GCC 7.0 vs. 6.3 vs. 5.4 vs. 4.9 Compiler Benchmarks On Linux x86_64

In many of the benchmarks there was little change in the results, so for most of those results I have left them out but you can view them all if desired via the OpenBenchmarking.org result file.

HPC challenge's EP-STREAM Triad performance appears to be getting slower with each succeeding GCC release.

With some Parboil OpenMP workloads, we're seeing GCC 6/7 being faster than GCC 5/4.

Rodinia also saw some significant gains with GCC 6 while with GCC 7 the gains are basically just maintained.