdge : exitEdges) {
      BlockNode exit = exitEdge.getTarget();
      if (insertBreak(stack, exit, exitEdge)) {
        BlockNode nextBlock = getNextBlock(exit);
        if (nextBlock != null) {
          stack.addExit(nextBlock);
          loopExit = nextBlock;
        }
      }
    }

    Region body = makeRegion(loopStart, stack);
    BlockNode loopEnd = loop.getEnd();
    if (!RegionUtils.isRegionContainsBlock(body, loopEnd)
        && !loopEnd.contains(AType.EXC_HANDLER)
        && !inExceptionHandlerBlocks(loopEnd)) {
      body.getSubBlocks().add(loopEnd);
    }
    loopRegion.setBody(body);

    if (loopExit == null) {
      BlockNode next = getNextBlock(loopEnd);
      loopExit = RegionUtils.isRegionContainsBlock(body, next) ? null : next;
    }
    stack.pop();
    loopStart.addAttr(AType.LOOP, loop);
    return loopExit;
  }
Exemplo n.º 5
0
 /** Select loop exit and construct LoopRegion */
 private LoopRegion makeLoopRegion(IRegion curRegion, LoopInfo loop, List<BlockNode> exitBlocks) {
   for (BlockNode block : exitBlocks) {
     if (block.contains(AType.EXC_HANDLER)
         || block.getInstructions().size() != 1
         || block.getInstructions().get(0).getType() != InsnType.IF) {
       continue;
     }
     List<LoopInfo> loops = block.getAll(AType.LOOP);
     if (!loops.isEmpty() && loops.get(0) != loop) {
       // skip nested loop condition
       continue;
     }
     LoopRegion loopRegion = new LoopRegion(curRegion, loop, block, block == loop.getEnd());
     boolean found;
     if (block == loop.getStart()
         || block == loop.getEnd()
         || BlockUtils.isEmptySimplePath(loop.getStart(), block)) {
       found = true;
     } else if (block.getPredecessors().contains(loop.getStart())) {
       loopRegion.setPreCondition(loop.getStart());
       // if we can't merge pre-condition this is not correct header
       found = loopRegion.checkPreCondition();
     } else {
       found = false;
     }
     if (found) {
       List<LoopInfo> list = mth.getAllLoopsForBlock(block);
       if (list.size() >= 2) {
         // bad condition if successors going out of all loops
         boolean allOuter = true;
         for (BlockNode outerBlock : block.getCleanSuccessors()) {
           List<LoopInfo> outLoopList = mth.getAllLoopsForBlock(outerBlock);
           outLoopList.remove(loop);
           if (!outLoopList.isEmpty()) {
             // goes to outer loop
             allOuter = false;
             break;
           }
         }
         if (allOuter) {
           found = false;
         }
       }
     }
     if (found) {
       return loopRegion;
     }
   }
   // no exit found => endless loop
   return null;
 }
Exemplo n.º 6
0
  private BlockNode processSwitch(
      IRegion currentRegion, BlockNode block, SwitchNode insn, RegionStack stack) {
    SwitchRegion sw = new SwitchRegion(currentRegion, block);
    currentRegion.getSubBlocks().add(sw);

    int len = insn.getTargets().length;
    // sort by target
    Map<Integer, List<Object>> casesMap = new LinkedHashMap<Integer, List<Object>>(len);
    for (int i = 0; i < len; i++) {
      Object key = insn.getKeys()[i];
      int targ = insn.getTargets()[i];
      List<Object> keys = casesMap.get(targ);
      if (keys == null) {
        keys = new ArrayList<Object>(2);
        casesMap.put(targ, keys);
      }
      keys.add(key);
    }

    Map<BlockNode, List<Object>> blocksMap = new LinkedHashMap<BlockNode, List<Object>>(len);
    for (Map.Entry<Integer, List<Object>> entry : casesMap.entrySet()) {
      BlockNode c = getBlockByOffset(entry.getKey(), block.getSuccessors());
      assert c != null;
      blocksMap.put(c, entry.getValue());
    }
    BlockNode defCase = getBlockByOffset(insn.getDefaultCaseOffset(), block.getSuccessors());
    if (defCase != null) {
      blocksMap.remove(defCase);
    }
    LoopInfo loop = mth.getLoopForBlock(block);

