| <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| <html> |
| <!-- Copyright (C) 1988-2015 Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 or |
| any later version published by the Free Software Foundation; with the |
| Invariant Sections being "Funding Free Software", the Front-Cover |
| Texts being (a) (see below), and with the Back-Cover Texts being (b) |
| (see below). A copy of the license is included in the section entitled |
| "GNU Free Documentation License". |
| |
| (a) The FSF's Front-Cover Text is: |
| |
| A GNU Manual |
| |
| (b) The FSF's Back-Cover Text is: |
| |
| You have freedom to copy and modify this GNU Manual, like GNU |
| software. Copies published by the Free Software Foundation raise |
| funds for GNU development. --> |
| <!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ --> |
| <head> |
| <title>GNU Compiler Collection (GCC) Internals: Functions for C++</title> |
| |
| <meta name="description" content="GNU Compiler Collection (GCC) Internals: Functions for C++"> |
| <meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Functions for C++"> |
| <meta name="resource-type" content="document"> |
| <meta name="distribution" content="global"> |
| <meta name="Generator" content="makeinfo"> |
| <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> |
| <link href="index.html#Top" rel="start" title="Top"> |
| <link href="Option-Index.html#Option-Index" rel="index" title="Option Index"> |
| <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> |
| <link href="C-and-C_002b_002b-Trees.html#C-and-C_002b_002b-Trees" rel="up" title="C and C++ Trees"> |
| <link href="Statements-for-C_002b_002b.html#Statements-for-C_002b_002b" rel="next" title="Statements for C++"> |
| <link href="Classes.html#Classes" rel="prev" title="Classes"> |
| <style type="text/css"> |
| <!-- |
| a.summary-letter {text-decoration: none} |
| blockquote.smallquotation {font-size: smaller} |
| div.display {margin-left: 3.2em} |
| div.example {margin-left: 3.2em} |
| div.indentedblock {margin-left: 3.2em} |
| div.lisp {margin-left: 3.2em} |
| div.smalldisplay {margin-left: 3.2em} |
| div.smallexample {margin-left: 3.2em} |
| div.smallindentedblock {margin-left: 3.2em; font-size: smaller} |
| div.smalllisp {margin-left: 3.2em} |
| kbd {font-style:oblique} |
| pre.display {font-family: inherit} |
| pre.format {font-family: inherit} |
| pre.menu-comment {font-family: serif} |
| pre.menu-preformatted {font-family: serif} |
| pre.smalldisplay {font-family: inherit; font-size: smaller} |
| pre.smallexample {font-size: smaller} |
| pre.smallformat {font-family: inherit; font-size: smaller} |
| pre.smalllisp {font-size: smaller} |
| span.nocodebreak {white-space:nowrap} |
| span.nolinebreak {white-space:nowrap} |
| span.roman {font-family:serif; font-weight:normal} |
| span.sansserif {font-family:sans-serif; font-weight:normal} |
| ul.no-bullet {list-style: none} |
| --> |
| </style> |
| |
| |
| </head> |
| |
| <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> |
| <a name="Functions-for-C_002b_002b"></a> |
| <div class="header"> |
| <p> |
| Next: <a href="Statements-for-C_002b_002b.html#Statements-for-C_002b_002b" accesskey="n" rel="next">Statements for C++</a>, Previous: <a href="Classes.html#Classes" accesskey="p" rel="prev">Classes</a>, Up: <a href="C-and-C_002b_002b-Trees.html#C-and-C_002b_002b-Trees" accesskey="u" rel="up">C and C++ Trees</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="Functions-for-C_002b_002b-1"></a> |
| <h4 class="subsection">10.10.4 Functions for C++</h4> |
