On 12.01.22 17:50, Ilya Leoshkevich wrote:
> An overflow occurs for SLAG when at least one shifted bit is not equal
> to sign bit. Therefore, we need to check that `shift + 1` bits are
> neither all 0s nor all 1s. The current code checks only `shift` bits,
> missing some overflows.
>
> Fixes: cbe24bfa91d2 ("target-s390: Convert SHIFT, ROTATE SINGLE")
> Co-developed-by: David Hildenbrand <da...@redhat.com>
> Signed-off-by: Ilya Leoshkevich <i...@linux.ibm.com>
> ---
> target/s390x/tcg/cc_helper.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target/s390x/tcg/cc_helper.c b/target/s390x/tcg/cc_helper.c
> index c2c96c3a3c..c9b7b0e8c6 100644
> --- a/target/s390x/tcg/cc_helper.c
> +++ b/target/s390x/tcg/cc_helper.c
> @@ -297,7 +297,7 @@ static uint32_t cc_calc_sla_32(uint32_t src, int shift)
>
> static uint32_t cc_calc_sla_64(uint64_t src, int shift)
> {
> - uint64_t mask = ((1ULL << shift) - 1ULL) << (64 - shift);
> + uint64_t mask = -1ULL << (63 - shift);
> uint64_t sign = 1ULL << 63;
> uint64_t match;
> int64_t r;
Reviewed-by: David Hildenbrand <da...@redhat.com>
--
Thanks,
David / dhildenb
