I know this is an optimization. I'm just seeking why the criterion to apply the optimization is made as the current implementation.
On Sunday, May 23, 2021 at 10:10:59 AM UTC-4 peterGo wrote: > Here, and elsewhere (Strange benchmark results), if you not sure what is > going on then you say that it must be weird, strange, an error, inaccurate, > and so on. The problem appears to be that you are not taking into account > that the Go gc and gccgo compilers are optimizing compilers. > > For your example, > > https://play.golang.org/p/3Cst23vNkKI > > $ go version > go version devel go1.17-cca23a7373 Sat May 22 00:51:17 2021 +0000 > linux/amd64 > $ go run -gcflags='-m -m' tl.2.go > ./tl.2.go:18:6: can inline g with cost 8 as: func() []T { var ts []T; ts = > make([]T, N); return ts } > ./tl.2.go:9:6: can inline main with cost 28 as: func() { var r []T; r = > make([]T, N); println(r[i]); var r1 []T; r1 = g(); println(r1[i]) } > ./tl.2.go:13:15: inlining call to g func() []T { var ts []T; ts = > make([]T, N); return ts } > ./tl.2.go:10:17: make([]T, N) does not escape > ./tl.2.go:13:15: make([]T, N) does not escape > ./tl.2.go:19:18: make([]T, N) escapes to heap: > ./tl.2.go:19:18: flow: ts = &{storage for make([]T, N)}: > ./tl.2.go:19:18: from make([]T, N) (spill) at ./tl.2.go:19:18 > ./tl.2.go:19:18: from ts = make([]T, N) (assign) at ./tl.2.go:19:9 > ./tl.2.go:19:18: flow: ~r0 = ts: > ./tl.2.go:19:18: from return ts (return) at ./tl.2.go:20:5 > ./tl.2.go:19:18: make([]T, N) escapes to heap > > > On Sunday, May 23, 2021 at 5:01:38 AM UTC-4 tapi...@gmail.com wrote: > >> And how to interpret the conflicting messages for the following program? >> >> package main >> >> type T int >> >> const N = 1<<12 >> var i = N - 1 >> >> >> func main() { >> var r = make([]T, N) // make([]T, N) does not escape >> println(r[i]) >> >> var r1 = g() // make([]T, N) does not escape >> println(r1[i]) >> >> } >> >> func g() []T { >> var ts = make([]T, N) // make([]T, N) escapes to heap >> return ts >> } >> >> On Sunday, May 23, 2021 at 4:51:30 AM UTC-4 tapi...@gmail.com wrote: >> >>> In the following code, "make([]T, n)" is reported as escaped. >>> But does it really always escape at run time? >>> Does the report just mean "make([]T, n) possibly escapes to heap"? >>> >>> package main >>> >>> type T int >>> >>> const K = 1<<13 >>> const N = 1<<12 >>> var n = N >>> var i = n-1 >>> >>> func main() { >>> var r = make([]T, N) // make([]T, N) does not escape >>> println(r[i]) >>> >>> var r2 = make([]T, n) // make([]T, n) escapes to heap >>> println(r2[i]) >>> >>> var r3 = make([]T, K) // make([]T, K) escapes to heap >>> println(r3[i]) >>> } >>> >> -- 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/34565fef-a650-4790-8ad2-93fa527e9281n%40googlegroups.com.
