core: guess variable name from assign instruction

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

@@ -3,20 +3,46 @@ package jadx.core.codegen;
 import jadx.core.Consts;
 import jadx.core.deobf.NameMapper;
 import jadx.core.dex.info.ClassInfo;
+import jadx.core.dex.instructions.InvokeNode;
 import jadx.core.dex.instructions.args.ArgType;
+import jadx.core.dex.instructions.args.InsnArg;
+import jadx.core.dex.instructions.args.InsnWrapArg;
 import jadx.core.dex.instructions.args.NamedArg;
 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.nodes.InsnNode;
 import jadx.core.utils.Utils;
 
+import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Map;
 import java.util.Set;
 
 public class NameGen {
 
+	private static final Map<String, String> OBJ_ALIAS;
+
 	private final Set<String> varNames = new HashSet<String>();
 	private final boolean fallback;
 
+	static {
+		OBJ_ALIAS = new HashMap<String, String>();
+		OBJ_ALIAS.put(Consts.CLASS_STRING, "str");
+		OBJ_ALIAS.put(Consts.CLASS_CLASS, "cls");
+		OBJ_ALIAS.put(Consts.CLASS_THROWABLE, "th");
+		OBJ_ALIAS.put(Consts.CLASS_OBJECT, "obj");
+		OBJ_ALIAS.put("java.util.Iterator", "it");
+		OBJ_ALIAS.put("java.lang.Boolean", "bool");
+		OBJ_ALIAS.put("java.lang.Short", "sh");
+		OBJ_ALIAS.put("java.lang.Integer", "num");
+		OBJ_ALIAS.put("java.lang.Character", "ch");
+		OBJ_ALIAS.put("java.lang.Byte", "b");
+		OBJ_ALIAS.put("java.lang.Float", "f");
+		OBJ_ALIAS.put("java.lang.Long", "l");
+		OBJ_ALIAS.put("java.lang.Double", "d");
+	}
+
 	public NameGen(boolean fallback) {
 		this.fallback = fallback;
 	}
@@ -72,7 +98,7 @@ public class NameGen {
 		}
 		String varName;
 		if (name != null) {
-			if (name.equals("this")) {
+			if ("this".equals(name)) {
 				return name;
 			}
 			varName = name;
@@ -101,34 +127,92 @@ public class NameGen {
 
 	private static String makeNameForObject(ArgType type) {
 		if (type.isObject()) {
-			String obj = type.getObject();
-			if (obj.startsWith("java.lang.")) {
-				if (obj.equals(Consts.CLASS_STRING)) {
-					return "str";
-				}
-				if (obj.equals(Consts.CLASS_OBJECT)) {
-					return "obj";
-				}
-				if (obj.equals(Consts.CLASS_CLASS)) {
-					return "cls";
-				}
-				if (obj.equals(Consts.CLASS_THROWABLE)) {
-					return "th";
-				}
+			String alias = getAliasForObject(type.getObject());
+			if (alias != null) {
+				return alias;
 			}
 			ClassInfo clsInfo = ClassInfo.fromType(type);
 			String shortName = clsInfo.getShortName();
-			if (shortName.toUpperCase().equals(shortName)) {
-				// all characters are upper case
-				return shortName.toLowerCase();
-			}
-			if (!shortName.isEmpty()) {
-				String v1 = Character.toLowerCase(shortName.charAt(0)) + shortName.substring(1);
-				if (!v1.equals(shortName)) {
-					return v1;
-				}
+			String vName = fromName(shortName);
+			if (vName != null) {
+				return vName;
 			}
 		}
 		return Utils.escape(type.toString());
 	}
+
+	private static String fromName(String name) {
+		if (name == null || name.isEmpty()) {
+			return null;
+		}
+		if (name.toUpperCase().equals(name)) {
+			// all characters are upper case
+			return name.toLowerCase();
+		}
+		String v1 = Character.toLowerCase(name.charAt(0)) + name.substring(1);
+		if (!v1.equals(name)) {
+			return v1;
+		}
+		if (name.length() < 3) {
+			return name + "Var";
+		}
+		return null;
+	}
+
+	public static void guessName(RegisterArg arg) {
+		SSAVar sVar = arg.getSVar();
+		if (sVar == null || sVar.getName() != null) {
+			return;
+		}
+		RegisterArg assignArg = sVar.getAssign();
+		InsnNode assignInsn = assignArg.getParentInsn();
+		String name = makeNameFromInsn(assignInsn);
+		if (name != null && !NameMapper.isReserved(name)) {
+			assignArg.setName(name);
+		}
+	}
+
+	public static String getAliasForObject(String name) {
+		return OBJ_ALIAS.get(name);
+	}
+
+	private static String makeNameFromInsn(InsnNode insn) {
+		switch (insn.getType()) {
+			case INVOKE:
+				InvokeNode inv = (InvokeNode) insn;
+				String name = inv.getCallMth().getName();
+				if (name.startsWith("get") || name.startsWith("set")) {
+					return fromName(name.substring(3));
+				}
+				if ("iterator".equals(name)) {
+					return "it";
+				}
+				return name;
+
+			case CONSTRUCTOR:
+				ConstructorInsn co = (ConstructorInsn) insn;
+				return makeNameForObject(co.getClassType().getType());
+
+			case ARRAY_LENGTH:
+				return "length";
+
+			case ARITH:
+			case TERNARY:
+			case CAST:
+				for (InsnArg arg : insn.getArguments()) {
+					if (arg.isInsnWrap()) {
+						InsnNode wrapInsn = ((InsnWrapArg) arg).getWrapInsn();
+						String wName = makeNameFromInsn(wrapInsn);
+						if (wName != null) {
+							return wName;
+						}
+					}
+				}
+				break;
+
+			default:
+				break;
+		}
+		return null;
+	}
 }

jadx-core/src/main/java/jadx/core/dex/instructions/args/MthParameterArg.java

@@ -41,4 +41,24 @@ public class MthParameterArg extends RegisterArg {
 		}
 		super.setSVar(sVar);
 	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) {
+			return true;
+		}
+		if (!(obj instanceof MthParameterArg)) {
+			return false;
+		}
+		if (!super.equals(obj)) {
+			return false;
+		}
+		MthParameterArg that = (MthParameterArg) obj;
+		return isThis == that.isThis;
+	}
+
+	@Override
+	public int hashCode() {
+		return 31 * super.hashCode() + (isThis ? 1 : 0);
+	}
 }

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

 package jadx.core.dex.visitors.regions;
 
+import jadx.core.codegen.NameGen;
 import jadx.core.dex.attributes.AFlag;
 import jadx.core.dex.attributes.AType;
 import jadx.core.dex.attributes.nodes.DeclareVariablesAttr;
@@ -179,6 +180,7 @@ public class ProcessVariables extends AbstractVisitor {
 				if (u.getArgRegion() == assignRegion
 						&& canDeclareInRegion(u, assignRegion, regionsOrder)) {
 					u.getArg().getParentInsn().add(AFlag.DECLARE_VAR);
+					processVar(u.getArg());
 					it.remove();
 					break;
 				}
@@ -248,6 +250,11 @@ public class ProcessVariables extends AbstractVisitor {
 			region.addAttr(dv);
 		}
 		dv.addVar(arg);
+		processVar(arg);
+	}
+
+	private static void processVar(RegisterArg arg) {
+		NameGen.guessName(arg);
 	}
 
 	private static int calculateOrder(IContainer container, Map<IContainer, Integer> regionsOrder,