re PR middle-end/24263 (gcc.dg/torture/builtin-convert-1.c fails)

	PR middle-end/24263
	* convert.c (convert_to_real): Revert 2005-10-05 patch.
	Only apply the optimization for rounding builtins if the inner
	cast is also an extension.

From-SVN: r105249

gcc/ChangeLog

+2005-10-11  Eric Botcazou  <ebotcazou@libertysurf.fr>
+
+	PR middle-end/24263 
+	* convert.c (convert_to_real): Revert 2005-10-05 patch.
+	Only apply the optimization for rounding builtins if the inner
+	cast is also an extension.
+
 2005-10-11  Andrew Pinski  <pinskia@physics.uc.edu>
 
 	PR tree-opt/23946

gcc/convert.c

@@ -200,9 +200,41 @@ convert_to_real (tree type, tree expr)
 	  break;
 	}
     }
-  /* This code formerly changed (float)floor(double d) to
-     floorf((float)d).  This is incorrect, because (float)d uses
-     round-to-nearest and can round up to the next integer. */
+  if (optimize
+      && (((fcode == BUILT_IN_FLOORL
+	   || fcode == BUILT_IN_CEILL
+	   || fcode == BUILT_IN_ROUNDL
+	   || fcode == BUILT_IN_RINTL
+	   || fcode == BUILT_IN_TRUNCL
+	   || fcode == BUILT_IN_NEARBYINTL)
+	  && (TYPE_MODE (type) == TYPE_MODE (double_type_node)
+	      || TYPE_MODE (type) == TYPE_MODE (float_type_node)))
+	  || ((fcode == BUILT_IN_FLOOR
+	       || fcode == BUILT_IN_CEIL
+	       || fcode == BUILT_IN_ROUND
+	       || fcode == BUILT_IN_RINT
+	       || fcode == BUILT_IN_TRUNC
+	       || fcode == BUILT_IN_NEARBYINT)
+	      && (TYPE_MODE (type) == TYPE_MODE (float_type_node)))))
+    {
+      tree fn = mathfn_built_in (type, fcode);
+
+      if (fn)
+	{
+	  tree arg
+	    = strip_float_extensions (TREE_VALUE (TREE_OPERAND (expr, 1)));
+
+	  /* Make sure (type)arg0 is an extension, otherwise we could end up
+	     changing (float)floor(double d) into floorf((float)d), which is
+	     incorrect because (float)d uses round-to-nearest and can round
+	     up to the next integer.  */
+	  if (TYPE_PRECISION (type) >= TYPE_PRECISION (TREE_TYPE (arg)))
+	    return
+	      build_function_call_expr (fn,
+					build_tree_list (NULL_TREE,
+					  fold (convert_to_real (type, arg))));
+	}
+    }
 
   /* Propagate the cast into the operation.  */
   if (itype != type && FLOAT_TYPE_P (type))