feat: add 'simple' decompilation mode

README.md

@@ -84,6 +84,11 @@ options:
   --output-format                     - can be 'java' or 'json', default: java
   -e, --export-gradle                 - save as android gradle project
   -j, --threads-count                 - processing threads count, default: 4
+  -m, --decompilation-mode            - code output mode:
+                                         'auto' - trying best options (default)
+                                         'restructure' - restore code structure (normal java code)
+                                         'simple' - simplified instructions (linear, with goto's)
+                                         'fallback' - raw instructions without modifications
   --show-bad-code                     - show inconsistent code (incorrectly decompiled)
   --no-imports                        - disable use of imports, always write entire package name
   --no-debug-info                     - disable debug info
@@ -115,7 +120,7 @@ options:
   --fs-case-sensitive                 - treat filesystem as case sensitive, false by default
   --cfg                               - save methods control flow graph to dot file
   --raw-cfg                           - save methods control flow graph (use raw instructions)
-  -f, --fallback                      - make simple dump (using goto instead of 'if', 'for', etc)
+  -f, --fallback                      - set '--decompilation-mode' to 'fallback' (deprecated)
   --use-dx                            - use dx/d8 to convert java bytecode
   --comments-level                    - set code comments level, values: error, warn, info, debug, user-only, none, default: info
   --log-level                         - set log level, values: quiet, progress, error, warn, info, debug, default: progress

jadx-cli/src/main/java/jadx/cli/JadxCLIArgs.java

@@ -15,6 +15,7 @@ import com.beust.jcommander.IStringConverter;
 import com.beust.jcommander.Parameter;
 
 import jadx.api.CommentsLevel;
+import jadx.api.DecompilationMode;
 import jadx.api.JadxArgs;
 import jadx.api.JadxArgs.RenameEnum;
 import jadx.api.JadxArgs.UseKotlinMethodsForVarNames;
@@ -58,6 +59,17 @@ public class JadxCLIArgs {
 	@Parameter(names = { "-j", "--threads-count" }, description = "processing threads count")
 	protected int threadsCount = JadxArgs.DEFAULT_THREADS_COUNT;
 
+	@Parameter(
+			names = { "-m", "--decompilation-mode" },
+			description = "code output mode:"
+					+ "\n 'auto' - trying best options (default)"
+					+ "\n 'restructure' - restore code structure (normal java code)"
+					+ "\n 'simple' - simplified instructions (linear, with goto's)"
+					+ "\n 'fallback' - raw instructions without modifications",
+			converter = RenameConverter.class
+	)
+	protected DecompilationMode decompilationMode = DecompilationMode.AUTO;
+
 	@Parameter(names = { "--show-bad-code" }, description = "show inconsistent code (incorrectly decompiled)")
 	protected boolean showInconsistentCode = false;
 
@@ -148,7 +160,7 @@ public class JadxCLIArgs {
 	@Parameter(names = { "--raw-cfg" }, description = "save methods control flow graph (use raw instructions)")
 	protected boolean rawCfgOutput = false;
 
-	@Parameter(names = { "-f", "--fallback" }, description = "make simple dump (using goto instead of 'if', 'for', etc)")
+	@Parameter(names = { "-f", "--fallback" }, description = "set '--decompilation-mode' to 'fallback' (deprecated)")
 	protected boolean fallbackMode = false;
 
 	@Parameter(names = { "--use-dx" }, description = "use dx/d8 to convert java bytecode")
@@ -236,7 +248,11 @@ public class JadxCLIArgs {
 		args.setThreadsCount(threadsCount);
 		args.setSkipSources(skipSources);
 		args.setSkipResources(skipResources);
-		args.setFallbackMode(fallbackMode);
+		if (fallbackMode) {
+			args.setDecompilationMode(DecompilationMode.FALLBACK);
+		} else {
+			args.setDecompilationMode(decompilationMode);
+		}
 		args.setShowInconsistentCode(showInconsistentCode);
 		args.setCfgOutput(cfgOutput);
 		args.setRawCFGOutput(rawCfgOutput);
@@ -313,6 +329,10 @@ public class JadxCLIArgs {
 		return useDx;
 	}
 
+	public DecompilationMode getDecompilationMode() {
+		return decompilationMode;
+	}
+
 	public boolean isShowInconsistentCode() {
 		return showInconsistentCode;
 	}
@@ -493,6 +513,19 @@ public class JadxCLIArgs {
 		}
 	}
 
+	public static class DecompilationModeConverter implements IStringConverter<DecompilationMode> {
+		@Override
+		public DecompilationMode convert(String value) {
+			try {
+				return DecompilationMode.valueOf(value.toUpperCase());
+			} catch (Exception e) {
+				throw new IllegalArgumentException(
+						'\'' + value + "' is unknown, possible values are: "
+								+ JadxCLIArgs.enumValuesString(DecompilationMode.values()));
+			}
+		}
+	}
+
 	public static String enumValuesString(Enum<?>[] values) {
 		return Stream.of(values)
 				.map(v -> v.name().replace('_', '-').toLowerCase(Locale.ROOT))

jadx-core/src/main/java/jadx/api/DecompilationMode.java

+package jadx.api;
+
+public enum DecompilationMode {
+	/**
+	 * Trying best options (default)
+	 */
+	AUTO,
+
+	/**
+	 * Restore code structure (normal java code)
+	 */
+	RESTRUCTURE,
+
+	/**
+	 * Simplified instructions (linear with goto's)
+	 */
+	SIMPLE,
+
+	/**
+	 * Raw instructions without modifications
+	 */
+	FALLBACK
+}

jadx-core/src/main/java/jadx/api/JadxArgs.java

@@ -38,7 +38,6 @@ public class JadxArgs {
 	private boolean cfgOutput = false;
 	private boolean rawCFGOutput = false;
 
-	private boolean fallbackMode = false;
 	private boolean showInconsistentCode = false;
 
 	private boolean useImports = true;
@@ -85,6 +84,8 @@ public class JadxArgs {
 
 	private OutputFormatEnum outputFormat = OutputFormatEnum.JAVA;
 
