Yep:

 * `noopt`: `-O0`
 * `lowopt`: `-O1`
 * `defaultopt`: `-O2` (also the default is nothing else is specified)
 * `opt`: `-O3`
 * `optarch`: `-xHOST` or `-march=native -mtune=native`

The (default) mapping is in `COMPILER_SHARED_OPTION_MAP` in `easybuild/tools/toolchain/compiler.py`, but can be tweaked by the support module for a particular compiler. Currently, GCC and Intel compilers use the default mapping.