volatile: a summary

[Steven Ryan]

In article <12020 at mimsy.UUCP> chris at mimsy.UUCP (Chris Torek) writes:
>>>Chris is correct when he says that "a perfect compiler
>>>would not need volatile" but he is not saying that such a
>>>compiler would be reasonable.
>I asserted not that it does exist, nor even that it could exist, but
>only that one `perfect enough' to understand volatility
                        ??????
>                                         in a way that is `good enough'
>(produces decent code even in the presence of its conservative erring)
>*could* *be* *written* at some time in the future.

Either it's perfect or it isn't. (Is `perfect enough' like `barely pregnant?')

If it isn't perfect, and it can't be, then the original argument that volatile
is never necessary is worthless. Obviously one could write a total recursive
predicate that partitions what can be handled by a `perfect enough' compiler
if conservative erring is accepted. What about what cannot be handled? Is it
deemed not worthy of optimisation? Property X (X=volatile or anything else)
cannot be determined for these outcasts. Either they are not optimised or
a `perfect enough' compiler must be given hints (maybe we could create
something like #hint or #pragma or create a new keyword like volatile).

                                            sm ryan

               Arrakis teaches the attitude of the knife: you
               cut that which is incomplete and say it is
               complete, because it ends here.
                              -- Frank Herbet/Dune