From: Peter Zijlstra <peterz@infradead.org>
To: "H. Peter Anvin" <hpa@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andy Lutomirski <luto@amacapital.net>,
Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH 00/10] x86: use gcc 6+ asm flag output feature
Date: Wed, 8 Jun 2016 10:00:29 +0200 [thread overview]
Message-ID: <20160608080029.GP30154@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1465342269-492350-1-git-send-email-hpa@linux.intel.com>
On Tue, Jun 07, 2016 at 04:30:59PM -0700, H. Peter Anvin wrote:
> From: "H. Peter Anvin" <hpa@zytor.com>
>
> gcc 6+ has the ability to let flags (actually, conditions, which are
> specific combinations of flags) to be used directly as asm() outputs.
> The syntax for that is "=@cc<cc>" where <cc> is the same set of
> letters that would be used in a j<cc> or set<cc> instruction
> (e.g. "=@ccz" to test the ZF flag.)
>
> This patchset by itself reduces the size of the x86-64 kernel by
> 0.12%, from a baseline of 4.7-rc2 built with gcc 6.1 (first line is
> with the patchset, the second one is without):
>
> text data bss dec hex filename
>
> 68245656 41004339 20533248 129783243 7bc55cb o.i386-allconfig/vmlinux
> 68355716 41008499 20533248 129897463 7be13f7 o.i386-allconfig/vmlinux
>
> 127384005 129742359 38150144 295276508 11998fdc o.x86_64-allconfig/vmlinux
> 127538765 129742295 38150144 295431204 119bec24 o.x86_64-allconfig/vmlinux
Very nice!
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Do you happen to know if GCC plans to support other architectures for
=@cc ?
next prev parent reply other threads:[~2016-06-08 8:00 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-07 23:30 [PATCH 00/10] x86: use gcc 6+ asm flag output feature H. Peter Anvin
2016-06-07 23:31 ` [PATCH 01/10] x86, bitops: remove use of "sbb" to return CF H. Peter Anvin
2016-06-07 23:39 ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-07 23:31 ` [PATCH 02/10] x86, asm: use bool for bitops and other assembly outputs H. Peter Anvin
2016-06-07 23:40 ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08 7:49 ` [PATCH 02/10] " Peter Zijlstra
2016-06-08 8:28 ` Ingo Molnar
2016-06-08 8:33 ` Ingo Molnar
2016-06-08 8:55 ` H. Peter Anvin
2016-06-08 9:01 ` Ingo Molnar
2016-06-08 9:12 ` H. Peter Anvin
2016-06-08 9:20 ` Ingo Molnar
2016-06-08 9:31 ` H. Peter Anvin
2016-06-08 9:39 ` Peter Zijlstra
2016-06-08 9:43 ` H. Peter Anvin
2016-06-08 9:40 ` H. Peter Anvin
2016-06-08 8:58 ` H. Peter Anvin
2016-06-08 9:06 ` Ingo Molnar
2016-06-07 23:31 ` [PATCH 03/10] x86, asm: change the GEN_*_RMWcc() macros to not quote the condition H. Peter Anvin
2016-06-07 23:40 ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-07 23:31 ` [PATCH 04/10] x86, asm: define CC_SET() and CC_OUT() macros H. Peter Anvin
2016-06-07 23:40 ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08 5:09 ` [PATCH 04/10] " Andy Lutomirski
2016-06-08 19:29 ` H. Peter Anvin
2016-06-08 19:34 ` H. Peter Anvin
2016-06-08 19:35 ` Borislav Petkov
2016-06-07 23:31 ` [PATCH 05/10] x86, asm: change GEN_*_RMWcc() to use CC_SET()/CC_OUT() H. Peter Anvin
2016-06-07 23:41 ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-07 23:31 ` [PATCH 06/10] x86, asm: Use CC_SET()/CC_OUT() in <asm/bitops.h> H. Peter Anvin
2016-06-07 23:41 ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-07 23:31 ` [PATCH 07/10] x86, asm: Use CC_SET()/CC_OUT() in <asm/percpu.h> H. Peter Anvin
2016-06-07 23:42 ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-07 23:31 ` [PATCH 08/10] x86, asm: Use CC_SET()/CC_OUT() in <asm/rwsem.h> H. Peter Anvin
2016-06-07 23:42 ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-07 23:31 ` [PATCH 09/10] x86, asm: Use CC_SET()/CC_OUT() and static_cpu_has() in archrandom.h H. Peter Anvin
2016-06-07 23:42 ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08 5:12 ` [PATCH 09/10] " Andy Lutomirski
2016-06-07 23:31 ` [PATCH 10/10] x86, asm, boot: Use CC_SET()/CC_OUT() in arch/x86/boot/boot.h H. Peter Anvin
2016-06-07 23:43 ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08 8:00 ` Peter Zijlstra [this message]
2016-06-08 8:56 ` [PATCH 00/10] x86: use gcc 6+ asm flag output feature H. Peter Anvin
2016-06-08 8:26 ` Ingo Molnar
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