[IR] Support reflection for MFVC

Signed-off-by: Evgeniy.Zhelenskiy <Evgeniy.Zhelenskiy@jetbrains.com>

#KT-1179

core/descriptors/src/org/jetbrains/kotlin/resolve/inlineClassesUtils.kt

@@ -9,6 +9,7 @@ import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.resolve.descriptorUtil.inlineClassRepresentation
+import org.jetbrains.kotlin.resolve.descriptorUtil.multiFieldValueClassRepresentation
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.TypeSubstitutor
 import org.jetbrains.kotlin.types.TypeUtils
@@ -42,6 +43,8 @@ fun KotlinType.unsubstitutedUnderlyingTypes(): List<KotlinType> {
 
 
 fun KotlinType.isInlineClassType(): Boolean = constructor.declarationDescriptor?.isInlineClass() ?: false
+fun KotlinType.isMultiFieldValueClassType(): Boolean = constructor.declarationDescriptor?.isMultiFieldValueClass() ?: false
+fun KotlinType.isValueClassType(): Boolean = constructor.declarationDescriptor?.isValueClass() ?: false
 
 fun KotlinType.needsMfvcFlattening(): Boolean =
     constructor.declarationDescriptor?.run { isMultiFieldValueClass() && !isNullableType() } == true
@@ -77,6 +80,20 @@ fun KotlinType.isNullableUnderlyingType(): Boolean {
 fun CallableDescriptor.isGetterOfUnderlyingPropertyOfInlineClass() =
     this is PropertyGetterDescriptor && correspondingProperty.isUnderlyingPropertyOfInlineClass()
 
+fun CallableDescriptor.isGetterOfUnderlyingPropertyOfMultiFieldValueClass() =
+    this is PropertyGetterDescriptor && correspondingProperty.isUnderlyingPropertyOfMultiFieldValueClass()
+
+fun CallableDescriptor.isGetterOfUnderlyingPropertyOfValueClass() =
+    this is PropertyGetterDescriptor && correspondingProperty.isUnderlyingPropertyOfValueClass()
+
 fun VariableDescriptor.isUnderlyingPropertyOfInlineClass(): Boolean =
     extensionReceiverParameter == null &&
             (containingDeclaration as? ClassDescriptor)?.inlineClassRepresentation?.underlyingPropertyName == this.name
+
+fun VariableDescriptor.isUnderlyingPropertyOfMultiFieldValueClass(): Boolean =
+    extensionReceiverParameter == null &&
+            (containingDeclaration as? ClassDescriptor)?.multiFieldValueClassRepresentation?.containsPropertyWithName(this.name) == true
+
+fun VariableDescriptor.isUnderlyingPropertyOfValueClass(): Boolean =
+    extensionReceiverParameter == null &&
+            (containingDeclaration as? ClassDescriptor)?.valueClassRepresentation?.containsPropertyWithName(this.name) == true

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KCallableImpl.kt

@@ -8,13 +8,14 @@ package kotlin.reflect.jvm.internal
 import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.load.java.descriptors.JavaCallableMemberDescriptor
+import org.jetbrains.kotlin.types.asSimpleType
 import java.lang.reflect.ParameterizedType
 import java.lang.reflect.Type
 import java.lang.reflect.WildcardType
-import java.util.*
 import kotlin.coroutines.Continuation
 import kotlin.reflect.*
 import kotlin.reflect.jvm.internal.calls.Caller
+import kotlin.reflect.jvm.internal.calls.getMfvcUnboxMethods
 import kotlin.reflect.jvm.javaType
 import kotlin.reflect.jvm.jvmErasure
 import java.lang.reflect.Array as ReflectArray
@@ -113,7 +114,9 @@ internal abstract class KCallableImpl<out R> : KCallable<R>, KTypeParameterOwner
 
     private val _absentArguments = ReflectProperties.lazySoft {
         val parameterSize = parameters.size + (if (isSuspend) 1 else 0)
-        val maskSize = (parameters.size + Integer.SIZE - 1) / Integer.SIZE
+        val flattenedParametersSize =
+            if (parametersNeedMFVCFlattening.value) parameters.sumOf { getParameterTypeSize(it) } else parameters.size
+        val maskSize = (flattenedParametersSize + Integer.SIZE - 1) / Integer.SIZE
 
         // Array containing the actual function arguments, masks, and +1 for DefaultConstructorMarker or MethodHandle.
         val arguments = arrayOfNulls<Any?>(parameterSize + maskSize + 1)
@@ -161,14 +164,23 @@ internal abstract class KCallableImpl<out R> : KCallable<R>, KTypeParameterOwner
         var valueParameterIndex = 0
         var anyOptional = false
 
