2011/3/22 Ian Lance Taylor <i...@google.com>: > roy rosen <roy.1ro...@gmail.com> writes: > >> 2010/10/26 Ian Lance Taylor <i...@google.com>: >>> roy rosen <roy.1ro...@gmail.com> writes: >>> >>>> I am trying to demonstrate my port capabilities. >>>> I am writing an application which needs to use instructions like max >>>> a,b,c,d,e,f where a,b,c are inputs and d,e,f are outputs. >>>> Is that possible to write an intrinsic function for that? >>>> I think not because that means that I need to pass d,e,f by reference >>>> which means that they would be in memory and not in a register as >>>> meant by the instruction. >>> >>> That is correct. An intrinsic function is a normal function. If you >>> want it to have multiple outputs, you need to pass in addresses, or you >>> need to have it return a struct. >>> >>> I'm a bit curious as to why a function named max would have multiple >>> outputs. >>> >>>> Is there any port with such an example? >>> >>> Not to my knowledge. I wrote a private port in which some intrinsics >>> returned a struct, and to keep everything out of memory I added >>> additional intrinsics to retrieve elements of the struct. It's awkward >>> to use but the resulting code is fine. >>> >> Can you please explain how this solution should work? >> First a code with memory accesses would be generated and then >> optimizations would optimize it to use registers directly? > > You build a RECORD_TYPE holding the fields you want to return. You > define the appropriate builtin functions to return that record type.
How is that done? using define_insn? How do I tell it to return a struct? Is there an example I can look at? Roy. > You define another builtin function for each field, which takes the > RECORD_TYPE as its argument and returns the type of the field. In > TARGET_FOLD_BUILTIN you convert the per-field functions into > COMPONENT_REFs. > > Ian >
