call.c (magic_varargs_p): Return 3 for __builtin_*_overflow_p.

	* call.c (magic_varargs_p): Return 3 for __builtin_*_overflow_p.
	(build_over_call): For magic == 3, do no conversion only on 3rd
	argument.

	* c-c++-common/torture/builtin-arith-overflow-p-19.c: Run for C++ too.
	* g++.dg/ext/builtin-arith-overflow-2.C: New test.

From-SVN: r237755

gcc/cp/ChangeLog

+2016-06-24  Jakub Jelinek  <jakub@redhat.com>
+
+	* call.c (magic_varargs_p): Return 3 for __builtin_*_overflow_p.
+	(build_over_call): For magic == 3, do no conversion only on 3rd
+	argument.
+
 2016-06-23  Andi Kleen  <ak@linux.intel.com>
 
 	* Make-lang.in: Add support for autofdo.

gcc/cp/call.c

@@ -7132,7 +7132,8 @@ convert_for_arg_passing (tree type, tree val, tsubst_flags_t complain)
    which just decay_conversion or no conversions at all should be done.
    This is true for some builtins which don't act like normal functions.
    Return 2 if no conversions at all should be done, 1 if just
-   decay_conversion.  */
+   decay_conversion.  Return 3 for special treatment of the 3rd argument
+   for __builtin_*_overflow_p.  */
 
 int
 magic_varargs_p (tree fn)
@@ -7149,6 +7150,11 @@ magic_varargs_p (tree fn)
       case BUILT_IN_VA_START:
 	return 1;
 
+      case BUILT_IN_ADD_OVERFLOW_P:
+      case BUILT_IN_SUB_OVERFLOW_P:
+      case BUILT_IN_MUL_OVERFLOW_P:
+	return 3;
+
       default:;
 	return lookup_attribute ("type generic",
 				 TYPE_ATTRIBUTES (TREE_TYPE (fn))) != 0;
@@ -7606,14 +7612,14 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain)
   for (; arg_index < vec_safe_length (args); ++arg_index)
     {
       tree a = (*args)[arg_index];
-      if (magic == 2)
+      if ((magic == 3 && arg_index == 2) || magic == 2)
 	{
 	  /* Do no conversions for certain magic varargs.  */
 	  a = mark_type_use (a);
 	  if (TREE_CODE (a) == FUNCTION_DECL && reject_gcc_builtin (a))
 	    return error_mark_node;
 	}
-      else if (magic == 1)
+      else if (magic != 0)
 	/* For other magic varargs only do decay_conversion.  */
 	a = decay_conversion (a, complain);
       else if (DECL_CONSTRUCTOR_P (fn)

gcc/testsuite/ChangeLog

 2016-06-24  Jakub Jelinek  <jakub@redhat.com>
 
+	* c-c++-common/torture/builtin-arith-overflow-p-19.c: Run for C++ too.
+	* g++.dg/ext/builtin-arith-overflow-2.C: New test.
+
 	* c-c++-common/builtin-arith-overflow-1.c (generic_wrong_type, f3,
 	f4): Adjust expected diagnostics.
 	* c-c++-common/torture/builtin-arith-overflow.h (TP): New macro.

gcc/testsuite/c-c++-common/torture/builtin-arith-overflow-p-19.c

 /* Test __builtin_{add,sub,mul}_overflow_p.  */
-/* { dg-do run { target c } } */
+/* { dg-do run } */
 /* { dg-skip-if "" { ! run_expensive_tests }  { "*" } { "-O0" "-O2" } } */
 
 #include "builtin-arith-overflow.h"

gcc/testsuite/g++.dg/ext/builtin-arith-overflow-2.C

+// { dg-do run }
+// { dg-options "-O2" }
+
+struct A { int i : 1; };
+struct B { int j : 3; };
+
+template <typename S>
+int
+foo (int x, int y)
+{
+  A a = {};
+  S s = {};
+  return __builtin_add_overflow_p (x, y, a.i) + 2 * __builtin_mul_overflow_p (x, y, s.j);
+}
+
+__attribute__((noinline, noclone)) int
+bar (int x, int y)
+{
+  return foo <B> (x, y);
+}
+
+#if __cplusplus >= 201402L
+template <typename S>
+constexpr int
+baz (int x, int y)
+{
+  A a = {};
+  S s = {};
+  return __builtin_add_overflow_p (x, y, a.i) + 2 * __builtin_mul_overflow_p (x, y, s.j);
+}
+
+constexpr int t1 = baz <B> (0, 0);
+constexpr int t2 = baz <B> (1, -1);
+constexpr int t3 = baz <B> (1, -4);
+constexpr int t4 = baz <B> (-4, 4);
+constexpr int t5 = baz <B> (4, 2);
+static_assert (t1 == 0, "");
+static_assert (t2 == 0, "");
+static_assert (t3 == 1, "");
+static_assert (t4 == 2, "");
+static_assert (t5 == 3, "");
+#endif
+
+int
+main ()
+{
+  if (bar (0, 0) != 0
+      || bar (-1, 1) != 0
+      || bar (-4, 1) != 1
+      || bar (4, -4) != 2
+      || bar (2, 4) != 3)
+    __builtin_abort ();
+}