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From: aglew@urbsdc.Urbana.Gould.COM
Newsgroups: comp.lang.c
Subject: Re: Re: volatile: is NOT a frill, i
Message-ID: <28700028@urbsdc>
Date: 14 Apr 88 15:33:00 GMT
References: <3950002@hplvly.HP.COM>
Lines: 25
Nf-ID: #R:hplvly.HP.COM:3950002:urbsdc:28700028:000:880
Nf-From: urbsdc.Urbana.Gould.COM!aglew    Apr 14 09:33:00 1988


>>      extern volatile int user_interrupt;
>>      while (!user_interrupt)
>> 	 sleep(1);
>> 
>> Carrick Talmadge			 clt@newton.physics.purdue.edu
>
>Please do not misunderstand me, I would like to see "volatile"
>added -- but why would it be required above? If "user_interrupt"
>is an external variable, then the compiler is not free to assume
>that it will not change across a function call. Since you call
>sleep() in the loop, the compiler is not free to use the cached value
>of user_interrupt from the previous iteration.
>
>Greg LImes [limes@sun.com]

I have some hope of seeing decent cross-procedural and global analysis
in production C compilers in my lifetime ;-}. In which case, the
compiler may be able to prove that user_interrupt is not modified
by any function called...

So, what do you want: "synchronous volatile" and "asynchronous
volatile"?

aglew@gould.com