#4943: Another odd missed SpecConstr opportunity
---------------------------------+------------------------------------------
Reporter: batterseapower | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 7.1
Keywords: | Testcase:
Blockedby: | Difficulty:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: Runtime performance bug
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Comment(by simonpj):
Are you sure? Here's what I get with HEAD (`-O2 -ddump-simpl`). Looks
good, except for the awkward felicity of passing unused arguments around
the loop (#4941):
{{{
Rec {
$s$wa_r1Hy
:: forall s_aIE.
GHC.Types.Int
-> GHC.Types.Int
-> GHC.Types.Int
-> GHC.Prim.MutableByteArray# s_aIE
-> GHC.Prim.Int#
-> GHC.Prim.Int#
-> GHC.Prim.Int#
-> GHC.Prim.State# s_aIE
-> (# GHC.Prim.State# s_aIE, () #)
[GblId, Arity=8, Caf=NoCafRefs, Str=DmdType LLLLLLLL]
$s$wa_r1Hy =
\ (@ s_aIE)
(sc_s1Gq :: GHC.Types.Int)
(sc1_s1Gr :: GHC.Types.Int)
(sc2_s1Gs :: GHC.Types.Int)
(sc3_s1Gt :: GHC.Prim.MutableByteArray# s_aIE)
(sc4_s1Gu :: GHC.Prim.Int#)
(sc5_s1Gv :: GHC.Prim.Int#)
(sc6_s1Gw :: GHC.Prim.Int#)
(sc7_s1Gx :: GHC.Prim.State# s_aIE) ->
case GHC.Prim.># sc5_s1Gv sc6_s1Gw of _ {
GHC.Types.False ->
case GHC.Prim.readIntArray# @ s_aIE sc3_s1Gt sc5_s1Gv sc7_s1Gx
of _ { (# s2#_aRI, e#_aRJ #) ->
case GHC.Prim.writeIntArray#
@ s_aIE sc3_s1Gt sc5_s1Gv (GHC.Prim.+# e#_aRJ sc4_s1Gu)
s2#_aRI
of s2#1_aS8 { __DEFAULT ->
$s$wa_r1Hy
@ s_aIE
sc_s1Gq
sc1_s1Gr
sc2_s1Gs
sc3_s1Gt
sc4_s1Gu
(GHC.Prim.+# sc5_s1Gv 1)
sc6_s1Gw
s2#1_aS8
}
};
GHC.Types.True -> (# sc7_s1Gx, GHC.Unit.() #)
}
end Rec }
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4943#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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