https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66511
--- Comment #1 from Georg-Johann Lay <gjl at gcc dot gnu.org> --- (In reply to Matthijs Kooijman from comment #0) > I haven't found a readily available 5.x package yet to test. It's the same. > As you can see, the versions operating on 64 bit values preserve the > 8-bit shift (which is very inefficient on AVR), while the versions > running on 32 bit values simply copy the right registers. Lib functions are used because users complained about bloated 64-bit arithmetic. Notice that indide these 64-bit shift functions byte-shifts are used. > The foo32_16 function still has some useless instructions (r27 and r26 > are not part of the return value, not sure why these are set) but that > is probably an unrelated problem. Yes. > I've marked this with component "target", since I think these > optimizations are avr-specific (or at least not applicable to bigger > architectures).
