optimize(3cl) - advise compiler of attention to be given to qualities

OPTIMIZE(3cl)

Common Lisp Reference

OPTIMIZE(3cl)

NAME

optimize – advise compiler of attention to be given to qualities (declaration)

SYNOPSIS

( optimize { quality | ( quality value ) }* )

ARGUMENTS and VALUES

quality —an optimize quality.

value—one of the integers 0, 1, 2, or 3.

VALID CONTEXT

declaration or proclamation

BINDING TYPES AFFECTED

DESCRIPTION

Advises the compiler that each quality should be given attention according to the specified corresponding value. Each quality must be a symbol naming an optimize quality; the names and meanings of the standard optimize qualities are:

compilation-speed	speed of the compilation process
debug	ease of debugging
safety	run-time error checking
space	both code size and run-time space
speed	speed of the object code

There may be other, implementation-defined optimize qualities.

A value 0 means that the corresponding quality is totally unimportant, and 3 that the quality is extremely important; 1 and 2 are intermediate values, with 1 the neutral value. (quality 3) can be abbreviated to quality .

Note that code which has the optimization (safety 3), or just safety, is called safe code.

The consequences are unspecified if a quality appears more than once with different values.

AFFECTED BY

(none)

EXCEPTIONAL SITUATIONS

(none)

NOTES

An optimize declaration never applies to either a variable or a function binding. An optimize declaration can only be a free declaration.

EXAMPLES

(defun often-used-subroutine (x y)
   (declare (optimize (safety 2)))
   (error-check x y)
   (hairy-setup x)
   (do ((i 0 (+ i 1))
           (z x (cdr z)))
           ((null z))
       ;; This inner loop really needs to burn.
       (declare (optimize speed))
       (declare (fixnum i))
       ...))