Optimized retargetable compiler for embedded processors - GCC vs LLVM

Retargetable compilers become more and more popular as they are involved even in the processors design phase. The reduced time-to-market period puts a challenge on optimized retargetable compilers. An optimized retargetable compiler gives a reliable feedback to tailor processors towards a certain application domain. The first choice in choosing a retargetable compiler may be an open-source one. This paper aims to compare two well-known open-source compilers: GCC and LLVM. The first is a mature compiler, retargeted for more than 100 processors, while the second is a new one, retargeted for less than 10 processors, but built on a very promising approach, one big plus being the latest release of Redhat (Linux operating system) which replaced the previously used GCC with LLVM. The paper compares the two compilers from both easiness of retargetability and the target specific optimizations enablement.