Quadratic constructor tag allocation
With a large data type like:
data A = A0
| A0001
| A0002
...
| A9999
GHC spends a lot of time allocating constructor tags. It accounts for half of allocations for large data types like this.
The hot piece of code is in mkDataCon
:
tag = assoc "mkDataCon" (tyConDataCons rep_tycon `zip` [fIRST_TAG..]) con
Previous discussion: https://mail.haskell.org/pipermail/ghc-devs/2017-October/014974.html
Trac metadata
Trac field | Value |
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Version | |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |