Revert "Make raiseIO# produce topRes"
authorDavid Feuer <david.feuer@gmail.com>
Tue, 4 Apr 2017 02:25:55 +0000 (22:25 -0400)
committerDavid Feuer <David.Feuer@gmail.com>
Tue, 4 Apr 2017 02:25:56 +0000 (22:25 -0400)
commite83af07e3d0b65fe6f37806e86d07f3e8dc1b01e
tree79aeba830a6aca1ae260950091e85462d09083fe
parent38f9eadd8e4746c2fabf83045073134f5a554a06
Revert "Make raiseIO# produce topRes"

This reverts commit da4687f63ffe5a6162e3d7856aa53de048dd0f42.

It's not entirely trivial to clean up the dead code this patch
introduced. In particular, when we see

```
case raiseIO# m s of
  s' -> e
```

we want to know that `e` is dead. For scrutinees that are properly
bottom (which we don't want to consider `raiseIO# m s` to be, this
is handled by rewriting `bot` to `case bot of {}`. But if we do
that for `raiseIO#`, we end up with

```
case raiseIO# m s of {}
```

which looks a lot like bottom and could confuse demand analysis.
I think we need to wait with this change until we have a more
complete story.

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3413
compiler/prelude/primops.txt.pp
testsuite/tests/stranal/should_run/all.T