GCCLLVM

GCCLLVM is a term used in technical discussions to describe an experimental or conceptual effort to bridge the GNU Compiler Collection (GCC) with the LLVM project. The idea centers on combining GCC’s mature language frontends and optimization passes with LLVM’s modular backend and tooling, in order to leverage LLVM’s ecosystem while preserving GCC’s language support.

Historically, there have been concrete attempts that frame the same goal from different angles. llvm-gcc was an early project that used LLVM as the back end for GCC’s front end, effectively marrying GCC’s frontend with LLVM’s backend. DragonEgg was a separate effort that provided a GCC plug-in to translate GCC’s intermediate representations into LLVM IR, enabling the use of LLVM passes on GCC-derived code. These endeavors illustrate both the interest in cross-pollinating GCC and LLVM and the technical challenges involved.

Approaches attributed to a GCCLLVM concept include generating LLVM IR from GCC’s middle-end representations, reusing GCC optimization passes within the LLVM workflow, or building an interoperability layer that allows GCC-frontends to target LLVM’s back end and toolchain. The potential benefits include access to LLVM’s growing suite of optimizations, sanitizers, debuggers, and instrumentation tools, as well as easier interoperability with non-GCC toolchains.

Challenges are substantial. Licensing compatibility, maintaining two large codebases, potential performance inconsistencies, and the complexity of aligning GCC’s and LLVM’s internal representations pose significant hurdles. As of now, GCCLLVM is not an official project of GCC or LLVM, and no widely adopted implementation exists. The prevailing paths in practice remain GCC for certain toolchains and clang/LLVM for others, with historical experiments like llvm-gcc and DragonEgg providing context for the ongoing discussion. See also GCC, LLVM, clang, llvm-gcc, DragonEgg.