runtime: optimize duffcopy on amd64
Use movups to copy 16 bytes at a time.
Results (haswell):
name old time/op new time/op delta
CopyFat8-48 0.62ns ± 3% 0.63ns ± 3% ~ (p=0.535 n=20+20)
CopyFat12-48 0.92ns ± 2% 0.93ns ± 3% ~ (p=0.594 n=17+18)
CopyFat16-48 1.23ns ± 2% 1.23ns ± 2% ~ (p=0.839 n=20+19)
CopyFat24-48 1.85ns ± 2% 1.84ns ± 0% -0.48% (p=0.014 n=19+20)
CopyFat32-48 2.45ns ± 0% 2.45ns ± 1% ~ (p=1.000 n=16+16)
CopyFat64-48 3.30ns ± 2% 2.14ns ± 1% -35.00% (p=0.000 n=20+18)
CopyFat128-48 6.05ns ± 0% 3.98ns ± 0% -34.22% (p=0.000 n=18+17)
CopyFat256-48 11.9ns ± 3% 7.7ns ± 0% -35.87% (p=0.000 n=20+17)
CopyFat512-48 23.0ns ± 2% 15.1ns ± 2% -34.52% (p=0.000 n=20+18)
CopyFat1024-48 44.8ns ± 1% 29.8ns ± 2% -33.48% (p=0.000 n=17+19)
Change-Id: I8a78773c656d400726a020894461e00c59f896bf
Reviewed-on: https://go-review.googlesource.com/14836
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
diff --git a/src/runtime/mkduff.go b/src/runtime/mkduff.go
index 41caa72..9187666 100644
--- a/src/runtime/mkduff.go
+++ b/src/runtime/mkduff.go
@@ -84,11 +84,11 @@
// for some reason that is 3.5x slower than this code.
// The STOSQ in duffzero seem fine, though.
fmt.Fprintln(w, "TEXT runtime·duffcopy(SB), NOSPLIT, $0-0")
- for i := 0; i < 128; i++ {
- fmt.Fprintln(w, "\tMOVQ\t(SI), CX")
- fmt.Fprintln(w, "\tADDQ\t$8, SI")
- fmt.Fprintln(w, "\tMOVQ\tCX, (DI)")
- fmt.Fprintln(w, "\tADDQ\t$8, DI")
+ for i := 0; i < 64; i++ {
+ fmt.Fprintln(w, "\tMOVUPS\t(SI), X0")
+ fmt.Fprintln(w, "\tADDQ\t$16, SI")
+ fmt.Fprintln(w, "\tMOVUPS\tX0, (DI)")
+ fmt.Fprintln(w, "\tADDQ\t$16, DI")
fmt.Fprintln(w)
}
fmt.Fprintln(w, "\tRET")
