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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.lang.c
Subject: Re: ANSII C, optimization, and "hardware registers"
Message-ID: <4453@utzoo.UUCP>
Date: Sat, 13-Oct-84 19:27:14 EDT
Article-I.D.: utzoo.4453
Posted: Sat Oct 13 19:27:14 1984
Date-Received: Sat, 13-Oct-84 19:27:14 EDT
References: <1538@wateng.UUCP>
Organization: U of Toronto Zoology
Lines: 13

> [Compiler is optimizing out a wait-for-hardware-done loop.]
> ...
> 1.  Was this legal code generation?
> 2.  Note that this compiler did "simple" optimizations as part of the code
> 	generation. Is this legal?

As to whether it's legal by K&R, the only answer is "mumble".  This
thorny issue was never addressed in the old days.  The draft ANSI standard
has a "volatile" declaration that you can use to tell the compiler "don't
get tricky with this variable, it may change underfoot".
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry