Add regression test for DAE and separate compile (#970)

Author: AlexeySachkov

SYCL/Regression/DAE-separate-compile.cpp

@@ -0,0 +1,38 @@
+// There was an issue with dead argument elminitaion optimization, which lead
+// to runtime errors when setting kernel arguments if the app was compiled with
+// optimizations, but linked without them.
+//
+// The test checks that the scenario works correctly.
+//
+// RUN: %clangxx -fsycl -fsycl-targets=%sycl_triple %s -O2 -c -o %t.o
+// RUN: %clangxx -fsycl -fsycl-targets=%sycl_triple %t.o -O0 -o %t.out
+// RUN: %CPU_RUN_PLACEHOLDER %t.out
+// RUN: %GPU_RUN_PLACEHOLDER %t.out
+// RUN: %ACC_RUN_PLACEHOLDER %t.out
+
+#include <iostream>
+#include <sycl/sycl.hpp>
+
+int main() {
+  constexpr int THE_ANSWER = 42;
+
+  sycl::queue q;
+
+  int storage;
+  int storage2;
+  {
+    sycl::buffer buf(&storage, sycl::range<1>(1));
+    sycl::buffer buf2(&storage2, sycl::range<1>(1));
+
+    q.submit([&](sycl::handler &h) {
+      auto acc = buf.get_access(h);
+      auto acc2 = buf2.get_access(h);
+      h.single_task([=]() {
+        (void)acc; // unused
+        acc2[0] = THE_ANSWER;
+      });
+    });
+  }
+
+  return storage2 != THE_ANSWER;
+}