diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
index 6d25477841a..7f1dcd0937b 100644
--- a/gcc/config/i386/i386-expand.cc
+++ b/gcc/config/i386/i386-expand.cc
@@ -23884,7 +23884,7 @@ expand_vec_perm_broadcast_1 (struct expand_vec_perm_d *d)
       if (d->testing_p)
 	return true;
 
-      rtx (*gen_interleave) (machine_mode, int, rtx, rtx, rtx);
+      rtx (*gen_interleave) (machine_mode, rtx, rtx, rtx);
       if (elt >= nelt2)
 	{
 	  gen_interleave = gen_vec_interleave_high;
@@ -23895,7 +23895,7 @@ expand_vec_perm_broadcast_1 (struct expand_vec_perm_d *d)
       nelt2 /= 2;
 
       dest = gen_reg_rtx (vmode);
-      emit_insn (gen_interleave (vmode, 1, dest, op0, op0));
+      emit_insn (gen_interleave (vmode, dest, op0, op0));
 
       vmode = V4SImode;
       op0 = gen_lowpart (vmode, dest);
diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
index 0457bb56dcd..82054b226ba 100644
--- a/gcc/doc/md.texi
+++ b/gcc/doc/md.texi
@@ -12405,4 +12405,9 @@ output and three inputs).  This combination would produce separate
 each operand count, but it would still produce a single
 @samp{maybe_code_for_@var{name}} and a single @samp{code_for_@var{name}}.
 
+Currently, these @code{@@} patterns only take into account patterns for
+which no @code{define_subst} has been applied (@pxref{Define Subst}).
+Any @samp{<@dots{}>} placeholders that refer to subst attributes
+(@pxref{Subst Iterators}) are ignored.
+
 @end ifset
diff --git a/gcc/read-rtl.cc b/gcc/read-rtl.cc
index 195f78bd5e1..49a5306254b 100644
--- a/gcc/read-rtl.cc
+++ b/gcc/read-rtl.cc
@@ -814,9 +814,14 @@ md_reader::handle_overloaded_name (rtx original, vec<mapping *> *iterators)
 	  pending_underscore_p = false;
 	}
 
-      /* Record an argument for ITERATOR.  */
-      iterators->safe_push (iterator);
-      tmp_oname.arg_types.safe_push (iterator->group->type);
+      /* Skip define_subst iterators, since define_substs are allowed to
+	 add new match_operands in their output templates.  */
+      if (iterator->group != &substs)
+	{
+	  /* Record an argument for ITERATOR.  */
+	  iterators->safe_push (iterator);
+	  tmp_oname.arg_types.safe_push (iterator->group->type);
+	}
     }
   if (base == copy)
     fatal_with_file_and_line ("no iterator attributes in name `%s'", name);
@@ -951,6 +956,7 @@ apply_iterators (rtx original, vec<rtx> *queue)
       /* We apply subst iterator after RTL-template is copied, as during
 	 subst-iterator processing, we could add an attribute to the
 	 RTL-template, and we don't want to do it in the original one.  */
+      bool add_oname = true;
       FOR_EACH_VEC_ELT (iterator_uses, i, iuse)
 	{
 	  v = iuse->iterator->current_value;
@@ -961,10 +967,14 @@ apply_iterators (rtx original, vec<rtx> *queue)
 	      current_iterator_name = iuse->iterator->name;
 	      iuse->iterator->group->apply_iterator (iuse->x, iuse->index,
 						     v->number);
+	      /* Only handle '@' overloading for the default value.
+		 See handle_overloaded_name for details.  */
+	      if (v != iuse->iterator->values)
+		add_oname = false;
 	    }
 	}
 
-      if (oname)
+      if (oname && add_oname)
 	add_overload_instance (oname, iterators, x);
 
       /* Add the new rtx to the end of the queue.  */