(simplify_and_const_int, LSHIFTRT case): Must be at

least as many sign bit copies as bits in mask.

From-SVN: r4868

diff --git a/gcc/combine.c b/gcc/combine.c
index b91558a..1c8295f 100644 (file)
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -6118,7 +6118,10 @@ simplify_and_const_int (x, mode, varop, constop)
                   + num_sign_bit_copies (XEXP (varop, 0),
                                          GET_MODE (XEXP (varop, 0))))
                  >= GET_MODE_BITSIZE (GET_MODE (varop)))
-             && exact_log2 (constop + 1) >= 0)
+             && exact_log2 (constop + 1) >= 0
+             && (num_sign_bit_copies (XEXP (varop, 0),
+                                      GET_MODE (XEXP (varop, 0)))
+                 >= exact_log2 (constop + 1)))
            varop
              = gen_rtx_combine (LSHIFTRT, GET_MODE (varop), XEXP (varop, 0),
                                 GEN_INT (GET_MODE_BITSIZE (GET_MODE (varop))