core: insert 'continue' instruction

jadx-core/src/main/java/jadx/core/codegen/InsnGen.java

@@ -440,7 +440,7 @@ public class InsnGen {
 				makeTernary((TernaryInsn) insn, code, state);
 				break;
 
-			case ARGS:
+			case ONE_ARG:
 				addArg(code, insn.getArg(0));
 				break;
 

jadx-core/src/main/java/jadx/core/dex/instructions/InsnType.java

 package jadx.core.dex.instructions;
 
 public enum InsnType {
-	NOP, // replacement for removed instructions
 
 	CONST,
 	CONST_STR,
@@ -48,16 +47,24 @@ public enum InsnType {
 
 	INVOKE,
 
-	// additional instructions
+	// *** Additional instructions ***
+
+	// replacement for removed instructions
+	NOP,
+
+	TERNARY,
 	CONSTRUCTOR,
+
 	BREAK,
 	CONTINUE,
 
-	STR_CONCAT, // strings concatenation
+	// strings concatenation
+	STR_CONCAT,
 
-	TERNARY,
-	ARGS, // just generate arguments
+	// just generate one argument
+	ONE_ARG,
 	PHI,
 
-	NEW_MULTIDIM_ARRAY // TODO: now multidimensional arrays created using Array.newInstance function
+	// TODO: now multidimensional arrays created using Array.newInstance function
+	NEW_MULTIDIM_ARRAY
 }

jadx-core/src/main/java/jadx/core/dex/nodes/InsnNode.java

@@ -36,7 +36,7 @@ public class InsnNode extends LineAttrNode {
 	}
 
 	public static InsnNode wrapArg(InsnArg arg) {
-		InsnNode insn = new InsnNode(InsnType.ARGS, 1);
+		InsnNode insn = new InsnNode(InsnType.ONE_ARG, 1);
 		insn.addArg(arg);
 		return insn;
 	}

jadx-core/src/main/java/jadx/core/dex/nodes/MethodNode.java

@@ -34,6 +34,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
+import org.jetbrains.annotations.NotNull;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -519,7 +520,7 @@ public class MethodNode extends LineAttrNode implements ILoadable {
 		return debugInfoOffset;
 	}
 
-	public SSAVar makeNewSVar(int regNum, int[] versions, RegisterArg arg) {
+	public SSAVar makeNewSVar(int regNum, int[] versions, @NotNull RegisterArg arg) {
 		SSAVar var = new SSAVar(regNum, versions[regNum], arg);
 		versions[regNum]++;
 		if (sVars.isEmpty()) {

jadx-core/src/main/java/jadx/core/dex/visitors/BlockMakerVisitor.java

@@ -427,9 +427,9 @@ public class BlockMakerVisitor extends AbstractVisitor {
 					return true;
 				}
 			}
-			// insert additional blocks if loop has several exits
 			if (loops.size() == 1) {
 				LoopInfo loop = loops.get(0);
+				// insert additional blocks for possible 'break' insertion
 				List<Edge> edges = loop.getExitEdges();
 				if (!edges.isEmpty()) {
 					boolean change = false;
@@ -444,6 +444,21 @@ public class BlockMakerVisitor extends AbstractVisitor {
 						return true;
 					}
 				}
+				// insert additional blocks for possible 'continue' insertion
+				BlockNode loopEnd = loop.getEnd();
+				if (loopEnd.getPredecessors().size() > 1) {
+					boolean change = false;
+					List<BlockNode> nodes = new ArrayList<BlockNode>(loopEnd.getPredecessors());
+					for (BlockNode pred : nodes) {
+						if (!pred.contains(AFlag.SYNTHETIC)) {
+							insertBlockBetween(mth, pred, loopEnd);
+							change = true;
+						}
+					}
+					if (change) {
+						return true;
+					}
+				}
 			}
 		}
 		return splitReturn(mth);

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

@@ -239,13 +239,19 @@ public class IfMakerHelper {
 	}
 
 	static void confirmMerge(IfInfo info) {
-		for (BlockNode block : info.getMergedBlocks()) {
-			block.add(AFlag.SKIP);
+		if (info.getMergedBlocks().size() > 1) {
+			for (BlockNode block : info.getMergedBlocks()) {
+				if (block != info.getIfBlock()) {
+					block.add(AFlag.SKIP);
+				}
+			}
 		}
-		for (BlockNode block : info.getSkipBlocks()) {
-			block.add(AFlag.SKIP);
+		if (!info.getSkipBlocks().isEmpty()) {
+			for (BlockNode block : info.getSkipBlocks()) {
+				block.add(AFlag.SKIP);
+			}
+			info.getSkipBlocks().clear();
 		}
-		info.getSkipBlocks().clear();
 	}
 
 	private static IfInfo getNextIf(IfInfo info, BlockNode block) {

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

@@ -166,7 +166,9 @@ public class RegionMaker {
 
 		LoopRegion loopRegion = makeLoopRegion(curRegion, loop, exitBlocks);
 		if (loopRegion == null) {
-			return makeEndlessLoop(curRegion, stack, loop, loopStart);
+			BlockNode exit = makeEndlessLoop(curRegion, stack, loop, loopStart);
+			insertContinueInsns(loop);
+			return exit;
 		}
 		curRegion.getSubBlocks().add(loopRegion);
 		IRegion outerRegion = stack.peekRegion();
@@ -233,6 +235,7 @@ public class RegionMaker {
 			loopRegion.setBody(body);
 		}
 		stack.pop();
+		insertContinueInsns(loop);
 		return out;
 	}
 
