From: Florian Weimer <fw@deneb.enyo.de>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: "H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org>,
Noah Goldstein <goldstein.w.n@gmail.com>,
GCC Development <gcc@gcc.gnu.org>,
Arjan van de Ven <arjan@linux.intel.com>
Subject: Re: [PATCH] x86-64: Optimize memset for zeroing
Date: Fri, 31 Dec 2021 22:02:45 +0100 [thread overview]
Message-ID: <878rw0fpxm.fsf@mid.deneb.enyo.de> (raw)
In-Reply-To: <CAMe9rOoY+=HqgDWAn7QZFTeLQZjJnr4AAFmmZ+zPqt+Hdj7MwQ@mail.gmail.com> (H. J. Lu's message of "Fri, 31 Dec 2021 12:52:52 -0800")
* H. J. Lu:
> On Fri, Dec 31, 2021 at 12:43 PM Florian Weimer <fw@deneb.enyo.de> wrote:
>>
>> * H. J. Lu via Libc-alpha:
>>
>> > bzero is an alias of SSE2 memset in glibc. Should we add __memsetzero
>> > like __memcmpeq? It should be almost free in glibc. GCC can use
>> > __memsetzero if it is available.
>>
>> bzero does not have the interface ambiguity that bcmp has. So the
>> only reason for not using it would be namespace cleanliness.
>
> bzero isn't a standard C function and it isn't optimized like memset
> in glibc.
GCC already uses non-standard functions whose names are not
implementation-defined for optimization purposes if a suitable
prototype is available. stpcpy is an example, for:
strcpy (a, b);
return a + strlen (a);
next prev parent reply other threads:[~2021-12-31 21:02 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20211231182010.107040-1-hjl.tools@gmail.com>
[not found] ` <CAFUsyfJ5wHJHkfcL84j+GLCX-Dba4qVt_RuCpu=aLy7-_YbHLA@mail.gmail.com>
2021-12-31 20:35 ` H.J. Lu
2021-12-31 20:43 ` Florian Weimer
2021-12-31 20:52 ` H.J. Lu
2021-12-31 21:02 ` Florian Weimer [this message]
2021-12-31 21:15 ` Noah Goldstein
2021-12-31 22:05 ` Florian Weimer
2021-12-31 22:14 ` Noah Goldstein
2021-12-31 22:19 ` Noah Goldstein
2021-12-31 22:21 ` H.J. Lu
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