I get a 16 diff too, but I'm seeing 3 5 7 on gcc on High Sierra with a 2013 Macbook Pro. I'm using gcc 8.2.0 installed via Homebrew. Did you run gcc-8 with the

I get a 16 diff too, but I'm seeing 3 5 7 on gcc on High Sierra with a 2013 Macbook Pro. I'm using gcc 8.2.0 installed via Homebrew. Did you run gcc-8 with the -O3 flag?