Predefined Version expansion

[Dan]

Derek Parnell Wrote:

> On Tue, 03 Apr 2007 10:48:01 -0400, Dan wrote:
> 
> > Walter Bright Wrote:
> >> I think what you need is a runtime check, which is provided in std.cpuid.
> > 
> > So what you're saying is, we can't optimize the compiler for a specific
> > variation of the x86, and are therefore stuck with writing generic 
> > programs that branch off for each cpu kind during runtime?
> 
> 
> No, maybe you missed the point. It certainly is possible for one to create
> editions of an application for specific hardware configurations; and using
> the version() statement is a reasonable way to do that.
> 
>   version(SSE2) { . . . }
>   version(SSE)  { . . . }
> etc...
> 
>   dmd -version=SSE2 myapp.d
>   dmd -version=SSE myapp.d
> 
> However, such editions should be able to be generated regardless of which
> hardware architecure the compiler just happens to be running on at the
> time. In other words, setting the version values within the compiler based
> on the hardware at compilation time is not very useful. It would be better
> to set these version values at the compiler command line level, if one does
> really want hardware-specific editions of the app.

Yeah, I guess defining the versions yourself is totally possible, and reasonable.  : p

Less persuasively, and more as a closing note, I tend to think that the more D is used for other platforms (GDC retargetable?) the more those predefined platform ones will be wanted.  

It's generally bad to have each programmer use different names for exactly the same thing.