private static void placePhi(MethodNode mth, int regNum, LiveVarAnalysis la) {
List<BlockNode> blocks = mth.getBasicBlocks();
int blocksCount = blocks.size();
BitSet hasPhi = new BitSet(blocksCount);
BitSet processed = new BitSet(blocksCount);
Deque<BlockNode> workList = new LinkedList<BlockNode>();
BitSet assignBlocks = la.getAssignBlocks(regNum);
for (int id = assignBlocks.nextSetBit(0); id >= 0; id = assignBlocks.nextSetBit(id + 1)) {
processed.set(id);
workList.add(blocks.get(id));
}
while (!workList.isEmpty()) {
BlockNode block = workList.pop();
BitSet domFrontier = block.getDomFrontier();
for (int id = domFrontier.nextSetBit(0); id >= 0; id = domFrontier.nextSetBit(id + 1)) {
if (!hasPhi.get(id) && la.isLive(id, regNum)) {
BlockNode df = blocks.get(id);
addPhi(df, regNum);
hasPhi.set(id);
if (!processed.get(id)) {
processed.set(id);
workList.add(df);
}
}
}
}
}
private static boolean removePhiList(MethodNode mth, List<PhiInsn> insnToRemove) {
if (insnToRemove.isEmpty()) {
return false;
}
for (BlockNode block : mth.getBasicBlocks()) {
PhiListAttr phiList = block.get(AType.PHI_LIST);
if (phiList == null) {
continue;
}
List<PhiInsn> list = phiList.getList();
for (PhiInsn phiInsn : insnToRemove) {
if (list.remove(phiInsn)) {
for (InsnArg arg : phiInsn.getArguments()) {
SSAVar sVar = ((RegisterArg) arg).getSVar();
if (sVar != null) {
sVar.setUsedInPhi(null);
}
}
InstructionRemover.remove(mth, block, phiInsn);
}
}
if (list.isEmpty()) {
block.remove(AType.PHI_LIST);
}
}
insnToRemove.clear();
return true;
}
private static void fixLastTryCatchAssign(MethodNode mth) {
for (BlockNode block : mth.getBasicBlocks()) {
PhiListAttr phiList = block.get(AType.PHI_LIST);
if (phiList == null || !block.contains(AType.EXC_HANDLER)) {
continue;
}
for (PhiInsn phi : phiList.getList()) {
for (int i = 0; i < phi.getArgsCount(); i++) {
RegisterArg arg = phi.getArg(i);
InsnNode parentInsn = arg.getAssignInsn();
if (parentInsn != null
&& parentInsn.getResult() != null
&& parentInsn.contains(AFlag.TRY_LEAVE)) {
phi.removeArg(arg);
}
}
}
}
}
private static boolean removeUselessPhi(MethodNode mth) {
List<PhiInsn> insnToRemove = new ArrayList<PhiInsn>();
for (SSAVar var : mth.getSVars()) {
// phi result not used
if (var.getUseCount() == 0) {
InsnNode assignInsn = var.getAssign().getParentInsn();
if (assignInsn != null && assignInsn.getType() == InsnType.PHI) {
insnToRemove.add((PhiInsn) assignInsn);
}
}
}
for (BlockNode block : mth.getBasicBlocks()) {
PhiListAttr phiList = block.get(AType.PHI_LIST);
if (phiList == null) {
continue;
}
for (PhiInsn phi : phiList.getList()) {
removePhiWithSameArgs(phi, insnToRemove);
}
}
return removePhiList(mth, insnToRemove);
}
public RegionMaker(MethodNode mth) {
this.mth = mth;
if (Consts.DEBUG) {
this.processedBlocks = new BitSet(mth.getBasicBlocks().size());
}
}
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;
}
