#3738: Typechecker floats stuff out of INLINE right hand sides -------------------------------------+------------------------------------- Reporter: rl | Owner: igloo Type: bug | Status: closed Priority: normal | Milestone: 7.0.1 Component: Compiler | Version: 6.13 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: T3738 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by bgamari: Old description:

Small program: {{{ foo :: Num a => [a] -> a {-# INLINE foo #-} foo = go 0 where go m (n:ns) = m `seq` go (m+n) ns go m [] = m

bar :: [Int] -> Int {-# INLINE bar #-} bar = foo }}} Here is what `bar` looks like in the interface file: {{{ a6de4c46e53e565ed25ab5a38910e9cb $wgo :: GHC.Prim.Int# -> [GHC.Types.Int] -> GHC.Prim.Int# {- Arity: 2, HasNoCafRefs, Strictness: LS -} 6838e3faa095285614477ebc92f54987 bar :: [GHC.Types.Int] -> GHC.Types.Int {- Arity: 1, HasNoCafRefs, Strictness: Sm, Inline: INLINE, Unfolding: InlineRule: (arity 0 False) (Foo.bar_foo) -} 5d06906ae99b9aefa1c6d251c3f2fc46 bar_foo :: [GHC.Types.Int] -> GHC.Types.Int {- Arity: 1, HasNoCafRefs, Strictness: Sm, Unfolding: InlineRule: (arity 0 True) (\ w :: [GHC.Types.Int] -> case @ GHC.Types.Int Foo.$wgo 0 w of ww { DEFAULT -> GHC.Types.I# ww }) -} }}} Note that the loop has disappeared from `bar`'s unfolding. Also, `bar_foo` doesn't have an INLINE pragma.

Incidentally, GHC specialises `foo` here and the specialisation doesn't get an INLINE pragma, either: {{{ foo :: forall a. GHC.Num.Num a => [a] -> a {- Arity: 1, HasNoCafRefs, Strictness: L, Inline: INLINE, Unfolding: InlineRule: (arity 1 False) ... -}

foo_$sfoo :: [GHC.Types.Int] -> GHC.Types.Int {- Arity: 1, HasNoCafRefs, Strictness: Sm, Unfolding: InlineRule: (arity 0 False) ... -}

"SPEC Foo.foo [GHC.Types.Int]" ALWAYS forall $dNum :: GHC.Num.Num GHC.Types.Int Foo.foo @ GHC.Types.Int $dNum = Foo.foo_$sfoo }}}

New description: Small program: {{{#!hs foo :: Num a => [a] -> a {-# INLINE foo #-} foo = go 0 where go m (n:ns) = m `seq` go (m+n) ns go m [] = m bar :: [Int] -> Int {-# INLINE bar #-} bar = foo }}} Here is what `bar` looks like in the interface file: {{{ a6de4c46e53e565ed25ab5a38910e9cb $wgo :: GHC.Prim.Int# -> [GHC.Types.Int] -> GHC.Prim.Int# {- Arity: 2, HasNoCafRefs, Strictness: LS -} 6838e3faa095285614477ebc92f54987 bar :: [GHC.Types.Int] -> GHC.Types.Int {- Arity: 1, HasNoCafRefs, Strictness: Sm, Inline: INLINE, Unfolding: InlineRule: (arity 0 False) (Foo.bar_foo) -} 5d06906ae99b9aefa1c6d251c3f2fc46 bar_foo :: [GHC.Types.Int] -> GHC.Types.Int {- Arity: 1, HasNoCafRefs, Strictness: Sm, Unfolding: InlineRule: (arity 0 True) (\ w :: [GHC.Types.Int] -> case @ GHC.Types.Int Foo.$wgo 0 w of ww { DEFAULT -> GHC.Types.I# ww }) -} }}} Note that the loop has disappeared from `bar`'s unfolding. Also, `bar_foo` doesn't have an INLINE pragma. Incidentally, GHC specialises `foo` here and the specialisation doesn't get an INLINE pragma, either: {{{ foo :: forall a. GHC.Num.Num a => [a] -> a {- Arity: 1, HasNoCafRefs, Strictness: L, Inline: INLINE, Unfolding: InlineRule: (arity 1 False) ... -} foo_$sfoo :: [GHC.Types.Int] -> GHC.Types.Int {- Arity: 1, HasNoCafRefs, Strictness: Sm, Unfolding: InlineRule: (arity 0 False) ... -} "SPEC Foo.foo [GHC.Types.Int]" ALWAYS forall $dNum :: GHC.Num.Num GHC.Types.Int Foo.foo @ GHC.Types.Int $dNum = Foo.foo_$sfoo }}} -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/3738#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler