feat: Improve Smali Compiler

- Branching support has been added. See InlineSmaliCompilerTest.kt for an example.
- Some other improvements have been made too.

src/main/kotlin/app/revanced/patcher/extensions/Extensions.kt

@@ -6,7 +6,10 @@ import app.revanced.patcher.util.smali.toInstruction
 import app.revanced.patcher.util.smali.toInstructions
 import org.jf.dexlib2.AccessFlags
 import org.jf.dexlib2.builder.BuilderInstruction
+import org.jf.dexlib2.builder.BuilderOffsetInstruction
+import org.jf.dexlib2.builder.Label
 import org.jf.dexlib2.builder.MutableMethodImplementation
+import org.jf.dexlib2.builder.instruction.*
 import org.jf.dexlib2.iface.Method
 import org.jf.dexlib2.iface.reference.MethodReference
 import org.jf.dexlib2.immutable.ImmutableMethod
@@ -23,6 +26,12 @@ fun MutableMethodImplementation.addInstructions(index: Int, instructions: List<B
     }
 }
 
+fun MutableMethodImplementation.addInstructions(instructions: List<BuilderInstruction>) {
+    for (instruction in instructions) {
+        this.addInstruction(instruction)
+    }
+}
+
 fun MutableMethodImplementation.replaceInstructions(index: Int, instructions: List<BuilderInstruction>) {
     for (i in instructions.lastIndex downTo 0) {
         this.replaceInstruction(index + i, instructions[i])
@@ -40,9 +49,7 @@ fun MutableMethodImplementation.removeInstructions(index: Int, count: Int) {
  * @param otherMethod The method to compare against.
  * @return True if the methods match given the conditions.
  */
-fun Method.softCompareTo(
+fun Method.softCompareTo(otherMethod: MethodReference): Boolean {
-    otherMethod: MethodReference
-): Boolean {
     if (MethodUtil.isConstructor(this) && !parametersEqual(this.parameterTypes, otherMethod.parameterTypes))
         return false
     return this.name == otherMethod.name
@@ -54,9 +61,7 @@ fun Method.softCompareTo(
  * This may be a positive or negative number.
  * @return The **immutable** cloned method. Call [toMutable] or [cloneMutable] to get a **mutable** copy.
  */
-internal fun Method.clone(
+internal fun Method.clone(registerCount: Int = 0): ImmutableMethod {
-    registerCount: Int = 0,
-): ImmutableMethod {
     val clonedImplementation = implementation?.let {
         ImmutableMethodImplementation(
             it.registerCount + registerCount,
@@ -110,10 +115,41 @@ fun MutableMethod.removeInstruction(index: Int) =
 /**
  * Add smali instructions to the method.
  * @param index The index to insert the instructions at.
+ * @param smali The smali instructions to add.
+ */
+fun MutableMethod.addInstructions(index: Int, smali: String, labels: List<Pair<String, Label>> = emptyList()) {
+    var code = smali
+    for ((name, _) in labels) {
+        code += "\n :$name \n nop"
+    }
+    val instructions = code.toInstructions(this).toMutableList()
+    var fixedInstructions: List<Int>? = null // find a better way to do this.
+
+    if (labels.isNotEmpty()) {
+        val labelRange = instructions.size - labels.size..instructions.size
+        fixedInstructions = mutableListOf()
+        for (instructionIndex in 0 until instructions.size - labels.size) {
+            val instruction = instructions[instructionIndex]
+            if (instruction !is BuilderOffsetInstruction || !instruction.target.isPlaced) continue
+            val fakeIndex = instruction.target.location.index
+            if (!labelRange.contains(fakeIndex)) continue
+            instructions[instructionIndex] = replaceOffset(instruction, labels[labelRange.indexOf(fakeIndex)].second)
+            fixedInstructions.add(instructionIndex + index)
+        }
+        // find a better way to drop the nop instructions.
+        instructions.subList(labelRange.first, labelRange.last).clear()
+    }
+
+    this.implementation!!.addInstructions(index, instructions)
+    this.fixInstructions(index, instructions, fixedInstructions)
+}
+
+/**
+ * Add smali instructions to the end of the method.
  * @param instructions The smali instructions to add.
  */
-fun MutableMethod.addInstructions(index: Int, instructions: String) =
+fun MutableMethod.addInstructions(instructions: String, labels: List<Pair<String, Label>> = emptyList()) =
-    this.implementation!!.addInstructions(index, instructions.toInstructions(this))
+    this.addInstructions(this.implementation!!.instructions.size, instructions, labels)
 
 /**
  * Replace smali instructions within the method.
@@ -131,15 +167,43 @@ fun MutableMethod.replaceInstructions(index: Int, instructions: String) =
 fun MutableMethod.removeInstructions(index: Int, count: Int) =
     this.implementation!!.removeInstructions(index, count)
 
+fun MutableMethod.label(index: Int) = this.implementation!!.newLabelForIndex(index)
+fun MutableMethod.instruction(index: Int): BuilderInstruction = this.implementation!!.instructions[index]
+
+private fun MutableMethod.fixInstructions(index: Int, instructions: List<BuilderInstruction>, skipInstructions: List<Int>?) {
+    for (instructionIndex in index until instructions.size + index) {
+        val instruction = this.implementation!!.instructions[instructionIndex]
+        if (instruction !is BuilderOffsetInstruction || !instruction.target.isPlaced) continue
+        if (skipInstructions?.contains(instructionIndex) == true) continue
+        val fakeIndex = instruction.target.location.index
+        val fixedIndex = fakeIndex + index
+        if (fakeIndex == fixedIndex) continue // no need to replace if the indexes are the same.
+        this.implementation!!.replaceInstruction(instructionIndex, replaceOffset(instruction, this.label(fixedIndex)))
+    }
+}
+
+private fun replaceOffset(
+    i: BuilderOffsetInstruction,
+    label: Label
+): BuilderOffsetInstruction {
+    return when (i) {
+        is BuilderInstruction10t -> BuilderInstruction10t(i.opcode, label)
+        is BuilderInstruction20t -> BuilderInstruction20t(i.opcode, label)
+        is BuilderInstruction21t -> BuilderInstruction21t(i.opcode, i.registerA, label)
+        is BuilderInstruction22t -> BuilderInstruction22t(i.opcode, i.registerA, i.registerB, label)
+        is BuilderInstruction30t -> BuilderInstruction30t(i.opcode, label)
+        is BuilderInstruction31t -> BuilderInstruction31t(i.opcode, i.registerA, label)
+        else -> throw IllegalStateException("A non-offset instruction was given, this should never happen!")
+    }
+}
+
 /**
  * Clones the method.
  * @param registerCount This parameter allows you to change the register count of the method.
  * This may be a positive or negative number.
  * @return The **mutable** cloned method. Call [clone] to get an **immutable** copy.
  */
-internal fun Method.cloneMutable(
+internal fun Method.cloneMutable(registerCount: Int = 0) = clone(registerCount).toMutable()
-    registerCount: Int = 0,
-) = clone(registerCount).toMutable()
 
 // FIXME: also check the order of parameters as different order equals different method overload
 internal fun parametersEqual(
@@ -155,10 +219,9 @@ internal fun parametersEqual(
     }
 }
 
-internal val nullOutputStream: OutputStream =
+internal val nullOutputStream = object : OutputStream() {
-    object : OutputStream() {
+    override fun write(b: Int) {}
-        override fun write(b: Int) {}
+}
-    }
 
 /**
  * Should be used to parse a list of parameters represented by their first letter,

src/main/kotlin/app/revanced/patcher/util/smali/InlineSmaliCompiler.kt

@@ -1,12 +1,12 @@
 package app.revanced.patcher.util.smali
 
+import app.revanced.patcher.util.proxy.mutableTypes.MutableMethod
 import org.antlr.runtime.CommonTokenStream
 import org.antlr.runtime.TokenSource
 import org.antlr.runtime.tree.CommonTreeNodeStream
 import org.jf.dexlib2.AccessFlags
 import org.jf.dexlib2.Opcodes
 import org.jf.dexlib2.builder.BuilderInstruction
-import org.jf.dexlib2.iface.Method
 import org.jf.dexlib2.writer.builder.DexBuilder
 import org.jf.smali.LexerErrorInterface
 import org.jf.smali.smaliFlexLexer
@@ -27,23 +27,25 @@ class InlineSmaliCompiler {
     companion object {
         /**
          * Compiles a string of Smali code to a list of instructions.
-         * p0, p1 etc. will only work correctly if the parameters and registers are passed.
+         * Special registers (such as p0, p1) will only work correctly
-         * Do not cross the boundaries of the control flow (if-nez insn, etc),
+         * if the parameters and registers of the method are passed.
-         * as that will result in exceptions since the labels cannot be calculated.
-         * Do not create dummy labels to fix the issue, since the code addresses will
-         * be messed up and results in broken Dalvik bytecode.
-         * FIXME: Fix the above issue. When this is fixed, add the proper conversions in [InstructionConverter].
          */
         fun compile(
             instructions: String, parameters: String, registers: Int, forStaticMethod: Boolean
         ): List<BuilderInstruction> {
-            val input =
+            val input = METHOD_TEMPLATE.format(
-                METHOD_TEMPLATE.format(if (forStaticMethod) "static" else "", parameters, registers, instructions)
+                if (forStaticMethod) {
+                    "static"
+                } else {
+                    ""
+                }, parameters, registers, instructions
+            )
             val reader = InputStreamReader(input.byteInputStream())
             val lexer: LexerErrorInterface = smaliFlexLexer(reader, 15)
             val tokens = CommonTokenStream(lexer as TokenSource)
             val parser = smaliParser(tokens)
             val result = parser.smali_file()
+            result.tree
             if (parser.numberOfSyntaxErrors > 0 || lexer.numberOfSyntaxErrors > 0) {
                 throw IllegalStateException(
                     "Encountered ${parser.numberOfSyntaxErrors} parser syntax errors and ${lexer.numberOfSyntaxErrors} lexer syntax errors!"
@@ -54,25 +56,30 @@ class InlineSmaliCompiler {
             val dexGen = smaliTreeWalker(treeStream)
             dexGen.setDexBuilder(DexBuilder(Opcodes.getDefault()))
             val classDef = dexGen.smali_file()
-            return classDef.methods.first().implementation!!.instructions.map { it.toBuilderInstruction() }
+            return classDef.methods.first().implementation!!.instructions.map { it as BuilderInstruction }
         }
     }
 }
 
 /**
  * Compile lines of Smali code to a list of instructions.
- * @param templateMethod The method to compile the instructions against.
+ *
+ * Note: Adding compiled instructions to an existing method with
+ * offset instructions WITHOUT specifying a parent method will not work.
+ * @param method The method to compile the instructions against.
  * @returns A list of instructions.
  */
-fun String.toInstructions(templateMethod: Method? = null) = InlineSmaliCompiler.compile(this,
+fun String.toInstructions(method: MutableMethod? = null): List<BuilderInstruction> {
-    templateMethod?.parameters?.joinToString("") { it } ?: "",
+    return InlineSmaliCompiler.compile(this,
-    templateMethod?.implementation?.registerCount ?: 1,
+        method?.parameters?.joinToString("") { it } ?: "",
-    templateMethod?.let { AccessFlags.STATIC.isSet(it.accessFlags) } ?: true
+        method?.implementation?.registerCount ?: 1,
-)
+        method?.let { AccessFlags.STATIC.isSet(it.accessFlags) } ?: true
+    )
+}
 
 /**
  * Compile a line of Smali code to an instruction.
  * @param templateMethod The method to compile the instructions against.
  * @return The instruction.
  */
-fun String.toInstruction(templateMethod: Method? = null) = this.toInstructions(templateMethod).first()
+fun String.toInstruction(templateMethod: MutableMethod? = null) = this.toInstructions(templateMethod).first()

src/main/kotlin/app/revanced/patcher/util/smali/InstructionConverter.kt

@@ -1,261 +0,0 @@
-package app.revanced.patcher.util.smali
-
-import org.jf.dexlib2.Format
-import org.jf.dexlib2.builder.instruction.*
-import org.jf.dexlib2.iface.instruction.Instruction
-import org.jf.dexlib2.iface.instruction.formats.*
-import org.jf.util.ExceptionWithContext
-
-fun Instruction.toBuilderInstruction() =
-    when (this.opcode.format) {
-        Format.Format10x -> InstructionConverter.newBuilderInstruction10x(this as Instruction10x)
-        Format.Format11n -> InstructionConverter.newBuilderInstruction11n(this as Instruction11n)
-        Format.Format11x -> InstructionConverter.newBuilderInstruction11x(this as Instruction11x)
-        Format.Format12x -> InstructionConverter.newBuilderInstruction12x(this as Instruction12x)
-        Format.Format20bc -> InstructionConverter.newBuilderInstruction20bc(this as Instruction20bc)
-        Format.Format21c -> InstructionConverter.newBuilderInstruction21c(this as Instruction21c)
-        Format.Format21ih -> InstructionConverter.newBuilderInstruction21ih(this as Instruction21ih)
-        Format.Format21lh -> InstructionConverter.newBuilderInstruction21lh(this as Instruction21lh)
-        Format.Format21s -> InstructionConverter.newBuilderInstruction21s(this as Instruction21s)
-        Format.Format22b -> InstructionConverter.newBuilderInstruction22b(this as Instruction22b)
-        Format.Format22c -> InstructionConverter.newBuilderInstruction22c(this as Instruction22c)
-        Format.Format22cs -> InstructionConverter.newBuilderInstruction22cs(this as Instruction22cs)
-        Format.Format22s -> InstructionConverter.newBuilderInstruction22s(this as Instruction22s)
-        Format.Format22x -> InstructionConverter.newBuilderInstruction22x(this as Instruction22x)
-        Format.Format23x -> InstructionConverter.newBuilderInstruction23x(this as Instruction23x)
-        Format.Format31c -> InstructionConverter.newBuilderInstruction31c(this as Instruction31c)
-        Format.Format31i -> InstructionConverter.newBuilderInstruction31i(this as Instruction31i)
-        Format.Format32x -> InstructionConverter.newBuilderInstruction32x(this as Instruction32x)
-        Format.Format35c -> InstructionConverter.newBuilderInstruction35c(this as Instruction35c)
-        Format.Format35mi -> InstructionConverter.newBuilderInstruction35mi(this as Instruction35mi)
-        Format.Format35ms -> InstructionConverter.newBuilderInstruction35ms(this as Instruction35ms)
-        Format.Format3rc -> InstructionConverter.newBuilderInstruction3rc(this as Instruction3rc)
-        Format.Format3rmi -> InstructionConverter.newBuilderInstruction3rmi(this as Instruction3rmi)
-        Format.Format3rms -> InstructionConverter.newBuilderInstruction3rms(this as Instruction3rms)
-        Format.Format51l -> InstructionConverter.newBuilderInstruction51l(this as Instruction51l)
-        else -> throw ExceptionWithContext("Instruction format %s not supported", this.opcode.format)
-    }
-
-internal class InstructionConverter {
-    companion object {
-        internal fun newBuilderInstruction10x(instruction: Instruction10x): BuilderInstruction10x {
-            return BuilderInstruction10x(
-                instruction.opcode
-            )
-        }
-
-        internal fun newBuilderInstruction11n(instruction: Instruction11n): BuilderInstruction11n {
-            return BuilderInstruction11n(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.narrowLiteral
-            )
-        }
-
-        internal fun newBuilderInstruction11x(instruction: Instruction11x): BuilderInstruction11x {
-            return BuilderInstruction11x(
-                instruction.opcode,
-                instruction.registerA
-            )
-        }
-
-        internal fun newBuilderInstruction12x(instruction: Instruction12x): BuilderInstruction12x {
-            return BuilderInstruction12x(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.registerB
-            )
-        }
-
-        internal fun newBuilderInstruction20bc(instruction: Instruction20bc): BuilderInstruction20bc {
-            return BuilderInstruction20bc(
-                instruction.opcode,
-                instruction.verificationError,
-                instruction.reference
-            )
-        }
-
-        internal fun newBuilderInstruction21c(instruction: Instruction21c): BuilderInstruction21c {
-            return BuilderInstruction21c(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.reference
-            )
-        }
-
-        internal fun newBuilderInstruction21ih(instruction: Instruction21ih): BuilderInstruction21ih {
-            return BuilderInstruction21ih(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.narrowLiteral
-            )
-        }
-
-        internal fun newBuilderInstruction21lh(instruction: Instruction21lh): BuilderInstruction21lh {
-            return BuilderInstruction21lh(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.wideLiteral
-            )
-        }
-
-        internal fun newBuilderInstruction21s(instruction: Instruction21s): BuilderInstruction21s {
-            return BuilderInstruction21s(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.narrowLiteral
-            )
-        }
-
-        internal fun newBuilderInstruction22b(instruction: Instruction22b): BuilderInstruction22b {
-            return BuilderInstruction22b(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.registerB,
-                instruction.narrowLiteral
-            )
-        }
-
-        internal fun newBuilderInstruction22c(instruction: Instruction22c): BuilderInstruction22c {
-            return BuilderInstruction22c(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.registerB,
-                instruction.reference
-            )
-        }
-
-        internal fun newBuilderInstruction22cs(instruction: Instruction22cs): BuilderInstruction22cs {
-            return BuilderInstruction22cs(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.registerB,
-                instruction.fieldOffset
-            )
-        }
-
-        internal fun newBuilderInstruction22s(instruction: Instruction22s): BuilderInstruction22s {
-            return BuilderInstruction22s(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.registerB,
-                instruction.narrowLiteral
-            )
-        }
-
-        internal fun newBuilderInstruction22x(instruction: Instruction22x): BuilderInstruction22x {
-            return BuilderInstruction22x(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.registerB
-            )
-        }
-
-        internal fun newBuilderInstruction23x(instruction: Instruction23x): BuilderInstruction23x {
-            return BuilderInstruction23x(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.registerB,
-                instruction.registerC
-            )
-        }
-
-        internal fun newBuilderInstruction31c(instruction: Instruction31c): BuilderInstruction31c {
-            return BuilderInstruction31c(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.reference
-            )
-        }
-
-        internal fun newBuilderInstruction31i(instruction: Instruction31i): BuilderInstruction31i {
-            return BuilderInstruction31i(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.narrowLiteral
-            )
-        }
-
-        internal fun newBuilderInstruction32x(instruction: Instruction32x): BuilderInstruction32x {
-            return BuilderInstruction32x(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.registerB
-            )
-        }
-
-        internal fun newBuilderInstruction35c(instruction: Instruction35c): BuilderInstruction35c {
-            return BuilderInstruction35c(
-                instruction.opcode,
-                instruction.registerCount,
-                instruction.registerC,
-                instruction.registerD,
-                instruction.registerE,
-                instruction.registerF,
-                instruction.registerG,
-                instruction.reference
-            )
-        }
-
-        internal fun newBuilderInstruction35mi(instruction: Instruction35mi): BuilderInstruction35mi {
-            return BuilderInstruction35mi(
-                instruction.opcode,
-                instruction.registerCount,
-                instruction.registerC,
-                instruction.registerD,
-                instruction.registerE,
-                instruction.registerF,
-                instruction.registerG,
-                instruction.inlineIndex
-            )
-        }
-
-        internal fun newBuilderInstruction35ms(instruction: Instruction35ms): BuilderInstruction35ms {
-            return BuilderInstruction35ms(
-                instruction.opcode,
-                instruction.registerCount,
-                instruction.registerC,
-                instruction.registerD,
-                instruction.registerE,
-                instruction.registerF,
-                instruction.registerG,
-                instruction.vtableIndex
-            )
-        }
-
-        internal fun newBuilderInstruction3rc(instruction: Instruction3rc): BuilderInstruction3rc {
-            return BuilderInstruction3rc(
-                instruction.opcode,
-                instruction.startRegister,
-                instruction.registerCount,
-                instruction.reference
-            )
-        }
-
-        internal fun newBuilderInstruction3rmi(instruction: Instruction3rmi): BuilderInstruction3rmi {
-            return BuilderInstruction3rmi(
-                instruction.opcode,
-                instruction.startRegister,
-                instruction.registerCount,
-                instruction.inlineIndex
-            )
-        }
-
-        internal fun newBuilderInstruction3rms(instruction: Instruction3rms): BuilderInstruction3rms {
-            return BuilderInstruction3rms(
-                instruction.opcode,
-                instruction.startRegister,
-                instruction.registerCount,
-                instruction.vtableIndex
-            )
-        }
-
-        internal fun newBuilderInstruction51l(instruction: Instruction51l): BuilderInstruction51l {
-            return BuilderInstruction51l(
-                instruction.opcode,
-                instruction.registerA,
-                instruction.wideLiteral
-            )
-        }
-    }
-}

src/test/kotlin/app/revanced/patcher/usage/PatcherTest.kt

@@ -1,46 +0,0 @@
-package app.revanced.patcher.usage
-
-import org.junit.jupiter.api.Test
-
-internal class PatcherTest {
-    @Test
-    fun testPatcher() {
-        return // FIXME: create a proper resource to pass this test
-        /**
-        val patcher = Patcher(
-        File(PatcherTest::class.java.getResource("/example.apk")!!.toURI()),
-        "exampleCacheDirectory",
-        patchResources = true
-        )
-
-        patcher.addPatches(listOf(ExampleBytecodePatch(), ExampleResourcePatch()))
-
-        for (signature in patcher.resolveSignatures()) {
-        if (!signature.resolved) {
-        throw Exception("Signature ${signature.metadata.name} was not resolved!")
-        }
-        val patternScanMethod = signature.metadata.patternScanMethod
-        if (patternScanMethod is PatternScanMethod.Fuzzy) {
-        val warnings = patternScanMethod.warnings
-        if (warnings != null) {
-        println("Signature ${signature.metadata.name} had ${warnings.size} warnings!")
-        for (warning in warnings) {
-        println(warning.toString())
-        }
-        } else {
-        println("Signature ${signature.metadata.name} used the fuzzy resolver, but the warnings list is null!")
-        }
-        }
-        }
-        for ((metadata, result) in patcher.applyPatches()) {
-        if (result.isFailure) {
-        throw Exception("Patch ${metadata.shortName} failed", result.exceptionOrNull()!!)
-        } else {
-        println("Patch ${metadata.shortName} applied successfully!")
-        }
-        }
-        val out = patcher.save()
-        assertTrue(out.isNotEmpty(), "Expected the output of Patcher#save() to not be empty.")
-         */
-    }
-}

src/test/kotlin/app/revanced/patcher/usage/bytecode/patch/ExampleBytecodePatch.kt

@@ -6,6 +6,7 @@ import app.revanced.patcher.annotation.Version
 import app.revanced.patcher.data.impl.BytecodeData
 import app.revanced.patcher.extensions.addInstructions
 import app.revanced.patcher.extensions.or
+import app.revanced.patcher.extensions.replaceInstruction
 import app.revanced.patcher.patch.PatchResult
 import app.revanced.patcher.patch.PatchResultSuccess
 import app.revanced.patcher.patch.annotations.Patch
@@ -14,7 +15,6 @@ import app.revanced.patcher.usage.bytecode.fingerprints.ExampleFingerprint
 import app.revanced.patcher.usage.resource.annotation.ExampleResourceCompatibility
 import app.revanced.patcher.util.proxy.mutableTypes.MutableField.Companion.toMutable
 import app.revanced.patcher.util.proxy.mutableTypes.MutableMethod.Companion.toMutable
-import app.revanced.patcher.util.smali.toInstruction
 import com.google.common.collect.ImmutableList
 import org.jf.dexlib2.AccessFlags
 import org.jf.dexlib2.Format
@@ -107,22 +107,21 @@ class ExampleBytecodePatch : BytecodePatch(listOf(ExampleFingerprint)) {
         )
 
         // store the fields initial value into the first virtual register
-        implementation.replaceInstruction(
+        method.replaceInstruction(0, "sget-object v0, LTestClass;->dummyField:Ljava/io/PrintStream;")
-            0,
-            "sget-object v0, LTestClass;->dummyField:Ljava/io/PrintStream;".toInstruction()
-        )
 