| <a name="index-function-1"></a> |
| <a name="index-FUNCTION_005fDECL-1"></a> |
| <a name="index-OVERLOAD"></a> |
| <a name="index-OVL_005fCURRENT"></a> |
| <a name="index-OVL_005fNEXT"></a> |
| |
| <p>A function is represented by a <code>FUNCTION_DECL</code> node. A set of |
| overloaded functions is sometimes represented by an <code>OVERLOAD</code> node. |
| </p> |
| <p>An <code>OVERLOAD</code> node is not a declaration, so none of the |
| ‘<samp>DECL_</samp>’ macros should be used on an <code>OVERLOAD</code>. An |
| <code>OVERLOAD</code> node is similar to a <code>TREE_LIST</code>. Use |
| <code>OVL_CURRENT</code> to get the function associated with an |
| <code>OVERLOAD</code> node; use <code>OVL_NEXT</code> to get the next |
| <code>OVERLOAD</code> node in the list of overloaded functions. The macros |
| <code>OVL_CURRENT</code> and <code>OVL_NEXT</code> are actually polymorphic; you can |
| use them to work with <code>FUNCTION_DECL</code> nodes as well as with |
| overloads. In the case of a <code>FUNCTION_DECL</code>, <code>OVL_CURRENT</code> |
| will always return the function itself, and <code>OVL_NEXT</code> will always |
| be <code>NULL_TREE</code>. |
| </p> |
| <p>To determine the scope of a function, you can use the |
| <code>DECL_CONTEXT</code> macro. This macro will return the class |
| (either a <code>RECORD_TYPE</code> or a <code>UNION_TYPE</code>) or namespace (a |
| <code>NAMESPACE_DECL</code>) of which the function is a member. For a virtual |
| function, this macro returns the class in which the function was |
| actually defined, not the base class in which the virtual declaration |
| occurred. |
| </p> |
| <p>If a friend function is defined in a class scope, the |
| <code>DECL_FRIEND_CONTEXT</code> macro can be used to determine the class in |
| which it was defined. For example, in |
| </p><div class="smallexample"> |
| <pre class="smallexample">class C { friend void f() {} }; |
| </pre></div> |
| <p>the <code>DECL_CONTEXT</code> for <code>f</code> will be the |
| <code>global_namespace</code>, but the <code>DECL_FRIEND_CONTEXT</code> will be the |
| <code>RECORD_TYPE</code> for <code>C</code>. |
| </p> |
| |
| <p>The following macros and functions can be used on a <code>FUNCTION_DECL</code>: |
| </p><dl compact="compact"> |
| <dt><code>DECL_MAIN_P</code> |
| <a name="index-DECL_005fMAIN_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds for a function that is the program entry point |
| <code>::code</code>. |
| </p> |
| </dd> |
| <dt><code>DECL_LOCAL_FUNCTION_P</code> |
| <a name="index-DECL_005fLOCAL_005fFUNCTION_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds if the function was declared at block scope, even |
| though it has a global scope. |
| </p> |
| </dd> |
| <dt><code>DECL_ANTICIPATED</code> |
| <a name="index-DECL_005fANTICIPATED"></a> |
| </dt> |
| <dd><p>This predicate holds if the function is a built-in function but its |
| prototype is not yet explicitly declared. |
| </p> |
| </dd> |
| <dt><code>DECL_EXTERN_C_FUNCTION_P</code> |
| <a name="index-DECL_005fEXTERN_005fC_005fFUNCTION_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds if the function is declared as an |
| ‘<code>extern "C"</code>’ function. |
| </p> |
| </dd> |
| <dt><code>DECL_LINKONCE_P</code> |
| <a name="index-DECL_005fLINKONCE_005fP"></a> |
| </dt> |
| <dd><p>This macro holds if multiple copies of this function may be emitted in |
| various translation units. It is the responsibility of the linker to |
| merge the various copies. Template instantiations are the most common |
