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<a name="Loc"></a>
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<a name="g_t_002eloc-fileno-lineno-_005bcolumn_005d-_005boptions_005d"></a>
<h3 class="section">7.57 <code>.loc <var>fileno</var> <var>lineno</var> [<var>column</var>] [<var>options</var>]</code></h3>
<a name="index-loc-directive"></a>
<p>When emitting DWARF2 line number information,
the <code>.loc</code> directive will add a row to the <code>.debug_line</code> line
number matrix corresponding to the immediately following assembly
instruction.  The <var>fileno</var>, <var>lineno</var>, and optional <var>column</var>
arguments will be applied to the <code>.debug_line</code> state machine before
the row is added.  It is an error for the input assembly file to generate
a non-empty <code>.debug_line</code> and also use <code>loc</code> directives.
</p>
<p>The <var>options</var> are a sequence of the following tokens in any order:
</p>
<dl compact="compact">
<dt><code>basic_block</code></dt>
<dd><p>This option will set the <code>basic_block</code> register in the
<code>.debug_line</code> state machine to <code>true</code>.
</p>
</dd>
<dt><code>prologue_end</code></dt>
<dd><p>This option will set the <code>prologue_end</code> register in the
<code>.debug_line</code> state machine to <code>true</code>.
</p>
</dd>
<dt><code>epilogue_begin</code></dt>
<dd><p>This option will set the <code>epilogue_begin</code> register in the
<code>.debug_line</code> state machine to <code>true</code>.
</p>
</dd>
<dt><code>is_stmt <var>value</var></code></dt>
<dd><p>This option will set the <code>is_stmt</code> register in the
<code>.debug_line</code> state machine to <code>value</code>, which must be
either 0 or 1.
</p>
</dd>
<dt><code>isa <var>value</var></code></dt>
<dd><p>This directive will set the <code>isa</code> register in the <code>.debug_line</code>
state machine to <var>value</var>, which must be an unsigned integer.
</p>
</dd>
<dt><code>discriminator <var>value</var></code></dt>
<dd><p>This directive will set the <code>discriminator</code> register in the <code>.debug_line</code>
state machine to <var>value</var>, which must be an unsigned integer.
</p>
</dd>
<dt><code>view <var>value</var></code></dt>
<dd><p>This option causes a row to be added to <code>.debug_line</code> in reference to the
current address (which might not be the same as that of the following assembly
instruction), and to associate <var>value</var> with the <code>view</code> register in the
<code>.debug_line</code> state machine.  If <var>value</var> is a label, both the
<code>view</code> register and the label are set to the number of prior <code>.loc</code>
directives at the same program location.  If <var>value</var> is the literal
<code>0</code>, the <code>view</code> register is set to zero, and the assembler asserts
that there aren&rsquo;t any prior <code>.loc</code> directives at the same program
location.  If <var>value</var> is the literal <code>-0</code>, the assembler arrange for
the <code>view</code> register to be reset in this row, even if there are prior
<code>.loc</code> directives at the same program location.
</p>
</dd>
</dl>

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