Volatile is Necessary

[Walter Bays]

In article <8107 at sol.ARPA> crowl at cs.rochester.edu (Lawrence Crowl) writes:
>The `volatile' type qualifier of ANSI C has recently been criticized as a
>frill.  While this assertion is arguable for uniprocessors, it is not true for
>shared-memory multiprocessors.  [...] If there is no mechanism to
>indicate when a variable referenced by one process may be modified by
>another process, the compiler must assume that all variables may be
>modified at any time.  [...] This limits the optimizing effectiveness
>of compilers substantially. [...]

The 'volatile' keyword would also work for uniprocessor device
drivers.  How about setjmp()?  Or side effects of functions with
"dangerous" pointers?
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