| example of functions for which <code>DECL_LINKONCE_P</code> holds; G++ |
| instantiates needed templates in all translation units which require them, |
| and then relies on the linker to remove duplicate instantiations. |
| </p> |
| <p>FIXME: This macro is not yet implemented. |
| </p> |
| </dd> |
| <dt><code>DECL_FUNCTION_MEMBER_P</code> |
| <a name="index-DECL_005fFUNCTION_005fMEMBER_005fP"></a> |
| </dt> |
| <dd><p>This macro holds if the function is a member of a class, rather than a |
| member of a namespace. |
| </p> |
| </dd> |
| <dt><code>DECL_STATIC_FUNCTION_P</code> |
| <a name="index-DECL_005fSTATIC_005fFUNCTION_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds if the function a static member function. |
| </p> |
| </dd> |
| <dt><code>DECL_NONSTATIC_MEMBER_FUNCTION_P</code> |
| <a name="index-DECL_005fNONSTATIC_005fMEMBER_005fFUNCTION_005fP"></a> |
| </dt> |
| <dd><p>This macro holds for a non-static member function. |
| </p> |
| </dd> |
| <dt><code>DECL_CONST_MEMFUNC_P</code> |
| <a name="index-DECL_005fCONST_005fMEMFUNC_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds for a <code>const</code>-member function. |
| </p> |
| </dd> |
| <dt><code>DECL_VOLATILE_MEMFUNC_P</code> |
| <a name="index-DECL_005fVOLATILE_005fMEMFUNC_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds for a <code>volatile</code>-member function. |
| </p> |
| </dd> |
| <dt><code>DECL_CONSTRUCTOR_P</code> |
| <a name="index-DECL_005fCONSTRUCTOR_005fP"></a> |
| </dt> |
| <dd><p>This macro holds if the function is a constructor. |
| </p> |
| </dd> |
| <dt><code>DECL_NONCONVERTING_P</code> |
| <a name="index-DECL_005fNONCONVERTING_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds if the constructor is a non-converting constructor. |
| </p> |
| </dd> |
| <dt><code>DECL_COMPLETE_CONSTRUCTOR_P</code> |
| <a name="index-DECL_005fCOMPLETE_005fCONSTRUCTOR_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds for a function which is a constructor for an object |
| of a complete type. |
| </p> |
| </dd> |
| <dt><code>DECL_BASE_CONSTRUCTOR_P</code> |
| <a name="index-DECL_005fBASE_005fCONSTRUCTOR_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds for a function which is a constructor for a base |
| class sub-object. |
| </p> |
| </dd> |
| <dt><code>DECL_COPY_CONSTRUCTOR_P</code> |
| <a name="index-DECL_005fCOPY_005fCONSTRUCTOR_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds for a function which is a copy-constructor. |
| </p> |
| </dd> |
| <dt><code>DECL_DESTRUCTOR_P</code> |
| <a name="index-DECL_005fDESTRUCTOR_005fP"></a> |
| </dt> |
| <dd><p>This macro holds if the function is a destructor. |
| </p> |
| </dd> |
| <dt><code>DECL_COMPLETE_DESTRUCTOR_P</code> |
| <a name="index-DECL_005fCOMPLETE_005fDESTRUCTOR_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds if the function is the destructor for an object a |
| complete type. |
| </p> |
| </dd> |
| <dt><code>DECL_OVERLOADED_OPERATOR_P</code> |
| <a name="index-DECL_005fOVERLOADED_005fOPERATOR_005fP"></a> |
| </dt> |
| <dd><p>This macro holds if the function is an overloaded operator. |
| </p> |
| </dd> |
| <dt><code>DECL_CONV_FN_P</code> |
| <a name="index-DECL_005fCONV_005fFN_005fP"></a> |
| </dt> |
| <dd><p>This macro holds if the function is a type-conversion operator. |
| </p> |
| </dd> |
| <dt><code>DECL_GLOBAL_CTOR_P</code> |
| <a name="index-DECL_005fGLOBAL_005fCTOR_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds if the function is a file-scope initialization |
| function. |
| </p> |
| </dd> |
