vect: vectorize via libfuncs

This patch allows vectorization when the libfuncs are defined.

gcc/ChangeLog:

	* tree-vect-generic.cc: Include optabs-libfuncs.h.
	(get_compute_type): Check optab_libfunc.
	* tree-vect-stmts.cc: Include optabs-libfuncs.h.
	(vectorizable_operation): Check optab_libfunc.

diff --git a/gcc/tree-vect-generic.cc b/gcc/tree-vect-generic.cc
index b7d4a919c55..4d784a70c0d 100644
--- a/gcc/tree-vect-generic.cc
+++ b/gcc/tree-vect-generic.cc
@@ -44,6 +44,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "gimple-fold.h"
 #include "gimple-match.h"
 #include "recog.h"		/* FIXME: for insn_data */
+#include "optabs-libfuncs.h"
 
 
 /* Build a ternary operation and gimplify it.  Emit code before GSI.
@@ -1714,7 +1715,8 @@ get_compute_type (enum tree_code code, optab op, tree type)
       machine_mode compute_mode = TYPE_MODE (compute_type);
       if (VECTOR_MODE_P (compute_mode))
 	{
-	  if (op && optab_handler (op, compute_mode) != CODE_FOR_nothing)
+	  if (op && (optab_handler (op, compute_mode) != CODE_FOR_nothing
+		     || optab_libfunc (op, compute_mode)))
 	    return compute_type;
 	  if (code == MULT_HIGHPART_EXPR
 	      && can_mult_highpart_p (compute_mode,
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index a7acc032d47..71a8cf2c6d4 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -56,6 +56,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "gimple-fold.h"
 #include "regs.h"
 #include "attribs.h"
+#include "optabs-libfuncs.h"
 
 /* For lang_hooks.types.type_for_mode.  */
 #include "langhooks.h"
@@ -6528,8 +6529,8 @@ vectorizable_operation (vec_info *vinfo,
                              "no optab.\n");
 	  return false;
 	}
-      target_support_p = (optab_handler (optab, vec_mode)
-			  != CODE_FOR_nothing);
+      target_support_p = (optab_handler (optab, vec_mode) != CODE_FOR_nothing
+			  || optab_libfunc (optab, vec_mode));
     }
 
   bool using_emulated_vectors_p = vect_emulated_vector_p (vectype);