fix: use correct top block for try blocks with same start (#1304)

jadx-core/src/main/java/jadx/core/dex/visitors/blocks/BlockExceptionHandler.java

@@ -323,23 +323,14 @@ public class BlockExceptionHandler {
 	private static boolean wrapBlocksWithTryCatch(MethodNode mth, TryCatchBlockAttr tryCatchBlock) {
 		List<BlockNode> blocks = tryCatchBlock.getBlocks();
 		BlockNode top = searchTopBlock(mth, blocks);
-		if (top.getPredecessors().isEmpty()) {
+		if (top.getPredecessors().isEmpty() && top != mth.getEnterBlock()) {
 			return false;
 		}
 		BlockNode bottom = searchBottomBlock(mth, blocks);
-
 		if (Consts.DEBUG_EXC_HANDLERS) {
 			LOG.debug("TryCatch #{} split: top {}, bottom: {}", tryCatchBlock.id(), top, bottom);
 		}
-
-		BlockNode topSplitterBlock;
-		if (top == mth.getEnterBlock()) {
-			BlockNode fixedTop = mth.getEnterBlock().getSuccessors().get(0);
-			topSplitterBlock = BlockSplitter.blockSplitTop(mth, fixedTop);
-		} else {
-			BlockNode existTopSplitter = BlockUtils.getBlockWithFlag(top.getPredecessors(), AFlag.EXC_TOP_SPLITTER);
-			topSplitterBlock = existTopSplitter != null ? existTopSplitter : BlockSplitter.blockSplitTop(mth, top);
-		}
+		BlockNode topSplitterBlock = getTopSplitterBlock(mth, top);
 		topSplitterBlock.add(AFlag.EXC_TOP_SPLITTER);
 		topSplitterBlock.add(AFlag.SYNTHETIC);
 
@@ -356,6 +347,10 @@ public class BlockExceptionHandler {
 			BlockSplitter.connect(bottom, bottomSplitterBlock);
 		}
 
+		if (Consts.DEBUG_EXC_HANDLERS) {
+			LOG.debug("TryCatch #{} result splitters: top {}, bottom: {}",
+					tryCatchBlock.id(), topSplitterBlock, bottomSplitterBlock);
+		}
 		connectSplittersAndHandlers(tryCatchBlock, topSplitterBlock, bottomSplitterBlock);
 
 		for (BlockNode block : blocks) {
@@ -373,6 +368,25 @@ public class BlockExceptionHandler {
 		return true;
 	}
 
+	private static BlockNode getTopSplitterBlock(MethodNode mth, BlockNode top) {
+		if (top == mth.getEnterBlock()) {
+			BlockNode fixedTop = mth.getEnterBlock().getSuccessors().get(0);
+			return BlockSplitter.blockSplitTop(mth, fixedTop);
+		}
+		BlockNode existPredTopSplitter = BlockUtils.getBlockWithFlag(top.getPredecessors(), AFlag.EXC_TOP_SPLITTER);
+		if (existPredTopSplitter != null) {
+			return existPredTopSplitter;
+		}
+		// try to reuse exists splitter on empty simple path below top block
+		if (top.getCleanSuccessors().size() == 1 && top.getInstructions().isEmpty()) {
+			BlockNode otherTopSplitter = BlockUtils.getBlockWithFlag(top.getCleanSuccessors(), AFlag.EXC_TOP_SPLITTER);
+			if (otherTopSplitter != null && otherTopSplitter.getPredecessors().size() == 1) {
+				return otherTopSplitter;
+			}
+		}
+		return BlockSplitter.blockSplitTop(mth, top);
+	}
+
 	private static BlockNode searchTopBlock(MethodNode mth, List<BlockNode> blocks) {
 		BlockNode top = BlockUtils.getTopBlock(blocks);
 		if (top != null) {

jadx-core/src/main/java/jadx/core/utils/BlockUtils.java

@@ -572,9 +572,9 @@ public class BlockUtils {
 		return traverseSuccessorsUntil(start, end, new BitSet(), false);
 	}
 
-	public static BlockNode getTopBlock(Collection<BlockNode> blocks) {
+	public static BlockNode getTopBlock(List<BlockNode> blocks) {
 		if (blocks.size() == 1) {
-			return blocks.iterator().next();
+			return blocks.get(0);
 		}
 		for (BlockNode from : blocks) {
 			boolean top = true;
@@ -594,9 +594,9 @@ public class BlockUtils {
 	/**
 	 * Search last block in control flow graph from input set.
 	 */
-	public static BlockNode getBottomBlock(Collection<BlockNode> blocks) {
+	public static BlockNode getBottomBlock(List<BlockNode> blocks) {
 		if (blocks.size() == 1) {
-			return blocks.iterator().next();
+			return blocks.get(0);
 		}
 		for (BlockNode bottomCandidate : blocks) {
 			boolean bottom = true;

jadx-core/src/main/java/jadx/core/utils/DebugUtils.java

@@ -59,6 +59,10 @@ public class DebugUtils {
 		}
 	}
 
+	public static void dumpRawTest(MethodNode mth, String desc) {
+		dumpRaw(mth, desc, method -> method.getName().equals("test"));
+	}
+
 	public static void dumpRaw(MethodNode mth, String desc) {
 		File out = new File("test-graph-" + desc + "-tmp");
 		DotGraphVisitor.dumpRaw().save(out, mth);

jadx-core/src/test/java/jadx/tests/integration/trycatch/TestTryCatchFinally13.java

+package jadx.tests.integration.trycatch;
+
+import jadx.tests.api.IntegrationTest;
+import jadx.tests.api.extensions.inputs.InputPlugin;
+import jadx.tests.api.extensions.inputs.TestWithInputPlugins;
+
+import static jadx.tests.api.utils.assertj.JadxAssertions.assertThat;
+
+public class TestTryCatchFinally13 extends IntegrationTest {
+
+	public static class TestCls {
+		public void test(int i) {
+			try {
+				doSomething1();
+				if (i == -12) {
+					return;
+				}
+				if (i > 10) {
+					doSomething2();
+				} else if (i == -1) {
+					doSomething3();
+				}
+			} catch (Exception ex) {
+				logError();
+			} finally {
+				doSomething4();
+			}
+		}
+
+		private void logError() {
+		}
+
+		private void doSomething1() {
+		}
+
+		private void doSomething2() {
+		}
+
+		private void doSomething3() {
+		}
+
+		private void doSomething4() {
+		}
+	}
+
+	@TestWithInputPlugins({ InputPlugin.DEX, InputPlugin.JAVA })
+	public void test() {
+		assertThat(getClassNode(TestCls.class))
+				.code()
+				.containsOne("} finally {");
+	}
+}