https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107617
Bug ID: 107617
Summary: SCC-VN with len_store and big endian
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: rdapp at gcc dot gnu.org
CC: richard.guenther at gmail dot com
Target Milestone: ---
Target: s
Created attachment 53871
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53871&action=edit
s390 patch for len_load/len_store
Hi,
Richard and I already quickly discussed this on the mailing list but I didn't
manage to progress analyzing as I was tied up with other things. Figured I
open a bug for tracking purposes and the possibility to maybe fix it in a later
stage.
I'm evaluating len_load/len_store support on s390 via the attached patch and
seeing a FAIL in
testsuite/gfortran.dg/power_3.f90
built with -march=z16 -O3 --param vect-partial-vector-usage=1
The problem seems to be that we evaluate a vector constant
{-1, 1, -1, 1} loaded with length 11 + 1(bias) = 12 as
{1, -1, 1} instead of {-1, 1, -1}.
Richard wrote on the mailing list:
> The error is probably in vn_reference_lookup_3 which assumes that
> 'len' applies to the vector elements in element order. See the part
> of the code where it checks for internal_store_fn_p. If 'len' is with
> respect to the memory and thus endianess has to be taken into
> account then for the IFN_LEN_STORE
>
> else if (fn == IFN_LEN_STORE)
> {
> pd.rhs_off = 0;
> pd.offset = offset2i;
> pd.size = (tree_to_uhwi (len)
> + -tree_to_shwi (bias)) * BITS_PER_UNIT;
> if (ranges_known_overlap_p (offset, maxsize,
> pd.offset, pd.size))
> return data->push_partial_def (pd, set, set,
> offseti, maxsizei);
>
> likely needs to adjust rhs_off from zero for big endian?
