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 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;
}
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;
}
