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From: Segher Boessenkool <segher@kernel.crashing.org>
To: Hollis Blanchard <hollis@penguinppc.org>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: [PATCH 5/8] ppc: use correct asm ops
Date: Tue, 27 Sep 2005 20:22:16 +0200	[thread overview]
Message-ID: <622be433ce70c3eb43d3dca513c1462e@kernel.crashing.org> (raw)
In-Reply-To: <96e9df75a769d22905026438cb4c5131@penguinppc.org>

> I don't see where this is explained in the GCC docs,

It is documented in gcc/gcc/config/rs6000/rs6000.c,
function print_operand() ;-)

> but as I understand it those %U %X things are allowing somebody to use 
> the "update" and "index" variants of the instruction.

Indeed.

> Why doesn't this work for you?

The code works fine.  The U and X have no effect at all,
though; they require a memory operand to do anything,
and __do_in_asm() c.q. __do_out_asm() take a register
input.  It would be better if __do_in_asm() would say

	"m" (*(port + ___IO_BASE))

where it now says

	"r" (port + ___IO_BASE)

and keep the %U %X stuff (and similarly for __do_out_asm()
of course).


Segher

      parent reply	other threads:[~2005-10-01 18:48 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-09-24 22:43 [PATCH 5/8] ppc: use correct asm ops Roman Zippel
2005-09-27  0:00 ` Hollis Blanchard
2005-09-27  0:36   ` Roman Zippel
2005-09-27 18:22   ` Segher Boessenkool [this message]

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