Add test for sycl-post-link removing llvm.used

Author: aidan.belton

clang/test/CodeGenSYCL/sycl-post-link-used-attr.cpp

@@ -0,0 +1,31 @@
+// RUN: %clang_cc1 -disable-llvm-passes %s -emit-llvm -o - | sycl-post-link -split=auto -ir-output-only -o %t.out_ir_only.bc
+// RUN: llvm-dis %t.out_ir_only.bc -o  %t.out_ir_only.ll
+// RUN: FileCheck %s --input-file %t.out_ir_only.ll
+//
+// RUN: %clang_cc1 -disable-llvm-passes %s -emit-llvm -o %t.out.bc
+// RUN: sycl-post-link -split=auto -symbols -split-esimd -lower-esimd -O2 -spec-const=default %t.out.bc -o %t.out.table
+// RUN: llvm-dis "$(sed -n '2p' %t.out.table | sed 's/|.*//')" -o %t.out.ll
+// RUN: FileCheck %s --input-file %t.out.ll
+// CHECK-NOT: @llvm.used
+
+struct a;
+class g {
+public:
+  int c;
+  ~g();
+};
+template <class>
+class h {
+public:
+  static const void k();
+  static g i;
+};
+template <class j>
+const void h<j>::k() { i.c = 0; }
+template <class j>
+g h<j>::i;
+template <class>
+struct f { f() __attribute__((used)); };
+template <class j>
+f<j>::f() { h<j>::k(); }
+template struct f<a>;