[SYCL] Add a test for wrapped pointer kernel args (#2298)

Before structs decomposition USM pointers that are wrapped by structs
were passsed with generic address space. It caused performance issues.
After structs decomposition all pointers are passed with global address
space, this test is added to save this behaviour.

Author: Fznamznon

clang/test/CodeGenSYCL/pointers-in-structs.cpp

@@ -0,0 +1,36 @@
+// RUN: %clang_cc1 -fsycl -fsycl-is-device -I %S/Inputs -triple spir64-unknown-unknown-sycldevice -disable-llvm-passes -emit-llvm %s -o - | FileCheck %s
+
+// This test checks that compiler generates correct address spaces for pointer
+// kernel arguments that are wrapped by struct.
+
+#include <sycl.hpp>
+
+struct A {
+  float *F;
+};
+
+struct B {
+  int *F1;
+  float *F2;
+  A F3;
+};
+
+int main() {
+  B Obj;
+  cl::sycl::kernel_single_task<class structs>(
+      [=]() {
+        (void)Obj;
+      });
+  float A = 1;
+  float *Ptr = &A;
+  auto Lambda = [=]() {
+    *Ptr += 1;
+  };
+  cl::sycl::kernel_single_task<class lambdas>([=]() {
+    Lambda();
+  });
+  return 0;
+}
+
+// CHECK: define spir_kernel void @{{.*}}structs{{.*}}(i32 addrspace(1)* %_arg_F1, float addrspace(1)* %_arg_F2, float addrspace(1)* %_arg_F)
+// CHECK: define spir_kernel void @{{.*}}lambdas{{.*}}(float addrspace(1)* %_arg_)