+	private DecompilationMode decompilationMode = DecompilationMode.AUTO;
+
 	private ICodeData codeData;
 
 	private CommentsLevel commentsLevel = CommentsLevel.INFO;
@@ -175,11 +176,17 @@ public class JadxArgs {
 	}
 
 	public boolean isFallbackMode() {
-		return fallbackMode;
+		return decompilationMode == DecompilationMode.FALLBACK;
 	}
 
+	/**
+	 * Deprecated: use 'decompilation mode' property
+	 */
+	@Deprecated
 	public void setFallbackMode(boolean fallbackMode) {
-		this.fallbackMode = fallbackMode;
+		if (fallbackMode) {
+			this.decompilationMode = DecompilationMode.FALLBACK;
+		}
 	}
 
 	public boolean isShowInconsistentCode() {
@@ -422,6 +429,14 @@ public class JadxArgs {
 		this.outputFormat = outputFormat;
 	}
 
+	public DecompilationMode getDecompilationMode() {
+		return decompilationMode;
+	}
+
+	public void setDecompilationMode(DecompilationMode decompilationMode) {
+		this.decompilationMode = decompilationMode;
+	}
+
 	public ICodeCache getCodeCache() {
 		return codeCache;
 	}
@@ -493,9 +508,7 @@ public class JadxArgs {
 				+ ", outDirSrc=" + outDirSrc
 				+ ", outDirRes=" + outDirRes
 				+ ", threadsCount=" + threadsCount
-				+ ", cfgOutput=" + cfgOutput
-				+ ", rawCFGOutput=" + rawCFGOutput
-				+ ", fallbackMode=" + fallbackMode
+				+ ", decompilationMode=" + decompilationMode
 				+ ", showInconsistentCode=" + showInconsistentCode
 				+ ", useImports=" + useImports
 				+ ", skipResources=" + skipResources
@@ -520,6 +533,8 @@ public class JadxArgs {
 				+ ", codeWriter=" + codeWriterProvider.apply(this).getClass().getSimpleName()
 				+ ", useDxInput=" + useDxInput
 				+ ", pluginOptions=" + pluginOptions
+				+ ", cfgOutput=" + cfgOutput
+				+ ", rawCFGOutput=" + rawCFGOutput
 				+ '}';
 	}
 }

jadx-core/src/main/java/jadx/core/Jadx.java

@@ -12,6 +12,7 @@ import org.slf4j.LoggerFactory;
 
 import jadx.api.CommentsLevel;
 import jadx.api.JadxArgs;
+import jadx.core.dex.attributes.AFlag;
 import jadx.core.dex.visitors.AnonymousClassVisitor;
 import jadx.core.dex.visitors.AttachCommentsVisitor;
 import jadx.core.dex.visitors.AttachMethodDetails;
@@ -32,6 +33,7 @@ import jadx.core.dex.visitors.InitCodeVariables;
 import jadx.core.dex.visitors.InlineMethods;
 import jadx.core.dex.visitors.MarkMethodsForInline;
 import jadx.core.dex.visitors.MethodInvokeVisitor;
+import jadx.core.dex.visitors.MethodVisitor;
 import jadx.core.dex.visitors.ModVisitor;
 import jadx.core.dex.visitors.MoveInlineVisitor;
 import jadx.core.dex.visitors.OverrideMethodVisitor;
@@ -62,6 +64,7 @@ import jadx.core.dex.visitors.shrink.CodeShrinkVisitor;
 import jadx.core.dex.visitors.ssa.SSATransform;
 import jadx.core.dex.visitors.typeinference.TypeInferenceVisitor;
 import jadx.core.dex.visitors.usage.UsageInfoVisitor;
+import jadx.core.utils.exceptions.JadxRuntimeException;
 
 public class Jadx {
 	private static final Logger LOG = LoggerFactory.getLogger(Jadx.class);
@@ -69,21 +72,20 @@ public class Jadx {
 	private Jadx() {
 	}
 
-	static {
-		if (Consts.DEBUG) {
-			LOG.info("debug enabled");
+	public static List<IDexTreeVisitor> getPassesList(JadxArgs args) {
+		switch (args.getDecompilationMode()) {
+			case AUTO:
+			case RESTRUCTURE:
+				return getRegionsModePasses(args);
+			case SIMPLE:
+				return getSimpleModePasses(args);
+			case FALLBACK:
+				return getFallbackPassesList();
+			default:
+				throw new JadxRuntimeException("Unknown decompilation mode: " + args.getDecompilationMode());
 		}
 	}
 
-	public static List<IDexTreeVisitor> getFallbackPassesList() {
-		List<IDexTreeVisitor> passes = new ArrayList<>();
-		passes.add(new AttachTryCatchVisitor());
-		passes.add(new AttachCommentsVisitor());
-		passes.add(new ProcessInstructionsVisitor());
-		passes.add(new FallbackModeVisitor());
-		return passes;
-	}
-
 	public static List<IDexTreeVisitor> getPreDecompilePassesList() {
 		List<IDexTreeVisitor> passes = new ArrayList<>();
 		passes.add(new SignatureProcessor());
@@ -95,12 +97,8 @@ public class Jadx {
 		return passes;
 	}
 
-	public static List<IDexTreeVisitor> getPassesList(JadxArgs args) {
-		if (args.isFallbackMode()) {
-			return getFallbackPassesList();
-		}
+	public static List<IDexTreeVisitor> getRegionsModePasses(JadxArgs args) {
 		List<IDexTreeVisitor> passes = new ArrayList<>();
-
 		// instructions IR
 		passes.add(new CheckCode());
 		if (args.isDebugInfo()) {
@@ -178,6 +176,56 @@ public class Jadx {
 		return passes;
 	}
 
