tree 083a15c0a31a1236aaa612177b88d7c7789ef59b
parent 8a45e6cdbd0a41a18463e79cd29055c258493c21
author Tim King <taking@google.com> 1718053223 -0700
committer Tim King <taking@google.com> 1718989197 +0000

go/ssa: wait for shared functions to finish building

Package.Build and Program.MethodValue can create and build
Functions that may be depended on by other calls to
Package.Build and Program.MethodValue. Both of these
APIs now wait for any Functions that are shared and depended
on to finish building before returning.

This fixes some data races observed when accessing the Blocks
field of shared functions.

Functions that are members of Packages (fn.Pkg != nil)
are still always built by fn.Pkg.Build().

These dependencies can be create cycles between public API
calls that both depend on Functions the other is building.
For example, both the "net/http" and "internal/trace/testtrace"
packages both depend on slices.Contains[[]string,string] and
slices.Index[[]string, string]. Under some schedules, building
both packages may need to wait for the other package to finish
building before finishing.

This introduces a new internal type task. tasks
allows for waiting on the transitive closure of builders iterating
to be marked as done before proceedind.

Also:
- Add a test that reliably reproduces the data race.
- Refactors creator.add calls to happen after the function is created.
- Merges creator into builder.
- Updates the builder to mark when it is done building and wait
  for dependencies.
- Define type unit = struct{} and clean up.

Fixes golang/go#67079

Change-Id: I34d2b8730b19609f5fbf6b55b3db33f59818a17b
Reviewed-on: https://go-review.googlesource.com/c/tools/+/591775
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>