Earlier this week I published some GCC 5.4 vs. GCC 6.2 vs. GCC 7.0 SVN development benchmarks with a Core i7 6800K Broadwell-E system. For those curious how the LLVM Clang compiler stack is comparing, here are some tests on the same system when running fresh benchmarks of LLVM Clang 3.9 as well as LLVM Clang 4.0 SVN.
These tests were done with LLVM Clang 3.9 and 4.0 SVN added in to the GCC results from this Core i7 6800K system running Ubuntu 16.10 with the Linux 4.8 kernel. The CFLAGS/CXXFLAGS were maintained the same throughout all testing with the "-O3 -march=native" flags.
All of these C/C++ compiler GCC vs. Clang benchmarks were facilitated in a fully-automated and reproducible manner using the open-source Phoronix Test Suite benchmarking software.