cmd/compile: keep all open-coded defer slots as used
Open-coded defer slots are assigned indices upfront, so they're
logically like elements in an array. Without reassigning the indices,
we need to keep all of the elements alive so their relative offsets
are correct.
Fixes #61895.
Change-Id: Ie0191fdb33276f4e8ed0becb69086524fff022b2
Reviewed-on: https://go-review.googlesource.com/c/go/+/517856 Reviewed-by: Keith Randall <khr@google.com> Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>