From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christopher Li <sparse@chrisli.org>
Subject: Re: [PATCH v2] implement constant-folding in __builtin_bswap*()
Date: Thu, 24 Nov 2016 08:56:45 +0800
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To: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Johannes Berg <johannes@sipsolutions.net>, Linux-Sparse <linux-sparse@vger.kernel.org>, Nicolai Stange <nicstange@gmail.com>

On Thu, Nov 24, 2016 at 4:48 AM, Luc Van Oostenryck
<luc.vanoostenryck@gmail.com> wrote:
> There is a problem though, with non-constant args.
> Now the predeclarations of the 3 __builtin_bswap16/32/64
> are gone, no more prototype and thus no more typing information.
>
> For example, if you call __builtin_bswap64() with an int argument,
> there is no way for the next steps to know the arg must first
> be 64 bit extended. Same for the result's type.

That is a very good point. Need more work on that.

The currently problem if I include the function prototype, the
function prototype symbol will over shadow the symbol contain
swap_op. We need to make sure the function prototype symbol
is the one loading with correct swap_op.

Ideally, all the "__builtin_xxx" related stuff should be move to a
separate builtin.c. Right now the function prototype is in lib.c
The implementation is sprinkle around symbol.c, evaluation.c
and expand.c.

Re-attach the V2 patch as last email I forget to CC sparse
mailing list. This V2 patch still have the missing prototype problem
you describe here.


Chris