+	public static List<IDexTreeVisitor> getSimpleModePasses(JadxArgs args) {
+		List<IDexTreeVisitor> passes = new ArrayList<>();
+		if (args.isDebugInfo()) {
+			passes.add(new DebugInfoAttachVisitor());
+		}
+		passes.add(new AttachTryCatchVisitor());
+		if (args.getCommentsLevel() != CommentsLevel.NONE) {
+			passes.add(new AttachCommentsVisitor());
+		}
+		passes.add(new ProcessInstructionsVisitor());
+		passes.add(new AttachMethodDetails());
+		passes.add(new ProcessInstructionsVisitor());
+
+		passes.add(new BlockSplitter());
+		passes.add(new MethodVisitor(mth -> mth.add(AFlag.DISABLE_BLOCKS_LOCK)));
+		passes.add(new BlockProcessor());
+		passes.add(new SSATransform());
+		passes.add(new MoveInlineVisitor());
+		passes.add(new ConstructorVisitor());
+		passes.add(new InitCodeVariables());
+		passes.add(new ConstInlineVisitor());
+		passes.add(new TypeInferenceVisitor());
+		if (args.isDebugInfo()) {
+			passes.add(new DebugInfoApplyVisitor());
+		}
+		passes.add(new CodeRenameVisitor());
+		passes.add(new DeboxingVisitor());
+		passes.add(new ModVisitor());
+		passes.add(new CodeShrinkVisitor());
+		passes.add(new ReSugarCode());
+		passes.add(new CodeShrinkVisitor());
+		passes.add(new SimplifyVisitor());
+		if (args.isRawCFGOutput()) {
+			passes.add(DotGraphVisitor.dumpRaw());
+		}
+		if (args.isCfgOutput()) {
+			passes.add(DotGraphVisitor.dump());
+		}
+		return passes;
+	}
+
+	public static List<IDexTreeVisitor> getFallbackPassesList() {
+		List<IDexTreeVisitor> passes = new ArrayList<>();
+		passes.add(new AttachTryCatchVisitor());
+		passes.add(new AttachCommentsVisitor());
+		passes.add(new ProcessInstructionsVisitor());
+		passes.add(new FallbackModeVisitor());
+		return passes;
+	}
+
 	public static final String VERSION_DEV = "dev";
 
 	private static String version;

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

@@ -356,7 +356,7 @@ public class ClassGen {
 				badCode = false;
 			}
 			MethodGen mthGen;
-			if (badCode || fallback || mth.contains(AType.JADX_ERROR) || mth.getRegion() == null) {
+			if (badCode || fallback || mth.contains(AType.JADX_ERROR)) {
 				mthGen = MethodGen.getFallbackMethodGen(mth);
 			} else {
 				mthGen = new MethodGen(this, mth);

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

@@ -50,6 +50,7 @@ import jadx.core.dex.instructions.args.RegisterArg;
 import jadx.core.dex.instructions.args.SSAVar;
 import jadx.core.dex.instructions.mods.ConstructorInsn;
 import jadx.core.dex.instructions.mods.TernaryInsn;
+import jadx.core.dex.nodes.BlockNode;
 import jadx.core.dex.nodes.ClassNode;
 import jadx.core.dex.nodes.FieldNode;
 import jadx.core.dex.nodes.InsnNode;
@@ -517,7 +518,7 @@ public class InsnGen {
 				code.add(' ');
 				code.add(ifInsn.getOp().getSymbol()).add(' ');
 				addArg(code, insn.getArg(1));
-				code.add(") goto ").add(MethodGen.getLabelName(ifInsn.getTarget()));
+				code.add(") goto ").add(MethodGen.getLabelName(ifInsn));
 				break;
 
 			case GOTO:
@@ -538,13 +539,24 @@ public class InsnGen {
 				code.add(") {");
 				code.incIndent();
 				int[] keys = sw.getKeys();
-				int[] targets = sw.getTargets();
-				for (int i = 0; i < keys.length; i++) {
-					code.startLine("case ").add(Integer.toString(keys[i])).add(": goto ");
-					code.add(MethodGen.getLabelName(targets[i])).add(';');
+				int size = keys.length;
+				BlockNode[] targetBlocks = sw.getTargetBlocks();
+				if (targetBlocks != null) {
+					for (int i = 0; i < size; i++) {
+						code.startLine("case ").add(Integer.toString(keys[i])).add(": goto ");
+						code.add(MethodGen.getLabelName(targetBlocks[i])).add(';');
+					}
+					code.startLine("default: goto ");
+					code.add(MethodGen.getLabelName(sw.getDefTargetBlock())).add(';');
+				} else {
+					int[] targets = sw.getTargets();
+					for (int i = 0; i < size; i++) {
+						code.startLine("case ").add(Integer.toString(keys[i])).add(": goto ");
+						code.add(MethodGen.getLabelName(targets[i])).add(';');
+					}
+					code.startLine("default: goto ");
+					code.add(MethodGen.getLabelName(sw.getDefaultCaseOffset())).add(';');
 				}
-				code.startLine("default: goto ");
-				code.add(MethodGen.getLabelName(sw.getDefaultCaseOffset())).add(';');
 				code.decIndent();
 				code.startLine('}');
 				break;

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

@@ -6,11 +6,13 @@ import java.util.List;
 import java.util.Objects;
 import java.util.stream.Stream;
 
+import org.jetbrains.annotations.Nullable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import jadx.api.CommentsLevel;
 import jadx.api.ICodeWriter;
+import jadx.api.JadxArgs;
 import jadx.api.data.annotations.InsnCodeOffset;
 import jadx.api.data.annotations.VarDeclareRef;
 import jadx.api.plugins.input.data.AccessFlags;
@@ -32,13 +34,14 @@ import jadx.core.dex.instructions.args.ArgType;
 import jadx.core.dex.instructions.args.CodeVar;
 import jadx.core.dex.instructions.args.RegisterArg;
 import jadx.core.dex.instructions.args.SSAVar;
+import jadx.core.dex.nodes.BlockNode;
 import jadx.core.dex.nodes.InsnNode;
 import jadx.core.dex.nodes.MethodNode;
 import jadx.core.dex.trycatch.CatchAttr;
+import jadx.core.dex.trycatch.ExceptionHandler;
 import jadx.core.dex.visitors.DepthTraversal;
 import jadx.core.dex.visitors.IDexTreeVisitor;
 import jadx.core.utils.CodeGenUtils;
-import jadx.core.utils.InsnUtils;
 import jadx.core.utils.Utils;
 import jadx.core.utils.exceptions.CodegenException;
 import jadx.core.utils.exceptions.JadxOverflowException;
@@ -252,12 +255,28 @@ public class MethodGen {
 	}
 
