#13143: NOINLINE and worker/wrapper -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by gridaphobe): Hi Simon, I'm a bit confused by your simplified example. On HEAD I get {{{ g = \ @ a @ p $dNum $dShow ds p1 -> case ds of { False -> + $dNum (case p1 of { (ds1, y) -> y }) (fromInteger $dNum g1); True -> f $dShow p1 } }}} No reboxing (or worker) in sight. But if I pattern match on the pair inside `g` {{{ g True (x,y) = f (x,y) g False (x,y) = x + 1 }}} I get {{{ $wg = \ @ b @ p w w1 w2 ww -> case w2 of { False -> + w ww (fromInteger w g2); True -> f w1 (ww, g1) } g = \ @ b @ p w w1 w2 w3 -> case w3 of { (ww1, ww2) -> $wg w w1 w2 ww1 } }}} which does do the needless reboxing. Unfortunately, removing the `isNeverActive` case in `tryWW` does not change the result, and glancing through `-dverbose-core2core` it doesn't appear that we end up performing W/W on `f`. It also doesn't improve the situation for the GHC.Arr example as you've written it, though interestingly it '''does''' improve over HEAD if you define `indexError` as a simple diverging loop {{{ indexError rng i tp = indexError rng i tp }}} rather than an explicit `error` call. Furthermore, even though the motivating example is not yet improved, there are some small gains in nofib {{{ -------------------------------------------------------------------------------- Program Size Allocs Runtime Elapsed TotalMem -------------------------------------------------------------------------------- Min -0.9% -0.3% -16.9% -24.7% -2.4% Max 0.0% 0.0% +14.5% +15.8% +0.9% Geometric Mean -0.1% -0.0% +0.4% -1.2% -0.0% }}} It seems we're on the right track, but there must be another missing piece to the puzzle. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13143#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler