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 <a name="Target-Attributes"></a>
 <div class="header">
 <p>
 Next: <a href="Emulated-TLS.html#Emulated-TLS" accesskey="n" rel="next">Emulated TLS</a>, Previous: <a href="Mode-Switching.html#Mode-Switching" accesskey="p" rel="prev">Mode Switching</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>
 </div>
 <hr>
 <a name="Defining-target_002dspecific-uses-of-_005f_005fattribute_005f_005f"></a>
 <h3 class="section">17.25 Defining target-specific uses of <code>__attribute__</code></h3>
 <a name="index-target-attributes"></a>
 <a name="index-machine-attributes"></a>
 <a name="index-attributes_002c-target_002dspecific"></a>

 <p>Target-specific attributes may be defined for functions, data and types.
 These are described using the following target hooks; they also need to
 be documented in <samp>extend.texi</samp>.
 </p>
 <dl>
 <dt><a name="index-TARGET_005fATTRIBUTE_005fTABLE"></a>Target Hook: <em>const struct attribute_spec *</em> <strong>TARGET_ATTRIBUTE_TABLE</strong></dt>
 <dd><p>If defined, this target hook points to an array of &lsquo;<samp>struct
 attribute_spec</samp>&rsquo; (defined in <samp>tree.h</samp>) specifying the machine
 specific attributes for this target and some of the restrictions on the
 entities to which these attributes are applied and the arguments they
 take.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fATTRIBUTE_005fTAKES_005fIDENTIFIER_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P</strong> <em>(const_tree <var>name</var>)</em></dt>
 <dd><p>If defined, this target hook is a function which returns true if the
 machine-specific attribute named <var>name</var> expects an identifier
 given as its first argument to be passed on as a plain identifier, not
 subjected to name lookup.  If this is not defined, the default is
 false for all machine-specific attributes.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fCOMP_005fTYPE_005fATTRIBUTES"></a>Target Hook: <em>int</em> <strong>TARGET_COMP_TYPE_ATTRIBUTES</strong> <em>(const_tree <var>type1</var>, const_tree <var>type2</var>)</em></dt>
 <dd><p>If defined, this target hook is a function which returns zero if the attributes on
 <var>type1</var> and <var>type2</var> are incompatible, one if they are compatible,
 and two if they are nearly compatible (which causes a warning to be
 generated).  If this is not defined, machine-specific attributes are
 supposed always to be compatible.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fSET_005fDEFAULT_005fTYPE_005fATTRIBUTES"></a>Target Hook: <em>void</em> <strong>TARGET_SET_DEFAULT_TYPE_ATTRIBUTES</strong> <em>(tree <var>type</var>)</em></dt>
 <dd><p>If defined, this target hook is a function which assigns default attributes to
 the newly defined <var>type</var>.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fMERGE_005fTYPE_005fATTRIBUTES"></a>Target Hook: <em>tree</em> <strong>TARGET_MERGE_TYPE_ATTRIBUTES</strong> <em>(tree <var>type1</var>, tree <var>type2</var>)</em></dt>
 <dd><p>Define this target hook if the merging of type attributes needs special
 handling.  If defined, the result is a list of the combined
 <code>TYPE_ATTRIBUTES</code> of <var>type1</var> and <var>type2</var>.  It is assumed
 that <code>comptypes</code> has already been called and returned 1.  This
 function may call <code>merge_attributes</code> to handle machine-independent
 merging.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fMERGE_005fDECL_005fATTRIBUTES"></a>Target Hook: <em>tree</em> <strong>TARGET_MERGE_DECL_ATTRIBUTES</strong> <em>(tree <var>olddecl</var>, tree <var>newdecl</var>)</em></dt>
 <dd><p>Define this target hook if the merging of decl attributes needs special
 handling.  If defined, the result is a list of the combined
 <code>DECL_ATTRIBUTES</code> of <var>olddecl</var> and <var>newdecl</var>.
 <var>newdecl</var> is a duplicate declaration of <var>olddecl</var>.  Examples of
 when this is needed are when one attribute overrides another, or when an
 attribute is nullified by a subsequent definition.  This function may
 call <code>merge_attributes</code> to handle machine-independent merging.
 </p>
 <a name="index-TARGET_005fDLLIMPORT_005fDECL_005fATTRIBUTES"></a>
 <p>If the only target-specific handling you require is &lsquo;<samp>dllimport</samp>&rsquo;
 for Microsoft Windows targets, you should define the macro
 <code>TARGET_DLLIMPORT_DECL_ATTRIBUTES</code> to <code>1</code>.  The compiler
 will then define a function called
 <code>merge_dllimport_decl_attributes</code> which can then be defined as
 the expansion of <code>TARGET_MERGE_DECL_ATTRIBUTES</code>.  You can also
 add <code>handle_dll_attribute</code> in the attribute table for your port
 to perform initial processing of the &lsquo;<samp>dllimport</samp>&rsquo; and
 &lsquo;<samp>dllexport</samp>&rsquo; attributes.  This is done in <samp>i386/cygwin.h</samp> and
 <samp>i386/i386.c</samp>, for example.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fVALID_005fDLLIMPORT_005fATTRIBUTE_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_VALID_DLLIMPORT_ATTRIBUTE_P</strong> <em>(const_tree <var>decl</var>)</em></dt>
 <dd><p><var>decl</var> is a variable or function with <code>__attribute__((dllimport))</code> specified.  Use this hook if the target needs to add extra validation checks to <code>handle_dll_attribute</code>.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fDECLSPEC"></a>Macro: <strong>TARGET_DECLSPEC</strong></dt>
 <dd><p>Define this macro to a nonzero value if you want to treat
 <code>__declspec(X)</code> as equivalent to <code>__attribute((X))</code>.  By
 default, this behavior is enabled only for targets that define
 <code>TARGET_DLLIMPORT_DECL_ATTRIBUTES</code>.  The current implementation
 of <code>__declspec</code> is via a built-in macro, but you should not rely
 on this implementation detail.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fINSERT_005fATTRIBUTES"></a>Target Hook: <em>void</em> <strong>TARGET_INSERT_ATTRIBUTES</strong> <em>(tree <var>node</var>, tree *<var>attr_ptr</var>)</em></dt>
 <dd><p>Define this target hook if you want to be able to add attributes to a decl
 when it is being created.  This is normally useful for back ends which
 wish to implement a pragma by using the attributes which correspond to
 the pragma&rsquo;s effect.  The <var>node</var> argument is the decl which is being
 created.  The <var>attr_ptr</var> argument is a pointer to the attribute list
 for this decl.  The list itself should not be modified, since it may be
 shared with other decls, but attributes may be chained on the head of
 the list and <code>*<var>attr_ptr</var></code> modified to point to the new
 attributes, or a copy of the list may be made if further changes are
 needed.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fFUNCTION_005fATTRIBUTE_005fINLINABLE_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P</strong> <em>(const_tree <var>fndecl</var>)</em></dt>
 <dd><a name="index-inlining"></a>
 <p>This target hook returns <code>true</code> if it is OK to inline <var>fndecl</var>
 into the current function, despite its having target-specific
 attributes, <code>false</code> otherwise.  By default, if a function has a
 target specific attribute attached to it, it will not be inlined.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fOPTION_005fVALID_005fATTRIBUTE_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_OPTION_VALID_ATTRIBUTE_P</strong> <em>(tree <var>fndecl</var>, tree <var>name</var>, tree <var>args</var>, int <var>flags</var>)</em></dt>
 <dd><p>This hook is called to parse <code>attribute(target(&quot;...&quot;))</code>, which
 allows setting target-specific options on individual functions.
 These function-specific options may differ
 from the options specified on the command line.  The hook should return
 <code>true</code> if the options are valid.
 </p>
 <p>The hook should set the <code>DECL_FUNCTION_SPECIFIC_TARGET</code> field in
 the function declaration to hold a pointer to a target-specific
 <code>struct cl_target_option</code> structure.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fOPTION_005fSAVE"></a>Target Hook: <em>void</em> <strong>TARGET_OPTION_SAVE</strong> <em>(struct cl_target_option *<var>ptr</var>, struct gcc_options *<var>opts</var>)</em></dt>
 <dd><p>This hook is called to save any additional target-specific information
 in the <code>struct cl_target_option</code> structure for function-specific
 options from the <code>struct gcc_options</code> structure.
