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<h4 class="subsection">9.27.3 Directives to override the size of symbols</h4>
<p><a name="index-g_t_0040code_007b_002eset-sym32_007d-1492"></a><a name="index-g_t_0040code_007b_002eset-nosym32_007d-1493"></a>The n64 ABI allows symbols to have any 64-bit value. Although this
provides a great deal of flexibility, it means that some macros have
much longer expansions than their 32-bit counterparts. For example,
the non-PIC expansion of ‘<samp><span class="samp">dla $4,sym</span></samp>’ is usually:
<pre class="smallexample"> lui $4,%highest(sym)
lui $1,%hi(sym)
daddiu $4,$4,%higher(sym)
daddiu $1,$1,%lo(sym)
dsll32 $4,$4,0
daddu $4,$4,$1
</pre>
<p>whereas the 32-bit expansion is simply:
<pre class="smallexample"> lui $4,%hi(sym)
daddiu $4,$4,%lo(sym)
</pre>
<p>n64 code is sometimes constructed in such a way that all symbolic
constants are known to have 32-bit values, and in such cases, it's
preferable to use the 32-bit expansion instead of the 64-bit
expansion.
<p>You can use the <code>.set sym32</code> directive to tell the assembler
that, from this point on, all expressions of the form
‘<samp><var>symbol</var></samp>’ or ‘<samp><var>symbol</var><span class="samp"> + </span><var>offset</var></samp>’
have 32-bit values. For example:
<pre class="smallexample"> .set sym32
dla $4,sym
lw $4,sym+16
sw $4,sym+0x8000($4)
</pre>
<p>will cause the assembler to treat ‘<samp><span class="samp">sym</span></samp>’, <code>sym+16</code> and
<code>sym+0x8000</code> as 32-bit values. The handling of non-symbolic
addresses is not affected.
<p>The directive <code>.set nosym32</code> ends a <code>.set sym32</code> block and
reverts to the normal behavior. It is also possible to change the
symbol size using the command-line options <samp><span class="option">-msym32</span></samp> and
<samp><span class="option">-mno-sym32</span></samp>.
<p>These options and directives are always accepted, but at present,
they have no effect for anything other than n64.
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