cmd/compile: fix a premature-deallocation of state in loopreschedchecks
lastMems is free-ed before it's actually used. This results in the pass
breaking: multiple mem phis will present in the instrumented ssa, and
essentially break tighten
pass(https://cs.opensource.google/go/go/+/master:src/cmd/compile/internal/ssa/tighten.go;l=240).
This CL fix that.
Change-Id: I30cf0c3300ed59d1a15d978757a3840fbe04484d
Reviewed-on: https://go-review.googlesource.com/c/go/+/632516
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: David Chase <drchase@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com>