From: Richard Biener <rguenther@suse.de>
To: Jakub Jelinek <jakub@redhat.com>
Cc: Bingfeng Mei <bmei@broadcom.com>, "gcc@gcc.gnu.org" <gcc@gcc.gnu.org>
Subject: Re: No TBAA before ptr_derefs_may_alias_p?
Date: Mon, 03 Feb 2014 10:36:00 -0000 [thread overview]
Message-ID: <alpine.LSU.2.11.1402031133100.29326@zhemvz.fhfr.qr> (raw)
In-Reply-To: <alpine.LSU.2.11.1402031104520.29326@zhemvz.fhfr.qr>
On Mon, 3 Feb 2014, Richard Biener wrote:
> And note that for the case in question we
> can derive non-aliasing because with
>
> p[i] += q[i];
>
> p[i] is both read _and_ written in the same iteration thus
> it cannot have the dynamic type of q[i] before it's stored
> into. Of course data-dependence doesn't do this kind of
> analysis currently, but it certainly could.
The vectorizer already has code to analyzes data-refs for groups,
not for read-write of the same loc as needed here, so it could
be reasonably easy to extend its analysis to detect this case
and mark the write DR with a flag so that in
vect_analyze_data_ref_dependence the _vectorizer_ could apply
TBAA to disambiguate the two DRs.
Richard.
next prev parent reply other threads:[~2014-02-03 10:36 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-31 15:24 Bingfeng Mei
2014-01-31 15:27 ` Richard Biener
2014-01-31 17:01 ` Bingfeng Mei
2014-01-31 17:18 ` Bingfeng Mei
2014-01-31 21:32 ` Richard Biener
2014-02-03 9:51 ` Bingfeng Mei
2014-02-03 9:59 ` Jakub Jelinek
2014-02-03 10:14 ` Florian Weimer
2014-02-03 10:19 ` Richard Biener
2014-02-03 11:49 ` Bingfeng Mei
2014-02-03 13:17 ` Richard Biener
2014-02-03 14:43 ` Bingfeng Mei
2014-02-03 14:45 ` Richard Biener
2014-02-03 10:15 ` Richard Biener
2014-02-03 10:36 ` Richard Biener [this message]
2014-02-03 11:58 ` Bingfeng Mei
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