cmd/compile/internal/inline: analyze function param properties
Add code to analyze properties of function params, specifically
heuristics to look for cases where unmodified params feed into "if"
and "switch" statements in ways that might enable constant folding
and/or dead code elimination if the call were inlined at a callsite
that passes a constant to the correct param. We also look for cases
where a function parameter feeds unmodified into an interface method
call or indirect call.
Updates #61502.
Change-Id: Iaf7297e19637daeabd0ec72be88d654b545546ae
Reviewed-on: https://go-review.googlesource.com/c/go/+/511561
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Matthew Dempsky <mdempsky@google.com>