testsuite: Add trivial tests for Go closures

testsuite/libffi.go/aa-direct.c

@@ -0,0 +1,34 @@
+/* { dg-do run } */
+
+#include "static-chain.h"
+
+#if defined(__GNUC__) && !defined(__clang__) && defined(STATIC_CHAIN_REG)
+
+#include "ffitest.h"
+
+/* Blatent assumption here that the prologue doesn't clobber the
+   static chain for trivial functions.  If this is not true, don't
+   define STATIC_CHAIN_REG, and we'll test what we can via other tests.  */
+void *doit(void)
+{
+  register void *chain __asm__(STATIC_CHAIN_REG);
+  return chain;
+}
+
+int main()
+{
+  ffi_cif cif;
+  void *result;
+
+  CHECK(ffi_prep_cif(&cif, ABI_NUM, 0, &ffi_type_pointer, NULL) == FFI_OK);
+
+  ffi_call_go(&cif, FFI_FN(doit), &result, NULL, &result);
+
+  CHECK(result == &result);
+
+  return 0;
+}
+
+#else /* UNSUPPORTED */
+int main() { return 0; }
+#endif