| <dt><code>DECL_GLOBAL_DTOR_P</code> |
| <a name="index-DECL_005fGLOBAL_005fDTOR_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds if the function is a file-scope finalization |
| function. |
| </p> |
| </dd> |
| <dt><code>DECL_THUNK_P</code> |
| <a name="index-DECL_005fTHUNK_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds if the function is a thunk. |
| </p> |
| <p>These functions represent stub code that adjusts the <code>this</code> pointer |
| and then jumps to another function. When the jumped-to function |
| returns, control is transferred directly to the caller, without |
| returning to the thunk. The first parameter to the thunk is always the |
| <code>this</code> pointer; the thunk should add <code>THUNK_DELTA</code> to this |
| value. (The <code>THUNK_DELTA</code> is an <code>int</code>, not an |
| <code>INTEGER_CST</code>.) |
| </p> |
| <p>Then, if <code>THUNK_VCALL_OFFSET</code> (an <code>INTEGER_CST</code>) is nonzero |
| the adjusted <code>this</code> pointer must be adjusted again. The complete |
| calculation is given by the following pseudo-code: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">this += THUNK_DELTA |
| if (THUNK_VCALL_OFFSET) |
| this += (*((ptrdiff_t **) this))[THUNK_VCALL_OFFSET] |
| </pre></div> |
| |
| <p>Finally, the thunk should jump to the location given |
| by <code>DECL_INITIAL</code>; this will always be an expression for the |
| address of a function. |
| </p> |
| </dd> |
| <dt><code>DECL_NON_THUNK_FUNCTION_P</code> |
| <a name="index-DECL_005fNON_005fTHUNK_005fFUNCTION_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds if the function is <em>not</em> a thunk function. |
| </p> |
| </dd> |
| <dt><code>GLOBAL_INIT_PRIORITY</code> |
| <a name="index-GLOBAL_005fINIT_005fPRIORITY"></a> |
| </dt> |
| <dd><p>If either <code>DECL_GLOBAL_CTOR_P</code> or <code>DECL_GLOBAL_DTOR_P</code> holds, |
| then this gives the initialization priority for the function. The |
| linker will arrange that all functions for which |
| <code>DECL_GLOBAL_CTOR_P</code> holds are run in increasing order of priority |
| before <code>main</code> is called. When the program exits, all functions for |
| which <code>DECL_GLOBAL_DTOR_P</code> holds are run in the reverse order. |
| </p> |
| </dd> |
| <dt><code>TYPE_RAISES_EXCEPTIONS</code> |
| <a name="index-TYPE_005fRAISES_005fEXCEPTIONS"></a> |
| </dt> |
| <dd><p>This macro returns the list of exceptions that a (member-)function can |
| raise. The returned list, if non <code>NULL</code>, is comprised of nodes |
| whose <code>TREE_VALUE</code> represents a type. |
| </p> |
| </dd> |
| <dt><code>TYPE_NOTHROW_P</code> |
| <a name="index-TYPE_005fNOTHROW_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds when the exception-specification of its arguments |
| is of the form ‘<code>()</code>’. |
| </p> |
| </dd> |
| <dt><code>DECL_ARRAY_DELETE_OPERATOR_P</code> |
| <a name="index-DECL_005fARRAY_005fDELETE_005fOPERATOR_005fP"></a> |
| </dt> |
| <dd><p>This predicate holds if the function an overloaded |
| <code>operator delete[]</code>. |
| </p> |
| </dd> |
| </dl> |
| |
| |
| <hr> |
| <div class="header"> |
| <p> |
| Next: <a href="Statements-for-C_002b_002b.html#Statements-for-C_002b_002b" accesskey="n" rel="next">Statements for C++</a>, Previous: <a href="Classes.html#Classes" accesskey="p" rel="prev">Classes</a>, Up: <a href="C-and-C_002b_002b-Trees.html#C-and-C_002b_002b-Trees" accesskey="u" rel="up">C and C++ Trees</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> |
| |
| |
| |
| </body> |
| </html> |