#7428: GHC compile times are seriously non-linear in program size
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Reporter: nudded | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 7.4.2
Resolution: | Keywords:
Os: MacOS X | Architecture: x86_64 (amd64)
Failure: Compile-time crash | Difficulty: Unknown
Testcase: | Blockedby:
Blocking: | Related:
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Changes (by simonpj):
* status: closed => new
* resolution: invalid =>
Comment:
I'm re-opening becuase I believe `nudded` is telling us that compilation
times are seriously non-linear in program size. That should not happen.
Moreover you were kind enough to profile the compiler and in the profile
you gave it seems that 64% of all allocation is in
`MkIface.addFingerprints` which is not supposed to be an expensive
function.
Could you help us some more?
* Give a table of compile times against program size (or number of state
transformers)
* Explain exactly how to reproduce (what flags, what changes to make to
the code to make N=1, N=2, N=4, etc
* Use `-dshow-passes` to see if the size of the simplified program is
blowing up
* If you feel up to it, drill down into `addFingerprints` to see where
the time is going.
Thanks!
Simon
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7428#comment:7>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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