Advanced Micro Devices Inc (AMD)

[HailMary]

if not most programs the advantage of more registers is completely counterbalanced by the fact that there is code bloat

BTW - that past presentation by Kevin McGrath (sp?) from AMD showed the average instruction size only increased around 10-15% when going from 32-bit to 64-bit. I don't remember the exact number. Anyone?

therefore QSORT would get no benefit from the extra registers

Judging by the c-code I used, I think there may in fact be some benefit to using extra registers. How else do we account for the fact that the optimized compile was significantly faster? I think wbmw may have suggested the 32-bit compiler is not as good as the 64-bit compiler at optimizations. This could be a factor. It is too bad we don't have a compiler that is identical other than enabling 64-bit and extra registers.

Anyone working on a thesis? This might make a good paper. I just don't have the time to pursue this much.

All I know is I can get significant gains in performance by using an Opteron running 64-bit Linux, even if I don't recompile the 32-bit app. That says something loud and clear. It says my company is going to buy a lot more Opterons.