sandbox executions?

[Gankra]

Right now we build DLLs and load them into the test harness. If a test is mega-busted this can result in corrupting the harness or just locking it up. In an ideal world we would maybe instead build binaries that do ipc or write out a file to disk, so that the test harness could survive crashes or timeout a hung test.

Of course it would also be nice if we could literally sandbox the tests and prevent them from doing anything interesting, since all they ever need to be able to do is call a set of specific functions. They don't need i/o of any kind except to send the harness a report.

[Gankra]

The prophecies are fulfilled: in #65 cranelift<->rustc with OptionU128 fully SIGILL's during execution, making the whole harness suddenly hard-abort, as the SIGILL is in our process.