Binary crashes under dtrace
When I'm trying to attach to the simple binary with DTrace command (`sudo dtrace -n 'pid$1:::' `ps aux | grep FibbSlow | grep -v grep | awk '{print $2}'` `) it crashes with various outcomes. This happens on both GHC 8.4.3 from `stack` and manually built ghc from the master branch.
Crashes:
```
lastg-mbp:t lastg$ ./FibbSlow.master 55
FibbSlow.master: internal error: scavenge: unimplemented/strange closure type 13369548 @ 0x420021abb0^[[B
(GHC version 8.7.20180817 for x86_64_apple_darwin)
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
```
```
lastg-mbp:t lastg$ ./FibbSlow.stack.8.4 55
FibbSlow.stack.8.4: internal error: scavenge_one: strange object 13369548
(GHC version 8.4.3 for x86_64_apple_darwin)
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
Abort trap: 6
```
```
lastg-mbp:t lastg$ ./FibbSlow.stack.8.4 55
FibbSlow.stack.8.4: internal error: scavenge_one: strange object 13369548
(GHC version 8.4.3 for x86_64_apple_darwin)
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
Abort trap: 6
```
```
lastg-mbp:t lastg$ ./FibbSlow.stack.8.4 55
Segmentation fault: 11
```
Source code for the binary:
https://gist.github.com/last-g/cfddab60a8520eb51214ef2a7bc48ec2
<details><summary>Trac metadata</summary>
| Trac field | Value |
| ---------------------- | ------------ |
| Version | 8.4.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture | |
</details>
<!-- {"blocked_by":[],"summary":"Binary crashes under dtrace","status":"New","operating_system":"","component":"Compiler","related":[],"milestone":"Research needed","resolution":"Unresolved","owner":{"tag":"Unowned"},"version":"8.4.3","keywords":["crash","dtrace,"],"differentials":[],"test_case":"","architecture":"","cc":[""],"type":"Bug","description":"When I'm trying to attach to the simple binary with DTrace command ({{{sudo dtrace -n 'pid$1:::' `ps aux | grep FibbSlow | grep -v grep | awk '{print $2}'` }}}) it crashes with various outcomes. This happens on both GHC 8.4.3 from `stack` and manually built ghc from the master branch.\r\n\r\nCrashes:\r\n\r\n{{{\r\nlastg-mbp:t lastg$ ./FibbSlow.master 55\r\nFibbSlow.master: internal error: scavenge: unimplemented/strange closure type 13369548 @ 0x420021abb0^[[B\r\n (GHC version 8.7.20180817 for x86_64_apple_darwin)\r\n Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug\r\n}}}\r\n\r\n{{{\r\nlastg-mbp:t lastg$ ./FibbSlow.stack.8.4 55\r\nFibbSlow.stack.8.4: internal error: scavenge_one: strange object 13369548\r\n (GHC version 8.4.3 for x86_64_apple_darwin)\r\n Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug\r\nAbort trap: 6\r\n}}}\r\n\r\n{{{\r\nlastg-mbp:t lastg$ ./FibbSlow.stack.8.4 55\r\nFibbSlow.stack.8.4: internal error: scavenge_one: strange object 13369548\r\n (GHC version 8.4.3 for x86_64_apple_darwin)\r\n Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug\r\nAbort trap: 6\r\n}}}\r\n\r\n{{{\r\nlastg-mbp:t lastg$ ./FibbSlow.stack.8.4 55\r\nSegmentation fault: 11\r\n}}}\r\n\r\nSource code for the binary:\r\nhttps://gist.github.com/last-g/cfddab60a8520eb51214ef2a7bc48ec2","type_of_failure":"OtherFailure","blocking":[]} -->
issue