Re: [9fans] how to avoid a memset() optimization

[William Josephson <spmmenotjkw@eecs.harvard.edu>]

On Fri, Nov 15, 2002 at 10:50:38AM +0000, Douglas A. Gwyn wrote:
> presotto@plan9.bell-labs.com wrote:
> > The idea that compiler optimization is a knob that you turn
> > till some assumption you made becomes incorrect is scarey to me.
>
> A major purpose of the language standard is to define the
> "treaty point": what a careful programmer has a right to expect
> from the implementation and what latitude the implementation is
> allowed.  The problem with assumptions is that there is no
> standard for them.

While this is a fine sentiment, it is, in practice, not so easily
applied by the programmer.  In general, it is easier for run of
the mill applications and much harder for operating systems.  Can
you name any major operating system written in C that actually
compiles reliably with more than one compiler?  How many even work
with different major releases of the compiler?  Some of this is
probably due to sloppiness, but I don't think it is reasonable to
claim that it is only due to sloppiness.  The fact of the matter
seems to be that in the real world the standard, although important,
isn't as useful as you're claiming.