To keep this thread going, I had a quick look at the reference
material of the dip and picked some thoughts.
In some languages volatile has a stronger meaning, like
guaranteeing an atomic access. In some languages it may not
guarantee anything.
In this proposal volatile is only for optimization, not for
protection. It does not add any code, it just prevents the
optimizer removing some code.
Read-modify-write and multi-word access are not guaranteed. The
user should be aware of possible failures and for example avoid
longer data types than the word size of the processor.
Volatile is never recommended to use for communicatin between
threads. It has been mentioned to be a reasonably good method to
exchange data with an interrupt program. It is the only
reasonable way to access hardware registers. The only others I
have seen are library functions and inline assembly and they are
not acceptable.
Walter has been against this and now also Martin. I think there
is no use to bring this to the main forum. I understand the point
that it is not very good to have something in the language specs
that can not be guaranteed.
We just need this to access registers. Dmd is more for desktop
and servers. It will never support all the targets gcc can. Could
we make this a gdc extension?
While writing this it just popped to my mind: if volatile is not
good, could we reuse the 'system' word? Then it would be clear
that this is for accessing system resources and not for
application level.
There seems not to be much documentation about system. Tdpl says
it may omit some checks and the website says it is quite the same
than not having any other attributes. So:
What system means in general?
What it currently means in gdc?
Could we use it instead of volatile?
