use build_one_cst in tree-ssa-loop-im.c

[Nathan Froyd <froydnj@codesourcery.com>]

This code in tree-ssa-loop-im.c:

  /* For vectors, create a VECTOR_CST full of 1's.  */
  if (TREE_CODE (type) == VECTOR_TYPE)
    {
      int i, len;
      tree list = NULL_TREE;
      real_one = build_real (TREE_TYPE (type), dconst1);
      len = TYPE_VECTOR_SUBPARTS (type);
      for (i = 0; i < len; i++)
	list = tree_cons (NULL, real_one, list);
      real_one = build_vector (type, list);
    }
  else
    real_one = build_real (type, dconst1);

reduces to:

  if (TREE_CODE (type) == VECTOR_TYPE)
    {
      real_one = build_real (TREE_TYPE (type), dconst1);
      real_one = build_vector_from_val (type, real_one);
    }
  else
    real_one - build_real (type, dconst1);

which is exactly what build_one_cst does.  So call that instead.

Tested on x86_64-unknown-linux-gnu.  Committed as obvious.

-Nathan

	* tree-ssa-loop-im.c (rewrite_reciprocal): Use build_one_cst.

Index: tree-ssa-loop-im.c
===================================================================
--- tree-ssa-loop-im.c	(revision 166100)
+++ tree-ssa-loop-im.c	(working copy)
@@ -910,19 +910,7 @@ rewrite_reciprocal (gimple_stmt_iterator
   add_referenced_var (var);
   DECL_GIMPLE_REG_P (var) = 1;
 
-  /* For vectors, create a VECTOR_CST full of 1's.  */
-  if (TREE_CODE (type) == VECTOR_TYPE)
-    {
-      int i, len;
-      tree list = NULL_TREE;
-      real_one = build_real (TREE_TYPE (type), dconst1);
-      len = TYPE_VECTOR_SUBPARTS (type);
-      for (i = 0; i < len; i++)
-	list = tree_cons (NULL, real_one, list);
-      real_one = build_vector (type, list);
-    }
-  else
-    real_one = build_real (type, dconst1);
+  real_one = build_one_cst (type);
 
   stmt1 = gimple_build_assign_with_ops (RDIV_EXPR,
 		var, real_one, gimple_assign_rhs2 (stmt));