cmd/compile: separate inline cost analysis from applying inlining
This CL separates the pass that computes inlinability from the pass
that performs inlinability. In particular, the latter can now happen
in any flat order, rather than bottom-up order. This also allows
inlining of calls exposed by devirtualization.
Change-Id: I389c0665fdc8288a6e25129a6744bfb1ace1eff7
Reviewed-on: https://go-review.googlesource.com/c/go/+/562319
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com> Reviewed-by: Than McIntosh <thanm@google.com>