cmd/compile: miscompilation of codependent global `var` assigments in go1.12 [1.12 backport]

[gopherbot]

@cherrymui requested issue #30977 to be considered for backport to the next 1.12 minor release.

@gopherbot please backport this to Go 1.12.

[gopherbot]

Change https://golang.org/cl/168817 mentions this issue: [release-branch.go1.12] cmd/compile: copy volatile values before emitting write barrier call

[thaJeztah]

@randall77 I saw you reviewed https://golang.org/cl/168817 - does that mean this should be labeled CherryPickApproved ?

[randall77]

No, that's still a call for the release guys to make.

Feel free to add pro-backport arguments to this issue.
I think it should be backported - it's a nasty bug with no easy workaround, and it was triggered in the wild.

[thaJeztah]

Thanks for explaining (and apologies for being a bit noisy 🤗)

For our next release, this one is definitely a show-stopper, as the result is unpredictable. Timing is a bit unfortunate as we'll have to decide to proceed with Go 1.12, or revert all repositories to Go 1.11.

@bradfitz (I saw you applied the labels on other issues; so hope you're the right person to ask); ptal

[thaJeztah]

For my information; Is there any documentation about the Go release procedure? (or a mailinglist / meeting people can attend to stay informed?)

[randall77]

https://github.com/golang/go/wiki/MinorReleases

[randall77]

Also https://github.com/golang/go/wiki/Go-Release-Cycle

[thaJeztah]

Awesome, thanks!

[gopherbot]

Closed by merging 8acc2ea to release-branch.go1.12.