From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: "Tom G. Christensen" <tgc@statsbiblioteket.dk>, git@vger.kernel.org
Subject: Re: [PATCH] ewah: fix building with gcc < 3.4.0
Date: Tue, 03 Feb 2015 13:48:18 -0800 [thread overview]
Message-ID: <xmqqlhkepsyl.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <20150203163545.GB9325@peff.net> (Jeff King's message of "Tue, 3 Feb 2015 11:35:45 -0500")
Jeff King <peff@peff.net> writes:
> On Tue, Feb 03, 2015 at 11:27:07AM +0100, Tom G. Christensen wrote:
>
>> The __builtin_ctzll function was added in gcc 3.4.0.
>> This extends the check for gcc so that use of __builtin_ctzll is only
>> enabled if gcc >= 3.4.0.
>> ---
>>
>> I noticed this on RHEL3 during 2.0.0rc phase but I see that the same
>> issue was noticed on Debian Sarge:
>> http://article.gmane.org/gmane.comp.version-control.git/255190
>> RHEL3 ships with gcc 3.2.3.
>>
>> With this patch git can build on RHEL3 provided cURL support is disabled.
>
> Thanks. I built with some older gcc's at the time this was developed,
> but I don't think I went past what was in Debian stable, which was
> probably 4.something.
>
>> -#ifdef __GNUC__
>> +/* __builtin_ctzll was not available until 3.4.0 */
>> +#if defined(__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR > 3))
>> #define ewah_bit_ctz64(x) __builtin_ctzll(x)
>> #else
>> static inline int ewah_bit_ctz64(uint64_t x)
>
> We could turn this into a HAS_CTZLL Makefile knob (and auto-set it as
> above), but I don't think it is worth it. I don't expect anybody to need
> to tweak it. I double-checked that clang sets the value of __GNUC__
> appropriately.
OK. I would imagine that this would go on top of jk/pack-bitmap,
which we could be merged down to 2.0.x maintenance track if we
wanted to.
Tom, can you make it a habit to sign-off your patch?
next prev parent reply other threads:[~2015-02-03 21:48 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-03 10:27 [PATCH] ewah: fix building with gcc < 3.4.0 Tom G. Christensen
2015-02-03 16:35 ` Jeff King
2015-02-03 21:48 ` Junio C Hamano [this message]
2015-02-04 8:23 ` [PATCH v2] " Tom G. Christensen
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