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From: Mikko Levanto <mikko.levanto@iki.fi>
Subject: Re: Handling Addressing Errors
Date: 1999/03/19
Message-ID: <36F21863.7D71@iki.fi>#1/1
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References: <1999Mar3.212443.1898@nosc.mil> <7bm0v3$933$1@nnrp1.dejanews.com>
 <1999Mar18.005620.19189@nosc.mil> <36F17DAC.E80F01DD@averstar.com>
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Organization: Technical Research Centre of Finland
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Date: 1999-03-19T00:00:00+00:00
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Tucker Taft wrote:

> This is made explicit in RM95 C.6(20) and 1.1.3(13), which indicates
> that the "external effect" of a program includes *each*
> read and update of a volatile or atomic object.
> It is illegal to optimize away an external effect (RM95 1.1.3(15)).

Can optimization affect the number of accesses ?
E.g., if A is volatile, does

   A := A + A;

always cause two reads and one write?

-- 
Mikko J. Levanto
mailto:mikko.levanto@vtt.fi