encoding/binary: speed up Size
Size() is currently not called from the fast path, since the package
handles the buffer sizing for Read and Write internally. This will change
when adding Append() because callers can use Size to avoid allocations when
writing into bytes.Buffer via AvailableBuffer for example.
Add a fast path for simple types and extend the existing struct size cache
to arrays of structs.
Change-Id: I3af16a2b6c9e2dbe6166a2f8c96bcd2e936719e2
Reviewed-on: https://go-review.googlesource.com/c/go/+/584358
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Austin Clements <austin@google.com>