2016-08-17  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/77259
	* tree-ssa-pre.c (eliminate_dom_walker::before_dom_children): If
	turning a call into __builtin_unreachable-like noreturn call, adjust
	gimple_call_set_fntype.
	* tree-cfgcleanup.c (fixup_noreturn_call): Remove lhs also if
	gimple_call_fntype has void return type.

	* g++.dg/ipa/devirt-52.C: New test.

--- gcc/tree-ssa-pre.c.jj	2016-08-16 13:22:49.095671219 +0200
+++ gcc/tree-ssa-pre.c	2016-08-17 10:24:42.498730917 +0200
@@ -4543,6 +4543,15 @@ eliminate_dom_walker::before_dom_childre
 				       lang_hooks.decl_printable_name (fn, 2));
 		    }
 		  gimple_call_set_fndecl (call_stmt, fn);
+		  /* If changing the call to __builtin_unreachable
+		     or similar noreturn function, adjust gimple_call_fntype
+		     too.  */
+		  if (gimple_call_noreturn_p (call_stmt)
+		      && VOID_TYPE_P (TREE_TYPE (TREE_TYPE (fn)))
+		      && TYPE_ARG_TYPES (TREE_TYPE (fn))
+		      && (TREE_VALUE (TYPE_ARG_TYPES (TREE_TYPE (fn)))
+			  == void_type_node))
+		    gimple_call_set_fntype (call_stmt, TREE_TYPE (fn));
 		  maybe_remove_unused_call_args (cfun, call_stmt);
 		  gimple_set_modified (stmt, true);
 		}
--- gcc/tree-cfgcleanup.c.jj	2016-08-09 09:41:14.000000000 +0200
+++ gcc/tree-cfgcleanup.c	2016-08-17 10:36:24.198791289 +0200
@@ -602,10 +602,15 @@ fixup_noreturn_call (gimple *stmt)
   /* If there is an LHS, remove it, but only if its type has fixed size.
      The LHS will need to be recreated during RTL expansion and creating
      temporaries of variable-sized types is not supported.  Also don't
-     do this with TREE_ADDRESSABLE types, as assign_temp will abort.  */
+     do this with TREE_ADDRESSABLE types, as assign_temp will abort.
+     Drop LHS regardless of TREE_ADDRESSABLE, if the function call
+     has been changed into a call that does not return a value, like
+     __builtin_unreachable or __cxa_pure_virtual.  */
   tree lhs = gimple_call_lhs (stmt);
-  if (lhs && TREE_CODE (TYPE_SIZE_UNIT (TREE_TYPE (lhs))) == INTEGER_CST
-      && !TREE_ADDRESSABLE (TREE_TYPE (lhs)))
+  if (lhs
+      && ((TREE_CODE (TYPE_SIZE_UNIT (TREE_TYPE (lhs))) == INTEGER_CST
+	   && !TREE_ADDRESSABLE (TREE_TYPE (lhs)))
+	  || VOID_TYPE_P (TREE_TYPE (gimple_call_fntype (stmt)))))
     {
       gimple_call_set_lhs (stmt, NULL_TREE);
 
--- gcc/testsuite/g++.dg/ipa/devirt-52.C.jj	2016-08-17 10:23:39.775528901 +0200
+++ gcc/testsuite/g++.dg/ipa/devirt-52.C	2016-08-17 10:23:39.775528901 +0200
@@ -0,0 +1,56 @@
+// PR middle-end/77259
+// { dg-do compile { target c++11 } }
+// { dg-options "-O2" }
+
+template <typename, typename = int> class A;
+template <typename, typename> struct A
+{
+  A (A &&);
+};
+template <typename S, typename T, typename U>
+A<S> operator+(S *, const A<T, U> &);
+template <typename S, typename T, typename U>
+void operator+(const A<T, U> &, S *);
+struct B
+{
+  template <typename V> B (V);
+};
+template <typename V> V foo (B) {}
+class C;
+template <typename> struct D
+{
+  C *operator->() { return d; }
+  C *d;
+};
+struct C
+{
+  virtual A<int> bar ();
+};
+struct E
+{
+  ~E ();
+  virtual A<char> bar (const B &) const;
+};
+template <typename> struct F : E
+{
+};
+template <typename W> struct F<D<W>> : E
+{
+  A<char> bar (const B &) const try
+    {
+      D<W> a = baz ();
+    }
+  catch (int)
+    {
+    }
+  D<W> baz () const
+  {
+    D<C> b = foo<D<C>>(0);
+    "" + b->bar () + "";
+  }
+};
+struct G : F<D<int>>
+{
+  G (int);
+};
+void test () { G (0); }