 	public void addInstructions(ICodeWriter code) throws CodegenException {
-		if (mth.root().getArgs().isFallbackMode()) {
-			addFallbackMethodCode(code, FALLBACK_MODE);
-		} else if (classGen.isFallbackMode()) {
-			dumpInstructions(code);
-		} else {
-			addRegionInsns(code);
+		JadxArgs args = mth.root().getArgs();
+		switch (args.getDecompilationMode()) {
+			case AUTO:
+				if (classGen.isFallbackMode()) {
+					// TODO: try simple mode first
+					dumpInstructions(code);
+				} else {
+					addRegionInsns(code);
+				}
+				break;
+
+			case RESTRUCTURE:
+				addRegionInsns(code);
+				break;
+
+			case SIMPLE:
+				addSimpleMethodCode(code);
+				break;
+
+			case FALLBACK:
+				addFallbackMethodCode(code, FALLBACK_MODE);
+				break;
 		}
 	}
 
@@ -279,6 +298,55 @@ public class MethodGen {
 		}
 	}
 
+	private void addSimpleMethodCode(ICodeWriter code) {
+		if (mth.getBasicBlocks() == null) {
+			code.startLine("// Blocks not ready for simple mode, using fallback");
+			addFallbackMethodCode(code, FALLBACK_MODE);
+			return;
+		}
+		JadxArgs args = mth.root().getArgs();
+		ICodeWriter tmpCode = args.getCodeWriterProvider().apply(args);
+		try {
+			tmpCode.setIndent(code.getIndent());
+			generateSimpleCode(tmpCode);
+			code.add(tmpCode);
+		} catch (Exception e) {
+			mth.addError("Simple mode code generation failed", e);
+			CodeGenUtils.addError(code, "Simple mode code generation failed", e);
+			dumpInstructions(code);
+		}
+	}
+
+	private void generateSimpleCode(ICodeWriter code) throws CodegenException {
+		SimpleModeHelper helper = new SimpleModeHelper(mth);
+		List<BlockNode> blocks = helper.prepareBlocks();
+		InsnGen insnGen = new InsnGen(this, true);
+		for (BlockNode block : blocks) {
+			if (block.contains(AFlag.DONT_GENERATE)) {
+				continue;
+			}
+			if (helper.isNeedStartLabel(block)) {
+				code.decIndent();
+				code.startLine(getLabelName(block)).add(':');
+				code.incIndent();
+			}
+			for (InsnNode insn : block.getInstructions()) {
+				if (!insn.contains(AFlag.DONT_GENERATE)) {
+					if (insn.getResult() != null) {
+						insn.add(AFlag.DECLARE_VAR);
+					}
+					InsnCodeOffset.attach(code, insn);
+					insnGen.makeInsn(insn, code);
+					addCatchComment(code, insn);
+					CodeGenUtils.addCodeComments(code, mth, insn);
+				}
+			}
+			if (helper.isNeedEndGoto(block)) {
+				code.startLine("goto ").add(getLabelName(block.getSuccessors().get(0)));
+			}
+		}
+	}
+
 	public void dumpInstructions(ICodeWriter code) {
 		if (mth.checkCommentsLevel(CommentsLevel.ERROR)) {
 			code.startLine("/*");
@@ -353,60 +421,77 @@ public class MethodGen {
 
 	public static void addFallbackInsns(ICodeWriter code, MethodNode mth, InsnNode[] insnArr, FallbackOption option) {
 		int startIndent = code.getIndent();
-		InsnGen insnGen = new InsnGen(getFallbackMethodGen(mth), true);
+		MethodGen methodGen = getFallbackMethodGen(mth);
+		InsnGen insnGen = new InsnGen(methodGen, true);
 		InsnNode prevInsn = null;
 		for (InsnNode insn : insnArr) {
 			if (insn == null) {
 				continue;
 			}
-			if (insn.contains(AType.JADX_ERROR)) {
-				for (JadxError error : insn.getAll(AType.JADX_ERROR)) {
-					code.startLine("// ").add(error.getError());
-				}
-				continue;
+			methodGen.dumpInsn(code, insnGen, option, startIndent, prevInsn, insn);
+			prevInsn = insn;
+		}
+	}
+
+	private boolean dumpInsn(ICodeWriter code, InsnGen insnGen, FallbackOption option, int startIndent,
+			@Nullable InsnNode prevInsn, InsnNode insn) {
+		if (insn.contains(AType.JADX_ERROR)) {
+			for (JadxError error : insn.getAll(AType.JADX_ERROR)) {
+				code.startLine("// ").add(error.getError());
 			}
-			if (option != BLOCK_DUMP && needLabel(insn, prevInsn)) {
+			return true;
+		}
+		if (option != BLOCK_DUMP && needLabel(insn, prevInsn)) {
+			code.decIndent();
+			code.startLine(getLabelName(insn.getOffset()) + ':');
+			code.incIndent();
+		}
+		if (insn.getType() == InsnType.NOP) {
+			return true;
+		}
+		try {
+			boolean escapeComment = isCommentEscapeNeeded(insn, option);
+			if (escapeComment) {
 				code.decIndent();
-				code.startLine(getLabelName(insn.getOffset()) + ':');
-				code.incIndent();
-			}
-			if (insn.getType() == InsnType.NOP) {
-				continue;
+				code.startLine("*/");
+				code.startLine("//  ");
+			} else {
+				code.startLineWithNum(insn.getSourceLine());
 			}
-			try {
-				boolean escapeComment = isCommentEscapeNeeded(insn, option);
-				if (escapeComment) {
-					code.decIndent();
-					code.startLine("*/");
-					code.startLine("//  ");
-				} else {
-					code.startLineWithNum(insn.getSourceLine());
-				}
-				InsnCodeOffset.attach(code, insn);
-				RegisterArg resArg = insn.getResult();
-				if (resArg != null) {
-					ArgType varType = resArg.getInitType();
-					if (varType.isTypeKnown()) {
-						code.add(varType.toString()).add(' ');
-					}
-				}
-				insnGen.makeInsn(insn, code, InsnGen.Flags.INLINE);
-				if (escapeComment) {
-					code.startLine("/*");
-					code.incIndent();
-				}
-
-				CatchAttr catchAttr = insn.get(AType.EXC_CATCH);
-				if (catchAttr != null) {
-					code.add("     // " + catchAttr);
+			InsnCodeOffset.attach(code, insn);
+			RegisterArg resArg = insn.getResult();
+			if (resArg != null) {
+				ArgType varType = resArg.getInitType();
+				if (varType.isTypeKnown()) {
+					code.add(varType.toString()).add(' ');
 				}
-				CodeGenUtils.addCodeComments(code, mth, insn);
-			} catch (Exception e) {
-				LOG.debug("Error generate fallback instruction: ", e.getCause());
-				code.setIndent(startIndent);
-				code.startLine("// error: " + insn);
 			}
-			prevInsn = insn;
+			insnGen.makeInsn(insn, code, InsnGen.Flags.INLINE);
+			if (escapeComment) {
+				code.startLine("/*");
+				code.incIndent();
+			}
+			addCatchComment(code, insn);
+			CodeGenUtils.addCodeComments(code, mth, insn);
+		} catch (Exception e) {
+			LOG.debug("Error generate fallback instruction: ", e.getCause());
+			code.setIndent(startIndent);
+			code.startLine("// error: " + insn);
+		}
+		return false;
+	}
+
+	private void addCatchComment(ICodeWriter code, InsnNode insn) {
+		CatchAttr catchAttr = insn.get(AType.EXC_CATCH);
+		if (catchAttr == null) {
+			return;
+		}
+		code.add("     // Catch:");
+		for (ExceptionHandler handler : catchAttr.getHandlers()) {
+			code.add(' ');
+			classGen.useClass(code, handler.getArgType());
+			code.add(" -> ");
+			code.add(getLabelName(handler.getHandlerOffset()));
 		}
 	}
 
