linux-kernel - Re: Why is the kfree() argument const?

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Date:	Fri, 18 Jan 2008 12:31:05 -0700
From:	Zan Lynx <zlynx@....org>
To:	Vadim Lobanov <vlobanov@...akeasy.net>
Cc:	Andy Lutomirski <luto@...ealbox.com>, linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	David Schwartz <davids@...master.com>,
	Johannes Weiner <hannes@...urebad.de>, clameter@....com,
	penberg@...helsinki.fi
Subject: Re: Why is the kfree() argument const?


On Fri, 2008-01-18 at 11:14 -0800, Vadim Lobanov wrote:
[cut]
> Second, even if const did have stronger semantics that forbade the value of x 
> from being modified during execution of foo, the compiler still could not 
> reorder the two function calls, before it cannot assume that the two 
> functions (in their internal implementations) do not touch some other, 
> unknown to this code, global variable.

This is why GCC has the pure and const function attributes.  These
attributes are more powerful than the "const" keyword, and do allow
optimizations with assumptions about global state.
-- 
Zan Lynx <zlynx@....org>

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