From: Junio C Hamano <gitster@pobox.com>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: git@vger.kernel.org, Jeff King <peff@peff.net>,
Michael Kebe <michael.kebe@gmail.com>,
"Liam R . Howlett" <Liam.Howlett@Oracle.com>,
Adam Dinwoodie <adam@dinwoodie.org>,
Stefan Beller <sbeller@google.com>
Subject: Re: [PATCH 1/3] sha1dc: update from my PR #36
Date: Tue, 27 Jun 2017 08:22:15 -0700 [thread overview]
Message-ID: <xmqqmv8t317c.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <20170627121718.12078-2-avarab@gmail.com> ("Ævar Arnfjörð Bjarmason"'s message of "Tue, 27 Jun 2017 12:17:16 +0000")
Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
> Update sha1dc from my PR #36[1] which'll hopefully be integrated by
> upstream soon.
Please be careful about the title of the patch. "log --oneline"
does not even let you tell your readers who calls this as "my"
change, and readers would be clueless what PR #36 is. Something
like
sha1dc: correct endian detection for Solaris
may give us more relevant information in the oneline output.
> @@ -23,6 +23,13 @@
> #include "sha1.h"
> #include "ubc_check.h"
>
> +#if (defined(__amd64__) || defined(__amd64) || defined(__x86_64__) || defined(__x86_64) || \
> + defined(i386) || defined(__i386) || defined(__i386__) || defined(__i486__) || \
> + defined(__i586__) || defined(__i686__) || defined(_M_IX86) || defined(__X86__) || \
> + defined(_X86_) || defined(__THW_INTEL__) || defined(__I86__) || defined(__INTEL__) || \
> + defined(__386) || defined(_M_X64) || defined(_M_AMD64))
> +#define SHA1DC_ON_INTEL_LIKE_PROCESSOR
> +#endif
It is good that you made this orthogonal to the rest.
> +#else /* Not under GCC-alike */
>
> +#if defined(__BYTE_ORDER) && defined(__BIG_ENDIAN)
> +/*
> + * Should detect Big Endian under glibc.git since 14245eb70e ("entered
> + * into RCS", 1992-11-25). Defined in <endian.h> which will have been
> + * brought in by standard headers. See glibc.git and
> + * https://sourceforge.net/p/predef/wiki/Endianness/
> + */
> +#if __BYTE_ORDER == __BIG_ENDIAN
> #define SHA1DC_BIGENDIAN
> #endif
Note that this part of the file considers it a valid way for a
platform to define a constant BIG_ENDIAN that can be compared to
BYTE_ORDER to determine the endianness, implying that such a scheme
would also define LITTLE_ENDIAN and a port of such a platform to a
little endian box will still _define_ the constant BIG_ENDIAN; it
aill have BYTE_ORDER defined to the same value as LITTLE_ENDIAN,
though.
> +#if (defined(__ARMEB__) || defined(__THUMBEB__) || defined(__AARCH64EB__) || \
> defined(__MIPSEB__) || defined(__MIPSEB) || defined(_MIPSEB) || \
> defined(__sparc))
> +/*
> + * Should define Big Endian for a whitelist of known processors. See
> + * https://sourceforge.net/p/predef/wiki/Endianness/ and
> + * http://www.oracle.com/technetwork/server-storage/solaris/portingtosolaris-138514.html
> + */
> #define SHA1DC_BIGENDIAN
These look sensible.
> +#else /* Not under GCC-alike or glibc or <processor whitelist> */
> +
> +#if defined(SHA1DC_ON_INTEL_LIKE_PROCESSOR)
> +/*
> + * As a last resort before we fall back on _BIG_ENDIAN or whatever
> + * else we're not 100% sure about below, we blacklist specific
> + * processors here. We could add more, see
> + * e.g. https://wiki.debian.org/ArchitectureSpecificsMemo
> + */
> +#else /* Not under GCC-alike or glibc or <processor whitelist> or <processor blacklist> */
> +
> +#ifdef _BIG_ENDIAN
> +/*
> + * Solaris / illumos defines either _LITTLE_ENDIAN or _BIG_ENDIAN in
> + * <sys/isa_defs.h>.
> + */
> +#define SHA1DC_BIGENDIAN
This makes readers of this patch wonder why we assume platforms
won't define _LITTLE_ENDIAN and _BIG_ENDIAN at the same time, just
like we saw in the section with __BIG_ENDIAN above.
Thanks, but this is starting to feel like watching a whack-a-mole
played while blindfolded. At some point, somebody upstream should
declare that enough is enough and introduce the "SHA1DC_FORCE_ENDIAN"
macro.
next prev parent reply other threads:[~2017-06-27 15:22 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-26 7:32 Compile Error v2.13.2 on Solaris SPARC Michael Kebe
[not found] ` <87lgofcf7r.fsf@gmail.com>
2017-06-26 12:36 ` Michael Kebe
2017-06-26 12:47 ` Ævar Arnfjörð Bjarmason
2017-06-26 14:00 ` Michael Kebe
2017-06-26 18:31 ` Ævar Arnfjörð Bjarmason
2017-06-26 18:29 ` Liam R. Howlett
[not found] ` <87fuem7aw2.fsf@gmail.com>
2017-06-27 5:41 ` Michael Kebe
2017-06-27 6:28 ` Michael Kebe
2017-06-27 16:28 ` Liam R. Howlett
2017-06-27 17:38 ` Junio C Hamano
2017-06-27 18:29 ` Liam R. Howlett
2017-06-27 18:55 ` Ævar Arnfjörð Bjarmason
2017-06-27 17:59 ` Ævar Arnfjörð Bjarmason
2017-06-27 12:17 ` [PATCH 0/3] update sha1dc from PR #36 Ævar Arnfjörð Bjarmason
2017-06-27 18:37 ` Stefan Beller
2017-06-27 20:33 ` [PATCH v2 " Ævar Arnfjörð Bjarmason
2017-06-27 21:37 ` Junio C Hamano
2017-06-27 21:38 ` Junio C Hamano
2017-06-27 22:24 ` Ævar Arnfjörð Bjarmason
2017-06-28 21:42 ` Ævar Arnfjörð Bjarmason
2017-06-28 22:02 ` Junio C Hamano
2017-06-27 20:33 ` [PATCH v2 1/3] sha1dc: correct endian detection for Solaris (and others?) Ævar Arnfjörð Bjarmason
2017-06-27 20:33 ` [PATCH v2 2/3] sha1dc: optionally use sha1collisiondetection as a submodule Ævar Arnfjörð Bjarmason
2017-06-27 20:33 ` [PATCH v2 3/3] sha1collisiondetection: automatically enable when submodule is populated Ævar Arnfjörð Bjarmason
2017-07-01 22:05 ` [PATCH v3 0/3] Update sha1dc from upstream Ævar Arnfjörð Bjarmason
2017-07-01 22:05 ` [PATCH v3 1/3] sha1dc: update " Ævar Arnfjörð Bjarmason
2017-07-01 22:05 ` [PATCH v3 2/3] sha1dc: optionally use sha1collisiondetection as a submodule Ævar Arnfjörð Bjarmason
2017-07-03 17:11 ` Junio C Hamano
2017-07-03 20:29 ` Ævar Arnfjörð Bjarmason
2017-07-04 17:26 ` Junio C Hamano
2017-07-04 22:50 ` Ævar Arnfjörð Bjarmason
2017-07-05 0:36 ` Stefan Beller
2017-07-05 1:56 ` Junio C Hamano
2017-07-05 17:46 ` Stefan Beller
2017-07-05 18:03 ` Ævar Arnfjörð Bjarmason
2017-07-01 22:05 ` [PATCH v3 3/3] sha1collisiondetection: automatically enable when submodule is populated Ævar Arnfjörð Bjarmason
2017-06-27 12:17 ` [PATCH 1/3] sha1dc: update from my PR #36 Ævar Arnfjörð Bjarmason
2017-06-27 15:22 ` Junio C Hamano [this message]
2017-06-27 15:53 ` Junio C Hamano
2017-06-27 18:07 ` Ævar Arnfjörð Bjarmason
2017-06-27 15:55 ` Junio C Hamano
2017-06-27 16:31 ` Liam R. Howlett
2017-06-27 18:11 ` Ævar Arnfjörð Bjarmason
2017-06-27 19:10 ` Junio C Hamano
2017-06-27 19:33 ` Junio C Hamano
2017-06-27 19:35 ` Ævar Arnfjörð Bjarmason
2017-06-27 19:38 ` Junio C Hamano
2017-06-27 19:38 ` Liam R. Howlett
2017-06-27 19:48 ` Junio C Hamano
2017-06-27 18:06 ` Ævar Arnfjörð Bjarmason
2017-06-27 18:12 ` Junio C Hamano
2017-06-27 18:19 ` Ævar Arnfjörð Bjarmason
2017-06-27 20:17 ` Junio C Hamano
2017-06-27 18:23 ` Junio C Hamano
2017-06-27 18:52 ` Ævar Arnfjörð Bjarmason
2017-06-27 12:17 ` [PATCH 2/3] sha1dc: optionally use sha1collisiondetection as a submodule Ævar Arnfjörð Bjarmason
2017-06-27 18:46 ` Stefan Beller
2017-06-27 18:56 ` Ævar Arnfjörð Bjarmason
2017-06-27 12:17 ` [PATCH 3/3] sha1collisiondetection: automatically enable when submodule is populated Ævar Arnfjörð Bjarmason
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