From: Peter Zijlstra <peterz@infradead.org>
To: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, akpm@linux-foundation.org,
mingo@kernel.org, will.deacon@arm.com,
paulmck@linux.vnet.ibm.com,
Haavard Skinnemoen <hskinnemoen@gmail.com>
Subject: Re: [PATCH 06/20] arch,avr32: Fold atomic_ops
Date: Tue, 13 May 2014 22:50:45 +0200 [thread overview]
Message-ID: <20140513205045.GK2485@laptop.programming.kicks-ass.net> (raw)
In-Reply-To: <20140513204032.GB14023@samfundet.no>
On Tue, May 13, 2014 at 10:40:32PM +0200, Hans-Christian Egtvedt wrote:
> Probably found the reason why we want to use sub with the signed 21-bit
> limit, it uses one less register than the add instruction that can add up to
> 32-bit values.
>
> Both instructions are 32-bit, to use a 16-bit instruction the immediate is
> very small; 4 bit.
>
> sub 32-bit, type IV, takes a register and subtracts a 21-bit immediate.
> add 32-bit, type II, adds two register values together.
>
> So by simplifying you loose this optimization.
OK, let me try if I can come up with anything sane for this.
Re, adding atomic_{or,and,xor}() those should all use the same bits as
add, right, except for the special case using sub.
next prev parent reply other threads:[~2014-05-13 20:51 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-08 13:58 [PATCH 00/20] arch atomic 'cleanup' Peter Zijlstra
2014-05-08 13:58 ` [PATCH 01/20] x86: Kill atomic_or_long() Peter Zijlstra
2014-08-14 17:18 ` [tip:locking/arch] locking,x86: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 02/20] arch,alpha: Fold atomic_ops Peter Zijlstra
2014-08-14 17:18 ` [tip:locking/arch] locking,arch,alpha: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 03/20] arch,arc: " Peter Zijlstra
2014-05-09 9:34 ` Vineet Gupta
2014-05-09 10:22 ` Peter Zijlstra
2014-08-14 17:19 ` [tip:locking/arch] locking,arch,arc: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 04/20] arch,arm: " Peter Zijlstra
2014-05-08 18:31 ` Will Deacon
2014-08-14 17:19 ` [tip:locking/arch] locking,arch,arm: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 05/20] arch,arm64: " Peter Zijlstra
2014-05-08 18:31 ` Will Deacon
2014-08-14 17:19 ` [tip:locking/arch] locking,arch,arm64: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 06/20] arch,avr32: " Peter Zijlstra
2014-05-09 18:32 ` Hans-Christian Egtvedt
2014-05-09 20:43 ` Peter Zijlstra
2014-05-09 20:51 ` Peter Zijlstra
2014-05-09 21:17 ` Peter Zijlstra
2014-05-13 20:40 ` Hans-Christian Egtvedt
2014-05-13 20:50 ` Peter Zijlstra [this message]
2014-05-14 7:43 ` Hans-Christian Egtvedt
2014-05-31 14:14 ` Peter Zijlstra
2014-06-06 6:25 ` Hans-Christian Egtvedt
2014-08-14 17:19 ` [tip:locking/arch] locking,arch,avr32: " tip-bot for Peter Zijlstra
2014-08-14 19:27 ` Hans-Christian Egtvedt
2014-08-14 19:30 ` Peter Zijlstra
2014-08-14 19:32 ` Hans-Christian Egtvedt
2014-05-08 13:58 ` [PATCH 07/20] arch,cris: " Peter Zijlstra
2014-05-08 15:12 ` Geert Uytterhoeven
2014-05-08 16:06 ` Peter Zijlstra
2014-05-08 17:34 ` David Miller
2014-05-08 18:17 ` Peter Zijlstra
2014-05-08 20:27 ` David Miller
2014-05-09 8:14 ` Jesper Nilsson
2014-08-14 17:19 ` [tip:locking/arch] locking,arch,cris: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 08/20] arch,hexagon: " Peter Zijlstra
2014-05-12 17:28 ` rkuo
2014-08-14 17:20 ` [tip:locking/arch] locking,arch,hexagon: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 09/20] arch,ia64: " Peter Zijlstra
2014-08-14 17:20 ` [tip:locking/arch] locking,arch,ia64: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 10/20] arch,m32r: " Peter Zijlstra
2014-08-14 17:20 ` [tip:locking/arch] locking,arch,m32r: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 11/20] arch,m68k: " Peter Zijlstra
2014-05-09 9:08 ` Geert Uytterhoeven
2014-05-09 9:16 ` Peter Zijlstra
2014-05-09 9:44 ` Geert Uytterhoeven
2014-08-14 17:20 ` [tip:locking/arch] locking,arch,m68k: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 12/20] arch,metag: " Peter Zijlstra
2014-05-13 10:06 ` James Hogan
2014-08-14 17:21 ` [tip:locking/arch] locking,arch,metag: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 13/20] arch,mips: " Peter Zijlstra
2014-08-14 17:21 ` [tip:locking/arch] locking,arch,mips: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 14/20] arch,mn10300: " Peter Zijlstra
2014-08-14 17:21 ` [tip:locking/arch] locking,arch,mn10300: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 15/20] arch,parisc: " Peter Zijlstra
2014-08-14 17:21 ` [tip:locking/arch] locking,arch,parisc: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 16/20] arch,powerpc: " Peter Zijlstra
2014-08-14 17:22 ` [tip:locking/arch] locking,arch,powerpc: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 17/20] arch,sh: " Peter Zijlstra
2014-08-14 17:22 ` [tip:locking/arch] locking,arch,sh: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 18/20] arch,sparc: " Peter Zijlstra
2014-08-14 17:22 ` [tip:locking/arch] locking,arch,sparc: " tip-bot for Peter Zijlstra
2014-05-08 13:58 ` [PATCH 19/20] arch,xtensa: " Peter Zijlstra
2014-08-14 17:22 ` [tip:locking/arch] locking,arch,xtensa: " tip-bot for Peter Zijlstra
2014-05-08 13:59 ` [PATCH 20/20] arch: Rewrite generic atomic support Peter Zijlstra
2014-05-08 15:24 ` Sam Ravnborg
2014-05-08 18:26 ` Peter Zijlstra
2014-08-14 17:23 ` [tip:locking/arch] locking,arch: " tip-bot for Peter Zijlstra
2014-05-20 13:05 ` [PATCH 14/20] arch,mn10300: Fold atomic_ops David Howells
2014-05-20 13:16 ` Peter Zijlstra
2014-09-24 16:54 ` [PATCH 00/20] arch atomic 'cleanup' Will Deacon
2014-09-24 18:06 ` Peter Zijlstra
2014-09-24 18:09 ` Will Deacon
2014-09-25 5:03 ` Ingo Molnar
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