GNU Compiler Collection

The GNU Compiler Collection (GCC) is a compiler system produced by the GNU Project supporting various programming languages. GCC is a key component of the GNU toolchain. As well as being the official compiler of the unfinished GNU operating system, GCC has been adopted as the standard compiler by most other modern Unix-like computer operating systems, including Linux, the BSD family and Mac OS X.

GCC has been ported to a wide variety of processor architectures, and is widely deployed as a tool in commercial, proprietary and closed source software development environments. GCC is also available for most embedded platforms, for example Symbian (called gcce), AMCC and Freescale Power Architecture-based chips. The compiler can target a wide variety of platforms, including videogame consoles such as the PlayStation 2 and Dreamcast. Several companies make a business out of supplying and supporting GCC ports to various platforms, and chip manufacturers today consider a GCC port almost essential to the success of an architecture.

Originally named the GNU C Compiler, because it only handled the C programming language, GCC 1.0 was released in 1987, and the compiler was extended to compile C++ in December of that year. Front ends were later developed for Fortran, Pascal, Objective-C, Java, and Ada, among others.

The Free Software Foundation (FSF) distributes GCC under the GNU General Public License (GNU GPL). GCC has played an important role in the growth of free software, as both a tool and an example.

GCC stable release

The current stable version of GCC is 4.6.1, which was released on June 27, 2011.

GCC 4.6 supports many new Objective-C features, such as declared and synthesized properties, dot syntax, fast enumeration, optional protocol methods, method/protocol/class attributes, class extensions and a new GNU Objective-C runtime API. It also supports the Go programming language and includes the libquadmath library, which provides quadruple-precision mathematical functions on targets supporting the __float128 datatype. The library is used to provide the REAL(16) type in GNU Fortran on such targets.

The previous major version, 4.5, was initially released on April 14, 2010 (last minor version is 4.5.2, released on December 16, 2010). It included several minor new features (new targets, new language dialects) and a couple major new features:

• Link-time optimization optimizes across object file boundaries to directly improve the linked binary. Link-time optimization relies on an intermediate file containing the serialization of some -Gimple- representation included in the object file. The file is generated alongside the object file during source compilation. Each source compilation generates a separate object file and link-time helper file. When the object files are linked, the compiler is executed again and uses the helper files to optimize code across the separately compiled object files.
• Plugins can extend the GCC compiler directly. Plugins allow a stock compiler to be tailored to specific needs by external code loaded as plugins. For example, plugins can add, replace, or even remove middle–end passes operating on Gimple representations. Several GCC plugins have already been published, notably:
  • TreeHydra to help with Mozilla code development
  • DragonEgg to use the GCC front-end with LLVM
  • MELT (site GCC MELT) to enable coding GCC extensions in a lispy domain-specific language providing powerful Pattern-matching
  • MILEPOST CTuning to use machine learning techniques to tune the compiler.