[SYCL] Add regression test for spec constants & debug info (#307)

Author: AlexeySachkov

SYCL/Regression/2020-spec-constants-debug-info.cpp

@@ -0,0 +1,29 @@
+// RUN: %clangxx -fsycl -g %s -o %t.out
+// RUN: %clangxx -fsycl -g -O0 %s -o %t.out
+// RUN: %clangxx -fsycl -g -O2 %s -o %t.out
+//
+// The idea of this test is to make sure that we can compile the following
+// simple example without crashes/assertions firing at llvm-spirv step due to
+// debug info corrupted by sycl-post-link
+
+#include <sycl/sycl.hpp>
+
+constexpr sycl::specialization_id<int> test_id_1{42};
+
+int main() {
+
+  sycl::queue q;
+  {
+    sycl::buffer<double, 1> Buf{sycl::range{1}};
+    q.submit([&](sycl::handler &cgh) {
+      auto Acc = Buf.get_access<sycl::access::mode::read_write>(cgh);
+      cgh.set_specialization_constant<test_id_1>(1);
+      cgh.single_task<class Kernel1>([=](sycl::kernel_handler kh) {
+        Acc[0] = kh.get_specialization_constant<test_id_1>();
+      });
+    });
+    auto Acc = Buf.get_access<sycl::access::mode::read>();
+    assert(Acc[0] == 1);
+  }
+  return 0;
+}