core: fix variable names propagation (#219)

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

@@ -63,6 +63,21 @@ public class RegisterArg extends InsnArg implements Named {
 		return n.equals(((Named) arg).getName());
 	}
 
+	public void mergeName(InsnArg arg) {
+		if (arg instanceof Named) {
+			Named otherArg = (Named) arg;
+			String otherName = otherArg.getName();
+			String name = getName();
+			if (!Objects.equals(name, otherName)) {
+				if (name == null) {
+					setName(otherName);
+				} else if (otherName == null) {
+					otherArg.setName(name);
+				}
+			}
+		}
+	}
+
 	@Override
 	public void setType(ArgType type) {
 		if (sVar != null) {

jadx-core/src/main/java/jadx/core/dex/nodes/parser/DebugInfoParser.java

@@ -78,6 +78,8 @@ public class DebugInfoParser {
 		addrChange(-1, 1, line);
 		setLine(addr, line);
 
+		boolean varsInfoFound = false;
+
 		int c = section.readByte() & 0xFF;
 		while (c != DBG_END_SEQUENCE) {
 			switch (c) {
@@ -98,6 +100,7 @@ public class DebugInfoParser {
 					int type = section.readUleb128() - 1;
 					LocalVar var = new LocalVar(dex, regNum, nameId, type, DexNode.NO_INDEX);
 					startVar(var, addr, line);
+					varsInfoFound = true;
 					break;
 				}
 				case DBG_START_LOCAL_EXTENDED: {
@@ -107,6 +110,7 @@ public class DebugInfoParser {
 					int sign = section.readUleb128() - 1;
 					LocalVar var = new LocalVar(dex, regNum, nameId, type, sign);
 					startVar(var, addr, line);
+					varsInfoFound = true;
 					break;
 				}
 				case DBG_RESTART_LOCAL: {
@@ -118,6 +122,7 @@ public class DebugInfoParser {
 						}
 						var.start(addr, line);
 					}
+					varsInfoFound = true;
 					break;
 				}
 				case DBG_END_LOCAL: {
@@ -127,6 +132,7 @@ public class DebugInfoParser {
 						var.end(addr, line);
 						setVar(var);
 					}
+					varsInfoFound = true;
 					break;
 				}
 
@@ -160,10 +166,12 @@ public class DebugInfoParser {
 			c = section.readByte() & 0xFF;
 		}
 
-		for (LocalVar var : locals) {
-			if (var != null && !var.isEnd()) {
-				var.end(mth.getCodeSize() - 1, line);
-				setVar(var);
+		if (varsInfoFound) {
+			for (LocalVar var : locals) {
+				if (var != null && !var.isEnd()) {
+					var.end(mth.getCodeSize() - 1, line);
+					setVar(var);
+				}
 			}
 		}
 		setSourceLines(addr, insnByOffset.length, line);

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

@@ -142,6 +142,7 @@ public class PrepareForCodeGen extends AbstractVisitor {
 				}
 				if (replace) {
 					insn.add(AFlag.ARITH_ONEARG);
+					insn.getResult().mergeName(arg);
 				}
 			}
 		}

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

@@ -22,7 +22,6 @@ import jadx.core.utils.exceptions.JadxException;
 
 import java.util.ArrayList;
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;