+        val hasMfvcParameters = parametersNeedMFVCFlattening.value
         for (parameter in parameters) {
+            val parameterTypeSize = if (hasMfvcParameters) getParameterTypeSize(parameter) else 1
             when {
                 args.containsKey(parameter) -> {
                     arguments[parameter.index] = args[parameter]
                 }
                 parameter.isOptional -> {
-                    val maskIndex = parameterSize + (valueParameterIndex / Integer.SIZE)
-                    arguments[maskIndex] = (arguments[maskIndex] as Int) or (1 shl (valueParameterIndex % Integer.SIZE))
+                    if (hasMfvcParameters) {
+                        for (valueSubParameterIndex in valueParameterIndex until (valueParameterIndex + parameterTypeSize)) {
+                            val maskIndex = parameterSize + (valueSubParameterIndex / Integer.SIZE)
+                            arguments[maskIndex] = (arguments[maskIndex] as Int) or (1 shl (valueSubParameterIndex % Integer.SIZE))
+                        }
+                    } else {
+                        val maskIndex = parameterSize + (valueParameterIndex / Integer.SIZE)
+                        arguments[maskIndex] = (arguments[maskIndex] as Int) or (1 shl (valueParameterIndex % Integer.SIZE))
+                    }
                     anyOptional = true
                 }
                 parameter.isVararg -> {}
@@ -178,7 +190,7 @@ internal abstract class KCallableImpl<out R> : KCallable<R>, KTypeParameterOwner
             }
 
             if (parameter.kind == KParameter.Kind.VALUE) {
-                valueParameterIndex++
+                valueParameterIndex += parameterTypeSize
             }
         }
 
@@ -197,6 +209,20 @@ internal abstract class KCallableImpl<out R> : KCallable<R>, KTypeParameterOwner
         }
     }
 
+    private val parametersNeedMFVCFlattening = lazy(LazyThreadSafetyMode.PUBLICATION) {
+        parameters.any { it.type.needsMultiFieldValueClassFlattening }
+    }
+
+    private fun getParameterTypeSize(parameter: KParameter): Int {
+        require(parametersNeedMFVCFlattening.value) { "Check if parametersNeedMFVCFlattening is true before" }
+        return if (parameter.type.needsMultiFieldValueClassFlattening) {
+            val type = (parameter.type as KTypeImpl).type.asSimpleType()
+            getMfvcUnboxMethods(type)!!.size
+        } else {
+            1
+        }
+    }
+
     private fun callAnnotationConstructor(args: Map<KParameter, Any?>): R {
         val arguments = parameters.map { parameter ->
             when {

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KDeclarationContainerImpl.kt

@@ -24,10 +24,12 @@ import org.jetbrains.kotlin.descriptors.runtime.structure.wrapperByPrimitive
 import org.jetbrains.kotlin.load.java.JvmAbi
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.renderer.DescriptorRenderer
+import org.jetbrains.kotlin.resolve.isMultiFieldValueClass
 import org.jetbrains.kotlin.resolve.scopes.MemberScope
 import java.lang.reflect.Constructor
 import java.lang.reflect.Method
 import kotlin.jvm.internal.ClassBasedDeclarationContainer
+import kotlin.reflect.jvm.internal.calls.toJvmDescriptor
 
 internal abstract class KDeclarationContainerImpl : ClassBasedDeclarationContainer {
     abstract inner class Data {
@@ -119,9 +121,25 @@ internal abstract class KDeclarationContainerImpl : ClassBasedDeclarationContain
     }
 
     fun findFunctionDescriptor(name: String, signature: String): FunctionDescriptor {
-        val members = if (name == "<init>") constructorDescriptors.toList() else getFunctions(Name.identifier(name))
-        val functions = members.filter { descriptor ->
-            RuntimeTypeMapper.mapSignature(descriptor).asString() == signature
+        val members: Collection<FunctionDescriptor>
+        val functions: List<FunctionDescriptor>
+        if (name == "<init>") {
+            members = constructorDescriptors.toList()
+            functions = members.filter { descriptor ->
+                val descriptorSignature = if (descriptor.isPrimary && descriptor.containingDeclaration.isMultiFieldValueClass()) {
+                    val initial = RuntimeTypeMapper.mapSignature(descriptor).asString()
+                    require(initial.startsWith("constructor-impl") && initial.endsWith(")V")) {
+                        "Invalid signature of $descriptor: $initial"
+                    }
+                    initial.removeSuffix("V") + descriptor.containingDeclaration.toJvmDescriptor()
+                } else {
+                    RuntimeTypeMapper.mapSignature(descriptor).asString()
+                }
+                descriptorSignature == signature
+            }
+        } else {
+            members = getFunctions(Name.identifier(name))
+            functions = members.filter { descriptor -> RuntimeTypeMapper.mapSignature(descriptor).asString() == signature }
         }
 
         if (functions.size != 1) {

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KFunctionImpl.kt

@@ -17,8 +17,10 @@
 package kotlin.reflect.jvm.internal
 
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.descriptors.ConstructorDescriptor
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
-import org.jetbrains.kotlin.resolve.jvm.shouldHideConstructorDueToInlineClassTypeValueParameters
+import org.jetbrains.kotlin.resolve.isMultiFieldValueClass
+import org.jetbrains.kotlin.resolve.jvm.shouldHideConstructorDueToValueClassTypeValueParameters
 import java.lang.reflect.Constructor
 import java.lang.reflect.Member
 import java.lang.reflect.Method
@@ -66,7 +68,14 @@ internal class KFunctionImpl private constructor(
                     return@caller AnnotationConstructorCaller(container.jClass, parameters.map { it.name!! }, POSITIONAL_CALL, KOTLIN)
                 container.findConstructorBySignature(jvmSignature.constructorDesc)
             }
-            is KotlinFunction -> container.findMethodBySignature(jvmSignature.methodName, jvmSignature.methodDesc)
+            is KotlinFunction -> {
+                if (descriptor.let { it.containingDeclaration.isMultiFieldValueClass() && it is ConstructorDescriptor && it.isPrimary }) {
+                    return@caller ValueClassAwareCaller.MultiFieldValueClassPrimaryConstructorCaller(
+                        descriptor, container, jvmSignature.methodDesc, descriptor.valueParameters
+                    )
+                }
+                container.findMethodBySignature(jvmSignature.methodName, jvmSignature.methodDesc)
+            }
             is JavaMethod -> jvmSignature.method
             is JavaConstructor -> jvmSignature.constructor
             is FakeJavaAnnotationConstructor -> {
@@ -87,13 +96,16 @@ internal class KFunctionImpl private constructor(
                     createStaticMethodCaller(member)
             }
             else -> throw KotlinReflectionInternalError("Could not compute caller for function: $descriptor (member = $member)")
-        }.createInlineClassAwareCallerIfNeeded(descriptor)
+        }.createValueClassAwareCallerIfNeeded(descriptor)
     }
 
