# [PATCH] ewah: fix building with gcc < 3.4.0 4 messages from 2015-02-03 to 2015-02-04. Participants: Tom G. Christensen, Jeff King, Junio C Hamano. Thread: https://gitlist.dev/t/38492 ## Tom G. Christensen, 2015-02-03 10:27 Subject: [PATCH] ewah: fix building with gcc < 3.4.0 Message-ID: <1422959227-3046-1-git-send-email-tgc@statsbiblioteket.dk> URL: https://gitlist.dev/e/1422959227-3046-1-git-send-email-tgc%40statsbiblioteket.dk ``` 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. ewah/ewok.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/ewah/ewok.h b/ewah/ewok.h index f6ad190..13c6e20 100644 --- a/ewah/ewok.h +++ b/ewah/ewok.h @@ -47,7 +47,8 @@ static inline uint32_t ewah_bit_popcount64(uint64_t x) return (x * 0x0101010101010101ULL) >> 56; } -#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) -- 2.2.2 ``` ## Jeff King, 2015-02-03 16:35 Subject: Re: [PATCH] ewah: fix building with gcc < 3.4.0 Message-ID: <20150203163545.GB9325@peff.net> URL: https://gitlist.dev/e/20150203163545.GB9325%40peff.net 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 ``` ## Junio C Hamano, 2015-02-03 21:48 Subject: Re: [PATCH] ewah: fix building with gcc < 3.4.0 Message-ID: URL: https://gitlist.dev/e/xmqqlhkepsyl.fsf%40gitster.dls.corp.google.com In-Reply-To: <20150203163545.GB9325@peff.net> ``` Jeff King 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? ``` ## Tom G. Christensen, 2015-02-04 08:23 Subject: [PATCH v2] ewah: fix building with gcc < 3.4.0 Message-ID: <1423038196-804-1-git-send-email-tgc@statsbiblioteket.dk> URL: https://gitlist.dev/e/1423038196-804-1-git-send-email-tgc%40statsbiblioteket.dk In-Reply-To: ``` 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. Signed-off-by: Tom G. Christensen --- v2: Add S-o-b v1: 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. ewah/ewok.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/ewah/ewok.h b/ewah/ewok.h index f6ad190..13c6e20 100644 --- a/ewah/ewok.h +++ b/ewah/ewok.h @@ -47,7 +47,8 @@ static inline uint32_t ewah_bit_popcount64(uint64_t x) return (x * 0x0101010101010101ULL) >> 56; } -#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) -- 2.2.2 ```