CL 541715 added an optimization to copy SSA-able variables.
When handling m[k] = append(m[k], ...) case, it uses ir.SameSafeExpr to
check that m[k] expressions are the same, then doing type assertion to
convert the map index to ir.IndexExpr node. However, this assertion is
not safe for m[k] expression in append(m[k], ...), since it may be
wrapped by ir.OCONVNOP node.
Fixing this by un-wrapping any ir.OCONVNOP before doing type assertion.
Fixes#66096
Change-Id: I9ff7165ab97bc7f88d0e9b7b31604da19a8ca206
Reviewed-on: https://go-review.googlesource.com/c/go/+/569716
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