@@ -359,9 +362,12 @@ public class RegionMaker {
 			if (source.contains(AType.CATCH_BLOCK)
 					&& source.getSuccessors().size() == 2) {
 				BlockNode other = BlockUtils.selectOther(loopExit, source.getSuccessors());
-				if (other != null && other.contains(AType.EXC_HANDLER)) {
-					insertBlock = source;
-					confirm = true;
+				if (other != null) {
+					other = BlockUtils.skipSyntheticSuccessor(other);
+					if (other.contains(AType.EXC_HANDLER)) {
+						insertBlock = source;
+						confirm = true;
+					}
 				}
 			}
 		}
@@ -405,6 +411,45 @@ public class RegionMaker {
 		return true;
 	}
 
+	private static void insertContinueInsns(LoopInfo loop) {
+		BlockNode loopEnd = loop.getEnd();
+		List<BlockNode> predecessors = loopEnd.getPredecessors();
+		if (predecessors.size() <= 1) {
+			return;
+		}
+		for (BlockNode pred : predecessors) {
+			if (!pred.contains(AFlag.SYNTHETIC)
+					|| BlockUtils.checkLastInsnType(pred, InsnType.CONTINUE)) {
+				continue;
+			}
+			List<BlockNode> nodes = pred.getPredecessors();
+			if (nodes.isEmpty()) {
+				continue;
+			}
+			BlockNode codePred = nodes.get(0);
+			if (codePred.contains(AFlag.SKIP)) {
+				continue;
+			}
+			if (!isDominatedOnBlocks(codePred, predecessors)) {
+				for (BlockNode blockNode : predecessors) {
+					if (blockNode != pred && BlockUtils.isPathExists(codePred, blockNode)) {
+						InsnNode cont = new InsnNode(InsnType.CONTINUE, 0);
+						pred.getInstructions().add(cont);
+					}
+				}
+			}
+		}
+	}
+
+	private static boolean isDominatedOnBlocks(BlockNode dom, List<BlockNode> blocks) {
+		for (BlockNode node : blocks) {
+			if (!node.isDominator(dom)) {
+				return false;
+			}
+		}
+		return true;
+	}
+
 	private final Set<BlockNode> cacheSet = new HashSet<BlockNode>();
 
 	private BlockNode processMonitorEnter(IRegion curRegion, BlockNode block, InsnNode insn, RegionStack stack) {
@@ -444,7 +489,7 @@ public class RegionMaker {
 	 * Traverse from monitor-enter thru successors and collect blocks contains monitor-exit
 	 */
 	private static void traverseMonitorExits(SynchronizedRegion region, InsnArg arg, BlockNode block,
-	                                         Set<BlockNode> exits, Set<BlockNode> visited) {
+			Set<BlockNode> exits, Set<BlockNode> visited) {
 		visited.add(block);
 		for (InsnNode insn : block.getInstructions()) {
 			if (insn.getType() == InsnType.MONITOR_EXIT

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

@@ -439,4 +439,14 @@ public class BlockUtils {
 		}
 		return block == end;
 	}
+
+	/**
+	 * Return successor of synthetic block or same block otherwise.
+	 */
+	public static BlockNode skipSyntheticSuccessor(BlockNode block) {
+		if (block.isSynthetic() && !block.getSuccessors().isEmpty()) {
+			return block.getSuccessors().get(0);
+		}
+		return block;
+	}
 }

jadx-core/src/test/java/jadx/tests/integration/loops/TestContinueInLoop.java

+package jadx.tests.integration.loops;
+
+import jadx.core.dex.nodes.ClassNode;
+import jadx.tests.api.IntegrationTest;
+
+import org.junit.Test;
+
+import static jadx.tests.api.utils.JadxMatchers.containsOne;
+import static org.junit.Assert.assertThat;
+
+public class TestContinueInLoop extends IntegrationTest {
+
+	public static class TestCls {
+		private int f;
+
+		private void test(int[] a, int b) {
+			for (int i = 0; i < a.length; i++) {
+				int v = a[i];
+				if (v < b) {
+					a[i]++;
+				} else if (v > b) {
+					a[i]--;
+				} else {
+					continue;
+				}
+				if (i < b) {
+					break;
+				}
+			}
+			this.f++;
+		}
+	}
+
+	@Test
+	public void test() {
+		ClassNode cls = getClassNode(TestCls.class);
+		String code = cls.getCode().toString();
+
+		assertThat(code, containsOne("for (int i = 0; i < a.length; i++) {"));
+		assertThat(code, containsOne("if (i < b) {"));
+		assertThat(code, containsOne("continue;"));
+		assertThat(code, containsOne("break;"));
+		assertThat(code, containsOne("this.f++;"));
+	}
+}