Re: glib/gatomic.c

[John Emmas <johne53 tiscali co uk>]

Hi Behdad - to answer your questions:-

On 08/03/2013 00:33, Behdad Esfahbod wrote:
> Do all versions of MSVC have MemoryBarrier? In that case, we should 
> make sure we never try the function path for MSVC. Perhaps I should 
> just do that for mingw32? 

I had to do some research into this so I may have reached the wrong 
conclusions but from what I could tell, all version of Windows support 
InterlockedAnd / InterlockedExchange etc (with a few caveats) but 
MemoryBarrier is less clear.  That article you linked to seemed to 
suggest that it's only available from Vista onwards

FWIW Behdad, your code builds fine as you've written it, except that the 
'inline' keyword needs those leading underscores to be compliant with MSVC.


> Interesting. I'll push. Just curious: can you also try building 
> HarfBuzz and see if we need those there too? Thanks, behdad 

I think we already build Harfbuzz as part of Pango but our Pango version 
is about a year old.  There are no references to MemoryBarrier or 
Interlocked<whatever> AFAICT.  Is this something that's been added 
recently?


> > +#include <intrin.h>                   /* Added by JE - 02-12-2012 */
> > +
> > +#pragma intrinsic (_InterlockedAnd)   /* Added by JE - 02-12-2012 */
> > +#pragma intrinsic (_InterlockedOr)    /* Added by JE - 02-12-2012 */
> > +#pragma intrinsic (_InterlockedXor)   /* Added by JE - 02-12-2012 */
> > +
> >   #define InterlockedAnd _InterlockedAnd
> >   #define InterlockedOr _InterlockedOr
> >   #define InterlockedXor _InterlockedXor
> > +
> >   #endif
> Humm.  Does removing the defines do the trick?  I can't find any 
> references to
> the difference between the underscored and plain versions of these .

No, I don't know what the difference is either but it's quite common for 
MS functions to need leading underscores these days.  Even the more 
common ones like _strcpy() won't compile any more if there's no leading 
underscore.  I've always assumed it's something to do with ANSI or C99 
or some other standards committee.  Removing the #defines makes no 
difference from what I can recall.  I remember trying that at the time.  
Hope that helps.

John