Experimental Physics and
Industrial Control System

"Jeff Hill" <[email protected]> · Mon, 4 Dec 2006 12:13:54 -0700

> 2) The signed/unsigned unions in osiWireFormat.h to avoid overzealous
> aliasing optimizations are not necessary since the the strict
> aliasing rules say that types which differ only in signed-ness can
> not be assumed to be non-overlapping.
> 

If this is true then it wouldn't be difficult to special case the situation
for same sized integers which differ only in sign in osiWireFormat.h.

However, there would be more source code to maintain, and there might be
minimal real world gains realized because, for modern compilers at least,
the optimizer probably is already doing this same optimization behind the
scenes, and just eliminating the copy through the temporary union.

Considering that it won't make the source code that much larger, I am
willing to implement this optimization (it should require a change only to
osiWireFormat.h). It is important to know for certain that this isn't going
to cause problems with a standards compliant compiler. Could you point me to
a reference on the web documenting the gory details?

Thanks,

Jeff

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System