From: Jeff King <peff@peff•net>
To: "Tom G. Christensen" <tgc@statsbiblioteket•dk>
Cc: git@vger•kernel.org
Subject: Re: [PATCH] ewah: fix building with gcc < 3.4.0
Date: Tue, 3 Feb 2015 11:35:45 -0500 [thread overview]
Message-ID: <20150203163545.GB9325@peff.net> (raw)
In-Reply-To: <1422959227-3046-1-git-send-email-tgc@statsbiblioteket.dk>
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.
-Peff
next prev parent reply other threads:[~2015-02-03 16:35 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 [this message]
2015-02-03 21:48 ` Junio C Hamano
2015-02-04 8:23 ` [PATCH v2] " Tom G. Christensen
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