re PR c++/68847 (ICE in cxx_eval_constant_expression on…

re PR c++/68847 (ICE in cxx_eval_constant_expression on __atomic_compare_exchange (constexpr.c:3719) in c++)

	PR c++/68847
	* call.c (build_cxx_call): Use fold_non_dependent_expr.

From-SVN: r232438

gcc/cp/ChangeLog

 2016-01-15  Jason Merrill  <jason@redhat.com>
 
+	PR c++/68847
+	* call.c (build_cxx_call): Use fold_non_dependent_expr.
+
 	* typeck2.c (cxx_incomplete_type_diagnostic): Use the location of
 	value.
 

gcc/cp/call.c

@@ -7755,7 +7755,7 @@ build_cxx_call (tree fn, int nargs, tree *argarray,
       /* We need to take care that values to BUILT_IN_NORMAL
          are reduced.  */
       for (i = 0; i < nargs; i++)
-	argarray[i] = maybe_constant_value (argarray[i]);
+	argarray[i] = fold_non_dependent_expr (argarray[i]);
 
       if (!check_builtin_function_arguments (fndecl, nargs, argarray))
 	return error_mark_node;

gcc/testsuite/g++.dg/delayedfold/builtin1.C

+// PR c++/68847
+// { dg-do compile { target cas_int } }
+
+class RegionLock {
+  template <unsigned long> void m_fn1();
+  int spinlock;
+} acquire_zero;
+int acquire_one;
+template <unsigned long> void RegionLock::m_fn1() {
+  __atomic_compare_exchange(&spinlock, &acquire_zero, &acquire_one, false, 2, 2);
+}