Exponential inlining code blowup
(Transferring a new thread from #5539 (closed) to a new ticket, since it's really a separate problem.) kosmikus helpfully provided this program
module TestCase where
import Control.Applicative
data X = X
(Maybe String)
(Maybe String)
(Maybe String)
(Maybe String)
(Maybe String)
(Maybe String)
(Maybe String)
(Maybe String)
(Maybe String)
mb :: (String -> Maybe a) -> String -> Maybe (Maybe a)
mb _ "" = Just Nothing
mb _ "-" = Just Nothing
mb p xs = Just <$> p xs
run :: [String] -> Maybe X
run
[ x1
, x2
, x3
, x4
, x5
, x6
, x7
, x8
, x9
] = X
<$> mb pure x1
<*> mb pure x2
<*> mb pure x3
<*> mb pure x4
<*> mb pure x5
<*> mb pure x6
<*> mb pure x7
<*> mb pure x8
<*> mb pure x9
Unless mb
is marked as NOINLINE
, it gets expanded in the body of run a number of times that seems to grow exponentially with the size of the list (9 in the example).
Trac metadata
Trac field | Value |
---|---|
Version | 7.4.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |