Re: [PATCH 1/2] compat: move unaligned helpers to bswap.h

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Jan 23, 2014, 19:56 UTC
Message-ID: <20140123195643.GV18964@google.com>
In-Reply-To: <20140123194401.GA31412@sigill.intra.peff.net>

Jeff King wrote:

> I think it was a bug waiting to surface if index v4 ever got wide use.

Ah, ok.

In that case I think git-compat-util.h should include something like what block-sha1/sha1.c has:

	#if !defined(__i386__) && !defined(__x86_64__) && \
	    !defined(_M_IX86) && !defined(_M_X64) && \
	    !defined(__ppc__) && !defined(__ppc64__) && \
	    !defined(__powerpc__) && !defined(__powerpc64__) && \
	    !defined(__s390__) && !defined(__s390x__)
	#define NEEDS_ALIGNED_ACCESS
	#endif

Otherwise we are relying on the person building to know their own architecture intimately, which shouldn't be necessary.

Meanwhile, as mentioned in the other message, I suspect the NEEDS_ALIGNED_ACCESS code path is broken for aggressive compilers anyway. Looking more.

Thanks, Jonathan