3 Dec
2010
3 Dec
'10
3:10 p.m.
> Whether a programmer or a compiler produce better
code would seem to
> depend on how well one can get the compiler to understand all of the
> details of what one WANTS the code to do, and just how weird THAT might
> be. Some things, such as deliberately wasting time, or polling a memory
> location that is influenced externally, need additional explanation for
> the compiler to understand not to optimize them out.
On Fri, 3 Dec 2010, Guy Sotomayor wrote:
See my previous post. Using the volatile keyword on a
variable requires
the compiler to read/write it as expressed in the program (ie if in a
loop, the compiler can't just read it once and be done). If the
compiler doesn't do that, it's a bug if it in any way claimed be a
standards compliant compiler.
You are absolutely correct.
If there is a VOLATILE keyword, and the compiler ignored it, then that is
certainly a bug. There is certainly no argument about THAT.
But, see MY previous posts.
My ORIGINAL post (the origin of this sub-thread) was that the first
attempt at an optimizing compiler from Microsoft DID NOT HAVE a VOLATILE
keyword.
The second attempt, as would be expected, added the VOLATILE keyword, as
well as a few others to permit over-riding the oprimizations.
"Standards compliant"??
I'm talking about before that, when "standards compliant" was a CLAIM that
it was "K&R".
--
Grumpy Ol' Fred cisin at xenosoft.com