#13253: Exponential compilation time with RWST & ReaderT stack with `-02`
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Reporter: phadej | Owner: bgamari, osa1
Type: bug | Status: new
Priority: normal | Milestone: 8.4.1
Component: Compiler | Version: 8.0.1
Resolution: | Keywords:
Operating System: Unknown/Multiple | Architecture:
Type of failure: Compile-time | Unknown/Multiple
performance bug | Test Case:
Blocked By: | Blocking:
Related Tickets: | Differential Rev(s):
Wiki Page: |
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Comment (by osa1):
ManyConstructors outputs are exactly the same with and without this patch,
so any changes in the stats should be because of the compiler itself doing
the same work more or less efficiently.
In T13056 there's only a small difference, with this patch there's this
join point:
{{{
join {
ds1_s5PK [Dmd=
Are those perf/compiler improvements happening because (a) GHC is generating less code of (b) GHC's code is running faster?
I think these are because GHC's code is running faster. FWIW, on my laptop this patch does not cause any perf failures. When I look at the stats files for these two tests I see that with this patch GHC allocates less in T13056 but more in ManyConstructors (just a few MB difference). Other stats differ (sometimes better with this patch, sometimes worse) but only very small amounts. Overall I don't get any perf failures. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13253#comment:29 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler