[GHC] #15019: Fix performance regressions from #14737
GHC
ghc-devs at haskell.org
Tue Apr 24 14:13:26 UTC 2018
#15019: Fix performance regressions from #14737
-------------------------------------+-------------------------------------
Reporter: tdammers | Owner: tdammers
Type: bug | Status: new
Priority: normal | Milestone: 8.6.1
Component: Compiler | Version:
Resolution: | Keywords:
Operating System: Unknown/Multiple | Architecture:
Type of failure: Compile-time | Unknown/Multiple
performance bug | Test Case:
Blocked By: | Blocking:
Related Tickets: #14737 | Differential Rev(s): phab:D4568
Wiki Page: |
-------------------------------------+-------------------------------------
Comment (by tdammers):
Looking at one of the regressions, T9010, I set up a trap to catch only
those coercions that are found to be equal by `eqType`, but don't match on
`isReflCo`. And they're all the same: `(State# RealWorld -> (# State#
RealWorld, () #), State# RealWorld -> (# State# RealWorld, () #))`. So
this one looks like it would be relatively easy to detect.
Unfortunately, the other one, T12707, paints a different picture; here,
the matches look like these:
{{{
(forall a. K1 R Bool a -> [String] -> [String],
forall a. K1 R Bool a -> [String] -> [String])
}}}
{{{
(forall a.
M1
S
('MetaSel
('Just "foo3Field08")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(K1 R (Maybe Bool))
a
-> [String] -> [String],
forall a.
M1
S
('MetaSel
('Just "foo3Field08")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 (Maybe Bool))
a
-> [String] -> [String])
}}}
{{{
(forall a.
(:*:)
(((S1
('MetaSel
('Just "foo0Field00")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 String)
:*: S1
('MetaSel
('Just "foo0Field01")
'NoSourceUnpackedness
'SourceStrict
'DecidedUnpack)
(Rec0 Int))
:*: (S1
('MetaSel
('Just "foo0Field02")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 [Int])
:*: (S1
('MetaSel
('Just "foo0Field03")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 (Maybe Bool))
:*: S1
('MetaSel
('Just "foo0Field04")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 Bool))))
:*: ((S1
('MetaSel
('Just "foo0Field05")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 String)
:*: S1
('MetaSel
('Just "foo0Field06")
'NoSourceUnpackedness
'SourceStrict
'DecidedUnpack)
(Rec0 Int))
:*: (S1
('MetaSel
('Just "foo0Field07")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 [Int])
:*: (S1
('MetaSel
('Just "foo0Field08")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 (Maybe Bool))
:*: S1
('MetaSel
('Just "foo0Field09")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 Bool)))))
(((S1
('MetaSel
('Just "foo0Field10")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 String)
:*: S1
('MetaSel
('Just "foo0Field11")
'NoSourceUnpackedness
'SourceStrict
'DecidedUnpack)
(Rec0 Int))
:*: (S1
('MetaSel
('Just "foo0Field12")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 [Int])
:*: (S1
('MetaSel
('Just "foo0Field13")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 (Maybe Bool))
:*: S1
('MetaSel
('Just "foo0Field14")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 Bool))))
:*: ((S1
('MetaSel
('Just "foo0Field15")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 String)
:*: S1
('MetaSel
('Just "foo0Field16")
'NoSourceUnpackedness
'SourceStrict
'DecidedUnpack)
(Rec0 Int))
:*: (S1
('MetaSel
('Just "foo0Field17")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 [Int])
:*: (S1
('MetaSel
('Just "foo0Field18")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 (Maybe Bool))
:*: S1
('MetaSel
('Just "foo0Field19")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 Bool)))))
a
-> [String] -> [String],
forall a.
(:*:)
(((S1
('MetaSel
('Just "foo0Field00")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 String)
:*: S1
('MetaSel
('Just "foo0Field01")
'NoSourceUnpackedness
'SourceStrict
'DecidedUnpack)
(Rec0 Int))
:*: (S1
('MetaSel
('Just "foo0Field02")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 [Int])
:*: (S1
('MetaSel
('Just "foo0Field03")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 (Maybe Bool))
:*: S1
('MetaSel
('Just "foo0Field04")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 Bool))))
:*: ((S1
('MetaSel
('Just "foo0Field05")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 String)
:*: S1
('MetaSel
('Just "foo0Field06")
'NoSourceUnpackedness
'SourceStrict
'DecidedUnpack)
(Rec0 Int))
:*: (S1
('MetaSel
('Just "foo0Field07")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 [Int])
:*: (S1
('MetaSel
('Just "foo0Field08")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 (Maybe Bool))
:*: S1
('MetaSel
('Just "foo0Field09")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 Bool)))))
(((S1
('MetaSel
('Just "foo0Field10")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 String)
:*: S1
('MetaSel
('Just "foo0Field11")
'NoSourceUnpackedness
'SourceStrict
'DecidedUnpack)
(Rec0 Int))
:*: (S1
('MetaSel
('Just "foo0Field12")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 [Int])
:*: (S1
('MetaSel
('Just "foo0Field13")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 (Maybe Bool))
:*: S1
('MetaSel
('Just "foo0Field14")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 Bool))))
:*: ((S1
('MetaSel
('Just "foo0Field15")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 String)
:*: S1
('MetaSel
('Just "foo0Field16")
'NoSourceUnpackedness
'SourceStrict
'DecidedUnpack)
(Rec0 Int))
:*: (S1
('MetaSel
('Just "foo0Field17")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 [Int])
:*: (S1
('MetaSel
('Just "foo0Field18")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 (Maybe Bool))
:*: S1
('MetaSel
('Just "foo0Field19")
'NoSourceUnpackedness
'SourceStrict
'DecidedStrict)
(Rec0 Bool)))))
a
-> [String] -> [String])
}}}
Further digging, however, reveals that these are all `Sym` coercions, so I
think I can figure out a faster way to detect these.
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15019#comment:4>
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