Add a new helper type 'ReassignOracle', useful for doing "batch mode"
reassignment analysis, e.g. deciding whether a given ir.Name or (chain
of connected names) has a single definition and is never reassigned.
The intended usage model is for clients to create/initialize a
ReassignOracle for a given function, then make a series of queries
using it (with the understanding that changing/mutating the func body
IR can invalidate the info cached in the oracle). This oracle is
intended to provide the same sort of analysis that ir.StaticValue and
ir.Reassigned carry out, but at a much reduced cost in compile
time.
Notes:
- the new helper isn't actually used for anything useful in this
patch; it will be hooked into the inline heuristics code as part of
a subsequent CL.
- this is probably not an ideal long-term solution; it would be better
to switch to a scheme based a flag on ir.Name, as opposed to a
side table.
Change-Id: I283e748e440a9f595df495f6aa48ee9c498702d9
Reviewed-on: https://go-review.googlesource.com/c/go/+/539319 Reviewed-by: Matthew Dempsky <mdempsky@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>