*** empty log message ***

From-SVN: r565

diff --git a/gcc/reorg.c b/gcc/reorg.c
index 160e49a155620c62cd553bdbd3d7fe2b9d762455..f518fb89880745ce09055bd1dd7a1bf35964afdc 100644 (file)
--- a/gcc/reorg.c
+++ b/gcc/reorg.c
@@ -2820,21 +2820,22 @@ fill_slots_from_thread (insn, condition, thread, opposite_thread, likely,
 
         We could check for more complex cases than those tested below,
         but it doesn't seem worth it.  It might also be a good idea to try
-        to swap the two insns.  That might do better.  */
+        to swap the two insns.  That might do better.
+
+        We can't do this if the next insn modifies our source, because that
+        would make the replacement into the insn invalid.  This also
+        prevents updating the contents of a PRE_INC.  */
 
       if (GET_CODE (trial) == INSN && GET_CODE (pat) == SET
          && GET_CODE (SET_SRC (pat)) == REG
          && GET_CODE (SET_DEST (pat)) == REG)
        {
          rtx next = next_nonnote_insn (trial);
-         int our_dest = REGNO (SET_DEST (pat));
 
          if (next && GET_CODE (next) == INSN
-             && GET_CODE (PATTERN (next)) == SET
-             && GET_CODE (SET_DEST (PATTERN (next))) == REG
-             && REGNO (SET_DEST (PATTERN (next))) != our_dest
-             && refers_to_regno_p (our_dest, our_dest + 1,
-                                   SET_SRC (PATTERN (next)), 0))
+             && GET_CODE (PATTERN (next)) != USE
+             && ! reg_set_p (SET_DEST (pat), next)
+             && reg_referenced_p (SET_DEST (pat), PATTERN (next)))
            validate_replace_rtx (SET_DEST (pat), SET_SRC (pat), next);
        }
     }