     override val defaultCaller: Caller<*>? by lazy(PUBLICATION) defaultCaller@{
         val jvmSignature = RuntimeTypeMapper.mapSignature(descriptor)
         val member: Member? = when (jvmSignature) {
             is KotlinFunction -> {
+                if (descriptor.let { it.containingDeclaration.isMultiFieldValueClass() && it is ConstructorDescriptor && it.isPrimary }) {
+                    throw KotlinReflectionInternalError("${descriptor.containingDeclaration} cannot have default arguments")
+                }
                 container.findDefaultMethod(jvmSignature.methodName, jvmSignature.methodDesc, !Modifier.isStatic(caller.member!!.modifiers))
             }
             is KotlinConstructor -> {
@@ -126,7 +138,7 @@ internal class KFunctionImpl private constructor(
                     createStaticMethodCaller(member)
             }
             else -> null
-        }?.createInlineClassAwareCallerIfNeeded(descriptor, isDefault = true)
+        }?.createValueClassAwareCallerIfNeeded(descriptor, isDefault = true)
     }
 
     private val boundReceiver
@@ -144,7 +156,7 @@ internal class KFunctionImpl private constructor(
     private fun createConstructorCaller(
         member: Constructor<*>, descriptor: FunctionDescriptor, isDefault: Boolean
     ): CallerImpl<Constructor<*>> {
-        return if (!isDefault && shouldHideConstructorDueToInlineClassTypeValueParameters(descriptor)) {
+        return if (!isDefault && shouldHideConstructorDueToValueClassTypeValueParameters(descriptor)) {
             if (isBound)
                 CallerImpl.AccessorForHiddenBoundConstructor(member, boundReceiver)
             else

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KParameterImpl.kt

@@ -18,8 +18,10 @@ package kotlin.reflect.jvm.internal
 
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.resolve.descriptorUtil.declaresOrInheritsDefaultValue
+import java.lang.reflect.Type
 import kotlin.reflect.KParameter
 import kotlin.reflect.KType
+import kotlin.reflect.jvm.internal.calls.ValueClassAwareCaller
 
 internal class KParameterImpl(
     val callable: KCallableImpl<*>,
@@ -39,6 +41,27 @@ internal class KParameterImpl(
             return if (name.isSpecial) null else name.asString()
         }
 
+
+    private fun compoundType(vararg types: Type): Type = when (types.size) {
+        0 -> throw KotlinReflectionNotSupportedError("Expected at least 1 type for compound type")
+        1 -> types.single()
+        else -> CompoundTypeImpl(types)
+    }
+
+    private class CompoundTypeImpl(val types: Array<out Type>) : Type {
+        private val hashCode = types.contentHashCode()
+        override fun getTypeName(): String {
+            return types.joinToString(", ", "[", "]")
+        }
+
+        override fun equals(other: Any?): Boolean =
+            other is CompoundTypeImpl && this.types contentEquals other.types
+
+        override fun hashCode(): Int = hashCode
+
+        override fun toString(): String = typeName
+    }
+
     override val type: KType
         get() = KTypeImpl(descriptor.type) {
             val descriptor = descriptor
@@ -53,7 +76,16 @@ internal class KParameterImpl(
                 (callable.descriptor.containingDeclaration as ClassDescriptor).toJavaClass()
                     ?: throw KotlinReflectionInternalError("Cannot determine receiver Java type of inherited declaration: $descriptor")
             } else {
-                callable.caller.parameterTypes[index]
+                when (val caller = callable.caller) {
+                    is ValueClassAwareCaller -> {
+                        val slice = caller.getRealSlicesOfParameters(index)
+                        val parameterTypes = caller.parameterTypes.slice(slice)
+                        compoundType(*parameterTypes.toTypedArray())
+                    }
+                    is ValueClassAwareCaller.MultiFieldValueClassPrimaryConstructorCaller ->
+                        compoundType(*caller.originalParametersGroups[index].toTypedArray())
+                    else -> caller.parameterTypes[index]
+                }
             }
         }
 

