diff options
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/combine.c | 29 |
2 files changed, 24 insertions, 10 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 1159790..91a921a 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2004-01-30 Richard Kenner <kenner@vlsi1.ultra.nyu.edu> + + * combine.c (simplify_shift_const, case XOR): Be careful when + commuting XOR with ASHIFTRT. + 2004-01-30 Kazu Hirata <kazu@cs.umass.edu> Eric Botcazou <ebotcazou@libertysurf.fr> diff --git a/gcc/combine.c b/gcc/combine.c index 9137076..130bda9 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -9568,6 +9568,11 @@ simplify_shift_const (rtx x, enum rtx_code code, (and (shift)) insns. */ if (GET_CODE (XEXP (varop, 1)) == CONST_INT + /* We can't do this if we have (ashiftrt (xor)) and the + constant has its sign bit set in shift_mode. */ + && !(code == ASHIFTRT && GET_CODE (varop) == XOR + && 0 > trunc_int_for_mode (INTVAL (XEXP (varop, 1)), + shift_mode)) && (new = simplify_binary_operation (code, result_mode, XEXP (varop, 1), GEN_INT (count))) != 0 @@ -9581,18 +9586,22 @@ simplify_shift_const (rtx x, enum rtx_code code, /* If we can't do that, try to simplify the shift in each arm of the logical expression, make a new logical expression, and apply - the inverse distributive law. */ - { - rtx lhs = simplify_shift_const (NULL_RTX, code, shift_mode, - XEXP (varop, 0), count); - rtx rhs = simplify_shift_const (NULL_RTX, code, shift_mode, - XEXP (varop, 1), count); + the inverse distributive law. This also can't be done + for some (ashiftrt (xor)). */ + if (code != ASHIFTRT || GET_CODE (varop)!= XOR + || 0 <= trunc_int_for_mode (INTVAL (XEXP (varop, 1)), + shift_mode)) + { + rtx lhs = simplify_shift_const (NULL_RTX, code, shift_mode, + XEXP (varop, 0), count); + rtx rhs = simplify_shift_const (NULL_RTX, code, shift_mode, + XEXP (varop, 1), count); - varop = gen_binary (GET_CODE (varop), shift_mode, lhs, rhs); - varop = apply_distributive_law (varop); + varop = gen_binary (GET_CODE (varop), shift_mode, lhs, rhs); + varop = apply_distributive_law (varop); - count = 0; - } + count = 0; + } break; case EQ: |