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<a name="Function-Properties"></a>
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<p>
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Previous: <a rel="previous" accesskey="p" href="Function-Basics.html#Function-Basics">Function Basics</a>,
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Up: <a rel="up" accesskey="u" href="Functions.html#Functions">Functions</a>
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<h4 class="subsection">10.8.2 Function Properties</h4>
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<p><a name="index-function-properties-1980"></a><a name="index-statements-1981"></a>
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To determine the scope of a function, you can use the
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<code>DECL_CONTEXT</code> macro. This macro will return the class
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(either a <code>RECORD_TYPE</code> or a <code>UNION_TYPE</code>) or namespace (a
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<code>NAMESPACE_DECL</code>) of which the function is a member. For a virtual
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function, this macro returns the class in which the function was
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actually defined, not the base class in which the virtual declaration
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occurred.
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<p>In C, the <code>DECL_CONTEXT</code> for a function maybe another function.
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This representation indicates that the GNU nested function extension
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is in use. For details on the semantics of nested functions, see the
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GCC Manual. The nested function can refer to local variables in its
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containing function. Such references are not explicitly marked in the
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tree structure; back ends must look at the <code>DECL_CONTEXT</code> for the
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referenced <code>VAR_DECL</code>. If the <code>DECL_CONTEXT</code> for the
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referenced <code>VAR_DECL</code> is not the same as the function currently
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being processed, and neither <code>DECL_EXTERNAL</code> nor
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<code>TREE_STATIC</code> hold, then the reference is to a local variable in
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a containing function, and the back end must take appropriate action.
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<dl>
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<dt><code>DECL_EXTERNAL</code><a name="index-DECL_005fEXTERNAL-1982"></a><dd>This predicate holds if the function is undefined.
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<br><dt><code>TREE_PUBLIC</code><a name="index-TREE_005fPUBLIC-1983"></a><dd>This predicate holds if the function has external linkage.
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<br><dt><code>TREE_STATIC</code><a name="index-TREE_005fSTATIC-1984"></a><dd>This predicate holds if the function has been defined.
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<br><dt><code>TREE_THIS_VOLATILE</code><a name="index-TREE_005fTHIS_005fVOLATILE-1985"></a><dd>This predicate holds if the function does not return normally.
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<br><dt><code>TREE_READONLY</code><a name="index-TREE_005fREADONLY-1986"></a><dd>This predicate holds if the function can only read its arguments.
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<br><dt><code>DECL_PURE_P</code><a name="index-DECL_005fPURE_005fP-1987"></a><dd>This predicate holds if the function can only read its arguments, but
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may also read global memory.
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<br><dt><code>DECL_VIRTUAL_P</code><a name="index-DECL_005fVIRTUAL_005fP-1988"></a><dd>This predicate holds if the function is virtual.
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<br><dt><code>DECL_ARTIFICIAL</code><a name="index-DECL_005fARTIFICIAL-1989"></a><dd>This macro holds if the function was implicitly generated by the
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compiler, rather than explicitly declared. In addition to implicitly
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generated class member functions, this macro holds for the special
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functions created to implement static initialization and destruction, to
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compute run-time type information, and so forth.
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<br><dt><code>DECL_FUNCTION_SPECIFIC_TARGET</code><a name="index-DECL_005fFUNCTION_005fSPECIFIC_005fTARGET-1990"></a><dd>This macro returns a tree node that holds the target options that are
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to be used to compile this particular function or <code>NULL_TREE</code> if
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the function is to be compiled with the target options specified on
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the command line.
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<br><dt><code>DECL_FUNCTION_SPECIFIC_OPTIMIZATION</code><a name="index-DECL_005fFUNCTION_005fSPECIFIC_005fOPTIMIZATION-1991"></a><dd>This macro returns a tree node that holds the optimization options
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that are to be used to compile this particular function or
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<code>NULL_TREE</code> if the function is to be compiled with the
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optimization options specified on the command line.
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