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Re: Volatile MEMs in statement expressions and functions inlined astrees



On Wed, 26 Dec 2001, Fergus Henderson wrote:
>
> "What constitutes an access to an object that has volatile-qualified type is
> implementation-defined."  That seems pretty clear to me.
>
> An implementation could say that *nothing* constitutes access to an
> object of volatile-qualified type, and could then entirely ignore
> volatile (except in as far as type checking and the effects on
> setjmp()/longjmp() are concerned).

Absolutely. Which is why I sayd it could play towers-of-hanoy if it wanted
to, but I claimed that from a QoI standpoint lcc was completely bogus.

Also, you're ignoring the difference between "undefined" and
"implementation defined". Go read that part of the standard again,

For example: I claim that it's ok to play towers-of-hanoy on "access" to a
volatile object, but because behaviour is _implementation_defined_ rather
than undefined, the compiler should (a) _document_ the choice to do so,
and (b) do so consistently (or document when it doesn't).

In contrast, you seem to think that implementation-defined means that the
compiler can choose to ignore the rules of C, and not just choose "what
constitues an access", but lcc _also_ seems to choose when to do the
access and when _not_ to do the access.

And that is BUGGY.

			Linus


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