volatile

[Wayne A. Christopher]

In article <11783 at mimsy.UUCP>, chris at mimsy.UUCP (Chris Torek) writes:
] This last point---that C without `volatile' has been used for systems
] work---seems to have been ignored by those who claim that volatile is
] necessary.  (Note that I claim only that it is unnecessary, not that it
] is bad.)

It's unnecessary only if you don't want to optimize the code.  The reason
we've gotten by without it is that we haven't had good compilers.

] Let us try an experiment:
] 
] 	f() {
] 		register int i, *ip;
] 		i = *ip;
] 		i = *ip;
] 	}
] 
] produces
] 
] 	movl	(r10),r11	# i = *ip
] 	movl	(r10),r11	# i = *ip
] 
] That sure looks like the code I would expect from
] 
] 	volatile int *ip;

Only because you're using a bad compiler.  I'll bet gcc would give you the
results you expect.  I don't think it makes any sense to declare an
automatic variable volatile anyway.

	Wayne