Test eax,eax

[Mark_Larson]

  I also CHEAT and use MMX registers to temporarily save register values.  I don't ever do MMX programming.  I always use SSE/SSE2.  So I can actually save it in the beginning of the program if need be.

You can also use the SSE2 registers the same way.  And you don't have to worry about overlapping registers with the FP registers.  However it is slower.  So it's a balance.

I just checked my core 2 duo optimization book and the delays are the same.  I know P4 is one cycle slower for the MOVD using the SSE2 registers.

Code Select Expand


movd xmm0,esp

;do code here

movd esp,xmm0