reload1.c (move2add_last_cc0): New.

	* reload1.c (move2add_last_cc0): New.
	(reload_cse_move2add): Detect implicit sets.
	(move2add_note_store): Notice a store into cc0.

From-SVN: r65754

gcc/ChangeLog

+2003-04-17  Kazu Hirata  <kazu@cs.umass.edu>
+
+	* reload1.c (move2add_last_cc0): New.
+	(reload_cse_move2add): Detect implicit sets.
+	(move2add_note_store): Notice a store into cc0.
+
 2003-04-17  Roger Sayle  <roger@eyesopen.com>
 
 	PR c/10375

gcc/reload1.c

@@ -9094,6 +9094,9 @@ static int move2add_last_label_luid;
        && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (OUTMODE), \
 				 GET_MODE_BITSIZE (INMODE))))
 
+/* The source of the last set to cc0 we've seen.  */
+static rtx move2add_last_cc0;
+
 static void
 reload_cse_move2add (first)
      rtx first;
@@ -9106,6 +9109,7 @@ reload_cse_move2add (first)
 
   move2add_last_label_luid = 0;
   move2add_luid = 2;
+  move2add_last_cc0 = NULL_RTX;
   for (insn = first; insn; insn = NEXT_INSN (insn), move2add_luid++)
     {
       rtx pat, note;
@@ -9288,6 +9292,29 @@ reload_cse_move2add (first)
 	    }
 	}
       note_stores (PATTERN (insn), move2add_note_store, NULL);
+
+      /* If INSN is a conditional branch, we try to extract an
+	 implicit set out of it.  */
+      if (any_condjump_p (insn) && onlyjump_p (insn))
+	{
+	  rtx cnd = get_condition (insn, NULL);
+
+#ifdef HAVE_cc0
+	  if (cnd != NULL_RTX && move2add_last_cc0 != NULL_RTX)
+	    cnd = simplify_replace_rtx (cnd, cc0_rtx, move2add_last_cc0);
+#endif
+	  if (cnd != NULL_RTX
+	      && GET_CODE (cnd) == NE
+	      && GET_CODE (XEXP (cnd, 0)) == REG
+	      && SCALAR_INT_MODE_P (GET_MODE (XEXP (cnd, 0)))
+	      && GET_CODE (XEXP (cnd, 1)) == CONST_INT)
+	    {
+	      rtx implicit_set =
+		gen_rtx_SET (VOIDmode, SET_DEST (cnd), SET_SRC (cnd));
+	      move2add_note_store (SET_DEST (implicit_set), implicit_set, 0);
+	    }
+	}
+
       /* If this is a CALL_INSN, all call used registers are stored with
 	 unknown values.  */
       if (GET_CODE (insn) == CALL_INSN)
@@ -9334,6 +9361,13 @@ move2add_note_store (dst, set, data)
 	reg_set_luid[REGNO (XEXP (dst, 0))] = 0;
       return;
     }
+  /* Note a store into cc0 so that we can later find an implicit
+     set.  */
+  if (CC0_P (dst))
+    {
+      move2add_last_cc0 = SET_SRC (set);
+      return;
+    }
   if (GET_CODE (dst) != REG)
     return;