fix: remove move instructions with unused result (#835)

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

@@ -86,6 +86,7 @@ public class ModVisitor extends AbstractVisitor {
 		InsnRemover remover = new InsnRemover(mth);
 		replaceStep(mth, remover);
 		removeStep(mth, remover);
+		iterativeRemoveStep(mth);
 	}
 
 	private static void replaceStep(MethodNode mth, InsnRemover remover) {
@@ -293,6 +294,9 @@ public class ModVisitor extends AbstractVisitor {
 						break;
 
 					default:
+						if (insn.contains(AFlag.REMOVE)) {
+							remover.addAndUnbind(insn);
+						}
 						break;
 				}
 			}
@@ -300,6 +304,33 @@ public class ModVisitor extends AbstractVisitor {
 		}
 	}
 
+	private static void iterativeRemoveStep(MethodNode mth) {
+		boolean changed;
+		do {
+			changed = false;
+			for (BlockNode block : mth.getBasicBlocks()) {
+				for (InsnNode insn : block.getInstructions()) {
+					if (insn.getType() == InsnType.MOVE
+							&& insn.isAttrStorageEmpty()
+							&& isResultArgNotUsed(insn)) {
+						InsnRemover.remove(mth, block, insn);
+						changed = true;
+						break;
+					}
+				}
+			}
+		} while (changed);
+	}
+
+	private static boolean isResultArgNotUsed(InsnNode insn) {
+		RegisterArg result = insn.getResult();
+		if (result != null) {
+			SSAVar ssaVar = result.getSVar();
+			return ssaVar.getUseCount() == 0;
+		}
+		return false;
+	}
+
 	private static void processAnonymousConstructor(MethodNode mth, ConstructorInsn co) {
 		MethodInfo callMth = co.getCallMth();
 		MethodNode callMthNode = mth.dex().resolveMethod(callMth);

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

@@ -422,6 +422,7 @@ public class SSATransform extends AbstractVisitor {
 			if (resArg.getRegNum() != arg.getRegNum()
 					&& !resArg.getSVar().isUsedInPhi()) {
 				markThisArgs(resArg);
+				parentInsn.add(AFlag.REMOVE);
 				parentInsn.add(AFlag.DONT_GENERATE);
 			}
 		}

jadx-core/src/test/java/jadx/tests/integration/others/TestInsnsBeforeSuper2.java

+package jadx.tests.integration.others;
+
+import org.junit.jupiter.api.Test;
+
+import jadx.tests.api.SmaliTest;
+
+import static jadx.tests.api.utils.assertj.JadxAssertions.assertThat;
+
+public class TestInsnsBeforeSuper2 extends SmaliTest {
+	// @formatter:off
+	/*
+		public class TestInsnsBeforeSuper2 extends java.lang.Exception {
+			private int mErrorType;
+
+			public TestInsnsBeforeSuper2(java.lang.String r9, int r10) {
+				r8 = this;
+				r0 = r8
+				r1 = r9
+				r2 = r10
+				r3 = r0
+				r4 = r1
+				r5 = r2
+				r6 = r1
+				r0.<init>(r6)
+				r7 = 0
+				r0.mErrorType = r7
+				r0.mErrorType = r2
+				return
+			}
+		}
+	*/
+	// @formatter:on
+
+	@Test
+	public void test() {
+		assertThat(getClassNodeFromSmali())
+				.code()
+				.containsOne("super(message);")
+				.containsOne("this.mErrorType = errorType;");
+	}
+}

jadx-core/src/test/smali/others/TestInsnsBeforeSuper2.smali

+.class public Lothers/TestInsnsBeforeSuper2;
+.super Ljava/lang/Exception;
+.source "MyException.java"
+
+# instance fields
+.field private mErrorType:I
+
+
+# direct methods
+.method public constructor <init>(Ljava/lang/String;I)V
+    .locals 8
+
+    .prologue
+    move-object v0, p0
+
+    .local v0, "this":Lothers/TestInsnsBeforeSuper2;
+    move-object v1, p1
+
+    .local v1, "message":Ljava/lang/String;
+    move v2, p2
+
+    .line 39
+    .local v2, "errorType":I
+    move-object v3, v0
+
+    .local v3, "this":Lothers/TestInsnsBeforeSuper2;
+    move-object v4, v1
+
+    .local v4, "message":Ljava/lang/String;
+    move v5, v2
+
+    .line 51
+    .end local v0    # "this":Lothers/TestInsnsBeforeSuper2;
+    .end local v1    # "message":Ljava/lang/String;
+    .end local v2    # "errorType":I
+    .local v5, "errorType":I
+    move-object v6, v1
+
+    invoke-direct {v0, v6}, Ljava/lang/Exception;-><init>(Ljava/lang/String;)V
+
+    .line 39
+    const/4 v7, 0x0
+
+    iput v7, v0, Lothers/TestInsnsBeforeSuper2;->mErrorType:I
+
+    .line 52
+    iput v2, v0, Lothers/TestInsnsBeforeSuper2;->mErrorType:I
+
+    .line 53
+    return-void
+.end method