runtime: crashes with "sys: trap: invalid opcode" on plan9/386 #50878
Description
#!watchflakes
post <- builder ~ `^plan9` && `sys: trap: invalid opcode`
greplogs --dashboard -md -l -e 'sys: trap: invalid opcode' --since=2021-01-01
2022-01-27T21:25:18-0f0bbfd-ad345c2/plan9-386-0intro
2022-01-18T21:38:42-71888fe/plan9-386-0intro
2021-07-29T15:30:38-70fd4e4/plan9-386-0intro
2021-03-25T20:57:58-691db37/plan9-386-0intro
2021-01-27T21:04:09-35334ca/plan9-386-0intro
2021-01-27T00:15:06-0f797f1/plan9-386-0intro
2021-01-25T19:32:27-6de8443/plan9-386-0intro
2021-01-19T12:07:43-9fed39d/plan9-386-0intro
This failure mode may be closely related to #50137.
(CC @0intro)