Re: [PATCH 1/3] sha1dc: update from my PR #36

From: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Date: Jun 27, 2017, 18:11 UTC
Message-ID: <87wp7xjo5x.fsf@gmail.com>
In-Reply-To: <xmqqefu52znl.fsf@gitster.mtv.corp.google.com>

On Tue, Jun 27 2017, Junio C. Hamano jotted:

Show 17 quoted lines

> Junio C Hamano <gitster@pobox.com> writes:
>
>>> +#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.
>
> By the way, I wonder why this didn't catch the sparc running
> Solaris.  What does Michael's system use to let the software know
> that it is targetted for a Sparc, if not __sparc?

Because in the current code is, abbreviated:

    #if (defined(_BYTE_ORDER) || defined(__BYTE_ORDER) || defined(__BYTE_ORDER__))
    #if /* byte order is bendian */
    #define SHA1DC_BIGENDIAN
    #endif
    #else
    #if /*some processor tests/* || defined(__sparc))
    #define SHA1DC_BIGENDIAN
    #endif

And since Solaris defines _BYTE_ORDER we never get to checking __sparc, and in fact the "/* byte order is bendian */" test errors out.

This is fixed by my patch, where we first check gcc settings, then glibc, then processors, and finally _BYTE_ORDER (but as discussed that last bit could be adjusted to sun && _BYTE_ORDER, if we can find what "sun" is.