From f0513a1a5512634b192b0c1f34f4d7cd496ab364 Mon Sep 17 00:00:00 2001
From: Skylot <118523+skylot@users.noreply.github.com>
Date: Thu, 7 Nov 2024 20:02:41 +0000
Subject: [PATCH] fix: insert new filled array insn before first usage (#2340)

---
 .../core/dex/visitors/ReplaceNewArray.java    | 22 +++++++++---
 .../arrays/TestArrayInitField2.java           | 17 +++++++++
 .../smali/arrays/TestArrayInitField2.smali    | 36 +++++++++++++++++++
 3 files changed, 71 insertions(+), 4 deletions(-)
 create mode 100644 jadx-core/src/test/java/jadx/tests/integration/arrays/TestArrayInitField2.java
 create mode 100644 jadx-core/src/test/smali/arrays/TestArrayInitField2.smali

diff --git a/jadx-core/src/main/java/jadx/core/dex/visitors/ReplaceNewArray.java b/jadx-core/src/main/java/jadx/core/dex/visitors/ReplaceNewArray.java
index 80ebc34ab..6bf592401 100644
--- a/jadx-core/src/main/java/jadx/core/dex/visitors/ReplaceNewArray.java
+++ b/jadx-core/src/main/java/jadx/core/dex/visitors/ReplaceNewArray.java
@@ -25,7 +25,6 @@ import jadx.core.dex.nodes.IFieldInfoRef;
 import jadx.core.dex.nodes.InsnNode;
 import jadx.core.dex.nodes.MethodNode;
 import jadx.core.dex.visitors.shrink.CodeShrinkVisitor;
-import jadx.core.utils.BlockUtils;
 import jadx.core.utils.InsnList;
 import jadx.core.utils.InsnRemover;
 import jadx.core.utils.InsnUtils;
@@ -109,11 +108,15 @@ public class ReplaceNewArray extends AbstractVisitor {
 		}
 		// collect put instructions sorted by array index
 		SortedMap<Long, InsnNode> arrPuts = new TreeMap<>();
+		InsnNode firstNotAPutUsage = null;
 		for (RegisterArg registerArg : useList) {
 			InsnNode parentInsn = registerArg.getParentInsn();
 			if (parentInsn == null
 					|| parentInsn.getType() != InsnType.APUT
 					|| !arrArg.sameRegAndSVar(parentInsn.getArg(0))) {
+				if (firstNotAPutUsage == null) {
+					firstNotAPutUsage = parentInsn;
+				}
 				continue;
 			}
 			Object constVal = InsnUtils.getConstValueByArg(mth.root(), parentInsn.getArg(1));
@@ -158,12 +161,23 @@ public class ReplaceNewArray extends AbstractVisitor {
 			remover.addAndUnbind(put);
 			prevIndex = index;
 		}
+		// add missing trailing zeros
+		for (long i = prevIndex + 1; i < len; i++) {
+			filledArr.addArg(InsnArg.lit(0, elemType));
+		}
 		remover.addAndUnbind(newArrayInsn);
 
+		// place new insn at last array put or before first usage
 		InsnNode lastPut = arrPuts.get(arrPuts.lastKey());
-		int replaceIndex = InsnList.getIndex(instructions, lastPut);
-		instructions.set(replaceIndex, filledArr);
-		BlockUtils.replaceInsn(mth, lastPut, filledArr);
+		int newInsnPos = InsnList.getIndex(instructions, lastPut);
+		if (firstNotAPutUsage != null) {
+			int idx = InsnList.getIndex(instructions, firstNotAPutUsage);
+			if (idx != -1) {
+				// TODO: check that all args already assigned
+				newInsnPos = Math.min(idx, newInsnPos);
+			}
+		}
+		instructions.add(newInsnPos, filledArr);
 		return true;
 	}
 
diff --git a/jadx-core/src/test/java/jadx/tests/integration/arrays/TestArrayInitField2.java b/jadx-core/src/test/java/jadx/tests/integration/arrays/TestArrayInitField2.java
new file mode 100644
index 000000000..a0509885c
--- /dev/null
+++ b/jadx-core/src/test/java/jadx/tests/integration/arrays/TestArrayInitField2.java
@@ -0,0 +1,17 @@
+package jadx.tests.integration.arrays;
+
+import org.junit.jupiter.api.Test;
+
+import jadx.tests.api.SmaliTest;
+
+import static jadx.tests.api.utils.assertj.JadxAssertions.assertThat;
+
+public class TestArrayInitField2 extends SmaliTest {
+	@Test
+	public void test() {
+		forceDecompiledCheck();
+		assertThat(getClassNodeFromSmali())
+				.code()
+				.containsOne("static long[] myArr = {1282979400, 0, 0};");
+	}
+}
diff --git a/jadx-core/src/test/smali/arrays/TestArrayInitField2.smali b/jadx-core/src/test/smali/arrays/TestArrayInitField2.smali
new file mode 100644
index 000000000..fc077c62a
--- /dev/null
+++ b/jadx-core/src/test/smali/arrays/TestArrayInitField2.smali
@@ -0,0 +1,36 @@
+.class public Larrays/TestArrayInitField2;
+.super Ljava/lang/Object;
+
+.field static myArr:[J
+
+.method static constructor <clinit>()V
+    .locals 4
+
+    const v0, 0x3
+    new-array v0, v0, [J
+    sput-object v0, Larrays/TestArrayInitField2;->myArr:[J
+    const/4 v1, 0x0
+    const-wide/32 v2, 0x4c78b648
+    aput-wide v2, v0, v1
+    return-void
+    nop
+
+.end method
+
+.method public check()V
+    .registers 5
+    sget-object v0, Larrays/TestArrayInitField2;->myArr:[J
+    invoke-static {v0}, Lorg/assertj/core/api/Assertions;->assertThat([J)Lorg/assertj/core/api/AbstractLongArrayAssert;
+    move-result-object v0
+    const/4 v1, 0x3
+    invoke-virtual {v0, v1}, Lorg/assertj/core/api/AbstractLongArrayAssert;->hasSize(I)Lorg/assertj/core/api/AbstractLongArrayAssert;
+
+    sget-object v0, Larrays/TestArrayInitField2;->myArr:[J
+    const/4 v1, 0x0
+    aget-wide v0, v0, v1
+    invoke-static {v0, v1}, Lorg/assertj/core/api/Assertions;->assertThat(J)Lorg/assertj/core/api/AbstractLongAssert;
+    move-result-object v0
+    const-wide/32 v2, 0x4c78b648
+    invoke-virtual {v0, v2, v3}, Lorg/assertj/core/api/AbstractLongAssert;->isEqualTo(J)Lorg/assertj/core/api/AbstractLongAssert;
+    return-void
+.end method