2012/1/4 Manu <turkey...@gmail.com>
> Does returning a tuple give any ABI guarantees? How can I be sure multiple > return values will return in consecutive registers? > What if the return types are of different types, a float and an int... can > I expect each to return in their own register types respectively? > This needs to be defined and loosely guaranteed (within reason) so people > can expect multiple return values to behave as expected on any architecture. > > > On 4 January 2012 01:02, Sean Kelly <s...@invisibleduck.org> wrote: > >> It's easy enough with Tuple, though better language support would be nice. >> >> Sent from my iPhone >> >> On Jan 3, 2012, at 2:40 PM, Manu <turkey...@gmail.com> wrote: >> >> > Why doesn't D support multiple return values like many other modern >> languages? >> > >> > Clearly the same syntax as Go wouldn't work, but I'm sure a neat and >> tidy syntax could be invented? >> > I constantly want to be able to return x,y from a function, or >> retVal,errorCode and I want the language to make some rough ABI guarantees, >> like multiple return values will be returned in consecutive registers, >> rather than a single return value register like C/C++, avoiding the need to >> pass output addresses through ref function parameters (slow!). >> > > Returning multiple values in registers might not always be the best idea from the performance point of view. The caller must make sure the appropriate registers don't hold any intermediate values before calling the function, so overall complier optimization may be poorer. Of course, this only applies when function is actually called. When it is inlined, having multiple return values could result in better optimization.
