Interestingly, with the HPC Challenge's HPL test, Clang is running much faster than GCC 7.

With the EP-DGEMM test, the Clang performance also was much higher than GCC but for these other HPCC runs the performance was close between these competing compilers.

Clang is a tiny bit slower than GCC with the FFTW performance.

The HMMer scientific benchmark results were dead on between GCC and Clang.