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 for <linuxppc-dev@ozlabs.org>; Sat,  9 Jun 2012 19:39:53 +1000 (EST)
From: Andreas Schwab <schwab@linux-m68k.org>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH 10/15] powerpc: fixes for instructions not using correct
 register naming
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Date: Sat, 09 Jun 2012 11:39:43 +0200
In-Reply-To: <1339226228.24838.74.camel@pasglop> (Benjamin Herrenschmidt's
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Cc: Michael Neuling <mikey@neuling.org>,
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Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:

> On Sat, 2012-06-09 at 08:53 +0200, Andreas Schwab wrote:
>> 
>> > The macro system we use cannot do that (it will prefix with REG_),
>> since
>> > both arguments are registers we must use R0 in this case.
>> 
>> So define a ___PPC_RA0 macro that doesn't do that.
>
> But then we lose the checking for other instructions :-)

??? There is no loss of checking for instructions that do not use
___PPC_RA0.

> Unless we start being nasty and defining a different macro form for RA
> which can be 0...

That's what ___PPC_RA0 is all about.

> I'd rather not go there unless we absolutely have to...

Having to use R0 for an insn that does *not* use r0 is clearly a step
backwards.

> What would be nice also would be if we had a gas option to enforce the
> use of % for register names.

If gas is ever changed that way you have to be explict about 0 vs. %r0
anyway.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."