 See <a href="Option-file-format.html#Option-file-format">Option file format</a>.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fOPTION_005fRESTORE"></a>Target Hook: <em>void</em> <strong>TARGET_OPTION_RESTORE</strong> <em>(struct gcc_options *<var>opts</var>, struct cl_target_option *<var>ptr</var>)</em></dt>
 <dd><p>This hook is called to restore any additional target-specific
 information in the <code>struct cl_target_option</code> structure for
 function-specific options to the <code>struct gcc_options</code> structure.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fOPTION_005fPRINT"></a>Target Hook: <em>void</em> <strong>TARGET_OPTION_PRINT</strong> <em>(FILE *<var>file</var>, int <var>indent</var>, struct cl_target_option *<var>ptr</var>)</em></dt>
 <dd><p>This hook is called to print any additional target-specific
 information in the <code>struct cl_target_option</code> structure for
 function-specific options.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fOPTION_005fPRAGMA_005fPARSE"></a>Target Hook: <em>bool</em> <strong>TARGET_OPTION_PRAGMA_PARSE</strong> <em>(tree <var>args</var>, tree <var>pop_target</var>)</em></dt>
 <dd><p>This target hook parses the options for <code>#pragma GCC target</code>, which
 sets the target-specific options for functions that occur later in the
 input stream.  The options accepted should be the same as those handled by the
 <code>TARGET_OPTION_VALID_ATTRIBUTE_P</code> hook.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fOPTION_005fOVERRIDE"></a>Target Hook: <em>void</em> <strong>TARGET_OPTION_OVERRIDE</strong> <em>(void)</em></dt>
 <dd><p>Sometimes certain combinations of command options do not make sense on
 a particular target machine.  You can override the hook
 <code>TARGET_OPTION_OVERRIDE</code> to take account of this.  This hooks is called
 once just after all the command options have been parsed.
 </p>
 <p>Don&rsquo;t use this hook to turn on various extra optimizations for
 <samp>-O</samp>.  That is what <code>TARGET_OPTION_OPTIMIZATION</code> is for.
 </p>
 <p>If you need to do something whenever the optimization level is
 changed via the optimize attribute or pragma, see
 <code>TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE</code>
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fOPTION_005fFUNCTION_005fVERSIONS"></a>Target Hook: <em>bool</em> <strong>TARGET_OPTION_FUNCTION_VERSIONS</strong> <em>(tree <var>decl1</var>, tree <var>decl2</var>)</em></dt>
 <dd><p>This target hook returns <code>true</code> if <var>DECL1</var> and <var>DECL2</var> are
 versions of the same function.  <var>DECL1</var> and <var>DECL2</var> are function
 versions if and only if they have the same function signature and
 different target specific attributes, that is, they are compiled for
 different target machines.
 </p></dd></dl>

 <dl>
 <dt><a name="index-TARGET_005fCAN_005fINLINE_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_CAN_INLINE_P</strong> <em>(tree <var>caller</var>, tree <var>callee</var>)</em></dt>
 <dd><p>This target hook returns <code>false</code> if the <var>caller</var> function
 cannot inline <var>callee</var>, based on target specific information.  By
 default, inlining is not allowed if the callee function has function
 specific target options and the caller does not use the same options.
 </p></dd></dl>

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	<a name="Target-Attributes"></a>
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	<p>
	Next: <a href="Emulated-TLS.html#Emulated-TLS" accesskey="n" rel="next">Emulated TLS</a>, Previous: <a href="Mode-Switching.html#Mode-Switching" accesskey="p" rel="prev">Mode Switching</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="Defining-target_002dspecific-uses-of-_005f_005fattribute_005f_005f"></a>
	<h3 class="section">17.25 Defining target-specific uses of <code>__attribute__</code></h3>
	<a name="index-target-attributes"></a>
	<a name="index-machine-attributes"></a>
	<a name="index-attributes_002c-target_002dspecific"></a>

	<p>Target-specific attributes may be defined for functions, data and types.
	These are described using the following target hooks; they also need to
	be documented in <samp>extend.texi</samp>.
