That's a good point, but the -O3 doesn't actually do a whole lot here. I recompiled the Futhark-generated C code with just -O and performance was unchanged. If you look at the generated C code, there isn't really a lot to do either: https://gist.github.com/athas/7c8ffc2620a9406e4bbb0df89f2fc9...
I hope I can assume that RHEL compiles their wc with at least -O.
I hope I can assume that RHEL compiles their wc with at least -O.