#5767: Integer inefficiencies
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Reporter: rl | Owner: igloo
Type: bug | Status: new
Priority: highest | Milestone: 7.4.1
Component: Compiler | Version: 7.5
Resolution: | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: Runtime performance bug | Difficulty: Unknown
Testcase: | Blockedby:
Blocking: | Related:
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Comment(by simonpj):
Note: the call to `smallInteger` arises from the `fromIntegral` method of
`Integral Int` (in `base:GHC.Real`):
{{{
instance Integral Int where
toInteger (I# i) = smallInteger i
}}}
So, yes we need a `integerToInt (smallInteger n)` RULE.
Ditto `int64ToInteger` and `wordToInteger`.
Also we'd like a RULE for `(smallInteger (I# n)`, which should generate an
`Integer` literal. This isn't easy right now for tiresome reasons. !ToDo
for 7.6. The most plausible route for doing it is to take `mkIntegerLit`
out of `Integer` literals, and keep it somewhere global instead.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5767#comment:7>
GHC <http://www.haskell.org/ghc/>
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