[dataflow]: PATCH COMMITTED to fix dse regression.

[Eric Botcazou]

>     * dse.c (const_or_frame_p): New function.

+/* Return true if X is a constant or one of the registers that behaves
+   as a constant over the life of a function.  */
+
+static bool
+const_or_frame_p (rtx x)
+{
+  if (!x)
+    return true;
+
+  switch (GET_CODE (x))
+    {
+    case MEM:
+      return !MEM_READONLY_P (x);

That's counter-intuitive at best, so a comment would seem appropriate here.

-- 
Eric Botcazou