On 8/5/23 01:03, Ilya Leoshkevich wrote:
> Currently the emulation of VSTRS recognizes partial matches in presence
> of \0 in the haystack, which, according to PoP, is not correct:
>
> If the ZS flag is one and a zero byte was detected
> in the second operand, then there can not be a
> partial match ...
>
> Add a check for this. While at it, fold a number of explicitly handled
> special cases into the generic logic.
>
> Cc: qemu-sta...@nongnu.org
> Reported-by: Claudio Fontana <cfont...@suse.de>
> Closes: https://lists.gnu.org/archive/html/qemu-devel/2023-08/msg00633.html
> Fixes: 1d706f314191 ("target/s390x: vxeh2: vector string search")
> Signed-off-by: Ilya Leoshkevich <i...@linux.ibm.com>
verified that it fixes the problem I encountered,
Tested-by: Claudio Fontana <cfont...@suse.de>
> ---
> target/s390x/tcg/vec_string_helper.c | 54 +++++++++-------------------
> 1 file changed, 17 insertions(+), 37 deletions(-)
>
> diff --git a/target/s390x/tcg/vec_string_helper.c
> b/target/s390x/tcg/vec_string_helper.c
> index 9b85becdfbf..a19f429768f 100644
> --- a/target/s390x/tcg/vec_string_helper.c
> +++ b/target/s390x/tcg/vec_string_helper.c
> @@ -474,9 +474,9 @@ DEF_VSTRC_CC_RT_HELPER(32)
> static int vstrs(S390Vector *v1, const S390Vector *v2, const S390Vector *v3,
> const S390Vector *v4, uint8_t es, bool zs)
> {
> - int substr_elen, substr_0, str_elen, i, j, k, cc;
> + int substr_elen, i, j, k, cc;
> int nelem = 16 >> es;
> - bool eos = false;
> + int str_leftmost_0;
>
> substr_elen = s390_vec_read_element8(v4, 7) >> es;
>
> @@ -498,47 +498,20 @@ static int vstrs(S390Vector *v1, const S390Vector *v2,
> const S390Vector *v3,
> }
>
> /* If ZS, look for eos in the searched string. */
> + str_leftmost_0 = nelem;
> if (zs) {
> for (k = 0; k < nelem; k++) {
> if (s390_vec_read_element(v2, k, es) == 0) {
> - eos = true;
> + str_leftmost_0 = k;
> break;
> }
> }
> - str_elen = k;
> - } else {
> - str_elen = nelem;
> }
>
> - substr_0 = s390_vec_read_element(v3, 0, es);
> -
> - for (k = 0; ; k++) {
> - for (; k < str_elen; k++) {
> - if (s390_vec_read_element(v2, k, es) == substr_0) {
> - break;
> - }
> - }
> -
> - /* If we reached the end of the string, no match. */
> - if (k == str_elen) {
> - cc = eos; /* no match (with or without zero char) */
> - goto done;
> - }
> -
> - /* If the substring is only one char, match. */
> - if (substr_elen == 1) {
> - cc = 2; /* full match */
> - goto done;
> - }
> -
> - /* If the match begins at the last char, we have a partial match. */
> - if (k == str_elen - 1) {
> - cc = 3; /* partial match */
> - goto done;
> - }
> -
> + cc = str_leftmost_0 == nelem ? 0 : 1; /* No match. */
> + for (k = 0; k < nelem; k++) {
> i = MIN(nelem, k + substr_elen);
> - for (j = k + 1; j < i; j++) {
> + for (j = k; j < i; j++) {
> uint32_t e2 = s390_vec_read_element(v2, j, es);
> uint32_t e3 = s390_vec_read_element(v3, j - k, es);
> if (e2 != e3) {
> @@ -546,9 +519,16 @@ static int vstrs(S390Vector *v1, const S390Vector *v2,
> const S390Vector *v3,
> }
> }
> if (j == i) {
> - /* Matched up until "end". */
> - cc = i - k == substr_elen ? 2 : 3; /* full or partial match */
> - goto done;
> + /* All elements matched. */
> + if (k > str_leftmost_0) {
> + cc = 1; /* Ignored match. */
> + k = nelem;
> + } else if (i - k == substr_elen) {
> + cc = 2; /* Full match. */
> + } else {
> + cc = 3; /* Partial match. */
> + }
> + break;
> }
> }
>
