RE: [PATCH][GCC][PR target/98177] aarch64: SVE: ICE in expand_direct_optab_fn

[Przemyslaw Wirkus via Gcc-patches]

> Przemyslaw Wirkus <przemyslaw.wir...@arm.com> writes:
> > Hi,
> >
> > Recent 'support SVE comparisons for unpacked integers' patch extends
> > operands of define_expands from SVE_FULL to SVE_ALL. This causes an
> > ICE hence this PR patch.
> >
> > This patch adds this relaxation for:
> > + reduc_<optab>_scal_<mode> and
> > + arch64_pred_reduc_<optab>_<mode>
> > in order to support extra modes. Missing modes were used in REDUC_MAX.
> >
> > Original PR snippet proposed to reproduce issue was only causing ICE
> > for C++ compiler (see pr98177-1 test cases). I've slightly modified
> > original snippet in order to reproduce issue on both C and C++
> > compilers. These are pr98177-2 test cases.
> >
> > Bootstrap/regression test for AArch64 aarch64-elf and no issues.
> 
> This is a bug in the vectoriser: the vectoriser shouldn't generate
> IFN_REDUC_MAX calls that the target doesn't support.
> 
> I think the problem comes from using the wrong interface to get the index
> type for a COND_REDUCTION.  vectorizable_reduction has:
> 
>       cr_index_vector_type = build_vector_type (cr_index_scalar_type,
>                                                 nunits_out);
> 
> which means that for fixed-length SVE we get a V2SI (a 64-bit Advanced SIMD
> vector) instead of a VNx2SI (an SVE vector that stores SI elements in DI
> containers).  It should be using:
> 
>       cr_index_vector_type = get_same_sized_vectype (cr_index_scalar_type,
>                                                      vectype_out);
> 
> instead.  Same idea for the build_vector_type call in
> vect_create_epilog_for_reduction.

Hi Richard,
I've followed your guidance and indeed root cause was as you described.
Please see new patch in attachment.

Bootstrap/regression test for AArch64 aarch64-elf and no issues.

OK for master?

gcc/ChangeLog:

        PR target/98177
        * tree-vect-loop.c (vectorizable_reduction): Use get_same_sized_vectype 
to
        obtain index type.

gcc/testsuite/ChangeLog:

        PR target/98177
        * g++.target/aarch64/pr98177-1.C: New test.
        * g++.target/aarch64/pr98177-2.C: New test.
        * gcc.target/aarch64/pr98177-1.c: New test.
        * gcc.target/aarch64/pr98177-2.c: New test.

> Thanks,
> Richard

rb13905_v2.patch
Description: rb13905_v2.patch