	</p>
	<dl>
	<dt><a name="index-TARGET_005fATTRIBUTE_005fTABLE"></a>Target Hook: <em>const struct attribute_spec *</em> <strong>TARGET_ATTRIBUTE_TABLE</strong></dt>
	<dd><p>If defined, this target hook points to an array of ‘<samp>struct
	attribute_spec</samp>’ (defined in <samp>tree.h</samp>) specifying the machine
	specific attributes for this target and some of the restrictions on the
	entities to which these attributes are applied and the arguments they
	take.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fATTRIBUTE_005fTAKES_005fIDENTIFIER_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P</strong> <em>(const_tree <var>name</var>)</em></dt>
	<dd><p>If defined, this target hook is a function which returns true if the
	machine-specific attribute named <var>name</var> expects an identifier
	given as its first argument to be passed on as a plain identifier, not
	subjected to name lookup. If this is not defined, the default is
	false for all machine-specific attributes.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fCOMP_005fTYPE_005fATTRIBUTES"></a>Target Hook: <em>int</em> <strong>TARGET_COMP_TYPE_ATTRIBUTES</strong> <em>(const_tree <var>type1</var>, const_tree <var>type2</var>)</em></dt>
	<dd><p>If defined, this target hook is a function which returns zero if the attributes on
	<var>type1</var> and <var>type2</var> are incompatible, one if they are compatible,
	and two if they are nearly compatible (which causes a warning to be
	generated). If this is not defined, machine-specific attributes are
	supposed always to be compatible.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fSET_005fDEFAULT_005fTYPE_005fATTRIBUTES"></a>Target Hook: <em>void</em> <strong>TARGET_SET_DEFAULT_TYPE_ATTRIBUTES</strong> <em>(tree <var>type</var>)</em></dt>
	<dd><p>If defined, this target hook is a function which assigns default attributes to
	the newly defined <var>type</var>.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fMERGE_005fTYPE_005fATTRIBUTES"></a>Target Hook: <em>tree</em> <strong>TARGET_MERGE_TYPE_ATTRIBUTES</strong> <em>(tree <var>type1</var>, tree <var>type2</var>)</em></dt>
	<dd><p>Define this target hook if the merging of type attributes needs special
	handling. If defined, the result is a list of the combined
	<code>TYPE_ATTRIBUTES</code> of <var>type1</var> and <var>type2</var>. It is assumed
	that <code>comptypes</code> has already been called and returned 1. This
	function may call <code>merge_attributes</code> to handle machine-independent
	merging.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fMERGE_005fDECL_005fATTRIBUTES"></a>Target Hook: <em>tree</em> <strong>TARGET_MERGE_DECL_ATTRIBUTES</strong> <em>(tree <var>olddecl</var>, tree <var>newdecl</var>)</em></dt>
	<dd><p>Define this target hook if the merging of decl attributes needs special
	handling. If defined, the result is a list of the combined
	<code>DECL_ATTRIBUTES</code> of <var>olddecl</var> and <var>newdecl</var>.
	<var>newdecl</var> is a duplicate declaration of <var>olddecl</var>. Examples of
	when this is needed are when one attribute overrides another, or when an
	attribute is nullified by a subsequent definition. This function may
	call <code>merge_attributes</code> to handle machine-independent merging.
	</p>
	<a name="index-TARGET_005fDLLIMPORT_005fDECL_005fATTRIBUTES"></a>
	<p>If the only target-specific handling you require is ‘<samp>dllimport</samp>’
	for Microsoft Windows targets, you should define the macro
	<code>TARGET_DLLIMPORT_DECL_ATTRIBUTES</code> to <code>1</code>. The compiler
	will then define a function called
	<code>merge_dllimport_decl_attributes</code> which can then be defined as
	the expansion of <code>TARGET_MERGE_DECL_ATTRIBUTES</code>. You can also
	add <code>handle_dll_attribute</code> in the attribute table for your port
	to perform initial processing of the ‘<samp>dllimport</samp>’ and
	‘<samp>dllexport</samp>’ attributes. This is done in <samp>i386/cygwin.h</samp> and
	<samp>i386/i386.c</samp>, for example.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fVALID_005fDLLIMPORT_005fATTRIBUTE_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_VALID_DLLIMPORT_ATTRIBUTE_P</strong> <em>(const_tree <var>decl</var>)</em></dt>
	<dd><p><var>decl</var> is a variable or function with <code>__attribute__((dllimport))</code> specified. Use this hook if the target needs to add extra validation checks to <code>handle_dll_attribute</code>.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fDECLSPEC"></a>Macro: <strong>TARGET_DECLSPEC</strong></dt>
	<dd><p>Define this macro to a nonzero value if you want to treat
	<code>__declspec(X)</code> as equivalent to <code>__attribute((X))</code>. By
	default, this behavior is enabled only for targets that define
	<code>TARGET_DLLIMPORT_DECL_ATTRIBUTES</code>. The current implementation
	of <code>__declspec</code> is via a built-in macro, but you should not rely
	on this implementation detail.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fINSERT_005fATTRIBUTES"></a>Target Hook: <em>void</em> <strong>TARGET_INSERT_ATTRIBUTES</strong> <em>(tree <var>node</var>, tree *<var>attr_ptr</var>)</em></dt>
	<dd><p>Define this target hook if you want to be able to add attributes to a decl
	when it is being created. This is normally useful for back ends which
	wish to implement a pragma by using the attributes which correspond to
	the pragma’s effect. The <var>node</var> argument is the decl which is being
	created. The <var>attr_ptr</var> argument is a pointer to the attribute list
	for this decl. The list itself should not be modified, since it may be
	shared with other decls, but attributes may be chained on the head of
	the list and <code>*<var>attr_ptr</var></code> modified to point to the new
	attributes, or a copy of the list may be made if further changes are
	needed.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fFUNCTION_005fATTRIBUTE_005fINLINABLE_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P</strong> <em>(const_tree <var>fndecl</var>)</em></dt>
	<dd><a name="index-inlining"></a>
	<p>This target hook returns <code>true</code> if it is OK to inline <var>fndecl</var>
	into the current function, despite its having target-specific
	attributes, <code>false</code> otherwise. By default, if a function has a
	target specific attribute attached to it, it will not be inlined.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fOPTION_005fVALID_005fATTRIBUTE_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_OPTION_VALID_ATTRIBUTE_P</strong> <em>(tree <var>fndecl</var>, tree <var>name</var>, tree <var>args</var>, int <var>flags</var>)</em></dt>
	<dd><p>This hook is called to parse <code>attribute(target("..."))</code>, which
	allows setting target-specific options on individual functions.
