len(map) is lowered to loading the first field of the map
structure, which is the length. Currently it is a load of an int.
With the old map, the first field is indeed an int. With Swiss
map, however, it is a uint64. On big-endian 32-bit machine,
loading an (32-bit) int from a uint64 would load just the high
bits, which are (probably) all 0. Change to a load with the proper
type.
Fixes #70248.
Change-Id: I39cf2d1e6658dac5a8de25c858e1580e2a14b894
Reviewed-on: https://go-review.googlesource.com/c/go/+/638375
Run-TryBot: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Keith Randall <khr@google.com> Reviewed-by: Keith Randall <khr@golang.org>