It would be nice if the compiler could figure this out (both for *new(T) and zeroT). When 61372 is implemented it will certainly be easier to just detect the zero builtin. Perhaps we should just wait for that.
On Monday, August 14, 2023 at 5:31:16 PM UTC-7 Diego Augusto Molina wrote: > Thank you very much, that's actually what I was looking for. > > On Monday, 14 August 2023 at 13:57:35 UTC-3 Axel Wagner wrote: > >> You might be interested in https://github.com/golang/go/issues/61372 >> >> On Mon, Aug 14, 2023 at 3:52 PM Diego Augusto Molina < >> diegoaugu...@gmail.com> wrote: >> >>> Hi, thank you for reading. Whenever I need to use a zero value for a >>> generic type in a func I do something like the following: >>> >>> <code> >>> func SetZero[T any](pt *T) T { >>> var zeroT T >>> *pt = zeroT >>> } >>> </code> >>> >>> That's all good, but I wonder how, if possible, it could be proved to >>> the compiler that zeroT is the zero value for T. That would be to >>> enable memclr optimization when bulk setting slice or array values to the >>> zero value of their element type. Currently, as of 1.21, this only works >>> when the src is a constant holding the zero value of the type. I also tried >>> with something like *new(T), and it doesn't work either. But proving >>> that the expression *new(T) in the src is the zero value for the type >>> could potentially be easier than checking back if a certain variable (e.g. >>> zeroT in the example) hasn't yet been reassigned or initialized to a >>> non-zero value. >>> Also, as there's no guarantee of what would T could hold, it could use >>> memclrHasPointers if that makes sense, which seems like a fare tradeoff >>> at least for now if we want to play with slices with generic element type. >>> For reference, this is the code I'm trying: >>> >>> <code> >>> package main >>> // file generic_slice_element_type_memclr.go >>> >>> func clear[T any](s []T) { >>> for i := range s { >>> s[i] = *new(T) >>> } >>> } >>> >>> func main() { >>> clear([]int{1, 2, 3}) >>> } >>> </code> >>> >>> And I'm compiling it with: >>> >>> <code> >>> $ go version >>> go version go1.21.0 darwin/amd64 >>> $ go tool compile -S generic_slice_element_type_memclr.go >>> ... >>> </code> >>> >>> Kind regards. >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "golang-nuts" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to golang-nuts...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/golang-nuts/b8ec1335-911c-42ed-96ce-a4b50153b8c9n%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/golang-nuts/b8ec1335-911c-42ed-96ce-a4b50153b8c9n%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/a5b9c2d8-d715-4829-bfc8-c47384979f21n%40googlegroups.com.
