volatile: is NOT a frill, i

[aglew at urbsdc.Urbana.Gould.COM]

>>      extern volatile int user_interrupt;
>>      while (!user_interrupt)
>> 	 sleep(1);
>> 
>> Carrick Talmadge			 clt at 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 at 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 at gould.com