AMD 250 Manuale Utente
142
Branch Optimizations
Chapter 6
25112
Rev. 3.06
September 2005
Software Optimization Guide for AMD64 Processors
6.9
Far Control-Transfer Instructions
Optimization
Use far control-transfer instructions only when necessary. (Far control-transfer instructions include
the far forms of JMP, CALL, and RET, as well as the INT, INTO, and IRET instructions.)
the far forms of JMP, CALL, and RET, as well as the INT, INTO, and IRET instructions.)
Application
This optimization applies to:
•
32-bit software
•
64-bit software
Rationale
The processor’s branch-prediction unit, which is used for both conditional and unconditional
branches, does not predict far branches.
branches, does not predict far branches.