linux-kernel - Re: [PATCH] X86-32: Let gcc decide whether to inline memcpy was Re: New x86 warning

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Message-ID: <3605561d0904231422s57bd4cedl722be1dabf27428f@mail.gmail.com>
Date:	Thu, 23 Apr 2009 14:22:02 -0700
From:	Joe Damato <ice799@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Andi Kleen <andi@...stfloor.org>, Ingo Molnar <mingo@...e.hu>,
	Jeff Garzik <jeff@...zik.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, x86@...nel.org
Subject: Re: [PATCH] X86-32: Let gcc decide whether to inline memcpy was Re: 
	New x86 warning

On Wed, Apr 22, 2009 at 6:48 PM, H. Peter Anvin <hpa@...or.com> wrote:
> Joe Damato wrote:
>>
>> I think this patch is great. Perhaps this would be a good time to also
>> clean out memset for x86_32? (If needed, I can start a new email
>> thread with this patch) I've built and booted this on my x86_32
>> hardware.
>>
>
> Under the same conditions, i.e. making sure that with the oldest gcc we
> still care about (3.2) we don't end up uninlining any new cases we
> shouldn't.

Looks like this thread is dead/dying, but figured I should reply with
my test findings. The number of out-of-line calls (as determined by:
make mrproper && make defconfig && make && objdump -d vmlinux | grep
"call.*\<memset" | wc -l))

gcc 4.2.4 - withOUT memset patch: 20
gcc 4.2.4 - with memset patch: 365

gcc 3.4 - withOUT memset patch: 17
gcc 3.4 - with memset patch: 349

I'm guessing this is probably not acceptable, so I won't bother
installing/trying gcc-3.2 unless anyone thinks that a 300+ increase in
out-of-line calls is OK.

Joe
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