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 <a name="PIC"></a>
 <div class="header">
 <p>
 Next: <a href="Assembler-Format.html#Assembler-Format" accesskey="n" rel="next">Assembler Format</a>, Previous: <a href="Sections.html#Sections" accesskey="p" rel="prev">Sections</a>, Up: <a href="Target-Macros.html#Target-Macros" accesskey="u" rel="up">Target Macros</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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 <hr>
 <a name="Position-Independent-Code"></a>
 <h3 class="section">17.20 Position Independent Code</h3>
 <a name="index-position-independent-code"></a>
 <a name="index-PIC"></a>

 <p>This section describes macros that help implement generation of position
 independent code.  Simply defining these macros is not enough to
 generate valid PIC; you must also add support to the hook
 <code>TARGET_LEGITIMATE_ADDRESS_P</code> and to the macro
 <code>PRINT_OPERAND_ADDRESS</code>, as well as <code>LEGITIMIZE_ADDRESS</code>.  You
 must modify the definition of &lsquo;<samp>movsi</samp>&rsquo; to do something appropriate
 when the source operand contains a symbolic address.  You may also
 need to alter the handling of switch statements so that they use
 relative addresses.
 </p>
 <dl>
 <dt><a name="index-PIC_005fOFFSET_005fTABLE_005fREGNUM"></a>Macro: <strong>PIC_OFFSET_TABLE_REGNUM</strong></dt>
 <dd><p>The register number of the register used to address a table of static
 data addresses in memory.  In some cases this register is defined by a
 processor&rsquo;s &ldquo;application binary interface&rdquo; (ABI).  When this macro
 is defined, RTL is generated for this register once, as with the stack
 pointer and frame pointer registers.  If this macro is not defined, it
 is up to the machine-dependent files to allocate such a register (if
 necessary).  Note that this register must be fixed when in use (e.g.
 when <code>flag_pic</code> is true).
 </p></dd></dl>

 <dl>
 <dt><a name="index-PIC_005fOFFSET_005fTABLE_005fREG_005fCALL_005fCLOBBERED"></a>Macro: <strong>PIC_OFFSET_TABLE_REG_CALL_CLOBBERED</strong></dt>
 <dd><p>A C expression that is nonzero if the register defined by
 <code>PIC_OFFSET_TABLE_REGNUM</code> is clobbered by calls.  If not defined,
 the default is zero.  Do not define
 this macro if <code>PIC_OFFSET_TABLE_REGNUM</code> is not defined.
 </p></dd></dl>

 <dl>
 <dt><a name="index-LEGITIMATE_005fPIC_005fOPERAND_005fP"></a>Macro: <strong>LEGITIMATE_PIC_OPERAND_P</strong> <em>(<var>x</var>)</em></dt>
 <dd><p>A C expression that is nonzero if <var>x</var> is a legitimate immediate
 operand on the target machine when generating position independent code.
 You can assume that <var>x</var> satisfies <code>CONSTANT_P</code>, so you need not
 check this.  You can also assume <var>flag_pic</var> is true, so you need not
 check it either.  You need not define this macro if all constants
 (including <code>SYMBOL_REF</code>) can be immediate operands when generating
 position independent code.
 </p></dd></dl>

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	<a name="PIC"></a>
	<div class="header">
	<p>
	Next: <a href="Assembler-Format.html#Assembler-Format" accesskey="n" rel="next">Assembler Format</a>, Previous: <a href="Sections.html#Sections" accesskey="p" rel="prev">Sections</a>, Up: <a href="Target-Macros.html#Target-Macros" accesskey="u" rel="up">Target Macros</a>   [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
	</div>
	<hr>
	<a name="Position-Independent-Code"></a>
	<h3 class="section">17.20 Position Independent Code</h3>
	<a name="index-position-independent-code"></a>
	<a name="index-PIC"></a>

	<p>This section describes macros that help implement generation of position
	independent code. Simply defining these macros is not enough to
	generate valid PIC; you must also add support to the hook
	<code>TARGET_LEGITIMATE_ADDRESS_P</code> and to the macro
	<code>PRINT_OPERAND_ADDRESS</code>, as well as <code>LEGITIMIZE_ADDRESS</code>. You
	must modify the definition of ‘<samp>movsi</samp>’ to do something appropriate
	when the source operand contains a symbolic address. You may also
	need to alter the handling of switch statements so that they use
	relative addresses.
	</p>
	<dl>
	<dt><a name="index-PIC_005fOFFSET_005fTABLE_005fREGNUM"></a>Macro: <strong>PIC_OFFSET_TABLE_REGNUM</strong></dt>
	<dd><p>The register number of the register used to address a table of static
	data addresses in memory. In some cases this register is defined by a
	processor’s “application binary interface” (ABI). When this macro
	is defined, RTL is generated for this register once, as with the stack
	pointer and frame pointer registers. If this macro is not defined, it
	is up to the machine-dependent files to allocate such a register (if
	necessary). Note that this register must be fixed when in use (e.g.
	when <code>flag_pic</code> is true).
	</p></dd></dl>

	<dl>
	<dt><a name="index-PIC_005fOFFSET_005fTABLE_005fREG_005fCALL_005fCLOBBERED"></a>Macro: <strong>PIC_OFFSET_TABLE_REG_CALL_CLOBBERED</strong></dt>
	<dd><p>A C expression that is nonzero if the register defined by
	<code>PIC_OFFSET_TABLE_REGNUM</code> is clobbered by calls. If not defined,
	the default is zero. Do not define
	this macro if <code>PIC_OFFSET_TABLE_REGNUM</code> is not defined.
	</p></dd></dl>

	<dl>
	<dt><a name="index-LEGITIMATE_005fPIC_005fOPERAND_005fP"></a>Macro: <strong>LEGITIMATE_PIC_OPERAND_P</strong> <em>(<var>x</var>)</em></dt>
	<dd><p>A C expression that is nonzero if <var>x</var> is a legitimate immediate
	operand on the target machine when generating position independent code.
	You can assume that <var>x</var> satisfies <code>CONSTANT_P</code>, so you need not
	check this. You can also assume <var>flag_pic</var> is true, so you need not
	check it either. You need not define this macro if all constants
	(including <code>SYMBOL_REF</code>) can be immediate operands when generating
	position independent code.
	</p></dd></dl>

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