From: Richard Biener <richard.guenther@gmail.com>
To: Michael Collison <collison@rivosinc.com>,
Richard Sandiford <richard.sandiford@arm.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] vect: Check that vector factor is a compile-time constant
Date: Wed, 22 Feb 2023 09:20:13 +0100 [thread overview]
Message-ID: <CAFiYyc1VpMCFhafvZqL8mQvXMXW68bCMczJVvHBFuOSCEoRqHw@mail.gmail.com> (raw)
In-Reply-To: <3356a2e0-b402-de07-9374-6e5b5c59a2f2@rivosinc.com>
On Wed, Feb 22, 2023 at 12:03 AM Michael Collison <collison@rivosinc.com> wrote:
>
> While working on autovectorizing for the RISCV port I encountered an
> issue where vect_do_peeling assumes that the vectorization factor is a
> compile-time constant. The vectorization is not a compile-time constant
> on RISCV.
>
> Tested on RISCV and x86_64-linux-gnu. Okay?
I wonder how you arrive at prologue peeling with a non-constant VF?
In any case it would probably be better to use constant_lower_bound (vf)
here? Also it looks wrong to apply this limit in case we are using
a fully masked main vector loop. But as said, the specific case of
non-constant VF and prologue peeling probably wasn't supposed to happen,
instead the prologue usually is applied via an offset to a fully masked loop?
Richard?
Thanks,
Richard.
> Michael
>
> gcc/
>
> * tree-vect-loop-manip.cc (vect_do_peeling): Verify
> that vectorization factor is a compile-time constant.
>
> ---
> gcc/tree-vect-loop-manip.cc | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
> index 6aa3d2ed0bf..1ad1961c788 100644
> --- a/gcc/tree-vect-loop-manip.cc
> +++ b/gcc/tree-vect-loop-manip.cc
> @@ -2930,7 +2930,7 @@ vect_do_peeling (loop_vec_info loop_vinfo, tree
> niters, tree nitersm1,
> niters = vect_build_loop_niters (loop_vinfo, &new_var_p);
> /* It's guaranteed that vector loop bound before vectorization is at
> least VF, so set range information for newly generated var. */
> - if (new_var_p)
> + if (new_var_p && vf.is_constant ())
> {
> value_range vr (type,
> wi::to_wide (build_int_cst (type, vf)),
> --
> 2.34.1
>
next prev parent reply other threads:[~2023-02-22 8:20 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-21 23:02 Michael Collison
2023-02-22 8:20 ` Richard Biener [this message]
2023-02-22 16:42 ` Michael Collison
2023-02-23 9:08 ` Richard Biener
2023-02-27 14:51 ` Richard Sandiford
2023-03-01 21:00 ` Michael Collison
2023-03-02 7:56 ` Richard Biener
2023-02-22 15:27 juzhe.zhong
2023-02-22 17:54 ` Michael Collison
2023-02-23 4:01 ` Jeff Law
2023-02-23 4:50 ` Michael Collison
2023-02-24 3:34 ` Jeff Law
2023-02-24 4:04 ` Kito Cheng
2023-03-14 17:48 ` Jeff Law
2023-03-17 16:57 ` Palmer Dabbelt
2023-03-17 16:57 ` Palmer Dabbelt
2023-03-23 23:18 ` Jeff Law
2023-03-24 2:28 ` Palmer Dabbelt
2023-03-25 22:45 ` Jeff Law
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