GCC 9 Compiler Tuning Benchmarks On Intel Skylake AVX-512

With the FFTW benchmarks is an area where the Skylake-AVX512 tuning really pays off with the AVX-512 optimized builds yielding around 14% better performance than simply the Skylake tuned binaries. Hitting at least the -O2 optimization level delivered most of the performance gains with -O3 not helping out much more. Compared to "-O3 -march=x86-64" for generic Linux 64-bit binaries, the Skylake-AVX512 tuning yielded an improvement for this FFT benchmark of 55%.

Granted, the compiler tuning doesn't help out all C/C++ workloads.

Link-time optimizations were a big help to the BYTE benchmark.

The SciMark2 C benchmarks also do a good job usually showing the performance impact of different optimization levels.