@@ -449,7 +534,22 @@ public class MethodGen {
 		return new MethodGen(clsGen, mth);
 	}
 
+	public static String getLabelName(BlockNode block) {
+		return String.format("L%d", block.getId());
+	}
+
+	public static String getLabelName(IfNode insn) {
+		BlockNode thenBlock = insn.getThenBlock();
+		if (thenBlock != null) {
+			return getLabelName(thenBlock);
+		}
+		return getLabelName(insn.getTarget());
+	}
+
 	public static String getLabelName(int offset) {
-		return "L_" + InsnUtils.formatOffset(offset);
+		if (offset < 0) {
+			return String.format("LB_%x", -offset);
+		}
+		return String.format("L%x", offset);
 	}
 }

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

+package jadx.core.codegen;
+
+import java.util.ArrayList;
+import java.util.BitSet;
+import java.util.List;
+
+import org.jetbrains.annotations.Nullable;
+
+import jadx.core.dex.attributes.AFlag;
+import jadx.core.dex.attributes.AType;
+import jadx.core.dex.instructions.IfNode;
+import jadx.core.dex.instructions.TargetInsnNode;
+import jadx.core.dex.nodes.BlockNode;
+import jadx.core.dex.nodes.InsnNode;
+import jadx.core.dex.nodes.MethodNode;
+import jadx.core.dex.trycatch.ExceptionHandler;
+import jadx.core.dex.visitors.blocks.BlockProcessor;
+import jadx.core.dex.visitors.blocks.BlockSplitter;
+import jadx.core.utils.BlockUtils;
+
+public class SimpleModeHelper {
+
+	private final MethodNode mth;
+
+	private final BitSet startLabel;
+	private final BitSet endGoto;
+
+	public SimpleModeHelper(MethodNode mth) {
+		this.mth = mth;
+		this.startLabel = BlockUtils.newBlocksBitSet(mth);
+		this.endGoto = BlockUtils.newBlocksBitSet(mth);
+	}
+
+	public List<BlockNode> prepareBlocks() {
+		removeEmptyBlocks();
+		List<BlockNode> blocksList = getSortedBlocks();
+		blocksList.removeIf(b -> b.equals(mth.getEnterBlock()) || b.equals(mth.getExitBlock()));
+		unbindExceptionHandlers();
+		@Nullable
+		BlockNode prev = null;
+		int blocksCount = blocksList.size();
+		for (int i = 0; i < blocksCount; i++) {
+			BlockNode block = blocksList.get(i);
+			List<BlockNode> preds = block.getPredecessors();
+			int predsCount = preds.size();
+			if (predsCount > 1) {
+				startLabel.set(block.getId());
+			} else if (predsCount == 1 && prev != null) {
+				if (!prev.equals(preds.get(0))) {
+					startLabel.set(block.getId());
+					if (prev.getSuccessors().size() == 1 && !prev.contains(AFlag.RETURN)) {
+						endGoto.set(prev.getId());
+					}
+				}
+			}
+			InsnNode lastInsn = BlockUtils.getLastInsn(block);
+			if (lastInsn instanceof TargetInsnNode) {
+				processTargetInsn(block, lastInsn);
+			}
+			if (block.contains(AType.EXC_HANDLER)) {
+				startLabel.set(block.getId());
+			}
+			if (i + 1 >= blocksCount && !mth.isPreExitBlocks(block)) {
+				endGoto.set(block.getId());
+			}
+			prev = block;
+		}
+		return blocksList;
+	}
+
+	private void removeEmptyBlocks() {
+		for (BlockNode block : mth.getBasicBlocks()) {
+			if (block.getInstructions().isEmpty()
+					&& block.getPredecessors().size() > 0
+					&& block.getSuccessors().size() == 1) {
+				BlockNode successor = block.getSuccessors().get(0);
+				List<BlockNode> predecessors = block.getPredecessors();
+				BlockSplitter.removeConnection(block, successor);
+				if (predecessors.size() == 1) {
+					BlockSplitter.replaceConnection(predecessors.get(0), block, successor);
+				} else {
+					for (BlockNode pred : new ArrayList<>(predecessors)) {
+						BlockSplitter.replaceConnection(pred, block, successor);
+					}
+				}
+				block.add(AFlag.REMOVE);
+			}
+		}
+		BlockProcessor.removeMarkedBlocks(mth);
+	}
+
+	private void unbindExceptionHandlers() {
+		if (mth.isNoExceptionHandlers()) {
+			return;
+		}
+		for (ExceptionHandler handler : mth.getExceptionHandlers()) {
+			BlockNode handlerBlock = handler.getHandlerBlock();
+			if (handlerBlock != null) {
+				BlockSplitter.removePredecessors(handlerBlock);
+			}
+		}
+	}
+
+	private void processTargetInsn(BlockNode block, InsnNode lastInsn) {
+		if (lastInsn instanceof IfNode) {
+			BlockNode thenBlock = ((IfNode) lastInsn).getThenBlock();
+			startLabel.set(thenBlock.getId());
+		} else {
+			for (BlockNode successor : block.getSuccessors()) {
+				startLabel.set(successor.getId());
+			}
+		}
+	}
+
+	public boolean isNeedStartLabel(BlockNode block) {
+		return startLabel.get(block.getId());
+	}
+
+	public boolean isNeedEndGoto(BlockNode block) {
+		return endGoto.get(block.getId());
+	}
+
+	// DFS sort blocks to reduce goto count
+	private List<BlockNode> getSortedBlocks() {
+		List<BlockNode> list = new ArrayList<>(mth.getBasicBlocks().size());
+		BlockUtils.dfsVisit(mth, list::add);
+		return list;
+	}
+}

