From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: linuxppc-dev@lists.ozlabs.org, Paul Mackerras <paulus@samba.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] powerpc: rewrite LOAD_REG_IMMEDIATE() as an intelligent macro
Date: Wed, 14 Aug 2019 15:10:42 -0500 [thread overview]
Message-ID: <20190814201042.GH31406@gate.crashing.org> (raw)
In-Reply-To: <61d2a0b6f0c89b1ee546851ce9b6bd345e5ec968.1565690241.git.christophe.leroy@c-s.fr>
Hi Christophe,
On Tue, Aug 13, 2019 at 09:59:35AM +0000, Christophe Leroy wrote:
> + rldicr \r, \r, 32, 31
Could you please write this as
sldi \r, \r, 32
? It's much easier to read, imo (it's the exact same instruction).
You can do a lot cheaper sequences if you have a temporary reg, as well
(longest path of 3 insns instead of 5):
lis rt,A
ori rt,B
lis rd,C
ori rd,D
rldimi rd,rt,32,0
to load ABCD.
Segher
WARNING: multiple messages have this Message-ID (diff)
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 1/2] powerpc: rewrite LOAD_REG_IMMEDIATE() as an intelligent macro
Date: Wed, 14 Aug 2019 15:10:42 -0500 [thread overview]
Message-ID: <20190814201042.GH31406@gate.crashing.org> (raw)
In-Reply-To: <61d2a0b6f0c89b1ee546851ce9b6bd345e5ec968.1565690241.git.christophe.leroy@c-s.fr>
Hi Christophe,
On Tue, Aug 13, 2019 at 09:59:35AM +0000, Christophe Leroy wrote:
> + rldicr \r, \r, 32, 31
Could you please write this as
sldi \r, \r, 32
? It's much easier to read, imo (it's the exact same instruction).
You can do a lot cheaper sequences if you have a temporary reg, as well
(longest path of 3 insns instead of 5):
lis rt,A
ori rt,B
lis rd,C
ori rd,D
rldimi rd,rt,32,0
to load ABCD.
Segher
next prev parent reply other threads:[~2019-08-14 20:17 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-13 9:59 [PATCH 1/2] powerpc: rewrite LOAD_REG_IMMEDIATE() as an intelligent macro Christophe Leroy
2019-08-13 9:59 ` Christophe Leroy
2019-08-13 9:59 ` [PATCH 2/2] powerpc/32: replace LOAD_MSR_KERNEL() by LOAD_REG_IMMEDIATE() Christophe Leroy
2019-08-13 9:59 ` Christophe Leroy
2019-08-14 2:08 ` [PATCH 1/2] powerpc: rewrite LOAD_REG_IMMEDIATE() as an intelligent macro Paul Mackerras
2019-08-14 2:08 ` Paul Mackerras
2019-08-14 9:46 ` Christophe Leroy
2019-08-14 9:46 ` Christophe Leroy
2019-08-14 20:10 ` Segher Boessenkool [this message]
2019-08-14 20:10 ` Segher Boessenkool
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