Справочник Пользователя для AMD 250
208
Optimizing with SIMD Instructions
Chapter 9
25112
Rev. 3.06
September 2005
Software Optimization Guide for AMD64 Processors
9.8
Passing Data between MMX™ and 3DNow!™
Instructions
Instructions
Optimization
Avoid passing data between MMX and 3DNow!™ instructions.
Application
This optimization applies to:
•
32-bit software
•
64-bit software
Rational
The AMD Athlon 64 and AMD Opteron processors do not support bypassing register data between
MMX and 3DNow! instructions. One additional cycle of latency is added to a dependency chain
whenever data is passed between these instruction groups in either direction.
MMX and 3DNow! instructions. One additional cycle of latency is added to a dependency chain
whenever data is passed between these instruction groups in either direction.