private void processExcHandler(ExceptionHandler handler, Set<BlockNode> exits) {
BlockNode start = handler.getHandlerBlock();
if (start == null) {
return;
}
RegionStack stack = new RegionStack(mth);
BlockNode dom;
if (handler.isFinally()) {
SplitterBlockAttr splitterAttr = start.get(AType.SPLITTER_BLOCK);
if (splitterAttr == null) {
return;
}
dom = splitterAttr.getBlock();
} else {
dom = start;
stack.addExits(exits);
}
BitSet domFrontier = dom.getDomFrontier();
List<BlockNode> handlerExits = BlockUtils.bitSetToBlocks(mth, domFrontier);
boolean inLoop = mth.getLoopForBlock(start) != null;
for (BlockNode exit : handlerExits) {
if ((!inLoop || BlockUtils.isPathExists(start, exit))
&& RegionUtils.isRegionContainsBlock(mth.getRegion(), exit)) {
stack.addExit(exit);
}
}
handler.setHandlerRegion(makeRegion(start, stack));
ExcHandlerAttr excHandlerAttr = start.get(AType.EXC_HANDLER);
if (excHandlerAttr == null) {
LOG.warn("Missing exception handler attribute for start block");
} else {
handler.getHandlerRegion().addAttr(excHandlerAttr);
}
}
private static boolean canInsertContinue(
BlockNode pred,
List<BlockNode> predecessors,
BlockNode loopEnd,
Set<BlockNode> loopExitNodes) {
if (!pred.contains(AFlag.SYNTHETIC) || BlockUtils.checkLastInsnType(pred, InsnType.CONTINUE)) {
return false;
}
List<BlockNode> preds = pred.getPredecessors();
if (preds.isEmpty()) {
return false;
}
BlockNode codePred = preds.get(0);
if (codePred.contains(AFlag.SKIP)) {
return false;
}
if (loopEnd.isDominator(codePred) || loopExitNodes.contains(codePred)) {
return false;
}
if (isDominatedOnBlocks(codePred, predecessors)) {
return false;
}
boolean gotoExit = false;
for (BlockNode exit : loopExitNodes) {
if (BlockUtils.isPathExists(codePred, exit)) {
gotoExit = true;
break;
}
}
return gotoExit;
}
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);
}
}
private boolean insertBreak(RegionStack stack, BlockNode loopExit, Edge exitEdge) {
BlockNode exit = exitEdge.getTarget();
BlockNode insertBlock = null;
boolean confirm = false;
// process special cases
if (loopExit == exit) {
// try/catch at loop end
BlockNode source = exitEdge.getSource();
if (source.contains(AType.CATCH_BLOCK) && source.getSuccessors().size() == 2) {
BlockNode other = BlockUtils.selectOther(loopExit, source.getSuccessors());
if (other != null) {
other = BlockUtils.skipSyntheticSuccessor(other);
if (other.contains(AType.EXC_HANDLER)) {
insertBlock = source;
confirm = true;
}
}
}
}
if (!confirm) {
while (exit != null) {
if (insertBlock != null && isPathExists(loopExit, exit)) {
// found cross
if (canInsertBreak(insertBlock)) {
confirm = true;
break;
}
return false;
}
insertBlock = exit;
List<BlockNode> cs = exit.getCleanSuccessors();
exit = cs.size() == 1 ? cs.get(0) : null;
}
}
if (!confirm) {
return false;
}
InsnNode breakInsn = new InsnNode(InsnType.BREAK, 0);
insertBlock.getInstructions().add(breakInsn);
stack.addExit(exit);
// add label to 'break' if needed
addBreakLabel(exitEdge, exit, breakInsn);
return true;
}
private boolean canInsertBreak(BlockNode exit) {
if (exit.contains(AFlag.RETURN) || BlockUtils.checkLastInsnType(exit, InsnType.BREAK)) {
return false;
}
List<BlockNode> simplePath = BlockUtils.buildSimplePath(exit);
if (!simplePath.isEmpty()) {
BlockNode lastBlock = simplePath.get(simplePath.size() - 1);
if (lastBlock.contains(AFlag.RETURN) || lastBlock.getSuccessors().isEmpty()) {
return false;
}
}
// check if there no outer switch (TODO: very expensive check)
Set<BlockNode> paths = BlockUtils.getAllPathsBlocks(mth.getEnterBlock(), exit);
for (BlockNode block : paths) {
if (BlockUtils.checkLastInsnType(block, InsnType.SWITCH)) {
return false;
}
}
return true;
}
/** 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;
}
private static void insertContinueInSwitch(BlockNode block, BlockNode out, BlockNode end) {
int endId = end.getId();
for (BlockNode s : block.getCleanSuccessors()) {
if (s.getDomFrontier().get(endId) && s != out) {
// search predecessor of loop end on path from this successor
List<BlockNode> list = BlockUtils.collectBlocksDominatedBy(s, s);
for (BlockNode p : end.getPredecessors()) {
if (list.contains(p)) {
if (p.isSynthetic()) {
p.getInstructions().add(new InsnNode(InsnType.CONTINUE, 0));
}
break;
}
}
}
}
}
public void processTryCatchBlocks(MethodNode mth) {
Set<TryCatchBlock> tcs = new HashSet<TryCatchBlock>();
for (ExceptionHandler handler : mth.getExceptionHandlers()) {
tcs.add(handler.getTryBlock());
}
for (TryCatchBlock tc : tcs) {
List<BlockNode> blocks = new ArrayList<BlockNode>(tc.getHandlersCount());
Set<BlockNode> splitters = new HashSet<BlockNode>();
for (ExceptionHandler handler : tc.getHandlers()) {
BlockNode handlerBlock = handler.getHandlerBlock();
if (handlerBlock != null) {
blocks.add(handlerBlock);
splitters.addAll(handlerBlock.getPredecessors());
} else {
LOG.debug(ErrorsCounter.formatErrorMsg(mth, "No exception handler block: " + handler));
}
}
Set<BlockNode> exits = new HashSet<BlockNode>();
for (BlockNode splitter : splitters) {
for (BlockNode handler : blocks) {
List<BlockNode> s = splitter.getSuccessors();
if (s.isEmpty()) {
LOG.debug(ErrorsCounter.formatErrorMsg(mth, "No successors for splitter: " + splitter));
continue;
}
BlockNode ss = s.get(0);
BlockNode cross = BlockUtils.getPathCross(mth, ss, handler);
if (cross != null && cross != ss && cross != handler) {
exits.add(cross);
}
}
}
for (ExceptionHandler handler : tc.getHandlers()) {
processExcHandler(handler, exits);
}
}
}
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;
}
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;
}
