re PR middle-end/44203 (New prefetch test failures)

2010-05-25  Christian Borntraeger  <borntraeger@de.ibm.com>

	PR 44203
	* tree-ssa-loop-prefetch.c: Fix logic for step calculation to
	match the original (and intended) behaviour before r159557.  This
	changeset changed a=a+b*c to a=(a+b)*b which was obviously wrong
	in two ways.

From-SVN: r159816

gcc/ChangeLog

+2010-05-25  Christian Borntraeger  <borntraeger@de.ibm.com>
+
+	PR 44203
+	* tree-ssa-loop-prefetch.c: Fix logic for step calculation to
+	match the original (and intended) behaviour before r159557.  This
+	changeset changed a=a+b*c to a=(a+b)*b which was obviously wrong
+	in two ways.
+
 2010-05-25  Richard Guenther  <rguenther@suse.de>
 
 	* doc/invoke.texi: Document -Ofast.

gcc/tree-ssa-loop-prefetch.c

@@ -423,25 +423,24 @@ idx_analyze_ref (tree base, tree *index, void *data)
       ibase = build_int_cst (TREE_TYPE (ibase), 0);
     }
 
-  if (*ar_data->step == NULL_TREE)
-    *ar_data->step = step;
-  else
-    *ar_data->step = fold_build2 (PLUS_EXPR, sizetype,
-				  fold_convert (sizetype, *ar_data->step),
-				  fold_convert (sizetype, step));
   if (TREE_CODE (base) == ARRAY_REF)
     {
       stepsize = array_ref_element_size (base);
       if (!cst_and_fits_in_hwi (stepsize))
 	return false;
       imult = int_cst_value (stepsize);
-
-      *ar_data->step = fold_build2 (MULT_EXPR, sizetype,
-				    fold_convert (sizetype, *ar_data->step),
-				    fold_convert (sizetype, step));
+      step = fold_build2 (MULT_EXPR, sizetype,
+			  fold_convert (sizetype, step),
+			  fold_convert (sizetype, stepsize));
       idelta *= imult;
     }
 
+  if (*ar_data->step == NULL_TREE)
+    *ar_data->step = step;
+  else
+    *ar_data->step = fold_build2 (PLUS_EXPR, sizetype,
+				  fold_convert (sizetype, *ar_data->step),
+				  fold_convert (sizetype, step));
   *ar_data->delta += idelta;
   *index = ibase;