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RE: [pooma-dev] domain architecture diagram
From: |
Julian C. Cummings |
Subject: |
RE: [pooma-dev] domain architecture diagram |
Date: |
Fri, 6 Jul 2001 11:24:45 -0700 |
I meant to send a note about this a few days,
but anyway, the Intel VTune compiler "passes"
the empty base class test. The SGI MIPSpro
compiler on Nirvana does not. It gives a size
of "2" for the derived class rather than "1".
Julian C.
> -----Original Message-----
> From: Mark Mitchell [mailto:address@hidden
> Sent: Sunday, July 01, 2001 11:18 PM
> To: address@hidden; Pooma-Dev
> Subject: RE: [pooma-dev] domain architecture diagram
>
>
> I don't know if
> > this issue of the empty base class is important anymore
> > with current C++ compilers.
>
> This was the only part of this discussion I was smart enough to
> understand, so I decided to reply to it. :-)
>
> In G++ 3.0, there is no empty base class penalty. The same will
> be true for any IA64 C++ ABI compliant compiler. Modern versions
> of the EDG front end (used in KCC, the Intel compiler, the SGI
> compiler, the DEC/Compaq compiler, and elsewhere) are capable of
> avoiding the penalty. However, I do now know if the vendors were
> willing to turn on this feature, since it will break compatibility
> with previous versions of their compilers. And, I do not know
> whether VC++ is capable of avoiding the penalty.
>
> Irrelevant compilers for computers named after fruit are mentioned
> only because I know that the mere presence of this sentence will
> get people's adrenalin pumping in New Mexico. :-) Seriously, I
> know nothing of whether Metrowerks can do this or not.
>
> It would be great if someone could try out:
>
> struct S { };
> struct T : public S { char c; };
>
> int main () { return sizeof (T); }
>
> with KCC. If things are good, the program will return 1; if bad,
> some greater value.
>
> --
> Mark Mitchell address@hidden
> CodeSourcery, LLC http://www.codesourcery.com
>