    Map<BlockNode, BlockNode> fallThroughCases = new LinkedHashMap<BlockNode, BlockNode>();

    List<BlockNode> basicBlocks = mth.getBasicBlocks();
    BitSet outs = new BitSet(basicBlocks.size());
    outs.or(block.getDomFrontier());
    for (BlockNode s : block.getCleanSuccessors()) {
      BitSet df = s.getDomFrontier();
      // fall through case block
      if (df.cardinality() > 1) {
        if (df.cardinality() > 2) {
          LOG.debug("Unexpected case pattern, block: {}, mth: {}", s, mth);
        } else {
          BlockNode first = basicBlocks.get(df.nextSetBit(0));
          BlockNode second = basicBlocks.get(df.nextSetBit(first.getId() + 1));
          if (second.getDomFrontier().get(first.getId())) {
            fallThroughCases.put(s, second);
            df = new BitSet(df.size());
            df.set(first.getId());
          } else if (first.getDomFrontier().get(second.getId())) {
            fallThroughCases.put(s, first);
            df = new BitSet(df.size());
            df.set(second.getId());
          }
        }
      }
      outs.or(df);
    }
    outs.clear(block.getId());
    if (loop != null) {
      outs.clear(loop.getStart().getId());
    }

    stack.push(sw);
    stack.addExits(BlockUtils.bitSetToBlocks(mth, outs));

    // check cases order if fall through case exists
    if (!fallThroughCases.isEmpty()) {
      if (isBadCasesOrder(blocksMap, fallThroughCases)) {
        LOG.debug("Fixing incorrect switch cases order, method: {}", mth);
        blocksMap = reOrderSwitchCases(blocksMap, fallThroughCases);
        if (isBadCasesOrder(blocksMap, fallThroughCases)) {
          LOG.error("Can't fix incorrect switch cases order, method: {}", mth);
          mth.add(AFlag.INCONSISTENT_CODE);
        }
      }
    }

    // filter 'out' block
    if (outs.cardinality() > 1) {
      // remove exception handlers
      BlockUtils.cleanBitSet(mth, outs);
    }
    if (outs.cardinality() > 1) {
      // filter loop start and successors of other blocks
      for (int i = outs.nextSetBit(0); i >= 0; i = outs.nextSetBit(i + 1)) {
        BlockNode b = basicBlocks.get(i);
        outs.andNot(b.getDomFrontier());
        if (b.contains(AFlag.LOOP_START)) {
          outs.clear(b.getId());
        } else {
          for (BlockNode s : b.getCleanSuccessors()) {
            outs.clear(s.getId());
          }
        }
      }
    }

    if (loop != null && outs.cardinality() > 1) {
      outs.clear(loop.getEnd().getId());
    }
    if (outs.cardinality() == 0) {
      // one or several case blocks are empty,
      // run expensive algorithm for find 'out' block
      for (BlockNode maybeOut : block.getSuccessors()) {
        boolean allReached = true;
        for (BlockNode s : block.getSuccessors()) {
          if (!isPathExists(s, maybeOut)) {
            allReached = false;
            break;
          }
        }
        if (allReached) {
          outs.set(maybeOut.getId());
          break;
        }
      }
    }
    BlockNode out = null;
    if (outs.cardinality() == 1) {
      out = basicBlocks.get(outs.nextSetBit(0));
      stack.addExit(out);
    } else if (loop == null && outs.cardinality() > 1) {
      LOG.warn("Can't detect out node for switch block: {} in {}", block, mth);
    }
    if (loop != null) {
      // check if 'continue' must be inserted
      BlockNode end = loop.getEnd();
      if (out != end && out != null) {
        insertContinueInSwitch(block, out, end);
      }
    }

    if (!stack.containsExit(defCase)) {
      sw.setDefaultCase(makeRegion(defCase, stack));
    }
    for (Entry<BlockNode, List<Object>> entry : blocksMap.entrySet()) {
      BlockNode caseBlock = entry.getKey();
      if (stack.containsExit(caseBlock)) {
        // empty case block
        sw.addCase(entry.getValue(), new Region(stack.peekRegion()));
      } else {
        BlockNode next = fallThroughCases.get(caseBlock);
        stack.addExit(next);
        Region caseRegion = makeRegion(caseBlock, stack);
        stack.removeExit(next);
        if (next != null) {
          next.add(AFlag.FALL_THROUGH);
          caseRegion.add(AFlag.FALL_THROUGH);
        }
        sw.addCase(entry.getValue(), caseRegion);
        // 'break' instruction will be inserted in RegionMakerVisitor.PostRegionVisitor
      }
    }

    stack.pop();
    return out;
  }
Exemplo n.º 7
0
  private BlockNode processLoop(IRegion curRegion, LoopInfo loop, RegionStack stack) {
    BlockNode loopStart = loop.getStart();
    Set<BlockNode> exitBlocksSet = loop.getExitNodes();

