Calling the ProtoReflect method of the newly-constructed
message avoids an allocation in MessageInfo.MessageOf in
the common case of a generated message with an optimized
ProtoReflect method.
Benchmark for creating an empty message, darwin/arm64 M1 laptop:
name old time/op new time/op delta
EmptyMessage/New-10 32.1ns ± 2% 23.7ns ± 2% -26.06% (p=0.000 n=10+9)
name old alloc/op new alloc/op delta
EmptyMessage/New-10 64.0B ± 0% 48.0B ± 0% -25.00% (p=0.000 n=10+10)
name old allocs/op new allocs/op delta
EmptyMessage/New-10 2.00 ± 0% 1.00 ± 0% -50.00% (p=0.000 n=10+10)
Change-Id: Ifa3c3ffa8edc76f78399306d0f4964eae4aacd28
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/418677
Reviewed-by: Michael Stapelberg <stapelberg@google.com>
Reviewed-by: Lasse Folger <lassefolger@google.com>