AMD Typewriter x86 사용자 설명서
22007E/0—November 1999
AMD Athlon™ Processor x86 Code Optimization
Select DirectPath Over VectorPath Instructions
219
Appendix G
DirectPath versus
VectorPath Instructions
VectorPath Instructions
Select DirectPath Over VectorPath Instructions
U s e D i r e c t P a t h i n s t r u c t i o n s r a t h e r t h a n Ve c t o r P a t h
instructions. DirectPath instructions are optimized for decode
and execute efficiently by minimizing the number of operations
per x86 instruction, which includes ‘register
instructions. DirectPath instructions are optimized for decode
and execute efficiently by minimizing the number of operations
per x86 instruction, which includes ‘register
←
register op
memory’ as well as ‘register
←
register op register’ forms of
instructions.
DirectPath Instructions
The following tables contain DirectPath instructions, which
should be used in the AMD Athlon processor wherever possible:
should be used in the AMD Athlon processor wherever possible:
■
■
Table 26, “DirectPath MMX™ Instructions,” on page 227
and Table 27, “DirectPath MMX™ Extensions,” on page 228
and Table 27, “DirectPath MMX™ Extensions,” on page 228
■
■
All 3DNow! instructions, including the 3DNow! Extensions,
are DirectPath and are listed in Table 23, “3DNow!™
Instructions,” on page 217 and Table 24, “3DNow!™ Exten-
sions,” on page 218.
are DirectPath and are listed in Table 23, “3DNow!™
Instructions,” on page 217 and Table 24, “3DNow!™ Exten-
sions,” on page 218.