[Ti] A real world comparison

[Chris Olson]

On Jun 9, 2005, at 10:13 PM, Bill Fox wrote:

> ......because its Mac OS X running on Intel CPUs is more beleaguered 
> than Windows."

Well, this is a serious issue, and for those who have high hopes for OS 
X on x86 there's some caveats:

G4/G5 cpu's are unusual beasts that diverge from 'orthagonal' purist 
cpu design in a variety of ways; generally to get specific 
optimizations.

Apple is using GCC in Xcode 2.1  It runs on and builds code for a wide 
range of platforms.  And yet, it suffers from poor performance.  Not 
because it's a poor compiler - it's one of the best compilers on the 
market - but because it's a universal infrastructure, that models an 
orthagonal, generic cpu design.

GCC vs IBM XLC performance comparisons on PowerPC show optimized GCC vs 
optimized XLC compiles showing improvements of anywhere from 11% to 51% 
on SPECint2000 scores for the IBM compiler.  For floating point 
performance, the difference is even more extreme - more of the numbers 
are over the 50% mark than under.  The G4/G5 have always had stronger 
floating point, and the XLC compiler backs that up with the appropriate 
optimizations to make use of the unique features of the architecture 
that enables that to be true.

Apple is up against Microsoft's own optimized MS C++ compiler on 
Windows, and the Intel compiler that some mainstream software vendors 
will use on Windows for their builds.  Both provide better 
optimizations on x86 than GCC.  Apple is crippling its developers by 
requiring the use of Xcode, and therefore GCC, which is going to hurt 
performance seriously.

I really wish I could see a bright light at the end of the tunnel with 
this, but the more I look at it, I see a design for disaster on the 
development end.  Apple is now trying to play on Microsoft's home turf; 
an area where Microsoft has had *years* of experience with 
optimizations and development of tools for the platform.  It's way more 
complicated than simply dropping your codebase into Xcode, selecting 
the checkbox for "Intel", and compiling it.  All that'll get you is a 
program that runs.  How well it runs is another matter.
--
Chris