diff options
| author | kenner <kenner@138bc75d-0d04-0410-961f-82ee72b054a4> | 2004-01-30 15:36:11 +0000 |
|---|---|---|
| committer | kenner <kenner@138bc75d-0d04-0410-961f-82ee72b054a4> | 2004-01-30 15:36:11 +0000 |
| commit | ea1ac559daec84a01077e4c7b0eccf8db70d7507 (patch) | |
| tree | fe3e684ea383fae6e8ffa9fdc7fb53096a47d83e /gcc/combine.c | |
| parent | 754ccb76764048ae0de4458a8684c3ab7a63e492 (diff) | |
| download | gcc-ea1ac559daec84a01077e4c7b0eccf8db70d7507.tar.gz | |
* combine.c (simplify_shift_const, case XOR): Be careful when
commuting XOR with ASHIFTRT.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@76965 138bc75d-0d04-0410-961f-82ee72b054a4
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 29 |
1 files changed, 19 insertions, 10 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index 9137076ad30..130bda9c429 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: |