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diff --git a/src/libmach/gxxint_15.html b/src/libmach/gxxint_15.html new file mode 100644 index 00000000..cdee7dda --- /dev/null +++ b/src/libmach/gxxint_15.html @@ -0,0 +1,375 @@ +<HTML> +<HEAD> +<!-- This HTML file has been created by texi2html 1.52 + from gxxint.texi on 27 August 1999 --> + +<TITLE>G++ internals - Mangling</TITLE> +</HEAD> +<BODY> +Go to the <A HREF="gxxint_1.html">first</A>, <A HREF="gxxint_14.html">previous</A>, <A HREF="gxxint_16.html">next</A>, <A HREF="gxxint_16.html">last</A> section, <A HREF="gxxint_toc.html">table of contents</A>. +<P><HR><P> + + +<H2><A NAME="SEC20" HREF="gxxint_toc.html#TOC20">Function name mangling for C++ and Java</A></H2> + +<P> +Both C++ and Jave provide overloaded function and methods, +which are methods with the same types but different parameter lists. +Selecting the correct version is done at compile time. +Though the overloaded functions have the same name in the source code, +they need to be translated into different assembler-level names, +since typical assemblers and linkers cannot handle overloading. +This process of encoding the parameter types with the method name +into a unique name is called <EM>name mangling</EM>. The inverse +process is called <EM>demangling</EM>. + +</P> +<P> +It is convenient that C++ and Java use compatible mangling schemes, +since the makes life easier for tools such as gdb, and it eases +integration between C++ and Java. + +</P> +<P> +Note there is also a standard "Jave Native Interface" (JNI) which +implements a different calling convention, and uses a different +mangling scheme. The JNI is a rather abstract ABI so Java can call methods +written in C or C++; +we are concerned here about a lower-level interface primarily +intended for methods written in Java, but that can also be used for C++ +(and less easily C). + +</P> + + +<H3><A NAME="SEC21" HREF="gxxint_toc.html#TOC21">Method name mangling</A></H3> + +<P> +C++ mangles a method by emitting the function name, followed by <CODE>__</CODE>, +followed by encodings of any method qualifiers (such as <CODE>const</CODE>), +followed by the mangling of the method's class, +followed by the mangling of the parameters, in order. + +</P> +<P> +For example <CODE>Foo::bar(int, long) const</CODE> is mangled +as <SAMP>`bar__C3Fooil'</SAMP>. + +</P> +<P> +For a constructor, the method name is left out. +That is <CODE>Foo::Foo(int, long) const</CODE> is mangled +as <SAMP>`__C3Fooil'</SAMP>. + +</P> +<P> +GNU Java does the same. + +</P> + + +<H3><A NAME="SEC22" HREF="gxxint_toc.html#TOC22">Primitive types</A></H3> + +<P> +The C++ types <CODE>int</CODE>, <CODE>long</CODE>, <CODE>short</CODE>, <CODE>char</CODE>, +and <CODE>long long</CODE> are mangled as <SAMP>`i'</SAMP>, <SAMP>`l'</SAMP>, +<SAMP>`s'</SAMP>, <SAMP>`c'</SAMP>, and <SAMP>`x'</SAMP>, respectively. +The corresponding unsigned types have <SAMP>`U'</SAMP> prefixed +to the mangling. The type <CODE>signed char</CODE> is mangled <SAMP>`Sc'</SAMP>. + +</P> +<P> +The C++ and Java floating-point types <CODE>float</CODE> and <CODE>double</CODE> +are mangled as <SAMP>`f'</SAMP> and <SAMP>`d'</SAMP> respectively. + +</P> +<P> +The C++ <CODE>bool</CODE> type and the Java <CODE>boolean</CODE> type are +mangled as <SAMP>`b'</SAMP>. + +</P> +<P> +The C++ <CODE>wchar_t</CODE> and the Java <CODE>char</CODE> types are +mangled as <SAMP>`w'</SAMP>. + +</P> +<P> +The Java integral types <CODE>byte</CODE>, <CODE>short</CODE>, <CODE>int</CODE> +and <CODE>long</CODE> are mangled as <SAMP>`c'</SAMP>, <SAMP>`s'</SAMP>, <SAMP>`i'</SAMP>, +and <SAMP>`x'</SAMP>, respectively. + +</P> +<P> +C++ code that has included <CODE>javatypes.h</CODE> will mangle +the typedefs <CODE>jbyte</CODE>, <CODE>jshort</CODE>, <CODE>jint</CODE> +and <CODE>jlong</CODE> as respectively <SAMP>`c'</SAMP>, <SAMP>`s'</SAMP>, <SAMP>`i'</SAMP>, +and <SAMP>`x'</SAMP>. (This has not been implemented yet.) + +</P> + + +<H3><A NAME="SEC23" HREF="gxxint_toc.html#TOC23">Mangling of simple names</A></H3> + +<P> +A simple class, package, template, or namespace name is +encoded as the number of characters in the name, followed by +the actual characters. Thus the class <CODE>Foo</CODE> +is encoded as <SAMP>`3Foo'</SAMP>. + +</P> +<P> +If any of the characters in the name are not alphanumeric +(i.e not one of the standard ASCII letters, digits, or '_'), +or the initial character is a digit, then the name is +mangled as a sequence of encoded Unicode letters. +A Unicode encoding starts with a <SAMP>`U'</SAMP> to indicate +that Unicode escapes are used, followed by the number of +bytes used by the Unicode encoding, followed by the bytes +representing the encoding. ASSCI letters and +non-initial digits are encoded without change. However, all +other characters (including underscore and initial digits) are +translated into a sequence starting with an underscore, +followed by the big-endian 4-hex-digit lower-case encoding of the character. + +</P> +<P> +If a method name contains Unicode-escaped characters, the +entire mangled method name is followed by a <SAMP>`U'</SAMP>. + +</P> +<P> +For example, the method <CODE>X\u0319::M\u002B(int)</CODE> is encoded as +<SAMP>`M_002b__U6X_0319iU'</SAMP>. + +</P> + + +<H3><A NAME="SEC24" HREF="gxxint_toc.html#TOC24">Pointer and reference types</A></H3> + +<P> +A C++ pointer type is mangled as <SAMP>`P'</SAMP> followed by the +mangling of the type pointed to. + +</P> +<P> +A C++ reference type as mangled as <SAMP>`R'</SAMP> followed by the +mangling of the type referenced. + +</P> +<P> +A Java object reference type is equivalent +to a C++ pointer parameter, so we mangle such an parameter type +as <SAMP>`P'</SAMP> followed by the mangling of the class name. + +</P> + + +<H3><A NAME="SEC25" HREF="gxxint_toc.html#TOC25">Qualified names</A></H3> + +<P> +Both C++ and Java allow a class to be lexically nested inside another +class. C++ also supports namespaces (not yet implemented by G++). +Java also supports packages. + +</P> +<P> +These are all mangled the same way: First the letter <SAMP>`Q'</SAMP> +indicates that we are emitting a qualified name. +That is followed by the number of parts in the qualified name. +If that number is 9 or less, it is emitted with no delimiters. +Otherwise, an underscore is written before and after the count. +Then follows each part of the qualified name, as described above. + +</P> +<P> +For example <CODE>Foo::\u0319::Bar</CODE> is encoded as +<SAMP>`Q33FooU5_03193Bar'</SAMP>. + +</P> + + +<H3><A NAME="SEC26" HREF="gxxint_toc.html#TOC26">Templates</A></H3> + +<P> +A class template instantiation is encoded as the letter <SAMP>`t'</SAMP>, +followed by the encoding of the template name, followed +the number of template parameters, followed by encoding of the template +parameters. If a template parameter is a type, it is written +as a <SAMP>`Z'</SAMP> followed by the encoding of the type. + +</P> +<P> +A function template specialization (either an instantiation or an +explicit specialization) is encoded by an <SAMP>`H'</SAMP> followed by the +encoding of the template parameters, as described above, followed by +an <SAMP>`_'</SAMP>, the encoding of the argument types template function (not the +specialization), another <SAMP>`_'</SAMP>, and the return type. (Like the +argument types, the return type is the return type of the function +template, not the specialization.) Template parameters in the argument +and return types are encoded by an <SAMP>`X'</SAMP> for type parameters, or a +<SAMP>`Y'</SAMP> for constant parameters, and an index indicating their position +in the template parameter list declaration. + +</P> + + +<H3><A NAME="SEC27" HREF="gxxint_toc.html#TOC27">Arrays</A></H3> + +<P> +C++ array types are mangled by emitting <SAMP>`A'</SAMP>, followed by +the length of the array, followed by an <SAMP>`_'</SAMP>, followed by +the mangling of the element type. Of course, normally +array parameter types decay into a pointer types, so you +don't see this. + +</P> +<P> +Java arrays are objects. A Java type <CODE>T[]</CODE> is mangled +as if it were the C++ type <CODE>JArray<T></CODE>. +For example <CODE>java.lang.String[]</CODE> is encoded as +<SAMP>`Pt6JArray1ZPQ34java4lang6String'</SAMP>. + +</P> + + +<H3><A NAME="SEC28" HREF="gxxint_toc.html#TOC28">Table of demangling code characters</A></H3> + +<P> +The following special characters are used in mangling: + +</P> +<DL COMPACT> + +<DT><SAMP>`A'</SAMP> +<DD> +Indicates a C++ array type. + +<DT><SAMP>`b'</SAMP> +<DD> +Encodes the C++ <CODE>bool</CODE> type, +and the Java <CODE>boolean</CODE> type. + +<DT><SAMP>`c'</SAMP> +<DD> +Encodes the C++ <CODE>char</CODE> type, and the Java <CODE>byte</CODE> type. + +<DT><SAMP>`C'</SAMP> +<DD> +A modifier to indicate a <CODE>const</CODE> type. +Also used to indicate a <CODE>const</CODE> member function +(in which cases it precedes the encoding of the method's class). + +<DT><SAMP>`d'</SAMP> +<DD> +Encodes the C++ and Java <CODE>double</CODE> types. + +<DT><SAMP>`e'</SAMP> +<DD> +Indicates extra unknown arguments <CODE>...</CODE>. + +<DT><SAMP>`f'</SAMP> +<DD> +Encodes the C++ and Java <CODE>float</CODE> types. + +<DT><SAMP>`F'</SAMP> +<DD> +Used to indicate a function type. + +<DT><SAMP>`H'</SAMP> +<DD> +Used to indicate a template function. + +<DT><SAMP>`i'</SAMP> +<DD> +Encodes the C++ and Java <CODE>int</CODE> types. + +<DT><SAMP>`J'</SAMP> +<DD> +Indicates a complex type. + +<DT><SAMP>`l'</SAMP> +<DD> +Encodes the C++ <CODE>long</CODE> type. + +<DT><SAMP>`P'</SAMP> +<DD> +Indicates a pointer type. Followed by the type pointed to. + +<DT><SAMP>`Q'</SAMP> +<DD> +Used to mangle qualified names, which arise from nested classes. +Should also be used for namespaces (?). +In Java used to mangle package-qualified names, and inner classes. + +<DT><SAMP>`r'</SAMP> +<DD> +Encodes the GNU C++ <CODE>long double</CODE> type. + +<DT><SAMP>`R'</SAMP> +<DD> +Indicates a reference type. Followed by the referenced type. + +<DT><SAMP>`s'</SAMP> +<DD> +Encodes the C++ and java <CODE>short</CODE> types. + +<DT><SAMP>`S'</SAMP> +<DD> +A modifier that indicates that the following integer type is signed. +Only used with <CODE>char</CODE>. + +Also used as a modifier to indicate a static member function. + +<DT><SAMP>`t'</SAMP> +<DD> +Indicates a template instantiation. + +<DT><SAMP>`T'</SAMP> +<DD> +A back reference to a previously seen type. + +<DT><SAMP>`U'</SAMP> +<DD> +A modifier that indicates that the following integer type is unsigned. +Also used to indicate that the following class or namespace name +is encoded using Unicode-mangling. + +<DT><SAMP>`v'</SAMP> +<DD> +Encodes the C++ and Java <CODE>void</CODE> types. + +<DT><SAMP>`V'</SAMP> +<DD> +A modified for a <CODE>const</CODE> type or method. + +<DT><SAMP>`w'</SAMP> +<DD> +Encodes the C++ <CODE>wchar_t</CODE> type, and the Java <CODE>char</CODE> types. + +<DT><SAMP>`x'</SAMP> +<DD> +Encodes the GNU C++ <CODE>long long</CODE> type, and the Java <CODE>long</CODE> type. + +<DT><SAMP>`X'</SAMP> +<DD> +Encodes a template type parameter, when part of a function type. + +<DT><SAMP>`Y'</SAMP> +<DD> +Encodes a template constant parameter, when part of a function type. + +<DT><SAMP>`Z'</SAMP> +<DD> +Used for template type parameters. + +</DL> + +<P> +The letters <SAMP>`G'</SAMP>, <SAMP>`M'</SAMP>, <SAMP>`O'</SAMP>, and <SAMP>`p'</SAMP> +also seem to be used for obscure purposes ... + +</P> +<P><HR><P> +Go to the <A HREF="gxxint_1.html">first</A>, <A HREF="gxxint_14.html">previous</A>, <A HREF="gxxint_16.html">next</A>, <A HREF="gxxint_16.html">last</A> section, <A HREF="gxxint_toc.html">table of contents</A>. +</BODY> +</HTML> |