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<span id="optimize"></span><div class="header">
<p>
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<hr>
<span id="optimize-_005bDeclaration_005d"></span><h4 class="subsection">3.8.25 optimize [Declaration]</h4>
<span id="Syntax_003a_003a-8"></span><h4 class="subsubheading">Syntax::</h4>
<p><tt>(optimize {<i>quality</i> | (<i>quality</i> <i>value</i>)}*)</tt>
</p>
<span id="index-compilation_002dspeed"></span>
<span id="index-debug"></span>
<span id="index-safety-1"></span>
<span id="index-space-1"></span>
<span id="index-speed"></span>
<span id="Arguments_003a_003a-8"></span><h4 class="subsubheading">Arguments::</h4>
<p><i>quality</i>—an <i>optimize quality</i>.
</p>
<p><i>value</i>—one of the <i>integers</i> <tt>0</tt>, <tt>1</tt>, <tt>2</tt>, or <tt>3</tt>.
</p>
<span id="Valid-Context_003a_003a-6"></span><h4 class="subsubheading">Valid Context::</h4>
<p><i>declaration</i> or <i>proclamation</i>
</p>
<span id="Description_003a_003a-24"></span><h4 class="subsubheading">Description::</h4>
<p>Advises the compiler that each <i>quality</i> should be given attention
according to the specified corresponding <i>value</i>.
Each <i>quality</i> must be a <i>symbol</i> naming an <i>optimize quality</i>;
the names and meanings of the standard <i>optimize qualities</i> are shown in
Figure 3–25.
</p>
<div class="format">
<pre class="format"> Name Meaning <!-- /@w -->
<b>compilation-speed</b> speed of the compilation process <!-- /@w -->
<b>debug</b> ease of debugging <!-- /@w -->
<b>safety</b> run-time error checking <!-- /@w -->
<b>space</b> both code size and run-time space <!-- /@w -->
<b>speed</b> speed of the object code <!-- /@w -->
Figure 3–25: Optimize qualities <!-- /@w -->
</pre></div>
<p>There may be other, <i>implementation-defined</i> <i>optimize qualities</i>.
</p>
<p>A <i>value</i> <tt>0</tt> means that the corresponding <i>quality</i> is totally
unimportant, and <tt>3</tt> that the <i>quality</i> is extremely important;
<tt>1</tt> and <tt>2</tt> are intermediate values, with <tt>1</tt> the
neutral value.
<tt>(<i>quality</i> 3)</tt> can be abbreviated to <i>quality</i>.
</p>
<p>Note that <i>code</i> which has the optimization <tt>(safety 3)</tt>,
or just <b>safety</b>,
is called <i>safe</i> <i>code</i>.
</p>
<p>The consequences are unspecified if a <i>quality</i> appears more than once
with <i>different</i> <i>values</i>.
</p>
<span id="Examples_003a_003a-20"></span><h4 class="subsubheading">Examples::</h4>
<div class="example">
<pre class="example"> (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))
))
</pre></div>
<span id="See-Also_003a_003a-24"></span><h4 class="subsubheading">See Also::</h4>
<p><b>declare</b>,
<a href="declaim.html">declaim</a>
,
<a href="proclaim.html">proclaim</a>
,
<a href="Declaration-Scope.html">Declaration Scope</a>
</p>
<span id="Notes_003a_003a-14"></span><h4 class="subsubheading">Notes::</h4>
<p>An <b>optimize</b> declaration never applies to either a <i>variable</i> or
a <i>function</i> <i>binding</i>. An <b>optimize</b> declaration can only
be a <i>free declaration</i>. For more information, see <a href="Declaration-Scope.html">Declaration Scope</a>.
</p>
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