Some intrinsic functions map directly to library functions, and in most cases the name of the library function used depends on the type of the arguments. For some intrinsics we generate inline code, and for others, such as sin, cos and sqrt, we rely on the backend to use special instructions in the floating point unit of the CPU if available, or to fall back to a call to libm if these are not available.
Implementation of some non-elemental intrinsic functions (eg. DOT_PRODUCT, AVERAGE) is not yet optimal. This is hard because we have to make decisions whether to use inline code (good for small arrays as no function call overhead occurs) or generate function calls (good for large arrays as it allows use of hand-optimized assembly routines, SIMD instructions, etc.)
The IO library is still under development. The following features should be usable for real programs:
Usable with bugs:
Many Fortran programs only use a small subset of the available IO capabilities, so your mileage may vary.