    // set exit blocks scan order priority
    // this can help if loop have several exits (after using 'break' or 'return' in loop)
    List<BlockNode> exitBlocks = new ArrayList<BlockNode>(exitBlocksSet.size());
    BlockNode nextStart = getNextBlock(loopStart);
    if (nextStart != null && exitBlocksSet.remove(nextStart)) {
      exitBlocks.add(nextStart);
    }
    if (exitBlocksSet.remove(loopStart)) {
      exitBlocks.add(loopStart);
    }
    if (exitBlocksSet.remove(loop.getEnd())) {
      exitBlocks.add(loop.getEnd());
    }
    exitBlocks.addAll(exitBlocksSet);

    LoopRegion loopRegion = makeLoopRegion(curRegion, loop, exitBlocks);
    if (loopRegion == null) {
      BlockNode exit = makeEndlessLoop(curRegion, stack, loop, loopStart);
      insertContinue(loop);
      return exit;
    }
    curRegion.getSubBlocks().add(loopRegion);
    IRegion outerRegion = stack.peekRegion();
    stack.push(loopRegion);

    IfInfo condInfo = makeIfInfo(loopRegion.getHeader());
    condInfo = searchNestedIf(condInfo);
    confirmMerge(condInfo);
    if (!loop.getLoopBlocks().contains(condInfo.getThenBlock())) {
      // invert loop condition if 'then' points to exit
      condInfo = IfInfo.invert(condInfo);
    }
    loopRegion.setCondition(condInfo.getCondition());
    exitBlocks.removeAll(condInfo.getMergedBlocks());

    if (!exitBlocks.isEmpty()) {
      BlockNode loopExit = condInfo.getElseBlock();
      if (loopExit != null) {
        // add 'break' instruction before path cross between main loop exit and sub-exit
        for (Edge exitEdge : loop.getExitEdges()) {
          if (!exitBlocks.contains(exitEdge.getSource())) {
            continue;
          }
          insertBreak(stack, loopExit, exitEdge);
        }
      }
    }

    BlockNode out;
    if (loopRegion.isConditionAtEnd()) {
      BlockNode thenBlock = condInfo.getThenBlock();
      out = thenBlock == loopStart ? condInfo.getElseBlock() : thenBlock;
      loopStart.remove(AType.LOOP);
      loop.getEnd().add(AFlag.SKIP);
      stack.addExit(loop.getEnd());
      loopRegion.setBody(makeRegion(loopStart, stack));
      loopStart.addAttr(AType.LOOP, loop);
      loop.getEnd().remove(AFlag.SKIP);
    } else {
      out = condInfo.getElseBlock();
      if (outerRegion != null
          && out.contains(AFlag.LOOP_START)
          && !out.getAll(AType.LOOP).contains(loop)
          && RegionUtils.isRegionContainsBlock(outerRegion, out)) {
        // exit to already processed outer loop
        out = null;
      }
      stack.addExit(out);
      BlockNode loopBody = condInfo.getThenBlock();
      Region body = makeRegion(loopBody, stack);
      // add blocks from loop start to first condition block
      BlockNode conditionBlock = condInfo.getIfBlock();
      if (loopStart != conditionBlock) {
        Set<BlockNode> blocks = BlockUtils.getAllPathsBlocks(loopStart, conditionBlock);
        blocks.remove(conditionBlock);
        for (BlockNode block : blocks) {
          if (block.getInstructions().isEmpty()
              && !block.contains(AFlag.SKIP)
              && !RegionUtils.isRegionContainsBlock(body, block)) {
            body.add(block);
          }
        }
      }
      loopRegion.setBody(body);
    }
    stack.pop();
    insertContinue(loop);
    return out;
  }