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186 lines
7.3 KiB
HTML
186 lines
7.3 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1988-2018 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Funding Free Software", the Front-Cover
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Texts being (a) (see below), and with the Back-Cover Texts being (b)
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(see below). A copy of the license is included in the section entitled
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"GNU Free Documentation License".
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development. -->
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Function Properties (GNU Compiler Collection (GCC) Internals)</title>
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<meta name="description" content="Function Properties (GNU Compiler Collection (GCC) Internals)">
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<meta name="keywords" content="Function Properties (GNU Compiler Collection (GCC) Internals)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Functions.html#Functions" rel="up" title="Functions">
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<link href="Language_002ddependent-trees.html#Language_002ddependent-trees" rel="next" title="Language-dependent trees">
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<link href="Function-Basics.html#Function-Basics" rel="prev" title="Function Basics">
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-->
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</style>
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</head>
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<body lang="en">
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<a name="Function-Properties"></a>
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<div class="header">
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<p>
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Previous: <a href="Function-Basics.html#Function-Basics" accesskey="p" rel="prev">Function Basics</a>, Up: <a href="Functions.html#Functions" accesskey="u" rel="up">Functions</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>
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</div>
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<hr>
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<a name="Function-Properties-1"></a>
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<h4 class="subsection">11.8.2 Function Properties</h4>
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<a name="index-function-properties"></a>
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<a name="index-statements"></a>
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<p>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>
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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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</p>
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<dl compact="compact">
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<dt><code>DECL_EXTERNAL</code>
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<a name="index-DECL_005fEXTERNAL-1"></a>
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</dt>
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<dd><p>This predicate holds if the function is undefined.
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</p>
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</dd>
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<dt><code>TREE_PUBLIC</code>
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<a name="index-TREE_005fPUBLIC-1"></a>
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</dt>
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<dd><p>This predicate holds if the function has external linkage.
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</p>
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</dd>
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<dt><code>TREE_STATIC</code>
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<a name="index-TREE_005fSTATIC"></a>
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</dt>
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<dd><p>This predicate holds if the function has been defined.
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</p>
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</dd>
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<dt><code>TREE_THIS_VOLATILE</code>
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<a name="index-TREE_005fTHIS_005fVOLATILE"></a>
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</dt>
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<dd><p>This predicate holds if the function does not return normally.
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</p>
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</dd>
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<dt><code>TREE_READONLY</code>
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<a name="index-TREE_005fREADONLY"></a>
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</dt>
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<dd><p>This predicate holds if the function can only read its arguments.
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</p>
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</dd>
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<dt><code>DECL_PURE_P</code>
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<a name="index-DECL_005fPURE_005fP"></a>
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</dt>
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<dd><p>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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</p>
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</dd>
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<dt><code>DECL_VIRTUAL_P</code>
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<a name="index-DECL_005fVIRTUAL_005fP"></a>
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</dt>
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<dd><p>This predicate holds if the function is virtual.
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</p>
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</dd>
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<dt><code>DECL_ARTIFICIAL</code>
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<a name="index-DECL_005fARTIFICIAL-2"></a>
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</dt>
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<dd><p>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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</p>
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</dd>
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<dt><code>DECL_FUNCTION_SPECIFIC_TARGET</code>
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<a name="index-DECL_005fFUNCTION_005fSPECIFIC_005fTARGET-1"></a>
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</dt>
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<dd><p>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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</p>
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</dd>
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<dt><code>DECL_FUNCTION_SPECIFIC_OPTIMIZATION</code>
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<a name="index-DECL_005fFUNCTION_005fSPECIFIC_005fOPTIMIZATION-1"></a>
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</dt>
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<dd><p>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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</p>
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</dd>
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</dl>
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<hr>
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<div class="header">
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<p>
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Previous: <a href="Function-Basics.html#Function-Basics" accesskey="p" rel="prev">Function Basics</a>, Up: <a href="Functions.html#Functions" accesskey="u" rel="up">Functions</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>
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</div>
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</body>
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</html>
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