Adding a SPECIALIZE at a callsite in Main.hs is causing a regression
Github user jmoy documents an issue with lack of specialization happening for INLINABLE functions in GHC 8.0 here: https://github.com/jmoy/testing-specialize . Testing on 8.2.1 it seems that specialization happened (although I didn't verify this in the core) as the result was 10x faster. But the odd thing to me was uncommenting the SPECIALIZE pragma at the callsite actually resulted in a significant regression: https://github.com/jmoy/testing-specialize/issues/1#issuecomment-310868360
Maybe GHC is choosing the worse manual partial specialization for some reason. I'm sorry I can't produce a better ticket for this at the moment.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 8.2.1-rc2 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
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