JVM_IR: Fix bug in suspend function with many default arguments.

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt

@@ -197,7 +197,7 @@ fun IrFunction.copyValueParametersInsertingContinuationFrom(from: IrFunction, in
     var additionalShift = 0
     from.valueParameters.forEach {
         // The continuation parameter goes before the default argument mask and handler.
-        if (it.origin == IrDeclarationOrigin.MASK_FOR_DEFAULT_FUNCTION) {
+        if (it.origin == IrDeclarationOrigin.MASK_FOR_DEFAULT_FUNCTION && additionalShift == 0) {
             insertContinuation()
             additionalShift = 1
         }

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

@@ -167,7 +167,7 @@ private fun IrFunction.suspendFunctionView(context: JvmBackendContext): IrFuncti
         it.copyTypeParametersFrom(this)
 
         // Copy the value parameters and insert the continuation parameter. The continuation parameter
-        // goes before the default argument mask and handler for default argument stubs.
+        // goes before the default argument mask(s) and handler for default argument stubs.
         // TODO: It would be nice if AddContinuationLowering could insert the continuation argument before default stub generation.
         // That would avoid the reshuffling both here and in createSuspendFunctionClassViewIfNeeded.
         var continuationValueParam: IrValueParameter? = null
@@ -203,9 +203,9 @@ internal fun IrCall.createSuspendFunctionCallViewIfNeeded(
         it.copyTypeArgumentsFrom(this)
         it.dispatchReceiver = dispatchReceiver
         it.extensionReceiver = extensionReceiver
-        // Locate the caller continuation parameter. The continuation parameter is before default argument mask and handler params.
-        val callerHasDefaultMask = caller.valueParameters.lastOrNull()?.origin == IrDeclarationOrigin.METHOD_HANDLER_IN_DEFAULT_FUNCTION
-        val callerContinuationIndex = caller.valueParameters.size - 1 - (if (callerHasDefaultMask) 2 else 0)
+        // Locate the caller continuation parameter. The continuation parameter is before default argument mask(s) and handler params.
+        val callerNumberOfMasks = caller.valueParameters.count { it.origin == IrDeclarationOrigin.MASK_FOR_DEFAULT_FUNCTION }
+        val callerContinuationIndex = caller.valueParameters.size - 1 - (if (callerNumberOfMasks != 0) callerNumberOfMasks + 1 else 0)
         val continuationParameter =
             when {
                 caller.isInvokeSuspendOfLambda() || caller.isInvokeSuspendOfContinuation() ||
@@ -215,16 +215,17 @@ internal fun IrCall.createSuspendFunctionCallViewIfNeeded(
                 else -> IrGetValueImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, caller.valueParameters[callerContinuationIndex].symbol)
             }
         // If the suspend function view that we are calling has default parameters, we need to make sure to pass the
-        // continuation before the default parameter mask and handler.
-        val hasDefaultMask = view.valueParameters.last().origin == IrDeclarationOrigin.METHOD_HANDLER_IN_DEFAULT_FUNCTION
-        val continuationIndex = valueArgumentsCount - (if (hasDefaultMask) 2 else 0)
+        // continuation before the default parameter mask(s) and handler.
+        val numberOfMasks = view.valueParameters.count { it.origin == IrDeclarationOrigin.MASK_FOR_DEFAULT_FUNCTION }
+        val continuationIndex = valueArgumentsCount - (if (numberOfMasks != 0) numberOfMasks + 1 else 0)
         for (i in 0 until continuationIndex) {
             it.putValueArgument(i, getValueArgument(i))
         }
         it.putValueArgument(continuationIndex, continuationParameter)
-        if (hasDefaultMask) {
-            it.putValueArgument(valueArgumentsCount - 1, getValueArgument(continuationIndex))
-            it.putValueArgument(valueArgumentsCount, getValueArgument(continuationIndex + 1))
+        if (numberOfMasks != 0) {
+            for (i in 0 until numberOfMasks + 1) {
+                it.putValueArgument(valueArgumentsCount + i - 1, getValueArgument(continuationIndex + i))
+            }
         }
     }
 }

compiler/testData/codegen/box/coroutines/reflect/callSuspendBy.kt

@@ -24,6 +24,43 @@ fun ordinary() = "OK"
 
 suspend fun withDefault(s: String = "OK") = s
 
+suspend fun withManyDefault(
+    s0: String = "NOT OK 0",
+    s1: String = "NOT OK 1",
+    s2: String = "NOT OK 2",
+    s3: String = "NOT OK 3",
+    s4: String = "NOT OK 4",
+    s5: String = "NOT OK 5",
+    s6: String = "NOT OK 6",
+    s7: String = "NOT OK 7",
+    s8: String = "NOT OK 8",
+    s9: String = "NOT OK 9",
+    s10: String = "NOT OK 10",
+    s11: String = "NOT OK 11",
+    s12: String = "NOT OK 12",
+    s13: String = "NOT OK 13",
+    s14: String = "NOT OK 14",
+    s15: String = "NOT OK 15",
+    s16: String = "NOT OK 16",
+    s17: String = "NOT OK 17",
+    s18: String = "NOT OK 18",
+    s19: String = "NOT OK 19",
+    s20: String = "NOT OK 20",
+    s21: String = "NOT OK 21",
+    s22: String = "NOT OK 22",
+    s23: String = "NOT OK 23",
+    s24: String = "NOT OK 24",
+    s25: String = "NOT OK 25",
+    s26: String = "NOT OK 26",
+    s27: String = "NOT OK 27",
+    s28: String = "NOT OK 28",
+    s29: String = "NOT OK 29",
+    s30: String = "NOT OK 30",
+    s31: String = "NOT OK 31",
+    s32: String = "NOT OK 32",
+    ok: String = "OK"
+) = ok
+
 var log = ""
 
 var proceed = {}
@@ -64,6 +101,10 @@ fun box(): String {
     builder {
         res = ::withDefault.callSuspendBy(emptyMap()) as String?
     }
+    if (res != "OK") return res ?: "FAIL 5"
+    builder {
+        res = ::withManyDefault.callSuspendBy(emptyMap()) as String?
+    }
     builder {
         ::suspending.callSuspendBy(emptyMap())
     }