Go: x/build: add builder for macOS on Apple silicon

[cagedmantis]

Apple has announced plans to transition their Mac platform to run on Apple silicon chips. A set of builders would be needed for the resulting port.

/cc @andybons @dmitshur @toothrot

[cagedmantis]

38485 Tracks related changes to the runtime.

[dmitshur]

This issue corresponds to the following bullet points in https://golang.org/wiki/PortingPolicy#requirements-for-a-new-port:

• A developer must be named (and agree) to maintain the builder, the machine trying each git revision and providing data for https://build.golang.org.

• The builder must already be running (and failing, because the code is not yet in the main repository).

[eacp]

What about Universal Binaries?

[toothrot]

Hey @eacp, broader support for the new architecture will be discussed on a separate issue. This issue is just about our build infrastructure. Thanks!

[tzeejay]

@toothrot Hey I have just received my DTK earlier today. Is there anything I can do to help the project with adoption of the architecture or help build prebuilt packages? I just installed the darwin-amd64 macOS package from golang.org and it took a bit to install but succeeded and go version is giving me this:

cj@cjs-Mac ~ % go version
go version go1.14.4 darwin/amd64

(I used to work for CircleCI and helped maintain the macOS infrastructure so I have a little bit of experience with this but I am entirely clueless as to what is required for Go)

[dmitshur]

@tzeejay Thanks for the offer to help! We're currently in the release freeze period for Go 1.15, so active work on this will likely wait until the tree re-opens in a bit over a month from now. Also follow issue #38485 for any port-specific updates. We'll reach out to you if we find a way you can contribute.

Based on what you said, it seems like the darwin/amd64 port is working via Rosetta 2, which is great to see.

[tzeejay]

To be honest I have not yet had the time to compile the projects that I am working on for work (neither Objective-C nor Go).

Overall the system feels exactly like presented in the keynote. I can't wait to have code running on this that was actually compiled for it.
I am too young to have gone through an architecture transition like this so I am not sure where to begin. Once there is headroom to tackle this problem I would be very much interested in helping though 👍

[tzeejay]

Little update for anybody interested.

1. It does compile x86_64 code which can be executed through Rosetta 2 on the Mac itself. I develop our central server backend that way on my 16" MacBook Pro, and then deploy to Linux. Everything feels equivalent to a build on an Intel Mac.

2. It successfully cross compiles to Linux x86_64.
   Granted I haven't added any crazy dependencies to it. It mostly depends on lib/pg and julienschmidt/httprouter.
   It is interesting to see though that this is possible at all with a regular release of Go from the website compiled for a foreign architecture.

[eaglemoor]

Will be cool see native support M1 and what happen with Docker xD
M1 is out!

[bcmills]

Come to think of it, we should probably have two builder configurations, at least in the short term: one running native GOARCH=arm64 binaries, and one running GOARCH=amd64 binaries under Rosetta 2 (to catch issues like #42700).

[tzeejay]

@bcmills No idea where your CI currently runs. I used to work at macstadium.com . They ordered 600 M1 based Mac minis. Let me know if I should establish a connection for these machines

[aclements]

Once we do have builders for this, we should make sure they have mingw-llvm installed and that its GCC compatibility wrapper is in PATH (see the comments on CL 271178).

[bcmills]

(@aclements, was that last comment intended for #38607?)

[dmitshur]

@tzeejay Thanks. We do use MacStadium, as you can see at https://github.com/golang/build/tree/master/env/darwin/macstadium. @cagedmantis reached out to them on November 10, and we are now waiting for the new machines to become available.

[gopherbot]

Change https://golang.org/cl/278432 mentions this issue: dashboard: add new darwin-arm64-11_0-toothrot builder

[gopherbot]

Change https://golang.org/cl/278772 mentions this issue: dashboard: remove known issue for darwin arm builder