On Wed, Dec 18, 2024 at 6:48 PM Robin Dapp <rdapp....@gmail.com> wrote:
>
> Hi,
>
> in PR116351 we try to vectorize with -march=...zve32x which does not
> have 64-bit vector element sizes, don't find a proper mode and end up
> using word_mode = DImode.
>
> vect_verify_loop_lens calls get_len_load_store_mode which asserts
> VECTOR_MODE_P (vecmode) so DImode will cause an ICE.
>
> In check_load_store_for_partial_vectors we disable partial vectors
> when emulating vectors so this patch does the same in tree-vect-loop.cc
> before vect_verify_loop_lens is called.
>
> Is this the correct thing to do or should we have taken another
> turn somewhere else?
else /* !LOOP_VINFO_LENS (loop_vinfo).is_empty () */
if (!vect_verify_loop_lens (loop_vinfo))
LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
I wonder if LOOP_VINFO_LENS is really empty here? If not, who recorded
the len and why did that not disable partial vectors?
Maybe
if (LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo)
&& !LOOP_VINFO_MASKS (loop_vinfo).is_empty ()
&& !LOOP_VINFO_LENS (loop_vinfo).is_empty ())
should become !(LOOP_VINFO_MASKS (loop_vinfo).is_empty () ^
LOOP_VINFO_LENS (loop_vinfo).is_empty ()))?
> Bootstrapped and regtested on x86, aarch64, and power10.
> Regtested on rv64gcv_zvl512b.
>
> Regards
> Robin
>
> PR target/116351
>
> gcc/ChangeLog:
>
> * tree-vect-loop.cc: Disable partial vectors for emulated
> vectors.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/riscv/rvv/autovec/pr116351.c: New test.
> ---
> .../gcc.target/riscv/rvv/autovec/pr116351.c | 15 +++++++++++++++
> gcc/tree-vect-loop.cc | 10 ++++++++++
> 2 files changed, 25 insertions(+)
> create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/autovec/pr116351.c
>
> diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr116351.c
> b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr116351.c
> new file mode 100644
> index 00000000000..ed1b985d8fa
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr116351.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -march=rv64imd_zve32x -mrvv-vector-bits=zvl" } */
> +
> +int a, b, c;
> +short d, e, f;
> +long (g) (long h) { return h; }
> +
> +void i ()
> +{
> + for (; b; ++b)
> + {
> + f = 5 >> a ? d : d << a;
> + e &= c | g (f);
> + }
> +}
> diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> index 4f401cd2d0c..2cf5a05b70c 100644
> --- a/gcc/tree-vect-loop.cc
> +++ b/gcc/tree-vect-loop.cc
> @@ -3021,6 +3021,16 @@ start_over:
> LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
> }
>
> + if (LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo)
> + && !VECTOR_MODE_P (loop_vinfo->vector_mode))
> + {
> + if (dump_enabled_p ())
> + dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> + "can't operate on partial vectors when emulating"
> + " vector operations.\n");
> + LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
> + }
> +
> /* If we still have the option of using partial vectors,
> check whether we can generate the necessary loop controls. */
> if (LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo))
> --
> 2.47.1
>