jadx-core/src/main/java/jadx/core/dex/attributes/AFlag.java

@@ -81,6 +81,8 @@ public enum AFlag {
 
 	METHOD_CANDIDATE_FOR_INLINE,
 
+	DISABLE_BLOCKS_LOCK,
+
 	// Class processing flags
 	RESTART_CODEGEN, // codegen must be executed again
 	RELOAD_AT_CODEGEN_STAGE, // class can't be analyzed at 'process' stage => unload before 'codegen' stage

jadx-core/src/main/java/jadx/core/dex/attributes/nodes/JadxError.java

@@ -50,11 +50,7 @@ public class JadxError implements Comparable<JadxError> {
 	@Override
 	public String toString() {
 		StringBuilder str = new StringBuilder();
-		str.append("JadxError: ");
-		if (error != null) {
-			str.append(error);
-			str.append(' ');
-		}
+		str.append("JadxError: ").append(error).append(' ');
 		if (cause != null) {
 			str.append(cause.getClass());
 			str.append(':');

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

@@ -336,6 +336,14 @@ public class MethodNode extends NotificationAttrNode implements IMethodDetails,
 		return exitBlock.getPredecessors();
 	}
 
+	public boolean isPreExitBlocks(BlockNode block) {
+		List<BlockNode> successors = block.getSuccessors();
+		if (successors.size() == 1) {
+			return successors.get(0).equals(exitBlock);
+		}
+		return exitBlock.getPredecessors().contains(block);
+	}
+
 	public void registerLoop(LoopInfo loop) {
 		if (loops.isEmpty()) {
 			loops = new ArrayList<>(5);

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

+package jadx.core.dex.visitors;
+
+import java.util.function.Consumer;
+
+import jadx.core.dex.nodes.ClassNode;
+import jadx.core.dex.nodes.MethodNode;
+import jadx.core.dex.nodes.RootNode;
+import jadx.core.utils.exceptions.JadxException;
+
+public class MethodVisitor implements IDexTreeVisitor {
+
+	private final Consumer<MethodNode> visitor;
+
+	public MethodVisitor(Consumer<MethodNode> visitor) {
+		this.visitor = visitor;
+	}
+
+	@Override
+	public void visit(MethodNode mth) throws JadxException {
+		visitor.accept(mth);
+	}
+
+	@Override
+	public void init(RootNode root) throws JadxException {
+	}
+
+	@Override
+	public boolean visit(ClassNode cls) throws JadxException {
+		return true;
+	}
+}

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

@@ -149,12 +149,7 @@ public class BlockExceptionHandler {
 				continue;
 			}
 			firstInsn.remove(AType.EXC_HANDLER);
-			TmpEdgeAttr tmpEdgeAttr = block.get(AType.TMP_EDGE);
-			if (tmpEdgeAttr != null) {
-				// remove temp connection
-				BlockSplitter.removeConnection(tmpEdgeAttr.getBlock(), block);
-				block.remove(AType.TMP_EDGE);
-			}
+			removeTmpConnection(block);
 
 			ExceptionHandler excHandler = excHandlerAttr.getHandler();
 			if (block.getPredecessors().isEmpty()) {
@@ -176,6 +171,19 @@ public class BlockExceptionHandler {
 		}
 	}
 
+	protected static void removeTmpConnections(MethodNode mth) {
+		mth.getBasicBlocks().forEach(BlockExceptionHandler::removeTmpConnection);
+	}
+
+	private static void removeTmpConnection(BlockNode block) {
+		TmpEdgeAttr tmpEdgeAttr = block.get(AType.TMP_EDGE);
+		if (tmpEdgeAttr != null) {
+			// remove temp connection
+			BlockSplitter.removeConnection(tmpEdgeAttr.getBlock(), block);
+			block.remove(AType.TMP_EDGE);
+		}
+	}
+
 	private static List<TryCatchBlockAttr> prepareTryBlocks(MethodNode mth) {
 		Map<ExceptionHandler, List<BlockNode>> blocksByHandler = new HashMap<>();
 		for (BlockNode block : mth.getBasicBlocks()) {

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

@@ -77,7 +77,9 @@ public class BlockProcessor extends AbstractVisitor {
 		processNestedLoops(mth);
 
 		updateCleanSuccessors(mth);
-		mth.finishBasicBlocks();
+		if (!mth.contains(AFlag.DISABLE_BLOCKS_LOCK)) {
+			mth.finishBasicBlocks();
+		}
 	}
 
 	static void updateCleanSuccessors(MethodNode mth) {
@@ -686,7 +688,7 @@ public class BlockProcessor extends AbstractVisitor {
 		return false;
 	}
 
-	static void removeMarkedBlocks(MethodNode mth) {
+	public static void removeMarkedBlocks(MethodNode mth) {
 		mth.getBasicBlocks().removeIf(block -> {
 			if (block.contains(AFlag.REMOVE)) {
 				if (!block.getPredecessors().isEmpty() || !block.getSuccessors().isEmpty()) {

