#5642: Deriving Generic of a big type takes a long time and lots of space
---------------------------------+------------------------------------------
Reporter: basvandijk | Owner: dimitris
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.3 | Keywords:
Testcase: | Blockedby:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: Compile-time performance bug
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Changes (by dreixel):
* owner: dreixel => dimitris
* version: 7.2.1 => 7.3
Comment:
I thought the problem was the generation of Generic instances, but it
isn't. If you write the instance by hand, it still takes long. So the
bottleneck is the performance of the simplifier. Things have improved with
the new coercion solver; see the following figures for compiling `derive
Generic` on a datatype with 100/200/300 constructors:
{{{
ghc-7.2.1
100 0m30.079s
200 3m44.419s
300 12m52.306s
HEAD
100 0m8.302s
200 1m1.631s
300 3m32.507s
}}}
But they could probably be much better, since the coercions introduced are
not that complicated. I've notified Dimitrios, he'll look further into it.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5642#comment:6>
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