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Date:   Tue, 3 Sep 2019 22:11:21 +0200
From:   Gabriel Paubert <paubert@iram.es>
To:     Segher Boessenkool <segher@kernel.crashing.org>
Cc:     Christophe Leroy <christophe.leroy@c-s.fr>,
        Alastair D'Silva <alastair@au1.ibm.com>,
        David Hildenbrand <david@redhat.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, Nicholas Piggin <npiggin@gmail.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Paul Mackerras <paulus@samba.org>, alastair@d-silva.org,
        Qian Cai <cai@lca.pw>, Thomas Gleixner <tglx@linutronix.de>,
        linuxppc-dev@lists.ozlabs.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Allison Randal <allison@lohutok.net>
Subject: Re: [PATCH v2 3/6] powerpc: Convert flush_icache_range & friends to C
Message-ID: <20190903201121.GD3547@lt-gp.iram.es>
References: <20190903052407.16638-1-alastair@au1.ibm.com>
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 <20190903130430.GC31406@gate.crashing.org>
 <d268ee78-607e-5eb3-ed89-d5c07f672046@c-s.fr>
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On Tue, Sep 03, 2019 at 01:31:57PM -0500, Segher Boessenkool wrote:
> On Tue, Sep 03, 2019 at 07:05:19PM +0200, Christophe Leroy wrote:
> > Le 03/09/2019 ? 18:04, Segher Boessenkool a ?crit?:
> > >(Why are they separate though?  It could just be one loop var).
> > 
> > Yes it could just be a single loop var, but in that case it would have 
> > to be reset at the start of the second loop, which means we would have 
> > to pass 'addr' for resetting the loop anyway,
> 
> Right, I noticed that after hitting send, as usual.
> 
> > so I opted to do it 
> > outside the inline asm by using to separate loop vars set to their 
> > starting value outside the inline asm.
> 
> The thing is, the way it is written now, it will get separate registers
> for each loop (with proper earlyclobbers added).  Not that that really
> matters of course, it just feels wrong :-)

After "mtmsr %3", it is always possible to copy %0 to %3 and use it as
an address register for the second loop. One register less to allocate
for the compiler. Constraints of course have to be adjusted.

	Gabriel
> 
> 
> Segher