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KPropertyImpl.kt

@@ -271,8 +271,9 @@ private fun KPropertyImpl.Accessor<*, *>.computeCallerForAccessor(isGetter: Bool
                     if (property.descriptor.isUnderlyingPropertyOfInlineClass() &&
                         property.descriptor.visibility == DescriptorVisibilities.INTERNAL
                     ) {
-                        val unboxMethod = property.descriptor.containingDeclaration.toInlineClass()?.getUnboxMethod(property.descriptor)
-                            ?: throw KotlinReflectionInternalError("Underlying property of inline class $property should have a field")
+                        val unboxMethod =
+                            property.descriptor.containingDeclaration.toInlineClass()?.getInlineClassUnboxMethod(property.descriptor)
+                                ?: throw KotlinReflectionInternalError("Underlying property of inline class $property should have a field")
                         if (isBound) InternalUnderlyingValOfInlineClass.Bound(unboxMethod, boundReceiver)
                         else InternalUnderlyingValOfInlineClass.Unbound(unboxMethod)
                     } else {
@@ -316,7 +317,7 @@ private fun KPropertyImpl.Accessor<*, *>.computeCallerForAccessor(isGetter: Bool
             return if (isBound) CallerImpl.Method.BoundInstance(accessor, boundReceiver)
             else CallerImpl.Method.Instance(accessor)
         }
-    }.createInlineClassAwareCallerIfNeeded(descriptor)
+    }.createValueClassAwareCallerIfNeeded(descriptor)
 }
 
 private fun PropertyDescriptor.isJvmFieldPropertyInCompanionObject(): Boolean {

core/reflection.jvm/src/kotlin/reflect/jvm/internal/RuntimeTypeMapper.kt

@@ -44,6 +44,7 @@ import org.jetbrains.kotlin.resolve.DescriptorFactory
 import org.jetbrains.kotlin.resolve.DescriptorUtils
 import org.jetbrains.kotlin.resolve.descriptorUtil.propertyIfAccessor
 import org.jetbrains.kotlin.resolve.isInlineClass
+import org.jetbrains.kotlin.resolve.isMultiFieldValueClass
 import org.jetbrains.kotlin.resolve.jvm.JvmPrimitiveType
 import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedCallableMemberDescriptor
 import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedClassDescriptor
@@ -51,6 +52,7 @@ import org.jetbrains.kotlin.serialization.deserialization.descriptors.Deserializ
 import java.lang.reflect.Constructor
 import java.lang.reflect.Field
 import java.lang.reflect.Method
+import kotlin.reflect.jvm.internal.calls.toJvmDescriptor
 
 internal sealed class JvmFunctionSignature {
     abstract fun asString(): String
@@ -174,10 +176,27 @@ internal object RuntimeTypeMapper {
                 }
                 if (proto is ProtoBuf.Constructor) {
                     JvmProtoBufUtil.getJvmConstructorSignature(proto, function.nameResolver, function.typeTable)?.let { signature ->
-                        return if (possiblySubstitutedFunction.containingDeclaration.isInlineClass())
-                            JvmFunctionSignature.KotlinFunction(signature)
-                        else
-                            JvmFunctionSignature.KotlinConstructor(signature)
+                        return when {
+                            possiblySubstitutedFunction.containingDeclaration.isInlineClass() ->
+                                JvmFunctionSignature.KotlinFunction(signature)
+                            possiblySubstitutedFunction.containingDeclaration.isMultiFieldValueClass() -> {
+                                val realSignature = if ((possiblySubstitutedFunction as ConstructorDescriptor).isPrimary) {
+                                    require(signature.name == "constructor-impl" && signature.desc.endsWith(")V")) { "Invalid signature: $signature" }
+                                    signature
+                                } else {
+                                    require(signature.name == "constructor-impl") { "Invalid signature: $signature" }
+                                    val constructedClass = possiblySubstitutedFunction.constructedClass.toJvmDescriptor()
+                                    if (signature.desc.endsWith(")V")) {
+                                        signature.copy(desc = signature.desc.removeSuffix("V") + constructedClass)
+                                    } else {
+                                        require(signature.desc.endsWith(constructedClass)) { "Invalid signature: $signature" }
+                                        signature
+                                    }
+                                }
+                                JvmFunctionSignature.KotlinFunction(realSignature)
+                            }
+                            else -> JvmFunctionSignature.KotlinConstructor(signature)
+                        }
                     }
                 }
                 return mapJvmFunctionSignature(function)

core/reflection.jvm/src/kotlin/reflect/jvm/internal/calls/CallerImpl.kt

@@ -122,7 +122,7 @@ internal sealed class CallerImpl<out M : Member>(
             }
         }
 
-        class BoundStatic(method: ReflectMethod, private val boundReceiver: Any?) : BoundCaller, Method(
+        class BoundStatic(method: ReflectMethod, internal val boundReceiver: Any?) : BoundCaller, Method(
             method, requiresInstance = false, parameterTypes = method.genericParameterTypes.dropFirst()
         ) {
             override fun call(args: Array<*>): Any? {
@@ -131,6 +131,21 @@ internal sealed class CallerImpl<out M : Member>(
             }
         }
 
+        class BoundStaticMultiFieldValueClass(
+            method: ReflectMethod, internal val boundReceiverComponents: Array<Any?>
+        ) : BoundCaller, Method(
+            method = method,
+            requiresInstance = false,
+            parameterTypes = method.genericParameterTypes.drop(boundReceiverComponents.size).toTypedArray()
+        ) {
+            override fun call(args: Array<*>): Any? {
+                checkArguments(args)
+                return callMethod(null, arrayOf(*boundReceiverComponents, *args))
+            }
+
+            val receiverComponentsCount: Int get() = boundReceiverComponents.size
+        }
+
         class BoundInstance(method: ReflectMethod, private val boundReceiver: Any?) : BoundCaller,
             Method(method, requiresInstance = false) {
             override fun call(args: Array<*>): Any? {

core/reflection.jvm/src/kotlin/reflect/jvm/internal/calls/ValueClassAwareCaller.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -7,29 +7,50 @@ package kotlin.reflect.jvm.internal.calls
 