	These function-specific options may differ
	from the options specified on the command line. The hook should return
	<code>true</code> if the options are valid.
	</p>
	<p>The hook should set the <code>DECL_FUNCTION_SPECIFIC_TARGET</code> field in
	the function declaration to hold a pointer to a target-specific
	<code>struct cl_target_option</code> structure.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fOPTION_005fSAVE"></a>Target Hook: <em>void</em> <strong>TARGET_OPTION_SAVE</strong> <em>(struct cl_target_option <var>ptr</var>, struct gcc_options <var>opts</var>)</em></dt>
	<dd><p>This hook is called to save any additional target-specific information
	in the <code>struct cl_target_option</code> structure for function-specific
	options from the <code>struct gcc_options</code> structure.
	See <a href="Option-file-format.html#Option-file-format">Option file format</a>.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fOPTION_005fRESTORE"></a>Target Hook: <em>void</em> <strong>TARGET_OPTION_RESTORE</strong> <em>(struct gcc_options <var>opts</var>, struct cl_target_option <var>ptr</var>)</em></dt>
	<dd><p>This hook is called to restore any additional target-specific
	information in the <code>struct cl_target_option</code> structure for
	function-specific options to the <code>struct gcc_options</code> structure.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fOPTION_005fPRINT"></a>Target Hook: <em>void</em> <strong>TARGET_OPTION_PRINT</strong> <em>(FILE <var>file</var>, int <var>indent</var>, struct cl_target_option <var>ptr</var>)</em></dt>
	<dd><p>This hook is called to print any additional target-specific
	information in the <code>struct cl_target_option</code> structure for
	function-specific options.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fOPTION_005fPRAGMA_005fPARSE"></a>Target Hook: <em>bool</em> <strong>TARGET_OPTION_PRAGMA_PARSE</strong> <em>(tree <var>args</var>, tree <var>pop_target</var>)</em></dt>
	<dd><p>This target hook parses the options for <code>#pragma GCC target</code>, which
	sets the target-specific options for functions that occur later in the
	input stream. The options accepted should be the same as those handled by the
	<code>TARGET_OPTION_VALID_ATTRIBUTE_P</code> hook.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fOPTION_005fOVERRIDE"></a>Target Hook: <em>void</em> <strong>TARGET_OPTION_OVERRIDE</strong> <em>(void)</em></dt>
	<dd><p>Sometimes certain combinations of command options do not make sense on
	a particular target machine. You can override the hook
	<code>TARGET_OPTION_OVERRIDE</code> to take account of this. This hooks is called
	once just after all the command options have been parsed.
	</p>
	<p>Don’t use this hook to turn on various extra optimizations for
	<samp>-O</samp>. That is what <code>TARGET_OPTION_OPTIMIZATION</code> is for.
	</p>
	<p>If you need to do something whenever the optimization level is
	changed via the optimize attribute or pragma, see
	<code>TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE</code>
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fOPTION_005fFUNCTION_005fVERSIONS"></a>Target Hook: <em>bool</em> <strong>TARGET_OPTION_FUNCTION_VERSIONS</strong> <em>(tree <var>decl1</var>, tree <var>decl2</var>)</em></dt>
	<dd><p>This target hook returns <code>true</code> if <var>DECL1</var> and <var>DECL2</var> are
	versions of the same function. <var>DECL1</var> and <var>DECL2</var> are function
	versions if and only if they have the same function signature and
	different target specific attributes, that is, they are compiled for
	different target machines.
	</p></dd></dl>

	<dl>
	<dt><a name="index-TARGET_005fCAN_005fINLINE_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_CAN_INLINE_P</strong> <em>(tree <var>caller</var>, tree <var>callee</var>)</em></dt>
	<dd><p>This target hook returns <code>false</code> if the <var>caller</var> function
	cannot inline <var>callee</var>, based on target specific information. By
	default, inlining is not allowed if the callee function has function
	specific target options and the caller does not use the same options.
	</p></dd></dl>

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