cmd/compile,runtime: found pointer to free object on linux-amd64-noopt

[mknyszek]

2022-09-02T20:14:40-3e11e61/linux-amd64-noopt
2022-09-02T19:22:26-0fda8b1/linux-amd64-noopt

Since I only saw this failure mode on the noopt builders, I figure it's some kind of compiler/runtime interaction.

CC @golang/compiler @golang/runtime

[bcmills]

greplogs -l -e '\nfatal error: found pointer to free object' --since=2022-08-01 --omit=js-wasm\|plan9-arm
2022-09-02T20:14:40-3e11e61/linux-amd64-noopt
2022-09-02T19:22:26-0fda8b1/linux-amd64-noopt
2022-08-22T11:49:45-761db3e/linux-amd64-noopt
2022-08-09T16:09:24-e1a8e0e/solaris-amd64-oraclerel

[bcmills]

greplogs -l -e '\nfatal error: found pointer to free object' --since=2022-09-06 --omit=js-wasm\|plan9-arm\|openbsd
2022-09-08T14:33:43-c263fa0/linux-amd64-noopt
2022-09-07T01:48:31-ba1ef54/linux-amd64-noopt

[bcmills]

Marking as release-blocker because this very much looks to be a Go 1.20 regression.