From: Jakub Jelinek <jakub@redhat.com>
To: Richard Biener <rguenther@suse.de>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH][RFC] tree-optimization/107389 - use __builtin_assume_alignment at -O0
Date: Mon, 7 Nov 2022 10:08:40 +0100 [thread overview]
Message-ID: <Y2jLGAFoqYy7aVTv@tucnak> (raw)
In-Reply-To: <20221107090211.E59EA13494@imap2.suse-dmz.suse.de>
On Mon, Nov 07, 2022 at 10:02:11AM +0100, Richard Biener wrote:
> The following adds a fold_builtins pass at -O0, keying off some
> unwanted optimization and setting pointer alignment of the result
> of __builtin_assume_alignment before removing the call. This
> allows libatomic calls to be elided at -O0 on s390 for
>
> __uint128_t foo(__uint128_t *p)
> {
> return __atomic_load_n((__uint128_t *)__builtin_assume_aligned (p, 16), 0);
> }
>
> not sure how to reliably test this though.
>
> Thoughts?
Do we really need a separate pass for it?
Can't we do it say during gimplification?
> PR tree-optimization/107389
> * tree-pass.h (pass_fold_builtins_O0): Declare.
> * passes.def (pass_fold_builtins_O0): Schedule.
> * tree-ssa-ccp.cc (pass_fold_builtins_O0): Define.
> (pass_fold_builtins): Template, add gate.
> (pass_fold_builtins::execute): Apply alignment to the
> target of __builtin_assume_aligned at -O0. Disable most
> optimizations for the -O0 pass instance.
Jakub
next prev parent reply other threads:[~2022-11-07 9:08 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-07 9:02 Richard Biener
2022-11-07 9:08 ` Jakub Jelinek [this message]
2022-11-07 10:31 ` Richard Biener
2022-11-07 10:35 ` Jakub Jelinek
2022-11-07 9:48 ` Eric Botcazou
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