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

@@ -142,7 +142,7 @@ public class BlockSplitter extends AbstractVisitor {
 		return block;
 	}
 
-	static void connect(BlockNode from, BlockNode to) {
+	public static void connect(BlockNode from, BlockNode to) {
 		if (!from.getSuccessors().contains(to)) {
 			from.getSuccessors().add(to);
 		}
@@ -151,19 +151,19 @@ public class BlockSplitter extends AbstractVisitor {
 		}
 	}
 
-	static void removeConnection(BlockNode from, BlockNode to) {
+	public static void removeConnection(BlockNode from, BlockNode to) {
 		from.getSuccessors().remove(to);
 		to.getPredecessors().remove(from);
 	}
 
-	static void removePredecessors(BlockNode block) {
+	public static void removePredecessors(BlockNode block) {
 		for (BlockNode pred : block.getPredecessors()) {
 			pred.getSuccessors().remove(block);
 		}
 		block.getPredecessors().clear();
 	}
 
-	static void replaceConnection(BlockNode source, BlockNode oldDest, BlockNode newDest) {
+	public static void replaceConnection(BlockNode source, BlockNode oldDest, BlockNode newDest) {
 		removeConnection(source, oldDest);
 		connect(source, newDest);
 		replaceTarget(source, oldDest, newDest);

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

@@ -453,6 +453,31 @@ public class BlockUtils {
 		}
 	}
 
+	public static void dfsVisit(MethodNode mth, Consumer<BlockNode> visitor) {
+		BitSet visited = newBlocksBitSet(mth);
+		Deque<BlockNode> queue = new ArrayDeque<>();
+		BlockNode enterBlock = mth.getEnterBlock();
+		queue.addLast(enterBlock);
+		visited.set(mth.getEnterBlock().getId());
+		while (true) {
+			BlockNode current = queue.pollLast();
+			if (current == null) {
+				return;
+			}
+			visitor.accept(current);
+			List<BlockNode> successors = current.getSuccessors();
+			int count = successors.size();
+			for (int i = count - 1; i >= 0; i--) { // to preserve order in queue
+				BlockNode next = successors.get(i);
+				int nextId = next.getId();
+				if (!visited.get(nextId)) {
+					queue.addLast(next);
+					visited.set(nextId);
+				}
+			}
+		}
+	}
+
 	public static List<BlockNode> collectPredecessors(MethodNode mth, BlockNode start, Collection<BlockNode> stopBlocks) {
 		BitSet bs = newBlocksBitSet(mth);
 		if (!stopBlocks.isEmpty()) {

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

@@ -35,18 +35,21 @@ public class CodeGenUtils {
 		List<JadxError> errors = node.getAll(AType.JADX_ERROR);
 		if (!errors.isEmpty()) {
 			errors.stream().distinct().sorted().forEach(err -> {
-				code.startLine("/*  JADX ERROR: ").add(err.getError());
-				Throwable cause = err.getCause();
-				if (cause != null) {
-					code.incIndent();
-					Utils.appendStackTrace(code, cause);
-					code.decIndent();
-				}
-				code.add("*/");
+				addError(code, err.getError(), err.getCause());
 			});
 		}
 	}
 
+	public static void addError(ICodeWriter code, String errMsg, Throwable cause) {
+		code.startLine("/*  JADX ERROR: ").add(errMsg);
+		if (cause != null) {
+			code.incIndent();
+			Utils.appendStackTrace(code, cause);
+			code.decIndent();
+		}
+		code.add("*/");
+	}
+
 	public static void addComments(ICodeWriter code, NotificationAttrNode node) {
 		JadxCommentsAttr commentsAttr = node.get(AType.JADX_COMMENTS);
 		if (commentsAttr != null) {

jadx-gui/src/main/java/jadx/gui/settings/JadxSettings.java

@@ -27,6 +27,7 @@ import org.slf4j.LoggerFactory;
 import com.beust.jcommander.Parameter;
 
 import jadx.api.CommentsLevel;
+import jadx.api.DecompilationMode;
 import jadx.api.JadxArgs;
 import jadx.api.args.DeobfuscationMapFileMode;
 import jadx.cli.JadxCLIArgs;
@@ -44,7 +45,7 @@ public class JadxSettings extends JadxCLIArgs {
 
 	private static final Path USER_HOME = Paths.get(System.getProperty("user.home"));
 	private static final int RECENT_PROJECTS_COUNT = 15;
-	private static final int CURRENT_SETTINGS_VERSION = 16;
+	private static final int CURRENT_SETTINGS_VERSION = 17;
 
 	private static final Font DEFAULT_FONT = new RSyntaxTextArea().getFont();
 
@@ -291,6 +292,10 @@ public class JadxSettings extends JadxCLIArgs {
 		this.skipSources = skipSources;
 	}
 
+	public void setDecompilationMode(DecompilationMode decompilationMode) {
+		this.decompilationMode = decompilationMode;
+	}
+
 	public void setShowInconsistentCode(boolean showInconsistentCode) {
 		this.showInconsistentCode = showInconsistentCode;
 	}
@@ -672,6 +677,14 @@ public class JadxSettings extends JadxCLIArgs {
 			}
 			fromVersion++;
 		}
+		if (fromVersion == 16) {
+			if (fallbackMode) {
+				decompilationMode = DecompilationMode.FALLBACK;
+			} else {
+				decompilationMode = DecompilationMode.AUTO;
+			}
+			fromVersion++;
+		}
 		if (fromVersion != CURRENT_SETTINGS_VERSION) {
 			throw new JadxRuntimeException("Incorrect settings upgrade");
 		}

jadx-gui/src/main/java/jadx/gui/settings/JadxSettingsWindow.java

@@ -59,6 +59,7 @@ import com.google.gson.JsonObject;
 import say.swing.JFontChooser;
 
 import jadx.api.CommentsLevel;
+import jadx.api.DecompilationMode;
 import jadx.api.JadxArgs;
 import jadx.api.JadxArgs.UseKotlinMethodsForVarNames;
 import jadx.api.args.DeobfuscationMapFileMode;
@@ -419,13 +420,6 @@ public class JadxSettingsWindow extends JDialog {
 	}
 
 	private SettingsGroup makeDecompilationGroup() {
-		JCheckBox fallback = new JCheckBox();
-		fallback.setSelected(settings.isFallbackMode());
-		fallback.addItemListener(e -> {
-			settings.setFallbackMode(e.getStateChange() == ItemEvent.SELECTED);
-			needReload();
-		});
-
 		JCheckBox useDx = new JCheckBox();
 		useDx.setSelected(settings.isUseDx());
 		useDx.addItemListener(e -> {
@@ -433,6 +427,13 @@ public class JadxSettingsWindow extends JDialog {
 			needReload();
 		});
 
