C and real hardware

[utzoo!henry]

The old BLISS-11 compiler had an elaborate set of constructs for telling
the compiler what could and could not be safely assumed for purposes of
optimization.  For example, I think there was a way you could convince
it not to optimize a wait-on-device-register-bit loop into one register
access and an infinite loop.  It's rather unfortunate that C compilers
generally have not attempted enough optimization to run into these
problems.  Just how one solves them cleanly in C is not obvious.

					Henry Spencer
					U of Toronto