From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 31 Oct 2011 20:28:22 GMT
Subject: Re: jc/lookup-object-hash from pu crashes on ARM
Message-ID: <7vhb2oq521.fsf@alter.siamese.dyndns.org>
In-Reply-To: <20111031125648.GA1757@elie.hsd1.il.comcast.net>

Jonathan Nieder <jrnieder@gmail.com> writes:

> Even better could be to start aligning the hashes we pass around,
> using something like this:
>
> 	union object_hash {
> 		unsigned char sha1[20];
> 		uint32_t chunk[5];
> 	};
>
> which could speed up functions like hashcpy(), hashcmp(), and
> hasheq().  But it's probably not worth the fuss.

The "flag" field in struct ref_list should be moved down to assure
alignment.

        struct ref_list {
                struct ref_list *next;
                unsigned char flag; /* ISSYMREF? ISPACKED? */
                unsigned char sha1[20];
                unsigned char peeled[20];
                char name[FLEX_ARRAY];
        };

I am very tempted to take that "union" approach (modulo that I would call
that an "object_name") in the longer run, though.