Re: Make Panther slower on G4s.... Hmmm....
Originally posted by AidenShaw
Using a new compiler to optimize for the 970 would more than likely imply that it will slow down the G4 (unless the gcc today is really that poor on PPC).
The G4 will never run the 64 bits version of Panther. 64 bits libs and kernel will be 970 optimized; this could also mean that at installation time even 32 bits part of Panther could be delivered with the right sheduling for the 970.
Will Apple let the opportunity to run a 32 bits Panther kernel on the 970? To my knowledge all 64 bits vendors (SGI, Sun, IBM...) have let their customer choose between a 32 and a 64 bits kernel on 64 bits hardware for a few years.
Only a few apps would benefit from a 32 to 64 bits port (remember AltiVec is a powerful 128 bits SIMD engine), most would infact slow down.
This means developers would have to optimize 32 bits apps against 2 and a half (G3&G4, G4e, 970) different CPU cores, and 3 (7400, 7450, 970) different AltiVec implementation.
We are still far from the x86 instructions extension mess (MMX, SSE, SSE2, 3DNow!, 3DNow! Pro...).
Anyway I have no doubts about the fact that CPU specific builds are going to be pretty rare, most of today apps are targeted to the G3, and developers that do not overlook the 7400/7450 differences are God send.