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.descriptors.*
+import org.jetbrains.kotlin.descriptors.runtime.structure.desc
 import org.jetbrains.kotlin.load.java.JvmAbi
+import org.jetbrains.kotlin.metadata.jvm.deserialization.ClassMapperLite
 import org.jetbrains.kotlin.resolve.*
 import org.jetbrains.kotlin.resolve.descriptorUtil.classId
+import org.jetbrains.kotlin.resolve.descriptorUtil.multiFieldValueClassRepresentation
 import org.jetbrains.kotlin.types.KotlinType
+import org.jetbrains.kotlin.types.SimpleType
 import org.jetbrains.kotlin.types.TypeUtils
+import org.jetbrains.kotlin.types.asSimpleType
 import java.lang.reflect.Member
 import java.lang.reflect.Method
 import java.lang.reflect.Type
+import kotlin.reflect.jvm.internal.KDeclarationContainerImpl
 import kotlin.reflect.jvm.internal.KotlinReflectionInternalError
 import kotlin.reflect.jvm.internal.defaultPrimitiveValue
 import kotlin.reflect.jvm.internal.toJavaClass
 
 /**
- * A caller that is used whenever the declaration has inline classes in its parameter types or return type.
- * Each argument of an inline class type is unboxed, and the return value (if it's of an inline class type) is boxed.
+ * A caller that is used whenever the declaration has value classes in its parameter types or inline class in return type.
+ * Each argument of an value class type is unboxed, and the return value (if it's of an inline class type) is boxed.
  */
-internal class InlineClassAwareCaller<out M : Member?>(
+internal class ValueClassAwareCaller<out M : Member?>(
     descriptor: CallableMemberDescriptor,
-    private val caller: Caller<M>,
+    oldCaller: Caller<M>,
     private val isDefault: Boolean
 ) : Caller<M> {
-    override val member: M
-        get() = caller.member
+
+    private val caller: Caller<M> = if (oldCaller is CallerImpl.Method.BoundStatic) {
+        val receiverType = (descriptor.extensionReceiverParameter ?: descriptor.dispatchReceiverParameter)?.type
+        if (receiverType != null && receiverType.needsMfvcFlattening()) {
+            val unboxMethods = getMfvcUnboxMethods(receiverType.asSimpleType())!!
+            val boundReceiverComponents = unboxMethods.map { it.invoke(oldCaller.boundReceiver) }.toTypedArray()
+            @Suppress("UNCHECKED_CAST")
+            CallerImpl.Method.BoundStaticMultiFieldValueClass(oldCaller.member, boundReceiverComponents) as Caller<M>
+        } else {
+            oldCaller
+        }
+    } else {
+        oldCaller
+    }
+
+    override val member: M = caller.member
+
 
     override val returnType: Type
         get() = caller.returnType
@@ -37,24 +58,18 @@ internal class InlineClassAwareCaller<out M : Member?>(
     override val parameterTypes: List<Type>
         get() = caller.parameterTypes
 
-    private class BoxUnboxData(val argumentRange: IntRange, val unbox: Array<Method?>, val box: Method?) {
-        operator fun component1(): IntRange = argumentRange
-        operator fun component2(): Array<Method?> = unbox
-        operator fun component3(): Method? = box
-    }
+    private class BoxUnboxData(val argumentRange: IntRange, val unboxParameters: Array<List<Method>?>, val box: Method?)
 
     private val data: BoxUnboxData = run {
         val box = descriptor.returnType!!.toInlineClass()?.getBoxMethod(descriptor)
-
-        if (descriptor.isGetterOfUnderlyingPropertyOfInlineClass()) {
-            // Getter of the underlying val of an inline class is always called on a boxed receiver,
-            // no argument boxing/unboxing is required.
-            // However, its result might require boxing if it is an inline class type.
+        if (descriptor.isGetterOfUnderlyingPropertyOfValueClass()) {
+            // Getter of the underlying val of a value class is always called on a boxed receiver,
+            // no argument unboxing is required.
             return@run BoxUnboxData(IntRange.EMPTY, emptyArray(), box)
         }
 
         val shift = when {
-            caller is CallerImpl.Method.BoundStatic -> {
+            caller is CallerImpl.Method.BoundStatic || caller is CallerImpl.Method.BoundStaticMultiFieldValueClass -> {
                 // Bound reference to a static method is only possible for a top level extension function/property,
                 // and in that case the number of expected arguments is one less than usual, hence -1
                 -1
@@ -64,9 +79,9 @@ internal class InlineClassAwareCaller<out M : Member?>(
                 if (caller is BoundCaller) -1 else 0
 
             descriptor.dispatchReceiverParameter != null && caller !is BoundCaller -> {
-                // If we have an unbound reference to the inline class member,
+                // If we have an unbound reference to the value class member,
                 // its receiver (which is passed as argument 0) should also be unboxed.
-                if (descriptor.containingDeclaration.isInlineClass())
+                if (descriptor.containingDeclaration.isValueClass())
                     0
                 else
                     1
@@ -75,117 +90,229 @@ internal class InlineClassAwareCaller<out M : Member?>(
             else -> 0
         }
 
