JVM_IR: do not box inline classes in suspend synthetic accessors

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/CoroutineCodegen.kt

@@ -20,7 +20,6 @@ import org.jetbrains.kotlin.codegen.coroutines.CoroutineTransformerMethodVisitor
 import org.jetbrains.kotlin.codegen.coroutines.INVOKE_SUSPEND_METHOD_NAME
 import org.jetbrains.kotlin.codegen.coroutines.SUSPEND_IMPL_NAME_SUFFIX
 import org.jetbrains.kotlin.codegen.coroutines.reportSuspensionPointInsideMonitor
-import org.jetbrains.kotlin.codegen.inline.coroutines.FOR_INLINE_SUFFIX
 import org.jetbrains.kotlin.config.JVMConfigurationKeys
 import org.jetbrains.kotlin.config.isReleaseCoroutines
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
@@ -142,16 +141,19 @@ private fun IrFunction.isStaticInlineClassReplacementDelegatingCall(): Boolean =
             parentAsClass.declarations.find { it is IrAttributeContainer && it.attributeOwnerId == attributeOwnerId && it !== this }
                 ?.isStaticInlineClassReplacement == true
 
-internal fun IrFunction.shouldContainSuspendMarkers(): Boolean = !isInvokeSuspendOfContinuation() &&
-        // These are tail-call bridges and do not require any bytecode modifications.
-        origin != IrDeclarationOrigin.FUNCTION_FOR_DEFAULT_PARAMETER &&
-        origin != JvmLoweredDeclarationOrigin.JVM_OVERLOADS_WRAPPER &&
-        origin != JvmLoweredDeclarationOrigin.SYNTHETIC_ACCESSOR &&
-        origin != JvmLoweredDeclarationOrigin.SYNTHETIC_ACCESSOR_FOR_HIDDEN_CONSTRUCTOR &&
-        origin != JvmLoweredDeclarationOrigin.SUPER_INTERFACE_METHOD_BRIDGE &&
-        origin != IrDeclarationOrigin.BRIDGE &&
-        origin != IrDeclarationOrigin.BRIDGE_SPECIAL &&
+internal val BRIDGE_ORIGINS = setOf(
+    IrDeclarationOrigin.FUNCTION_FOR_DEFAULT_PARAMETER,
+    JvmLoweredDeclarationOrigin.JVM_OVERLOADS_WRAPPER,
+    JvmLoweredDeclarationOrigin.SYNTHETIC_ACCESSOR,
+    JvmLoweredDeclarationOrigin.SYNTHETIC_ACCESSOR_FOR_HIDDEN_CONSTRUCTOR,
+    JvmLoweredDeclarationOrigin.SUPER_INTERFACE_METHOD_BRIDGE,
+    IrDeclarationOrigin.BRIDGE,
+    IrDeclarationOrigin.BRIDGE_SPECIAL,
+)
+
+internal fun IrFunction.shouldContainSuspendMarkers(): Boolean = origin !in BRIDGE_ORIGINS &&
         origin != IrDeclarationOrigin.DELEGATED_MEMBER &&
+        !isInvokeSuspendOfContinuation() &&
         !isMultifileBridge() &&
         !isInvokeOfSuspendCallableReference() &&
         !isBridgeToSuspendImplMethod() &&

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ExpressionCodegen.kt

@@ -229,20 +229,17 @@ class ExpressionCodegen(
             if (irFunction.origin != JvmLoweredDeclarationOrigin.CLASS_STATIC_INITIALIZER) {
                 irFunction.markLineNumber(startOffset = irFunction is IrConstructor && irFunction.isPrimary)
             }
-            if (irFunction.isSuspend && irFunction.origin == IrDeclarationOrigin.BRIDGE) {
-                mv.areturn(OBJECT_TYPE)
+            val unboxedInlineClass =
+                irFunction.suspendFunctionOriginal().originalReturnTypeOfSuspendFunctionReturningUnboxedInlineClass()
+            if (unboxedInlineClass != null && irFunction.origin !in BRIDGE_ORIGINS) {
+                result.materializeAt(unboxedInlineClass.asmType, unboxedInlineClass)
             } else {
-                var returnType = signature.returnType
-                var returnIrType = if (irFunction !is IrConstructor) irFunction.returnType else context.irBuiltIns.unitType
-                val unboxedInlineClass =
-                    irFunction.suspendFunctionOriginal().originalReturnTypeOfSuspendFunctionReturningUnboxedInlineClass()
-                if (unboxedInlineClass != null) {
-                    returnIrType = unboxedInlineClass
-                    returnType = unboxedInlineClass.asmType
-                }
-                result.materializeAt(returnType, returnIrType)
-                mv.areturn(returnType)
+                val returnIrType = if (irFunction !is IrConstructor) irFunction.returnType else context.irBuiltIns.unitType
+                result.materializeAt(signature.returnType, returnIrType)
             }
+            // `signature.returnType` is valid here even if the return value of a suspend function was unboxed,
+            // as it's still a reference type.
+            mv.areturn(signature.returnType)
         }
         val endLabel = markNewLabel()
         writeLocalVariablesInTable(info, endLabel)
@@ -508,7 +505,7 @@ class ExpressionCodegen(
                 wrapJavaClassesIntoKClasses(mv)
                 MaterialValue(this, AsmTypes.K_CLASS_ARRAY_TYPE, expression.type)
             }
-            unboxedInlineClassIrType != null && !irFunction.isInvokeSuspendOfContinuation() ->
+            unboxedInlineClassIrType != null && !irFunction.isInvokeSuspendOfContinuation() && irFunction.origin !in BRIDGE_ORIGINS ->
                 object : PromisedValue(this, unboxedInlineClassIrType.asmType, unboxedInlineClassIrType) {
                     override fun materializeAt(target: Type, irTarget: IrType, castForReified: Boolean) {
                         mv.checkcast(unboxedInlineClassIrType.asmType)

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/SyntheticAccessorLowering.kt

@@ -416,7 +416,7 @@ internal class SyntheticAccessorLowering(val context: JvmBackendContext) : IrEle
             isSuspend = source.isSuspend // synthetic accessors of suspend functions are handled in codegen
         }.also { accessor ->
             accessor.parent = parent
-
+            accessor.copyAttributes(source)
             accessor.copyTypeParametersFrom(source, JvmLoweredDeclarationOrigin.SYNTHETIC_ACCESSOR)
             accessor.copyValueParametersToStatic(source, JvmLoweredDeclarationOrigin.SYNTHETIC_ACCESSOR, dispatchReceiverType)
             accessor.returnType = source.returnType.remapTypeParameters(source, accessor)