[ESIMD] Add a test specialization constant that is set but not used

SYCL/ESIMD/unused_spec_const.cpp

@@ -0,0 +1,51 @@
+// REQUIRES: gpu
+// UNSUPPORTED: cuda || hip
+// RUN: %clangxx -fsycl %s -o %t.out
+// RUN: %GPU_RUN_PLACEHOLDER %t.out
+
+// This test checks that if specialization constant is set but not used, then
+// 1) The kernel still works properly;
+// 2) The kernel parameter holding the buffer for specialization constants is
+//    optimized away.
+//    TODO: the second part of the check should be added to this test when
+//    DAE (Dead Arguments Elimination) optimization is enabled for ESIMD.
+
+#include <CL/sycl.hpp>
+#include <iostream>
+#include <sycl/ext/intel/esimd.hpp>
+
+constexpr sycl::specialization_id<int> Spec;
+
+int main() {
+  sycl::queue Q;
+  std::cout << "Running on: "
+            << Q.get_device().get_info<sycl::info::device::name>() << std::endl;
+
+  int *A = sycl::malloc_shared<int>(1, Q);
+  *A = 123;
+  Q.submit([&](sycl::handler &CGH) {
+     CGH.set_specialization_constant<Spec>(42);
+     CGH.single_task([=](sycl::kernel_handler KH) SYCL_ESIMD_KERNEL {
+       // This use of get_specializaiton_constant is commented out.
+       // Thus the device code doen't have info about it and cannot allocate
+       // memory/buffer for it on device side.
+       // The test checks that the unused kernel parameter is either
+       // eliminated by DAE optimization OR nullptr is passed for that argument.
+
+       // KH.get_specialization_constant<Spec>();
+       sycl::ext::intel::esimd::simd<int, 1> V(A);
+       V += 2;
+       V.copy_to(A);
+     });
+   }).wait();
+
+  int AVal = *A;
+  sycl::free(A, Q);
+
+  if (AVal != 125) {
+    std::cout << "Failed: " << AVal << " != 125" << std::endl;
+    return 1;
+  }
+  std::cout << "Passed" << std::endl;
+  return 0;
+}