loop fusion not working for Int32, Int64 as it does for Int ?

here is some code that works for Int, but gives me Stack Overflow for arguments 18 .. 24, and Out of memory for 25. (Just change the type annotation in main.)

import Data.Int
import System.Environment

bitcount x = if x > 0 
    then let (d,m) = divMod x 2 in  bitcount d + m
    else 0

main = do
    [ arg ]  <- getArgs
    print $ sum  $ map bitcount
          [ 0 :: Int64 .. 2^read arg - 1 ]

https://github.com/haskell-distributed/distributed-process/issues/91#issuecomment-11468092

Not sure whether it's a bug, but it's annoying. There is no conceptual difference between these numerical types, so I shouldn't have to rewrite my program when switching between them.

Trac metadata

Trac field	Value
Version	7.6.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

mentioned in issue #4321 (closed)

changed weight to 5

added Tbug Trac import labels

perhaps this is helpful: I was running ghc with -ddump-rule-firings, and the differences are:

diff rules.Int rules.Int64

4d3
< Rule fired: SPEC Data.List.sum
13a13,15
> Rule fired: Class op fromInteger
> Rule fired: Class op fromInteger
> Rule fired: Class op fromInteger
67a70,72
> Rule fired: integerToInt
> Rule fired: integerToInt
> Rule fired: integerToInt
69,70c74
<     SPEC GHC.Real.^ [GHC.Types.Int, GHC.Integer.Type.Integer]
< Rule fired: fold/build
---
>     SPEC GHC.Real.^ [GHC.Int.Int64, GHC.Integer.Type.Integer]
73,75c77
< Rule fired: >#
< Rule fired: <#
< Rule fired: >#
---
> Rule fired: mapList

mentioned in commit f251bf58

mentioned in commit 77dc6948

closed

See also #4321 (closed). Fixed by this patch to base:

commit 06e36c63fce9aef5d3d8d9efeab14263333d48bf
Author: Simon Peyton Jones <simonpj@microsoft.com>
Date:   Mon Dec 24 14:44:31 2012 +0000

    Make sum and product INLINABLE
    
    This was causing the bad behaviour in Trac #7507,
    because 'sum' wasn't getting specialised to Int64.
    
    It also deals with Trac #4321, which had the same cause.
    
    This has a big effect on some nofib programs too:
    
    --------------------------------------------------------------------------------
            Program           Allocs   Runtime   Elapsed  TotalMem
    ------------------------------------------------------------------------
         bernouilli            -2.6%     -2.0%     -2.0%     +0.0%
               fft2           -23.8%      0.09      0.09    -16.7%
              fluid            -4.4%      0.01      0.01     +0.0%
             hidden            -3.2%     +2.1%     +1.8%     +0.0%
          integrate           -38.0%    -47.7%    -47.7%     -1.0%
               x2n1           -30.2%      0.01      0.01    -50.0%
    ------------------------------------------------------------------------
                Min           -38.0%    -47.7%    -47.7%    -50.0%
                Max            +0.4%    +11.2%    +11.8%     +6.9%
     Geometric Mean            -1.3%     +0.2%     +0.2%     -0.8%

 Data/List.hs |    5 +++++
 1 file changed, 5 insertions(+)

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedFixed
Test case	- → perf/should_run/T7507

How does it affect code size?

added Pnormal label