[Openmcl-devel] Effects of optimization settings

Osei Poku osei.poku at gmail.com
Mon Apr 6 20:37:52 PDT 2009


Are there any guidelines on the effects that the various optimization  
settings have on the compiler?  After playing with them for a while,  
I'm not convinced that some settings have any effect (esp. (speed  
3)).  The output of disassemble looks exactly the same for the  
following functions.

(defun mathop (i j)
    (1+ (ash i j)))


(defun mathop-fast (i j)
    (declare (optimize (speed 3) (safety 0) (debug 0)) (fixnum i j))
    (1+ (ash i j)))

Interestingly, (debug 3) in the above function gives a shorter  
assembly listing.



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