binutils: c++filt
9 c++filt
*********
c++filt [-_|--strip-underscore]
[-n|--no-strip-underscore]
[-p|--no-params]
[-t|--types]
[-i|--no-verbose]
[-r|--no-recurse-limit]
[-R|--recurse-limit]
[-s FORMAT|--format=FORMAT]
[--help] [--version] [SYMBOL...]
The C++ and Java languages provide function overloading, which means
that you can write many functions with the same name, providing that
each function takes parameters of different types. In order to be able
to distinguish these similarly named functions C++ and Java encode them
into a low-level assembler name which uniquely identifies each different
version. This process is known as "mangling". The 'c++filt' (1)
program does the inverse mapping: it decodes ("demangles") low-level
names into user-level names so that they can be read.
Every alphanumeric word (consisting of letters, digits, underscores,
dollars, or periods) seen in the input is a potential mangled name. If
the name decodes into a C++ name, the C++ name replaces the low-level
name in the output, otherwise the original word is output. In this way
you can pass an entire assembler source file, containing mangled names,
through 'c++filt' and see the same source file containing demangled
names.
You can also use 'c++filt' to decipher individual symbols by passing
them on the command line:
c++filt SYMBOL
If no SYMBOL arguments are given, 'c++filt' reads symbol names from
the standard input instead. All the results are printed on the standard
output. The difference between reading names from the command line
versus reading names from the standard input is that command-line
arguments are expected to be just mangled names and no checking is
performed to separate them from surrounding text. Thus for example:
c++filt -n _Z1fv
will work and demangle the name to "f()" whereas:
c++filt -n _Z1fv,
will not work. (Note the extra comma at the end of the mangled name
which makes it invalid). This command however will work:
echo _Z1fv, | c++filt -n
and will display "f(),", i.e., the demangled name followed by a
trailing comma. This behaviour is because when the names are read from
the standard input it is expected that they might be part of an
assembler source file where there might be extra, extraneous characters
trailing after a mangled name. For example:
.type _Z1fv, @function
'-_'
'--strip-underscore'
On some systems, both the C and C++ compilers put an underscore in
front of every name. For example, the C name 'foo' gets the
low-level name '_foo'. This option removes the initial underscore.
Whether 'c++filt' removes the underscore by default is target
dependent.
'-n'
'--no-strip-underscore'
Do not remove the initial underscore.
'-p'
'--no-params'
When demangling the name of a function, do not display the types of
the function's parameters.
'-t'
'--types'
Attempt to demangle types as well as function names. This is
disabled by default since mangled types are normally only used
internally in the compiler, and they can be confused with
non-mangled names. For example, a function called "a" treated as a
mangled type name would be demangled to "signed char".
'-i'
'--no-verbose'
Do not include implementation details (if any) in the demangled
output.
'-r'
'-R'
'--recurse-limit'
'--no-recurse-limit'
'--recursion-limit'
'--no-recursion-limit'
Enables or disables a limit on the amount of recursion performed
whilst demangling strings. Since the name mangling formats allow
for an inifinite level of recursion it is possible to create
strings whose decoding will exhaust the amount of stack space
available on the host machine, triggering a memory fault. The
limit tries to prevent this from happening by restricting recursion
to 2048 levels of nesting.
The default is for this limit to be enabled, but disabling it may
be necessary in order to demangle truly complicated names. Note
however that if the recursion limit is disabled then stack
exhaustion is possible and any bug reports about such an event will
be rejected.
The '-r' option is a synonym for the '--no-recurse-limit' option.
The '-R' option is a synonym for the '--recurse-limit' option.
'-s FORMAT'
'--format=FORMAT'
'c++filt' can decode various methods of mangling, used by different
compilers. The argument to this option selects which method it
uses:
'auto'
Automatic selection based on executable (the default method)
'gnu'
the one used by the GNU C++ compiler (g++)
'lucid'
the one used by the Lucid compiler (lcc)
'arm'
the one specified by the C++ Annotated Reference Manual
'hp'
the one used by the HP compiler (aCC)
'edg'
the one used by the EDG compiler
'gnu-v3'
the one used by the GNU C++ compiler (g++) with the V3 ABI.
'java'
the one used by the GNU Java compiler (gcj)
'gnat'
the one used by the GNU Ada compiler (GNAT).
'--help'
Print a summary of the options to 'c++filt' and exit.
'--version'
Print the version number of 'c++filt' and exit.
_Warning:_ 'c++filt' is a new utility, and the details of its user
interface are subject to change in future releases. In particular,
a command-line option may be required in the future to decode a
name passed as an argument on the command line; in other words,
c++filt SYMBOL
may in a future release become
c++filt OPTION SYMBOL
---------- Footnotes ----------
(1) MS-DOS does not allow '+' characters in file names, so on MS-DOS
this program is named 'CXXFILT'.
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