#2747: Excessive Memory Usage: space leak with foldl' on Integer
-----------------------------------------+----------------------------------
Reporter: guest | Owner:
Type: run-time performance bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.10.1
Severity: blocker | Resolution:
Keywords: | Testcase:
Architecture: Unknown/Multiple | Os: Unknown/Multiple
-----------------------------------------+----------------------------------
Comment (by nominolo):
A heap profile shows ARR_WORDS as the culprit. The compiling the program
with {{{-O}}} with either version gives an equivalent inner loop:
{{{
-- 6.8.2
Rec {
Main.lgo :: GHC.Num.Integer -> [GHC.Num.Integer] -> GHC.Num.Integer
[GlobalId]
[Arity 2
NoCafRefs
Str: DmdType SS]
Main.lgo =
\ (z1_aw1 :: GHC.Num.Integer) (ds_aw2 :: [GHC.Num.Integer]) ->
case ds_aw2 of wild_aw3 {
[] -> z1_aw1;
: x_aw7 xs1_aw8 ->
case GHC.Num.timesInteger z1_aw1 x_aw7 of tpl_awa { __DEFAULT ->
Main.lgo tpl_awa xs1_aw8
}
}
end Rec }
}}}
{{{
-- HEAD (6.11.20081103)
Rec {
Main.lgo :: GHC.Integer.Internals.Integer
-> [GHC.Integer.Internals.Integer]
-> GHC.Integer.Internals.Integer
[GlobalId]
[Arity 2
NoCafRefs
Str: DmdType SS]
Main.lgo =
\ (z_ay4 :: GHC.Integer.Internals.Integer)
(ds_ay5 :: [GHC.Integer.Internals.Integer]) ->
case ds_ay5 of wild_ay6 {
[] -> z_ay4;
: x_aya xs_ayb ->
case GHC.Integer.timesInteger z_ay4 x_aya of z'_ayd { __DEFAULT ->
Main.lgo z'_ayd xs_ayb
}
}
end Rec }
}}}
My guess therefore is that {{{GHC.Integer.timesInteger}}} is the culprit.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2747#comment:2>
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