AMD Typewriter x86 사용자 설명서
Avoid the Loop Instruction
65
22007E/0—November 1999
AMD Athlon™ Processor x86 Code Optimization
Avoid the Loop Instruction
The LOOP instruction in the AMD Athlon processor requires
eight cycles to execute. Use the preferred code shown below:
eight cycles to execute. Use the preferred code shown below:
Example 1 (Avoid):
LOOP
LABEL
Example 2 (Preferred):
DEC
ECX
JNZ
LABEL
Avoid Far Control Transfer Instructions
Avoid using far control transfer instructions. Far control
transfer branches can not be predicted by the branch target
buffer (BTB).
transfer branches can not be predicted by the branch target
buffer (BTB).