Re: [objc-improvements] Just remembered something about multiple method signatures...

[Chris Hanson]

On Saturday, September 6, 2003, at 02:54  AM, David Ayers wrote:
> It doesn't on my architecture and probably not on the G4, but it would 
> on 64 bit archs where small enums (i.e. NSComparisionResult) are not 
> the same size as id (I'm not sure how the G5 handles small enums).

I've seen a couple of the comments and questions about the G5 so far in 
this and related threads.  I just thought I'd point out how Mac OS X 
and the G5 behave together.

Apple provides some details for developers here:

  http://developer.apple.com/hardware/g5/

Essentially, right now Mac OS X does not support user-level code with a 
64-bit address space (to my knowledge, anyway).  Instead, it only 
supports 64-bit integer operations.  Furthermore, it does so without 
changing the size of existing data types (int, long, void*, etc.).

The reason is compatibility.  A developer can release a single 
executable that supports G3, G4, and G5 without resorting to building a 
triple-fat executable (one binary for each architecture combined into a 
single file).  Instead, the developer can build a particular source 
file with PowerPC 970 optimization and PowerPC-64 integer instruction 
generation, detect which processor the user has at run time, and use 
the code in that file in that particular case.  This is the same way 
AltiVec & G4 optimization is done.

  -- Chris

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