Add mlir unit test for prioroty_route attribute on packet flows (#1758

)

test/create-packet-flows/packet_routing_priority_route.mlir

@@ -0,0 +1,44 @@
+//===- packet_routing_priority_route.mlir ----------------------*- MLIR -*-===//
+//
+// This file is licensed under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// (c) Copyright 2024 Xilinx Inc.
+//
+//===----------------------------------------------------------------------===//
+
+// RUN: aie-opt --aie-create-pathfinder-flows %s | FileCheck %s
+
+
+// CHECK:    aie.tile(6, 2)
+// CHECK:    aie.amsel<0> (0)
+// CHECK:    aie.tile(6, 3)
+// CHECK:    aie.amsel<0> (0)
+// CHECK:    aie.tile(7, 2)
+// CHECK:    aie.amsel<5> (3)
+// CHECK:    aie.tile(7, 0)
+// CHECK:    aie.amsel<5> (3)
+
+//
+// priority_route attribute overrides the downstream decision to assign arbiters and ports before other flows
+//
+
+module @aie_module  {
+ aie.device(xcvc1902) {
+  %t62 = aie.tile(6, 2)
+  %t63 = aie.tile(6, 3)
+  %t72 = aie.tile(7, 2)
+  %t70 = aie.tile(7, 0)
+
+  aie.packet_flow(0x1) {
+    aie.packet_source<%t63, DMA : 0>
+    aie.packet_dest<%t62, DMA : 1>
+  }
+
+  aie.packet_flow(0x2) {
+    aie.packet_source<%t70, DMA : 0>
+    aie.packet_dest<%t72, Ctrl : 0>
+  } {priority_route = true}
+ }
+}