Compilers front-end ¶
Introduction ¶
LLVM was originally written to be a replacement for the existing code generator in the GCC stack, and many of the GCC front ends have been modified to work with it.
LLVM currently supports compiling of Ada, C, C++, D, Delphi, Fortran, Haskell, Julia, Objective-C, Rust, and Swift using various front ends, some derived from version 4.0.1 and 4.2 of the GNU Compiler Collection (GCC).
Widespread interest in LLVM has led to several efforts to develop new front ends for a variety of languages.
The one that has received the most attention is Clang , a new compiler supporting C, C++, and Objective-C.
Primarily supported by Apple, Clang is aimed at replacing the C/Objective-C compiler in the GCC system with a system that is more easily integrated with integrated development environments (IDEs) and has wider support for multithreading. Support for OpenMP directives has been included in Clang since release 3.8.
The Utrecht Haskell compiler can generate code for LLVM. Though the generator is in the early stages of development, in many cases it has been more efficient than the C code generator.
The Glasgow Haskell Compiler (GHC) has a working LLVM backend that achieves a 30% speed-up of the compiled code relative to native code compiling via GHC or C code generation followed by compiling, missing only one of the many optimizing techniques implemented by the GHC.
Many other components are in various stages of development, including, but not limited to, the Rust compiler, a Java bytecode front end, a Common Intermediate Language (CIL) front end, the MacRuby implementation of Ruby 1.9, various front ends for Standard ML, and a new graph coloring register allocator.