// RUN: tf-opt %s -cse  | FileCheck %s
// Checks that CSE runs without generating invalid IR and doesn't CSE ops like
// NextIteration.Source and NextIteration.Sink.
// CHECK-LABEL: func @main
// CHECK: tf_executor.NextIteration.Source
// CHECK: tf_executor.NextIteration.Source
// CHECK: tf_executor.NextIteration.Sink
// CHECK: tf_executor.NextIteration.Sink
func.func @main() -> (tensor<1xi32>, tensor<1xi32>) {
  %0, %1 = tf_executor.graph {

}

def TfExecutor_NextIterationSourceOp : TfExecutor_Op<"NextIteration.Source",
    [HasParent<"GraphOp">]> {
  let summary = [{
    The "tf_executor.NextIteration.Source" is paired with a
    "tf_executor.NextIteration.sink" to represent NextIteration op in
    Tensorflow.
  }];

  let description = [{
    Tensorflow NextIteration operation forwards its input to the next iteration

  // CHECK:  op: "RefMerge"
  // CHECK:  op: "RefSwitch"
  // CHECK:  op: "RefExit"
  // CHECK:  op: "RefNextIteration"
  tf_executor.graph {
    %0:3 = tf_executor.NextIteration.Source : tensor<*x!tf_type.int32ref> {device = "", T = "tfdtype$DT_INT32"} loc("while/NextIteration")

    tf_executor.NextIteration.Sink[%1#1] %1#0 : i32
    tf_executor.fetch %1#0 : i32
  }
  func.return %0 : i32
}

// Check that NextIteration.sink node is deleted when the source does not have
// any user other than the sink.
// CHECK-LABEL: func @nextiteration_deleted(
func.func @nextiteration_deleted(%arg0 : i32) -> i32 {
// CHECK-NOT: tf_executor.NextIteration.Source
// CHECK-NOT: tf_executor.NextIteration.Sink

  }
  func.return
}

// Tests tf_executor.NextIteration.Source/tf_executor.NextIteration.Sink has a
// device when an intermediate op in its loop has a device.

// CHECK-LABEL: func @testNextIterationNoDevice
func.func @testNextIterationNoDevice() {
  tf_executor.graph {
    // CHECK:      tf_executor.NextIteration.Source
    // CHECK-SAME: device = "/job:localhost/replica:0/task:0/device:TPU:0"

  // CHECK-NEXT: input: "while/Enter"
  // CHECK-NEXT: input: "while/NextIteration"
  // CHECK:      name: "while/NextIteration"
  // CHECK-NEXT: op: "NextIteration"
  // CHECK-NEXT: input: "while/Add"
  tf_executor.graph {
    %0:3 = tf_executor.NextIteration.Source : tensor<*xi32> {device = "", T = "tfdtype$DT_INT32"} loc("while/NextIteration")

    %NextIteration, %ctl_1 = NextIteration(%Add) name("while/NextIteration") {T = i32} : (tensor<*xi32>) -> (tensor<*xi32>)
    %Merge:2, %ctl_2 = Merge(%Enter, %NextIteration) name("while/Merge") {N = 2 : i64, T = i32} : (tensor<*xi32>, tensor<*xi32>) -> (tensor<*xi32>, tensor<*xi32>)

    %NextIteration, %ctl_1 = NextIteration(%Const) [%arg.ctl] name("while/NextIteration") {T = i32} : (tensor<i32>) -> (tensor<*xi32>)
    %Merge:2, %ctl_2 = Merge(%Enter, %NextIteration) [%arg.ctl] name("while/Merge") {N = 2 : i64, T = i32} : (tensor<*xi32>, tensor<*xi32>) -> (tensor<*xi32>, tensor<i32>)

  %0 = tf_executor.graph {
    %1:3 = tf_executor.NextIteration.Source : tensor<*xf32>
    "tf_executor.NextIteration.Sink"(%1#1, %arg1) : (!tf_executor.token, i1) -> ()
// expected-error@-1 {{'tf_executor.NextIteration.Sink' op input type 'i1' mismatch the tf_executor.NextIteration.Source output type: 'tensor<*xf32>'}}
    tf_executor.fetch %1#0 : tensor<*xf32>
  }

defined as a non-dead input (selected in a non-defined way if multiple inputs
are non-dead). If all inputs are dead, the output is also dead.

### NextIteration: `tf_executor.NextIteration.Source` and `tf_executor.NextIteration.Sink` Operation

The TensorFlow
[`NextIteration`](https://www.tensorflow.org/api_docs/cc/class/tensorflow/ops/next-iteration)
op is modeled using these two paired operations. Since _NextIteration_ is