-        val kotlinParameterTypes: List<KotlinType> = ArrayList<KotlinType>().also { kotlinParameterTypes ->
-            val extensionReceiverType = descriptor.extensionReceiverParameter?.type
-            if (extensionReceiverType != null) {
-                kotlinParameterTypes.add(extensionReceiverType)
-            } else if (descriptor is ConstructorDescriptor) {
-                val constructedClass = descriptor.constructedClass
-                if (constructedClass.isInner) {
-                    kotlinParameterTypes.add((constructedClass.containingDeclaration as ClassDescriptor).defaultType)
-                }
-            } else {
-                val containingDeclaration = descriptor.containingDeclaration
-                if (containingDeclaration is ClassDescriptor && containingDeclaration.isInlineClass()) {
-                    kotlinParameterTypes.add(containingDeclaration.defaultType)
-                }
-            }
+        val flattenedShift = if (caller is CallerImpl.Method.BoundStaticMultiFieldValueClass) -caller.receiverComponentsCount else shift
 
-            descriptor.valueParameters.mapTo(kotlinParameterTypes, ValueParameterDescriptor::getType)
-        }
+        val kotlinParameterTypes: List<KotlinType> = makeKotlinParameterTypes(descriptor) { isValueClass() }
+
+        fun typeSize(type: KotlinType): Int = getMfvcUnboxMethods(type.asSimpleType())?.size ?: 1
 
         // If the default argument is set,
-        // (kotlinParameterTypes.size + Integer.SIZE - 1) / Integer.SIZE masks and one marker are added to the end of the argument.
-        val extraArgumentsTail = (if (isDefault) ((kotlinParameterTypes.size + Integer.SIZE - 1) / Integer.SIZE) + 1 else 0) +
-                (if (descriptor is FunctionDescriptor && descriptor.isSuspend) 1 else 0)
-        val expectedArgsSize = kotlinParameterTypes.size + shift + extraArgumentsTail
-        if (arity != expectedArgsSize) {
-            throw KotlinReflectionInternalError(
-                "Inconsistent number of parameters in the descriptor and Java reflection object: $arity != $expectedArgsSize\n" +
-                        "Calling: $descriptor\n" +
-                        "Parameter types: ${this.parameterTypes})\n" +
-                        "Default: $isDefault"
-            )
-        }
+        // (kotlinParameterTypes.size + Int.SIZE_BITS - 1) / Int.SIZE_BITS masks and one marker are added to the end of the argument.
+        val extraArgumentsTail =
+            (if (isDefault) ((kotlinParameterTypes.sumOf(::typeSize) + Int.SIZE_BITS - 1) / Int.SIZE_BITS) + 1 else 0) +
+                    (if (descriptor is FunctionDescriptor && descriptor.isSuspend) 1 else 0)
+        val expectedArgsSize = kotlinParameterTypes.sumOf(::typeSize) + flattenedShift + extraArgumentsTail
+        checkParametersSize(expectedArgsSize, descriptor, isDefault)
 
         // maxOf is needed because in case of a bound top level extension, shift can be -1 (see above). But in that case, we need not unbox
         // the extension receiver argument, since it has already been unboxed at compile time and generated into the reference
         val argumentRange = maxOf(shift, 0) until (kotlinParameterTypes.size + shift)
 
         val unbox = Array(expectedArgsSize) { i ->
-            if (i in argumentRange) {
-                kotlinParameterTypes[i - shift].toInlineClass()?.getUnboxMethod(descriptor)
-            } else null
+            if (i in argumentRange)
+                getValueClassUnboxMethods(kotlinParameterTypes[i - shift].asSimpleType(), descriptor)
+            else null
         }
 
         BoxUnboxData(argumentRange, unbox, box)
     }
 
+    private val slices = buildList {
+        var currentOffset = when (caller) {
+            is CallerImpl.Method.BoundStaticMultiFieldValueClass -> caller.boundReceiverComponents.size
+            is CallerImpl.Method.BoundStatic -> 1
+            else -> 0
+        }
+        if (currentOffset > 0) {
+            add(0 until currentOffset)
+        }
+        for (parameterUnboxMethods in data.unboxParameters) {
+            val length = parameterUnboxMethods?.size ?: 1
+            add(currentOffset until (currentOffset + length))
+            currentOffset += length
+        }
+    }.toTypedArray()
+
+    fun getRealSlicesOfParameters(index: Int): IntRange = when {
+        index in slices.indices -> slices[index]
+        slices.isEmpty() -> index..index
+        else -> {
+            val start = (index - slices.size) + (slices.last().last + 1)
+            start..start
+        }
+    }
+
+    private val hasMfvcParameters = data.argumentRange.any { (data.unboxParameters[it] ?: return@any false).size > 1 }
+
     override fun call(args: Array<*>): Any? {
-        val (range, unbox, box) = data
+        val range = data.argumentRange
+        val unbox = data.unboxParameters
+        val box = data.box
 
-        @Suppress("UNCHECKED_CAST")
-        val unboxed = Array(args.size) { index ->
-            val arg = args[index]
-
-            if (index in range) {
-                // Note that arg may be null in case we're calling a $default method and it's an optional parameter of an inline class type
-                val method = unbox[index]
-
-                if (method != null) {
-                    if (arg != null) {
-                        method.invoke(arg)
+        val unboxedArguments = when {
+            range.isEmpty() -> args
+            hasMfvcParameters -> buildList(args.size) {
+                for (index in 0 until range.first) {
+                    add(args[index])
+                }
+                for (index in range) {
+                    val methods = unbox[index]
+                    val arg = args[index]
+                    // Note that arg may be null in case we're calling a $default method, and it's an optional parameter of a value class type
+                    if (methods != null) {
+                        methods.mapTo(this) { if (arg != null) it.invoke(arg) else defaultPrimitiveValue(it.returnType) }
                     } else {
-                        defaultPrimitiveValue(method.returnType)
+                        add(arg)
+                    }
+                }
+                for (index in (range.last + 1)..args.lastIndex) {
+                    add(args[index])
+                }
+            }.toTypedArray()
+            else -> Array(args.size) { index ->
+                if (index in range) {
+                    val method = unbox[index]?.single()
+                    val arg = args[index]
+                    // Note that arg may be null in case we're calling a $default method, and it's an optional parameter of a inline class type
+                    when {
+                        method == null -> arg
+                        arg != null -> method.invoke(arg)
+                        else -> defaultPrimitiveValue(method.returnType)
                     }
                 } else {
-                    arg
+                    args[index]
                 }
-            } else {
-                arg
             }
         }
 
