linux-kernel - Re: [PATCH 0/2] __builtin

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Message-ID: <4AA89FDA.3090105@kernel.org>
Date:	Wed, 09 Sep 2009 23:42:34 -0700
From:	"H. Peter Anvin" <hpa@...nel.org>
To:	Américo Wang <xiyou.wangcong@...il.com>
CC:	Roland McGrath <roland@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jakub Jelinek <jakub@...hat.com>, linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH 0/2] __builtin_unreachable

On 09/09/2009 09:42 PM, Américo Wang wrote:
> 
> Just curious, what different asm code will gcc generate for this? Comparing it
> to for(;;) ? I am sorry that I don't have gcc 4.5 on hand.
> 

It generates nothing.  It is you as the programmer guaranteeing that we
will never get there, and as such gcc will generate no code at all.

	-hpa
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