         // Now let's create a new call to our method and print the return value!
         // You can also use the smali compiler to create instructions.
         // For this sake of example I reuse the TestClass field dummyField inside the virtual register 0.
         //
         // Control flow instructions are not supported as of now.
-        val instructions = """
+        method.addInstructions(
-                        invoke-static { }, LTestClass;->returnHello()Ljava/lang/String;
+            startIndex + 2,
-                        move-result-object v1
+            """
-                        invoke-virtual { v0, v1 }, Ljava/io/PrintStream;->println(Ljava/lang/String;)V
+                invoke-static { }, LTestClass;->returnHello()Ljava/lang/String;
-                    """
+                move-result-object v1
-        method.addInstructions(startIndex + 2, instructions)
+                invoke-virtual { v0, v1 }, Ljava/io/PrintStream;->println(Ljava/lang/String;)V
+                """
+        )
 
         // Finally, tell the patcher that this patch was a success.
         // You can also return PatchResultError with a message.

src/test/kotlin/app/revanced/patcher/util/smali/InlineSmaliCompilerTest.kt

@@ -0,0 +1,105 @@
+package app.revanced.patcher.util.smali
+
+import app.revanced.patcher.extensions.addInstructions
+import app.revanced.patcher.extensions.instruction
+import app.revanced.patcher.extensions.label
+import app.revanced.patcher.util.proxy.mutableTypes.MutableMethod.Companion.toMutable
+import org.jf.dexlib2.AccessFlags
+import org.jf.dexlib2.Opcode
+import org.jf.dexlib2.builder.BuilderInstruction
+import org.jf.dexlib2.builder.MutableMethodImplementation
+import org.jf.dexlib2.builder.instruction.BuilderInstruction21c
+import org.jf.dexlib2.builder.instruction.BuilderInstruction21t
+import org.jf.dexlib2.immutable.ImmutableMethod
+import org.jf.dexlib2.immutable.reference.ImmutableStringReference
+import java.util.*
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+
+internal class InlineSmaliCompilerTest {
+    @Test
+    fun `compiler should output valid instruction`() {
+        val want = BuilderInstruction21c(Opcode.CONST_STRING, 0, ImmutableStringReference("Test")) as BuilderInstruction
+        val have = "const-string v0, \"Test\"".toInstruction()
+        instructionEquals(want, have)
+    }
+
+    @Test
+    fun `compiler should support branching with own branches`() {
+        val method = createMethod()
+        val insnAmount = 8
+        val insnIndex = insnAmount - 2
+        val targetIndex = insnIndex - 1
+
+        method.addInstructions(arrayOfNulls<String>(insnAmount).also {
+            Arrays.fill(it, "const/4 v0, 0x0")
+        }.joinToString("\n"))
+        method.addInstructions(
+            targetIndex,
+            """
+                :test
+                const/4 v0, 0x1
+                if-eqz v0, :test
+            """
+        )
+
+        val insn = method.instruction(insnIndex) as BuilderInstruction21t
+        assertEquals(targetIndex, insn.target.location.index)
+    }
+
+    @Test
+    fun `compiler should support branching to outside branches`() {
+        val method = createMethod()
+        val insnIndex = 3
+        val labelIndex = 1
+
+        method.addInstructions(
+            """
+                const/4 v0, 0x1
+                :test
+                const/4 v0, 0x0
+            """
+        )
+
+        assertEquals(labelIndex, method.label(labelIndex).location.index)
+
+        method.addInstructions(
+            """
+                const/4 v0, 0x1
+                if-eqz v0, :test
+                return-void
+            """, listOf(
+                "test" to method.label(labelIndex)
+            )
+        )
+
+        val insn = method.instruction(insnIndex) as BuilderInstruction21t
+        assertTrue(insn.target.isPlaced, "Label was not placed")
+        assertEquals(labelIndex, insn.target.location.index)
+    }
+
+    companion object {
+        private fun createMethod(
+            name: String = "dummy",
+            returnType: String = "V",
+            accessFlags: Int = AccessFlags.STATIC.value,
+            registerCount: Int = 1,
+        ) = ImmutableMethod(
+            "Ldummy;",
+            name,
+            emptyList(), // parameters
+            returnType,
+            accessFlags,
+            emptySet(),
+            emptySet(),
+            MutableMethodImplementation(registerCount)
+        ).toMutable()
+
+        private fun instructionEquals(want: BuilderInstruction, have: BuilderInstruction) {
+            assertEquals(want.opcode, have.opcode)
+            assertEquals(want.format, have.format)
+            assertEquals(want.codeUnits, have.codeUnits)
+        }
+    }
+}