### 6.2 Top Level Source Directory

The top level source directory in a GCC distribution contains several files and directories that are shared with other software distributions such as that of GNU Binutils. It also contains several subdirectories that contain parts of GCC and its runtime libraries:

`boehm-gc`
  The Boehm conservative garbage collector, used as part of the Java runtime library.
`contrib`
  Contributed scripts that may be found useful in conjunction with GCC. One of these, `contrib/texi2pod.pl`, is used to generate man pages from Texinfo manuals as part of the GCC build process.
`fastjar`
  An implementation of the `jar` command, used with the Java front end.
`gcc`
  The main sources of GCC itself (except for runtime libraries), including optimizers, support for different target architectures, language front ends, and testsuites. See The `gcc` Subdirectory, for details.
`include`
  Headers for the `libiberty` library.
`libada`
  The Ada runtime library.
`libcpp`
  The C preprocessor library.
`libgfortran`
  The Fortran runtime library.
`libffi`
  The `libffi` library, used as part of the Java runtime library.
`libiberty`
  The `libiberty` library, used for portability and for some generally useful data structures and algorithms. See Introduction, for more information about this library.
`libjava`
  The Java runtime library.
`libmudflap`
  The `libmudflap` library, used for instrumenting pointer and array dereferencing operations.
`libobjc`
  The Objective-C and Objective-C++ runtime library.
`libstdc++-v3`
  The C++ runtime library.
`maintainer-scripts`
  Scripts used by the `gccadmin` account on `gcc.gnu.org`.
`zlib`
  The `zlib` compression library, used by the Java front end and as part of the Java runtime library.

The build system in the top level directory, including how recursion into subdirectories works and how building runtime libraries for multilibs is handled, is documented in a separate manual, included with GNU Binutils. See GNU configure and build system, for details.