jadx-core/src/main/java/jadx/core/dex/visitors/ssa/SSATransform.java

@@ -8,6 +8,7 @@ import jadx.core.dex.instructions.PhiInsn;
 import jadx.core.dex.instructions.args.InsnArg;
 import jadx.core.dex.instructions.args.RegisterArg;
 import jadx.core.dex.instructions.args.SSAVar;
+import jadx.core.dex.instructions.args.VarName;
 import jadx.core.dex.nodes.BlockNode;
 import jadx.core.dex.nodes.InsnNode;
 import jadx.core.dex.nodes.MethodNode;
@@ -141,14 +142,7 @@ public class SSATransform extends AbstractVisitor {
 		PhiListAttr phiList = enterBlock.get(AType.PHI_LIST);
 		if (phiList != null) {
 			for (PhiInsn phiInsn : phiList.getList()) {
-				int regNum = phiInsn.getResult().getRegNum();
-				SSAVar var = vars[regNum];
-				if (var == null) {
-					continue;
-				}
-				RegisterArg arg = phiInsn.bindArg(enterBlock);
-				var.use(arg);
-				var.setUsedInPhi(phiInsn);
+				bindPhiArg(vars, enterBlock, phiInsn);
 			}
 		}
 	}
@@ -183,14 +177,7 @@ public class SSATransform extends AbstractVisitor {
 				continue;
 			}
 			for (PhiInsn phiInsn : phiList.getList()) {
-				int regNum = phiInsn.getResult().getRegNum();
-				SSAVar var = vars[regNum];
-				if (var == null) {
-					continue;
-				}
-				RegisterArg arg = phiInsn.bindArg(block);
-				var.use(arg);
-				var.setUsedInPhi(phiInsn);
+				bindPhiArg(vars, block, phiInsn);
 			}
 		}
 		for (BlockNode domOn : block.getDominatesOn()) {
@@ -199,6 +186,17 @@ public class SSATransform extends AbstractVisitor {
 		System.arraycopy(inputVars, 0, vars, 0, vars.length);
 	}
 
+	private static void bindPhiArg(SSAVar[] vars, BlockNode block, PhiInsn phiInsn) {
+		int regNum = phiInsn.getResult().getRegNum();
+		SSAVar var = vars[regNum];
+		if (var == null) {
+			return;
+		}
+		RegisterArg arg = phiInsn.bindArg(block);
+		var.use(arg);
+		var.setUsedInPhi(phiInsn);
+	}
+
 	/**
 	 * Fix last try/catch assign instruction
 	 */

jadx-core/src/main/java/jadx/core/dex/visitors/typeinference/TypeInference.java

@@ -1,17 +1,21 @@
 package jadx.core.dex.visitors.typeinference;
 
+import java.util.List;
+
+import jadx.core.dex.attributes.AType;
+import jadx.core.dex.attributes.nodes.PhiListAttr;
 import jadx.core.dex.instructions.PhiInsn;
 import jadx.core.dex.instructions.args.ArgType;
 import jadx.core.dex.instructions.args.InsnArg;
 import jadx.core.dex.instructions.args.RegisterArg;
 import jadx.core.dex.instructions.args.SSAVar;
+import jadx.core.dex.instructions.args.VarName;
+import jadx.core.dex.nodes.BlockNode;
 import jadx.core.dex.nodes.DexNode;
 import jadx.core.dex.nodes.MethodNode;
 import jadx.core.dex.visitors.AbstractVisitor;
 import jadx.core.utils.exceptions.JadxException;
 
-import java.util.List;
-
 public class TypeInference extends AbstractVisitor {
 
 	@Override
@@ -19,6 +23,8 @@ public class TypeInference extends AbstractVisitor {
 		if (mth.isNoCode()) {
 			return;
 		}
+		fixPhiVarNames(mth);
+
 		DexNode dex = mth.dex();
 		for (SSAVar var : mth.getSVars()) {
 			// inference variable type
@@ -80,6 +86,32 @@ public class TypeInference extends AbstractVisitor {
 		}
 	}
 
+	private static void fixPhiVarNames(MethodNode mth) {
+		for (BlockNode block : mth.getBasicBlocks()) {
+			PhiListAttr phiList = block.get(AType.PHI_LIST);
+			if (phiList == null) {
+				continue;
+			}
+			for (PhiInsn phiInsn : phiList.getList()) {
+				RegisterArg resArg = phiInsn.getResult();
+				int argsCount = phiInsn.getArgsCount();
+				for (int i = 0; i < argsCount; i++) {
+					RegisterArg arg = phiInsn.getArg(i);
+					arg.mergeName(resArg);
+				}
+				VarName varName = resArg.getSVar().getVarName();
+				if (varName == null) {
+					varName = new VarName();
+					resArg.getSVar().setVarName(varName);
+				}
+				for (int i = 0; i < argsCount; i++) {
+					RegisterArg arg = phiInsn.getArg(i);
+					arg.getSVar().setVarName(varName);
+				}
+			}
+		}
+	}
+
 	private static String processVarName(SSAVar var) {
 		String name = var.getAssign().getName();
 		if (name != null) {