Fix ICE with __builtin_va_list on i?86 (PR middle-end/78716)

[Marek Polacek]

This test ICEs since r240072 where Tom disallowed using va_list * as a first
argument to va_arg.  I think the problem is in the ADDR_EXPR check in
gimplify_va_arg_expr.  It's meant to handle Case 1, but the valist doesn't
always have to be ADDR_EXPR.  E.g. for this testcase build_va_arg creates
VA_ARG_EXPR <&*s>
but during clone_body this is transformed into
VA_ARG_EXPR <s>
so we have a valid valist, but it's not an ADDR_EXPR, so we don't call
targetm.canonical_va_list_type and crash on the subsequent assert.

Tom, does this make sense to you?  [Although I haven't seen Tom here on ML
lately...]

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2016-12-08  Marek Polacek  <polacek@redhat.com>

	PR middle-end/78716
	* gimplify.c (gimplify_va_arg_expr): Don't require ADDR_EXPR for
	Case 1.

	* g++.dg/other/vararg-5.C: New.

diff --git gcc/gimplify.c gcc/gimplify.c
index 8611060..08c4faa 100644
--- gcc/gimplify.c
+++ gcc/gimplify.c
@@ -12642,8 +12642,7 @@ gimplify_va_arg_expr (tree *expr_p, gimple_seq *pre_p,
   if (have_va_type == error_mark_node)
     return GS_ERROR;
   have_va_type = targetm.canonical_va_list_type (have_va_type);
-  if (have_va_type == NULL_TREE
-      && TREE_CODE (valist) == ADDR_EXPR)
+  if (have_va_type == NULL_TREE)
     /* Handle 'Case 1: Not an array type' from c-common.c/build_va_arg.  */
     have_va_type
       = targetm.canonical_va_list_type (TREE_TYPE (TREE_TYPE (valist)));
diff --git gcc/testsuite/g++.dg/other/vararg-5.C gcc/testsuite/g++.dg/other/vararg-5.C
index e69de29..9327bd6 100644
--- gcc/testsuite/g++.dg/other/vararg-5.C
+++ gcc/testsuite/g++.dg/other/vararg-5.C
@@ -0,0 +1,24 @@
+// PR middle-end/78716
+// { dg-do compile }
+
+template <typename = int, typename = int, typename = int, typename = int,
+	           typename = int>
+		   struct a;
+		   template <typename> struct b;
+		   template <typename = int, typename d = void> class e : b<d>::c {
+		     public:
+		         typedef e f;
+			   typedef typename b<d>::c g;
+			     e(__builtin_va_list *s) : g(__builtin_va_arg(*s, int)) {}
+		   };
+template <> struct b<void> { typedef e<> c; };
+template <> struct e<> { template <typename h> e(h); };
+template <typename i> class a<i> : public e<i> {};
+template <typename i, typename j, typename k, typename l>
+class a<i, j, k, l> : e<typename a<j>::f> {
+  public:
+      template <typename m, typename n, typename o, typename p>
+	  a(a<m, n, o, p>) : a::f(0) {}
+};
+template <typename i, typename j, typename k, typename l> a<> r(i, j, k, l);
+void q() { a<float, float>(r(4, 6, 9, 7)); }

	Marek