AMD Typewriter x86 사용자 설명서

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22007E/0—November 1999
AMD Athlon™ Processor x86 Code Optimization 
Top Optimizations
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Top Optimizations
This  chapter contains  concise descriptions of the best
o p t i m i z a t i o n s   fo r   i m p rov i n g   t h e   p e r fo r m a n c e   o f   t h e
AMD Athlon™ processor. Subsequent chapters contain more
detailed descriptions of these and other optimizations. The
optimizations in this chapter are divided into two groups and
listed in order of importance.
Group I — Essential 
Optimizations
Group I contains essential optimizations. Users should follow
these critical guidelines closely. The optimizations in Group I
are as follows:
Memory Size and Alignment Issues—Avoid memory size
mismatches—Align data where possible
Use the 3DNow!™ PREFETCH and PREFETCHW
Instructions
Select DirectPath Over VectorPath Instructions
Group II — Secondary 
Optimizations
G r o u p   I I   c o n t a i n s   s e c o n d a ry   o p t i m i z a t i o n s   t h a t   c a n
significantly improve the performance of the AMD Athlon
processor. The optimizations in Group II are as follows:
Load-Execute Instruction Usage—Use Load-Execute
instructions—Avoid load-execute floating-point instructions
with integer operands
Take Advantage of Write Combining
Use 3DNow! Instructions
Avoid Branches Dependent on Random Data