Interpret getter with null body separately from common function

compiler/ir/ir.interpreter/src/org/jetbrains/kotlin/ir/interpreter/CallInterceptor.kt

@@ -65,8 +65,10 @@ internal class DefaultCallInterceptor(override val interpreter: IrInterpreter) :
             handleIntrinsicMethods(irFunction) -> return
             receiver.mustBeHandledAsReflection(call) -> Wrapper.getReflectionMethod(irFunction).invokeMethod(irFunction, args)
             receiver is Primitive<*> -> calculateBuiltIns(irFunction, args) // check for js char, js long and get field for primitives
-            irFunction.body == null ->
-                irFunction.trySubstituteFunctionBody() ?: irFunction.tryCalculateLazyConst() ?: calculateBuiltIns(irFunction, args)
+            // TODO try to save fields in Primitive -> then it is possible to move up next branch
+            // TODO try to create backing field if it is missing
+            irFunction.body == null && irFunction.isAccessorOfPropertyWithBackingField() -> callStack.pushInstruction(CompoundInstruction(irFunction.createGetField()))
+            irFunction.body == null -> irFunction.trySubstituteFunctionBody() ?: calculateBuiltIns(irFunction, args)
             else -> defaultAction()
         }
     }
@@ -209,11 +211,4 @@ internal class DefaultCallInterceptor(override val interpreter: IrInterpreter) :
         callStack.pushInstruction(CompoundInstruction(this))
         return body
     }
-
-    // TODO fix in FIR2IR; const val getter must have body with IrGetField node
-    private fun IrFunction.tryCalculateLazyConst(): IrExpression? {
-        if (this !is IrSimpleFunction) return null
-        val expression = this.correspondingPropertySymbol?.owner?.backingField?.initializer?.expression
-        return expression?.apply { callStack.pushInstruction(CompoundInstruction(this)) }
-    }
 }

compiler/ir/ir.interpreter/src/org/jetbrains/kotlin/ir/interpreter/IrTreeBuildUtils.kt

@@ -137,6 +137,12 @@ internal fun createTempClass(name: Name, origin: IrDeclarationOrigin = TEMP_CLAS
     )
 }
 
+internal fun IrFunction.createGetField(): IrExpression {
+    val backingField = (this as IrSimpleFunction).correspondingPropertySymbol?.owner?.backingField!!
+    val receiver = dispatchReceiverParameter ?: extensionReceiverParameter
+    return IrGetFieldImpl(SYNTHETIC_OFFSET, SYNTHETIC_OFFSET, backingField.symbol, backingField.type, receiver?.createGetValue())
+}
+
 internal fun List<IrStatement>.wrapWithBlockBody(): IrBlockBody {
     return IrBlockBodyImpl(SYNTHETIC_OFFSET, SYNTHETIC_OFFSET, this)
 }

compiler/ir/ir.interpreter/src/org/jetbrains/kotlin/ir/interpreter/Utils.kt

@@ -291,9 +291,13 @@ internal fun IrClass.getSingleAbstractMethod(): IrFunction {
     return declarations.filterIsInstance<IrSimpleFunction>().single { it.modality == Modality.ABSTRACT }
 }
 
-fun IrGetValue.isAccessToObject(): Boolean {
+internal fun IrGetValue.isAccessToObject(): Boolean {
     val owner = this.symbol.owner
     val expectedClass = this.type.classOrNull?.owner
     if (expectedClass == null || !expectedClass.isObject) return false
     return owner.origin == IrDeclarationOrigin.INSTANCE_RECEIVER || owner.name.asString() == "<this>"
 }
+
+internal fun IrFunction.isAccessorOfPropertyWithBackingField(): Boolean {
+    return this is IrSimpleFunction && this.correspondingPropertySymbol?.owner?.backingField != null
+}