id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
6048,Exponential inlining code blowup,simonpj,,"(Transferring a new thread from #5539 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). ",bug,closed,normal,,Compiler,7.4.1,fixed,,,Unknown/Multiple,Unknown/Multiple,None/Unknown,Unknown,perf/compiler/T6048,,,