-        val result = caller.call(unboxed)
+        val result = caller.call(unboxedArguments)
 
+        // box is not null only for inline classes
         return box?.invoke(null, result) ?: result
     }
+
+    class MultiFieldValueClassPrimaryConstructorCaller(
+        descriptor: FunctionDescriptor,
+        container: KDeclarationContainerImpl,
+        constructorDesc: String,
+        originalParameters: List<ParameterDescriptor>
+    ) : Caller<Nothing?> {
+        private val constructorImpl = container.findMethodBySignature("constructor-impl", constructorDesc)!!
+        private val boxMethod = container.findMethodBySignature("box-impl", constructorDesc.removeSuffix("V") + container.jClass.desc)!!
+        private val parameterUnboxMethods: List<List<Method>?> = originalParameters.map { parameter ->
+            getValueClassUnboxMethods(parameter.type.asSimpleType(), descriptor)
+        }
+        override val member: Nothing?
+            get() = null
+        override val returnType: Type
+            get() = boxMethod.returnType
+
+        val originalParametersGroups: List<List<Class<*>>> = originalParameters.mapIndexed { index, it ->
+            val classDescriptor = it.type.constructor.declarationDescriptor as ClassDescriptor
+            parameterUnboxMethods[index]?.map { it.returnType } ?: listOf(classDescriptor.toJavaClass()!!)
+        }
+
+        override val parameterTypes: List<Type> = originalParametersGroups.flatten()
+
+        override fun call(args: Array<*>): Any? {
+            val newArgs = (args zip parameterUnboxMethods)
+                .flatMap { (arg, unboxMethods) -> unboxMethods?.map { it.invoke(arg) } ?: listOf(arg) }.toTypedArray()
+            constructorImpl.invoke(null, *newArgs)
+            return boxMethod.invoke(null, *newArgs)
+        }
+    }
 }
 
-internal fun <M : Member?> Caller<M>.createInlineClassAwareCallerIfNeeded(
+internal fun ClassifierDescriptor.toJvmDescriptor(): String = ClassMapperLite.mapClass(classId!!.asString())
+
+
+private fun getValueClassUnboxMethods(type: SimpleType, descriptor: CallableMemberDescriptor): List<Method>? =
+    getMfvcUnboxMethods(type) ?: type.toInlineClass()?.getInlineClassUnboxMethod(descriptor)?.let(::listOf)
+
+internal fun getMfvcUnboxMethods(type: SimpleType): List<Method>? {
+    fun getUnboxMethodNameSuffixes(type: SimpleType): List<String>? =
+        if (type.needsMfvcFlattening()) (type.constructor.declarationDescriptor as ClassDescriptor)
+            .multiFieldValueClassRepresentation!!.underlyingPropertyNamesToTypes.flatMap { (name, innerType) ->
+                getUnboxMethodNameSuffixes(innerType)?.map { "${name.identifier}-${it}" } ?: listOf(name.identifier)
+            }
+        else null
+
+    val unboxMethodsNames = getUnboxMethodNameSuffixes(type.asSimpleType())?.map { "unbox-impl-$it" } ?: return null
+    val javaClass = (type.constructor.declarationDescriptor as ClassDescriptor).toJavaClass()!!
+    return unboxMethodsNames.map { javaClass.getDeclaredMethod(it) }
+}
+
+private fun Caller<*>.checkParametersSize(
+    expectedArgsSize: Int,
+    descriptor: CallableMemberDescriptor,
+    isDefault: Boolean,
+) {
+    if (arity != expectedArgsSize) {
+        throw KotlinReflectionInternalError(
+            "Inconsistent number of parameters in the descriptor and Java reflection object: $arity != $expectedArgsSize\n" +
+                    "Calling: $descriptor\n" +
+                    "Parameter types: ${this.parameterTypes})\n" +
+                    "Default: $isDefault"
+        )
+    }
+}
+
+private fun makeKotlinParameterTypes(
+    descriptor: CallableMemberDescriptor, isSpecificClass: ClassDescriptor.() -> Boolean
+): List<KotlinType> = ArrayList<KotlinType>().also { kotlinParameterTypes ->
+    val extensionReceiverType = descriptor.extensionReceiverParameter?.type
+    if (extensionReceiverType != null) {
+        kotlinParameterTypes.add(extensionReceiverType)
+    } else if (descriptor is ConstructorDescriptor) {
+        val constructedClass = descriptor.constructedClass
+        if (constructedClass.isInner) {
+            kotlinParameterTypes.add((constructedClass.containingDeclaration as ClassDescriptor).defaultType)
+        }
+    } else {
+        val containingDeclaration = descriptor.containingDeclaration
+        if (containingDeclaration is ClassDescriptor && containingDeclaration.isSpecificClass()) {
+            kotlinParameterTypes.add(containingDeclaration.defaultType)
+        }
+    }
+
+    descriptor.valueParameters.mapTo(kotlinParameterTypes, ValueParameterDescriptor::getType)
+}
+
+internal fun <M : Member?> Caller<M>.createValueClassAwareCallerIfNeeded(
     descriptor: CallableMemberDescriptor,
     isDefault: Boolean = false
 ): Caller<M> {
-    val needsInlineAwareCaller: Boolean =
-        descriptor.isGetterOfUnderlyingPropertyOfInlineClass() ||
-                descriptor.valueParameters.any { it.type.isInlineClassType() } ||
+    val needsValueClassAwareCaller: Boolean =
+        descriptor.isGetterOfUnderlyingPropertyOfValueClass() ||
+                descriptor.contextReceiverParameters.any { it.type.isValueClassType() } ||
+                descriptor.valueParameters.any { it.type.isValueClassType() } ||
                 descriptor.returnType?.isInlineClassType() == true ||
-                this !is BoundCaller && descriptor.hasInlineClassReceiver()
+                descriptor.hasValueClassReceiver()
 
