Re: [RFC] [v2] Extend fold_vec_perm to handle VLA vectors

[Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org>]

On Wed, 16 Aug 2023 at 15:21, Richard Sandiford
<richard.sandiford@arm.com> wrote:
>
> Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org> writes:
> >> Unfortunately, the patch regressed following tests on ppc64le and
> >> armhf respectively:
> >> gcc.target/powerpc/vec-perm-ctor.c scan-tree-dump-not optimized
> >> "VIEW_CONVERT_EXPR"
> >> gcc.dg/tree-ssa/forwprop-20.c scan-tree-dump-not forwprop1 "VEC_PERM_EXPR"
> >>
> >> This happens because of the change to vect_cst_ctor_array which
> >> removes handling of VECTOR_CST,
> >> and thus we return NULL_TREE for cases where VEC_PERM_EXPR has
> >> vector_cst, ctor input operands.
> >>
> >> For eg we fail to fold VEC_PERM_EXPR for the following test taken from
> >> forwprop-20.c:
> >> void f (double d, vecf* r)
> >> {
> >>   vecf x = { -d, 5 };
> >>   vecf y = {  1, 4 };
> >>   veci m = {  2, 0 };
> >>   *r = __builtin_shuffle (x, y, m); // { 1, -d }
> >> }
> >> because vect_cst_ctor_to_array will now return NULL_TREE for vector_cst {1, 4}.
> >>
> >> The attached patch thus reverts the changes to vect_cst_ctor_to_array,
> >> which makes the tests pass again.
> >> I have put the patch for another round of bootstrap+test on the above
> >> targets (aarch64, aarch64-sve, x86_64, armhf, ppc64le).
> >> OK to commit if it passes ?
> > The patch now passes bootstrap+test on all these targets.
>
> OK, thanks.
Thanks a lot for the helpful reviews! Committed in:
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=a7dba4a1c05a76026d88dcccc0b519cf83bff9a2

Thanks,
Prathamesh
>
> Richard