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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] [PATCH 3/3] tcg: declare internal helpers as const
	and pure
Date: Fri, 5 Mar 2010 11:15:45 +0000
References: <1267739110-26400-1-git-send-email-aurelien@aurel32.net>
	<1267739110-26400-4-git-send-email-aurelien@aurel32.net>
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To: qemu-devel@nongnu.org
Cc: Andrzej Zaborowski <andrew.zaborowski@intel.com>, Aurelien Jarno <aurelien@aurel32.net>

> TCG internal helpers only access to the values passed in arguments, and
> do not modify the CPU internal state. Thus they can be declared as
> const and pure.

I think this needs an explanatory comment. It's not immediately obvious that 
tcg_gen_helperN and tcg_gen_helper{32,64} have significantly different 
semantics.

tcg/README also needs updating, specifically:

"* Helpers:

Using the tcg_gen_helper_x_y it is possible to call any function
taking i32, i64 or pointer types. Before calling an helper, all
globals are stored at their canonical location and it is assumed that
the function can modify them. In the future, function modifiers will
be allowed to tell that the helper does not read or write some globals.
"

Paul