core: fix type inference for arguments in Phi node (fix #33)

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

@@ -8,7 +8,6 @@ import jadx.core.dex.instructions.args.ArgType;
 import jadx.core.dex.instructions.args.InsnArg;
 import jadx.core.dex.instructions.args.LiteralArg;
 import jadx.core.dex.instructions.args.RegisterArg;
-import jadx.core.dex.instructions.args.SSAVar;
 import jadx.core.dex.nodes.InsnNode;
 import jadx.core.dex.nodes.MethodNode;
 
@@ -100,18 +99,26 @@ public class PostTypeInference {
 
 			case PHI: {
 				PhiInsn phi = (PhiInsn) insn;
-				RegisterArg result = phi.getResult();
-				SSAVar resultSVar = result.getSVar();
-				if (resultSVar != null && !result.getType().isTypeKnown()) {
+				ArgType type = phi.getResult().getType();
+				if (!type.isTypeKnown()) {
 					for (InsnArg arg : phi.getArguments()) {
-						ArgType argType = arg.getType();
-						if (argType.isTypeKnown()) {
-							resultSVar.setType(argType);
-							return true;
+						if (arg.getType().isTypeKnown()) {
+							type = arg.getType();
+							break;
 						}
 					}
 				}
-				return false;
+				boolean changed = false;
+				if (updateType(phi.getResult(), type)) {
+					changed = true;
+				}
+				for (int i = 0; i < phi.getArgsCount(); i++) {
+					RegisterArg arg = phi.getArg(i);
+					if (updateType(arg, type)) {
+						changed = true;
+					}
+				}
+				return changed;
 			}
 
 			default:
@@ -120,6 +127,15 @@ public class PostTypeInference {
 		return false;
 	}
 
+	private static boolean updateType(RegisterArg arg, ArgType type) {
+		ArgType prevType = arg.getType();
+		if (prevType == null || !prevType.equals(type)) {
+			arg.setType(type);
+			return true;
+		}
+		return false;
+	}
+
 	private static boolean fixArrayTypes(InsnArg array, InsnArg elem) {
 		boolean change = false;
 		if (!elem.getType().isTypeKnown() && elem.merge(array.getType().getArrayElement())) {

jadx-core/src/test/java/jadx/tests/integration/types/TestTypeResolver3.java

@@ -0,0 +1,38 @@
+package jadx.tests.integration.types;
+
+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 TestTypeResolver3 extends IntegrationTest {
+
+	public static class TestCls {
+
+		public int test(String s1, String s2) {
+			int cmp = s2.compareTo(s1);
+			if (cmp != 0) {
+				return cmp;
+			}
+			return s1.length() == s2.length() ? 0 : s1.length() < s2.length() ? -1 : 1;
+		}
+	}
+
+	@Test
+	public void test() {
+		ClassNode cls = getClassNode(TestCls.class);
+		String code = cls.getCode().toString();
+
+		// TODO inline into return
+		assertThat(code, containsOne("s1.length() == s2.length() ? 0 : s1.length() < s2.length() ? -1 : 1;"));
+	}
+
+	@Test
+	public void test2() {
+		noDebugInfo();
+		getClassNode(TestCls.class);
+	}
+}