+		JComboBox<DecompilationMode> decompilationModeComboBox = new JComboBox<>(DecompilationMode.values());
+		decompilationModeComboBox.setSelectedItem(settings.getDecompilationMode());
+		decompilationModeComboBox.addActionListener(e -> {
+			settings.setDecompilationMode((DecompilationMode) decompilationModeComboBox.getSelectedItem());
+			needReload();
+		});
+
 		JCheckBox showInconsistentCode = new JCheckBox();
 		showInconsistentCode.setSelected(settings.isShowInconsistentCode());
 		showInconsistentCode.addItemListener(e -> {
@@ -543,6 +544,7 @@ public class JadxSettingsWindow extends JDialog {
 		other.addRow(NLS.str("preferences.excludedPackages"), NLS.str("preferences.excludedPackages.tooltip"),
 				editExcludedPackages);
 		other.addRow(NLS.str("preferences.start_jobs"), autoStartJobs);
+		other.addRow(NLS.str("preferences.decompilationMode"), decompilationModeComboBox);
 		other.addRow(NLS.str("preferences.showInconsistentCode"), showInconsistentCode);
 		other.addRow(NLS.str("preferences.escapeUnicode"), escapeUnicode);
 		other.addRow(NLS.str("preferences.replaceConsts"), replaceConsts);
@@ -551,7 +553,6 @@ public class JadxSettingsWindow extends JDialog {
 		other.addRow(NLS.str("preferences.inlineAnonymous"), inlineAnonymous);
 		other.addRow(NLS.str("preferences.inlineMethods"), inlineMethods);
 		other.addRow(NLS.str("preferences.fsCaseSensitive"), fsCaseSensitive);
-		other.addRow(NLS.str("preferences.fallback"), fallback);
 		other.addRow(NLS.str("preferences.useDx"), useDx);
 		other.addRow(NLS.str("preferences.skipResourcesDecode"), resourceDecode);
 		other.addRow(NLS.str("preferences.useKotlinMethodsForVarNames"), kotlinRenameVars);

jadx-gui/src/main/resources/i18n/Messages_de_DE.properties

@@ -127,6 +127,7 @@ preferences.lineNumbersMode=Editor Zeilennummern-Modus
 preferences.check_for_updates=Nach Updates beim Start suchen
 preferences.fallback=Zwischencode ausgeben (einfacher Speicherauszug)
 #preferences.useDx=Use dx/d8 to convert java bytecode
+#preferences.decompilationMode=Decompilation mode
 preferences.showInconsistentCode=Inkonsistenten Code anzeigen
 preferences.escapeUnicode=Unicodezeichen escapen
 preferences.replaceConsts=Konstanten ersetzen

jadx-gui/src/main/resources/i18n/Messages_en_US.properties

@@ -127,6 +127,7 @@ preferences.lineNumbersMode=Editor line numbers mode
 preferences.check_for_updates=Check for updates on startup
 preferences.fallback=Fallback mode (simple dump)
 preferences.useDx=Use dx/d8 to convert java bytecode
+preferences.decompilationMode=Decompilation mode
 preferences.showInconsistentCode=Show inconsistent code
 preferences.escapeUnicode=Escape unicode
 preferences.replaceConsts=Replace constants

jadx-gui/src/main/resources/i18n/Messages_es_ES.properties

@@ -127,6 +127,7 @@ preferences.language=Idioma
 preferences.check_for_updates=Buscar actualizaciones al iniciar
 preferences.fallback=Modo fallback (simple dump)
 #preferences.useDx=Use dx/d8 to convert java bytecode
+#preferences.decompilationMode=Decompilation mode
 preferences.showInconsistentCode=Mostrar código inconsistente
 preferences.escapeUnicode=Escape unicode
 preferences.replaceConsts=Reemplazar constantes

jadx-gui/src/main/resources/i18n/Messages_ko_KR.properties

@@ -127,6 +127,7 @@ preferences.lineNumbersMode=편집기 줄 번호 모드
 preferences.check_for_updates=시작시 업데이트 확인
 preferences.fallback=대체 모드 (단순 덤프)
 #preferences.useDx=Use dx/d8 to convert java bytecode
+#preferences.decompilationMode=Decompilation mode
 preferences.showInconsistentCode=디컴파일 안된 코드 표시
 preferences.escapeUnicode=유니코드 이스케이프
 preferences.replaceConsts=상수 바꾸기

jadx-gui/src/main/resources/i18n/Messages_zh_CN.properties

@@ -127,6 +127,7 @@ preferences.lineNumbersMode=编辑器行号模式
 preferences.check_for_updates=启动时检查更新
 preferences.fallback=输出中间代码
 #preferences.useDx=Use dx/d8 to convert java bytecode
+#preferences.decompilationMode=Decompilation mode
 preferences.showInconsistentCode=显示不一致的代码
 preferences.escapeUnicode=将 Unicode 字符转义
 preferences.replaceConsts=替换常量

jadx-gui/src/main/resources/i18n/Messages_zh_TW.properties

@@ -127,6 +127,7 @@ preferences.lineNumbersMode=編輯器行號模式
 preferences.check_for_updates=啟動時檢查更新
 preferences.fallback=後援模式 (簡易傾印)
 preferences.useDx=使用 dx/d8 來轉換 Java 位元組碼
+#preferences.decompilationMode=Decompilation mode
 preferences.showInconsistentCode=顯示不一致的程式碼
 preferences.escapeUnicode=Unicode 逸出
 preferences.replaceConsts=替換常數