The article compares performance with gcc 7, gcc 8 and llvm 6. This article goes through some of the benchmarks to understand what is measured. Overall, not sure the benchmarks chosen are particularly noteworthy. Some very small (tscp), non-cpu (redis) and some subtests strange (scimark2) but overall at least a few to give a generic comparison without big things standing out in the results.
|Benchmark||Phoronix observations||My observations||Analysis|
|fhourstones||AMD AOCC is fastest.||Single-threaded. High branch misses, also some backend stalls.||Analysis|
|scimark2||Four workloads and AMD AOCC is in position #1 (matrix multiply), #2 (composite), #3 (lu factorization) and #4 (jacobi).||Strange choice of tests since composite is an average of 5 and two others are missing.|
Benchmark is single-threaded with backend stalls being primary limiter.
|tscp||LLVM better than GCC, AOCC slightly slower than llvm 6.||Single-threaded toy benchmark that runs in 1.2 seconds.||Analysis|
|graphics-magick||gcc is better overall than clang; AOCC very close to llvm 6.||On_Cpu is 30%; IPC is moderate with issues varying by workload||Analysis|
|himeno||llvm 6 is fastest and AOCC is slowest.||Single-threaded. Small grid size but still limited by backend memory stalls.||Analysis|
|build-php||AOCC is slowest.||Compiletime performance measurement. Much of the time close to 100% CPU and then slow at the end.||Analysis|
|stockfish||AOCC is fastest.||Frontend stalls with some branch misses as well.||Analysis|
|aobench||GCC is faster with AOCC close.||Single-threaded. Moderately high IPC with some backend stalls.||Analysis|
|encode-flac||AOCC similar to llvm 6 and faster than gcc||Single-threaded. Five short processes run in quick succession. High IPC with some backend stalls.||Analysis|
|encode-mp3||GCC faster and AOCC similar to llvm 6||Single-threaded with some backend stalls.||Analysis|
|redis||AOCC often slightly better||Not CPU bound, short intervals where context switches are most important.||Analysis|
|nginx||All compilers almost the same.||Single-threaded backend server.||Analysis|