re PR c++/87861 (ICE in output_constructor_regular_field, at varasm.c:5165)

	PR c++/87861
	* class.c (build_vtbl_initializer): For TARGET_VTABLE_USES_DESCRIPTORS
	bump index for each added word.
	* constexpr.c (find_array_ctor_elt): Add forward declaration.
	(cxx_eval_call_expression): Handle TARGET_VTABLE_USES_DESCRIPTORS
	vtable calls.
	(cxx_eval_constant_expression) <case OBJ_TYPE_REF>: Divide token
	by TARGET_VTABLE_USES_DESCRIPTORS if non-zero.

From-SVN: r267032

gcc/cp/ChangeLog

+2018-12-11  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/87861
+	* class.c (build_vtbl_initializer): For TARGET_VTABLE_USES_DESCRIPTORS
+	bump index for each added word.
+	* constexpr.c (find_array_ctor_elt): Add forward declaration.
+	(cxx_eval_call_expression): Handle TARGET_VTABLE_USES_DESCRIPTORS
+	vtable calls.
+	(cxx_eval_constant_expression) <case OBJ_TYPE_REF>: Divide token
+	by TARGET_VTABLE_USES_DESCRIPTORS if non-zero.
+
 2018-12-11  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/86608 - reading constexpr volatile variable.

gcc/cp/class.c

@@ -9351,7 +9351,6 @@ build_vtbl_initializer (tree binfo,
       tree vcall_index;
       tree fn, fn_original;
       tree init = NULL_TREE;
-      tree idx = size_int (jx++);
 
       fn = BV_FN (v);
       fn_original = fn;
@@ -9455,7 +9454,7 @@ build_vtbl_initializer (tree binfo,
 	  int i;
 	  if (init == size_zero_node)
 	    for (i = 0; i < TARGET_VTABLE_USES_DESCRIPTORS; ++i)
-	      CONSTRUCTOR_APPEND_ELT (*inits, idx, init);
+	      CONSTRUCTOR_APPEND_ELT (*inits, size_int (jx++), init);
 	  else
 	    for (i = 0; i < TARGET_VTABLE_USES_DESCRIPTORS; ++i)
 	      {
@@ -9463,11 +9462,11 @@ build_vtbl_initializer (tree binfo,
 				     fn, build_int_cst (NULL_TREE, i));
 		TREE_CONSTANT (fdesc) = 1;
 
-		CONSTRUCTOR_APPEND_ELT (*inits, idx, fdesc);
+		CONSTRUCTOR_APPEND_ELT (*inits, size_int (jx++), fdesc);
 	      }
 	}
       else
-	CONSTRUCTOR_APPEND_ELT (*inits, idx, init);
+	CONSTRUCTOR_APPEND_ELT (*inits, size_int (jx++), init);
     }
 }
 

gcc/cp/constexpr.c

@@ -41,6 +41,9 @@ do {									\
     return t;								\
  } while (0)
 
+static HOST_WIDE_INT find_array_ctor_elt (tree ary, tree dindex,
+					  bool insert = false);
+
 /* Returns true iff FUN is an instantiation of a constexpr function
    template or a defaulted constexpr function.  */
 
@@ -1516,6 +1519,36 @@ cxx_eval_call_expression (const constexpr_ctx *ctx, tree t,
       STRIP_NOPS (fun);
       if (TREE_CODE (fun) == ADDR_EXPR)
 	fun = TREE_OPERAND (fun, 0);
+      /* For TARGET_VTABLE_USES_DESCRIPTORS targets, there is no
+	 indirection, the called expression is a pointer into the
+	 virtual table which should contain FDESC_EXPR.  Extract the
+	 FUNCTION_DECL from there.  */
+      else if (TARGET_VTABLE_USES_DESCRIPTORS
+	       && TREE_CODE (fun) == POINTER_PLUS_EXPR
+	       && TREE_CODE (TREE_OPERAND (fun, 0)) == ADDR_EXPR
+	       && TREE_CODE (TREE_OPERAND (fun, 1)) == INTEGER_CST)
+	{
+	  tree d = TREE_OPERAND (TREE_OPERAND (fun, 0), 0);
+	  if (VAR_P (d)
+	      && DECL_VTABLE_OR_VTT_P (d)
+	      && TREE_CODE (TREE_TYPE (d)) == ARRAY_TYPE
+	      && TREE_TYPE (TREE_TYPE (d)) == vtable_entry_type
+	      && DECL_INITIAL (d)
+	      && TREE_CODE (DECL_INITIAL (d)) == CONSTRUCTOR)
+	    {
+	      tree i = int_const_binop (TRUNC_DIV_EXPR, TREE_OPERAND (fun, 1),
+					TYPE_SIZE_UNIT (vtable_entry_type));
+	      HOST_WIDE_INT idx = find_array_ctor_elt (DECL_INITIAL (d), i);
+	      if (idx >= 0)
+		{
+		  tree fdesc
+		    = (*CONSTRUCTOR_ELTS (DECL_INITIAL (d)))[idx].value;
+		  if (TREE_CODE (fdesc) == FDESC_EXPR
+		      && integer_zerop (TREE_OPERAND (fdesc, 1)))
+		    fun = TREE_OPERAND (fdesc, 0);
+		}
+	    }
+	}
     }
   if (TREE_CODE (fun) != FUNCTION_DECL)
     {
@@ -2240,7 +2273,7 @@ array_index_cmp (tree key, tree index)
    if none.  If INSERT is true, insert a matching element rather than fail.  */
 
 static HOST_WIDE_INT
-find_array_ctor_elt (tree ary, tree dindex, bool insert = false)
+find_array_ctor_elt (tree ary, tree dindex, bool insert)
 {
   if (tree_int_cst_sgn (dindex) < 0)
     return -1;
@@ -4834,6 +4867,8 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
 	/* Find the function decl in the virtual functions list.  TOKEN is
 	   the DECL_VINDEX that says which function we're looking for.  */
 	tree virtuals = BINFO_VIRTUALS (TYPE_BINFO (objtype));
+	if (TARGET_VTABLE_USES_DESCRIPTORS)
+	  token /= MAX (TARGET_VTABLE_USES_DESCRIPTORS, 1);
 	r = TREE_VALUE (chain_index (token, virtuals));
 	break;
       }