fix: comment out instructions before super call in constructor (#685)

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

@@ -227,6 +227,9 @@ protected void makeInsn(InsnNode insn, CodeWriter code, Flags flag) throws Codeg
 					if (attachInsns) {
 						code.attachLineAnnotation(insn);
 					}
+					if (insn.contains(AFlag.COMMENT_OUT)) {
+						code.add("// ");
+					}
 				}
 				if (insn.getResult() != null) {
 					SSAVar var = insn.getResult().getSVar();

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

@@ -15,9 +15,11 @@ public enum AFlag {
 	DONT_WRAP,
 	DONT_INLINE,
 	DONT_GENERATE, // process as usual, but don't output to generated code
+	COMMENT_OUT, // process as usual, but comment insn in generated code
+	REMOVE, // can be completely removed
+
 	RESTART_CODEGEN,
 	DONT_RENAME, // do not rename during deobfuscation
-	REMOVE, // can be completely removed
 	ADDED_TO_REGION,
 
 	FINALLY_INSNS,

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

@@ -2,21 +2,26 @@
 
 import java.util.Iterator;
 import java.util.List;
+import java.util.Objects;
 
 import jadx.core.dex.attributes.AFlag;
 import jadx.core.dex.instructions.ArithNode;
 import jadx.core.dex.instructions.ArithOp;
 import jadx.core.dex.instructions.InsnType;
+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.RegisterArg;
 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.IBlock;
 import jadx.core.dex.nodes.InsnNode;
 import jadx.core.dex.nodes.MethodNode;
 import jadx.core.dex.regions.conditions.IfCondition;
 import jadx.core.dex.regions.conditions.IfCondition.Mode;
+import jadx.core.dex.visitors.regions.AbstractRegionVisitor;
+import jadx.core.dex.visitors.regions.DepthRegionTraversal;
 import jadx.core.dex.visitors.regions.variables.ProcessVariables;
 import jadx.core.dex.visitors.shrink.CodeShrinkVisitor;
 import jadx.core.utils.exceptions.JadxException;
@@ -33,6 +38,8 @@
 )
 public class PrepareForCodeGen extends AbstractVisitor {
 
+	public static final SuperCallRegionVisitor SUPER_CALL_REGION_VISITOR = new SuperCallRegionVisitor();
+
 	@Override
 	public void visit(MethodNode mth) throws JadxException {
 		List<BlockNode> blocks = mth.getBasicBlocks();
@@ -48,6 +55,7 @@ public void visit(MethodNode mth) throws JadxException {
 			removeParenthesis(block);
 			modifyArith(block);
 		}
+		commentOutInsnsBeforeSuper(mth);
 	}
 
 	private static void removeInstructions(BlockNode block) {
@@ -171,4 +179,33 @@ private static void modifyArith(BlockNode block) {
 			}
 		}
 	}
+
+	private void commentOutInsnsBeforeSuper(MethodNode mth) {
+		if (mth.isConstructor() && !Objects.equals(mth.getParentClass().getSuperClass(), ArgType.OBJECT)) {
+			DepthRegionTraversal.traverse(mth, SUPER_CALL_REGION_VISITOR);
+		}
+	}
+
+	private static final class SuperCallRegionVisitor extends AbstractRegionVisitor {
+		@Override
+		public void processBlock(MethodNode mth, IBlock container) {
+			for (InsnNode insn : container.getInstructions()) {
+				InsnType insnType = insn.getType();
+				if ((insnType == InsnType.CONSTRUCTOR) && ((ConstructorInsn) insn).isSuper()) {
+					// found super call
+					commentOutInsns(container, insn);
+					// TODO: process all previous regions (in case of branching before super call)
+				}
+			}
+		}
+
+		private static void commentOutInsns(IBlock container, InsnNode superInsn) {
+			for (InsnNode insn : container.getInstructions()) {
+				if (insn == superInsn) {
+					break;
+				}
+				insn.add(AFlag.COMMENT_OUT);
+			}
+		}
+	}
 }

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

@@ -0,0 +1,41 @@
+package jadx.tests.integration.others;
+
+import org.junit.jupiter.api.Test;
+
+import jadx.core.dex.nodes.ClassNode;
+import jadx.tests.api.SmaliTest;
+
+import static jadx.tests.api.utils.JadxMatchers.containsOne;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+public class TestInsnsBeforeSuper extends SmaliTest {
+	// @formatter:off
+	/*
+		public class A {
+			public A(String s) {
+			}
+		}
+
+		public class B extends A {
+			public B(String str) {
+				checkNull(str);
+				super(str);
+			}
+
+			public void checkNull(Object o) {
+				if (o == null) {
+					throw new NullPointerException();
+				}
+			}
+		}
+	*/
+	// @formatter:on
+
+	@Test
+	public void test() {
+		ClassNode cls = getClassNodeFromSmaliFiles("B");
+		String code = cls.getCode().toString();
+
+		assertThat(code, containsOne("// checkNull(str);"));
+	}
+}

jadx-core/src/test/smali/others/TestInsnsBeforeSuper/A.smali

@@ -0,0 +1,14 @@
+.class public Lothers/A;
+.super Ljava/lang/Object;
+
+
+# direct methods
+.method public constructor <init>(Ljava/lang/String;)V
+    .registers 3
+
+    .prologue
+
+    invoke-direct {p0}, Ljava/lang/Object;-><init>()V
+
+    return-void
+.end method

jadx-core/src/test/smali/others/TestInsnsBeforeSuper/B.smali

@@ -0,0 +1,30 @@
+.class public Lothers/B;
+.super Lothers/A;
+
+
+# direct methods
+.method public constructor <init>(Ljava/lang/String;)V
+    .registers 3
+
+    .prologue
+    invoke-static {p1}, Lothers/B;->checkNull(Ljava/lang/Object;)V
+
+    invoke-direct {p0, p1}, Lothers/A;-><init>(Ljava/lang/String;)V
+
+    return-void
+.end method
+
+
+.method public static checkNull(Ljava/lang/Object;)V
+    .registers 3
+
+    .prologue
+    if-nez p0, :cond_8
+
+    new-instance v0, Ljava/lang/NullPointerException;
+    invoke-direct {v0}, Ljava/lang/NullPointerException;-><init>()V
+    throw v0
+
+    :cond_8
+    return-void
+.end method