Re: Optimizing and Constraint Checks

[l107353@cliffy.lfwc.lockheed.com (Garlington KE)]

Robert Dewar (dewar@cs.nyu.edu) wrote:
: Wait a moment! In the absence of an numeration rep clause, this whole
: discussion is irrelevant. If you don't have a rep clause, you just use
: Pos and Val to go backwards andd forwards and the whole apparatus of
: the generic is junk!

Yes, I'm assuming it's supposed to support both cases (with and without a
rep clause).

There is one other obscure possibility that can hang this code as well,
even in the absense of a rep spec. A strange compiler could align enum
values in a storage unit differently than for integers. I've never seen
this in practice for enums, although it happens a lot for packed arrays
of BOOLEAN. If the compiler doesn't shift the value on an UNCHECKED_
CONVERSION (which, according to an AI, it's supposed to, although some
don't), then your results are trashed.

--
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Ken Garlington                  GarlingtonKE@lfwc.lockheed.com
F-22 Computer Resources         Lockheed Fort Worth Co.

If LFWC or the F-22 program has any opinions, they aren't telling me.