core: fix exit node search for synchronized block (fix #72)

jadx-core/src/main/java/jadx/core/dex/visitors/regions/RegionMaker.java

@@ -504,18 +504,21 @@ public class RegionMaker {
 		return true;
 	}
 
-	private final Set<BlockNode> cacheSet = new HashSet<BlockNode>();
-
 	private BlockNode processMonitorEnter(IRegion curRegion, BlockNode block, InsnNode insn, RegionStack stack) {
 		SynchronizedRegion synchRegion = new SynchronizedRegion(curRegion, insn);
 		synchRegion.getSubBlocks().add(block);
 		curRegion.getSubBlocks().add(synchRegion);
 
 		Set<BlockNode> exits = new HashSet<BlockNode>();
-		cacheSet.clear();
+		Set<BlockNode> cacheSet = new HashSet<BlockNode>();
 		traverseMonitorExits(synchRegion, insn.getArg(0), block, exits, cacheSet);
 
 		for (InsnNode exitInsn : synchRegion.getExitInsns()) {
+			BlockNode insnBlock = BlockUtils.getBlockByInsn(mth, exitInsn);
+			if (insnBlock != null) {
+				insnBlock.add(AFlag.SKIP);
+			}
+			exitInsn.add(AFlag.SKIP);
 			InstructionRemover.unbindInsn(mth, exitInsn);
 		}
 
@@ -524,16 +527,26 @@ public class RegionMaker {
 			ErrorsCounter.methodError(mth, "Unexpected end of synchronized block");
 			return null;
 		}
-		BlockNode exit;
+		BlockNode exit = null;
 		if (exits.size() == 1) {
 			exit = getNextBlock(exits.iterator().next());
-		} else {
+		} else if (exits.size() > 1) {
 			cacheSet.clear();
 			exit = traverseMonitorExitsCross(body, exits, cacheSet);
 		}
 
 		stack.push(synchRegion);
-		stack.addExit(exit);
+		if (exit != null) {
+			stack.addExit(exit);
+		} else {
+			for (BlockNode exitBlock : exits) {
+				// don't add exit blocks which leads to method end blocks ('return', 'throw', etc)
+				List<BlockNode> list = BlockUtils.buildSimplePath(exitBlock);
+				if (list.isEmpty() || !list.get(list.size() - 1).getSuccessors().isEmpty()) {
+					stack.addExit(exitBlock);
+				}
+			}
+		}
 		synchRegion.getSubBlocks().add(makeRegion(body, stack));
 		stack.pop();
 		return exit;

jadx-core/src/test/java/jadx/tests/integration/synchronize/TestSynchronized3.java

+package jadx.tests.integration.synchronize;
+
+import jadx.core.dex.nodes.ClassNode;
+import jadx.tests.api.IntegrationTest;
+
+import org.junit.Test;
+
+import static jadx.tests.api.utils.JadxMatchers.containsLines;
+import static org.junit.Assert.assertThat;
+
+public class TestSynchronized3 extends IntegrationTest {
+
+	public static class TestCls {
+		private int x;
+
+		public void f() {
+		}
+
+		public void test() {
+			while (true) {
+				synchronized (this) {
+					if (x == 0) {
+						throw new IllegalStateException("bad luck");
+					}
+					x++;
+					if (x == 10) {
+						break;
+					}
+				}
+				this.x++;
+				f();
+			}
+		}
+	}
+
+	@Test
+	public void test() {
+		ClassNode cls = getClassNode(TestCls.class);
+		String code = cls.getCode().toString();
+
+		assertThat(code, containsLines(3, "}", "this.x++;", "f();"));
+	}
+}