[backport from gcc-4.7/trunk <mikpe@it.uu.se>]

gcc/

2011-04-20  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/47892
	* tree-if-conv.c (if_convertible_stmt_p): Const builtins
	are if-convertible.

gcc/testsuite/

2011-04-20  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/47892
	* gcc.dg/vect/fast-math-ifcvt-1.c: New testcase.

--- gcc-4.6.0/gcc/testsuite/gcc.dg/vect/fast-math-ifcvt-1.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.6.0/gcc/testsuite/gcc.dg/vect/fast-math-ifcvt-1.c	2011-05-15 14:16:58.000000000 +0200
@@ -0,0 +1,18 @@
+/* PR 47892 */
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_float } */
+/* { dg-require-effective-target vect_condition } */
+
+void
+bestseries9 (float * __restrict__ arr, int len)
+{
+  int i;
+  for (i = 0; i < len; ++i)
+    {
+      float or = arr[i];
+      arr[i] = (or > 0.0f) * (2 - or * or);
+    }
+}
+
+/* { dg-final { scan-tree-dump "vectorized 1 loops" "vect" } } */
+/* { dg-final { cleanup-tree-dump "vect" } } */
--- gcc-4.6.0/gcc/tree-if-conv.c.~1~	2011-02-23 17:49:52.000000000 +0100
+++ gcc-4.6.0/gcc/tree-if-conv.c	2011-05-15 14:16:58.000000000 +0200
@@ -702,6 +702,22 @@ if_convertible_stmt_p (gimple stmt, VEC 
     case GIMPLE_ASSIGN:
       return if_convertible_gimple_assign_stmt_p (stmt, refs);
 
+    case GIMPLE_CALL:
+      {
+	tree fndecl = gimple_call_fndecl (stmt);
+	if (fndecl)
+	  {
+	    int flags = gimple_call_flags (stmt);
+	    if ((flags & ECF_CONST)
+		&& !(flags & ECF_LOOPING_CONST_OR_PURE)
+		/* We can only vectorize some builtins at the moment,
+		   so restrict if-conversion to those.  */
+		&& DECL_BUILT_IN (fndecl))
+	      return true;
+	  }
+	return false;
+      }
+
     default:
       /* Don't know what to do with 'em so don't do anything.  */
       if (dump_file && (dump_flags & TDF_DETAILS))