-    return if (needsInlineAwareCaller) InlineClassAwareCaller(descriptor, this, isDefault) else this
+    return if (needsValueClassAwareCaller) ValueClassAwareCaller(descriptor, this, isDefault) else this
 }
 
-private fun CallableMemberDescriptor.hasInlineClassReceiver() =
-    expectedReceiverType?.isInlineClassType() == true
+private fun CallableMemberDescriptor.hasValueClassReceiver() =
+    expectedReceiverType?.isValueClassType() == true
 
-internal fun Class<*>.getUnboxMethod(descriptor: CallableMemberDescriptor): Method =
+internal fun Class<*>.getInlineClassUnboxMethod(descriptor: CallableMemberDescriptor): Method =
     try {
         getDeclaredMethod("unbox" + JvmAbi.IMPL_SUFFIX_FOR_INLINE_CLASS_MEMBERS)
     } catch (e: NoSuchMethodException) {
         throw KotlinReflectionInternalError("No unbox method found in inline class: $this (calling $descriptor)")
     }
 
-internal fun Class<*>.getBoxMethod(descriptor: CallableMemberDescriptor): Method =
+private fun Class<*>.getBoxMethod(descriptor: CallableMemberDescriptor): Method =
     try {
-        getDeclaredMethod("box" + JvmAbi.IMPL_SUFFIX_FOR_INLINE_CLASS_MEMBERS, getUnboxMethod(descriptor).returnType)
+        getDeclaredMethod("box" + JvmAbi.IMPL_SUFFIX_FOR_INLINE_CLASS_MEMBERS, getInlineClassUnboxMethod(descriptor).returnType)
     } catch (e: NoSuchMethodException) {
         throw KotlinReflectionInternalError("No box method found in inline class: $this (calling $descriptor)")
     }
 
-internal fun KotlinType.toInlineClass(): Class<*>? {
+private fun KotlinType.toInlineClass(): Class<*>? {
     // See computeExpandedTypeForInlineClass.
-    // TODO: add tests on type parameters with inline class bounds.
-    // TODO: add tests on usages of inline classes in Java.
+    // TODO: add tests on type parameters with value class bounds.
+    // TODO: add tests on usages of value classes in Java.
     val klass = constructor.declarationDescriptor.toInlineClass() ?: return null
     if (!TypeUtils.isNullableType(this)) return klass
 
@@ -217,7 +344,7 @@ internal fun Any?.coerceToExpectedReceiverType(descriptor: CallableMemberDescrip
     if (descriptor is PropertyDescriptor && descriptor.isUnderlyingPropertyOfInlineClass()) return this
 
     val expectedReceiverType = descriptor.expectedReceiverType
-    val unboxMethod = expectedReceiverType?.toInlineClass()?.getUnboxMethod(descriptor) ?: return this
+    val unboxMethod = expectedReceiverType?.toInlineClass()?.getInlineClassUnboxMethod(descriptor) ?: return this
 
     return unboxMethod.invoke(this)
 }

core/reflection.jvm/src/kotlin/reflect/jvm/internal/util.kt

@@ -44,6 +44,7 @@ import org.jetbrains.kotlin.resolve.constants.*
 import org.jetbrains.kotlin.resolve.descriptorUtil.annotationClass
 import org.jetbrains.kotlin.resolve.descriptorUtil.classId
 import org.jetbrains.kotlin.resolve.isInlineClassType
+import org.jetbrains.kotlin.resolve.needsMfvcFlattening
 import org.jetbrains.kotlin.serialization.deserialization.DeserializationContext
 import org.jetbrains.kotlin.serialization.deserialization.MemberDeserializer
 import java.lang.reflect.Field
@@ -268,6 +269,8 @@ internal fun <M : MessageLite, D : CallableDescriptor> deserializeToDescriptor(
 
 internal val KType.isInlineClassType: Boolean
     get() = (this as? KTypeImpl)?.type?.isInlineClassType() == true
+internal val KType.needsMultiFieldValueClassFlattening: Boolean
+    get() = (this as? KTypeImpl)?.type?.needsMfvcFlattening() == true
 
 internal fun defaultPrimitiveValue(type: Type): Any? =
     if (type is Class<*> && type.isPrimitive) {