[Bug rtl-optimization/50891] move2add_note_store fails to properly track register content

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50891

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> 2011-10-27 23:20:47 UTC ---
Does this:

---
diff --git a/gcc/postreload.c b/gcc/postreload.c
index 0e50d85..526015b 100644
--- a/gcc/postreload.c
+++ b/gcc/postreload.c
@@ -2039,6 +2039,10 @@ reload_cse_move2add (rtx first)
       allocation if possible.  */
         && SCALAR_INT_MODE_P (GET_MODE (XEXP (cnd, 0)))
         && hard_regno_nregs[REGNO (XEXP (cnd, 0))][GET_MODE (XEXP (cnd, 0))]
== 1
+        /* Use implicit set only if the new mode is wider than
+      the previous mode since register isn't really set.  */
+        && (GET_MODE_SIZE (GET_MODE (XEXP (cnd, 0)))
+       >= GET_MODE_SIZE (reg_mode[REGNO (XEXP (cnd, 0))]))
         && CONST_INT_P (XEXP (cnd, 1)))
       {
         rtx implicit_set =
---

make any senses?