From: Jakub Jelinek <jakub@redhat.com>
To: "Martin Liška" <mliska@suse.cz>
Cc: "H.J. Lu" <hjl.tools@gmail.com>,
GCC Patches <gcc-patches@gcc.gnu.org>,
Marc Glisse <marc.glisse@inria.fr>
Subject: Re: [PATCH] Prefer mempcpy to memcpy on x86_64 target (PR middle-end/81657).
Date: Wed, 14 Mar 2018 13:43:00 -0000 [thread overview]
Message-ID: <20180314131013.GI8577@tucnak> (raw)
In-Reply-To: <79bacb3f-0665-bf77-b53e-08c3636189f1@suse.cz>
On Wed, Mar 14, 2018 at 02:08:07PM +0100, Martin Liška wrote:
> > diff --git a/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy.c
> > b/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy.c
> > index d82e2232d7b..91e1c87f83f 100644
> > --- a/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy.c
> > +++ b/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy.c
> > @@ -62,7 +62,7 @@ main_test (void)
> > mempcpy (p + 5, s3, 1);
> > if (memcmp (p, "ABCDEFg", 8))
> > abort ();
> > - mempcpy (p + 6, s1 + 1, l1);
> > + memcpy (p + 6, s1 + 1, l1);
> > if (memcmp (p, "ABCDEF2", 8))
> > abort ();
> > }
> >
> > This is a mempcpy test. Why is mempcpy changed to memcpy?
> >
>
> Because this mempcpy is not optimized out to memcpy and it then aborts.
Why it isn't optimized to memcpy? If the lhs is unused, it always should be
folded to memcpy, regardless of whether mempcpy is fast or not (I assume no
target has slow memcpy and fast mempcpy).
Jakub
next prev parent reply other threads:[~2018-03-14 13:10 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-12 8:57 Martin Liška
2018-03-12 9:40 ` Marc Glisse
2018-03-13 8:25 ` Martin Liška
2018-03-13 8:35 ` Jakub Jelinek
2018-03-13 9:22 ` Richard Biener
2018-03-13 15:19 ` Martin Liška
2018-03-13 20:35 ` Jakub Jelinek
2018-03-14 12:57 ` Martin Liška
2018-03-14 13:08 ` H.J. Lu
2018-03-14 13:10 ` Martin Liška
2018-03-14 13:43 ` Jakub Jelinek [this message]
2018-03-14 13:08 ` Jakub Jelinek
2018-03-14 14:04 ` Martin Liška
2018-03-18 22:18 ` Martin Liška
2018-03-21 10:37 ` Jakub Jelinek
2018-03-28 14:29 ` Martin Liška
2018-03-28 14:35 ` Jakub Jelinek
2018-03-28 17:59 ` Martin Liška
2018-03-28 18:35 ` Jakub Jelinek
2018-03-29 12:14 ` Martin Liška
2018-03-29 12:31 ` H.J. Lu
2018-03-29 12:43 ` Jakub Jelinek
2018-03-29 12:35 ` Martin Liška
2018-04-04 10:13 ` Martin Liška
2018-04-09 12:31 ` Martin Liška
2018-04-10 10:35 ` Jakub Jelinek
2018-04-10 12:28 ` Martin Liška
2018-04-12 13:22 ` Martin Liška
2018-04-12 13:42 ` Jan Hubicka
2018-04-12 13:52 ` Richard Biener
2018-04-12 14:35 ` Jakub Jelinek
2018-04-12 14:19 ` Richard Biener
2018-04-12 14:35 ` Jakub Jelinek
2018-04-12 15:17 ` Richard Biener
2018-04-12 17:35 ` Jakub Jelinek
2018-04-12 16:03 ` Richard Biener
2018-07-05 19:34 ` Jeff Law
2018-03-12 10:08 ` Richard Biener
2018-03-12 13:35 ` Jakub Jelinek
2018-04-12 15:53 Wilco Dijkstra
2018-04-12 16:11 ` H.J. Lu
2018-04-12 16:35 ` Jakub Jelinek
2018-04-12 16:30 ` Wilco Dijkstra
2018-04-12 17:35 ` Jakub Jelinek
2018-04-12 17:29 ` Wilco Dijkstra
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