#8892: Ghc panics (variable not found) ---------------------------------------+----------------------------------- Reporter: jwlato | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.1-rc2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time crash | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: ---------------------------------------+----------------------------------- Comment (by jwlato): Thanks Simon, with `-dcore-lint` I see *many* warnings like `INLINE binder is (non-rule) loop breaker:`, but they seem so common (and some are clearly unrelated) that I don't think it's relevant. In the module that errors, I see only this: {{{ *** Core Lint errors : in result of Simplifier *** <no location info>: Warning: [in body of letrec with binders a125_ajLr3 :: GHC.Prim.State# (Control.Monad.Primitive.PrimState (GHC.ST.ST s2_ajLm9)) -> (# GHC.Prim.State# (Control.Monad.Primitive.PrimState (GHC.ST.ST s2_ajLm9)), () #)] foldlM'_loop_ajLpg :: Data.Vector.Fusion.Stream.Monadic.SPEC -> GHC.Types.Int -> GHC.Types.Int -> GHC.ST.ST s2_ajLm9 GHC.Types.Int [LclId, Arity=4, Str=DmdType] is out of scope <no location info>: Warning: [in body of letrec with binders a125_ajLr3 :: GHC.Prim.State# (Control.Monad.Primitive.PrimState (GHC.ST.ST s2_ajLm9)) -> (# GHC.Prim.State# (Control.Monad.Primitive.PrimState (GHC.ST.ST s2_ajLm9)), () #)] foldlM'_loop_ajLpg :: Data.Vector.Fusion.Stream.Monadic.SPEC -> GHC.Types.Int -> GHC.Types.Int -> GHC.ST.ST s2_ajLm9 GHC.Types.Int [LclId, Arity=4, Str=DmdType] is out of scope }}} followed by the simplifier output. And indeed, there is a `case foldlM'_loop_ajLpg something of`, but no binding for `foldlM'_loop_ajLpg6`. At least I've found the offending function now, so I may be able to isolate a test case. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8892#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#8892: Ghc panics (variable not found) ---------------------------------------+----------------------------------- Reporter: jwlato | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.1-rc2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time crash | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: ---------------------------------------+----------------------------------- Comment (by jwlato): I've made a test case that I hope is small enough you can work with. This has dependencies on the `vector` and `vector-space` packages. There are two files, `Piecewise.hs` and `Broken.hs`. To trigger the bug, you need to first compile `Piecewise.hs` and install it to ghc's package database, then attempt to compile `Broken.hs` via `ghc -O Broken.hs`. Trying to compile `Broken.hs` when ghc can find `Piecewise.hs` works properly for me. I've put a repo on github with a minimal cabal file also, https://github.com/JohnLato/ghc-8892 I can trigger the bug with any optimization level except `-O0`. `Piecewise.hs` defines `instance (AdditiveGroup (poly a), Ord a) => AdditiveGroup (Piecewise poly a)`, with `{-# SPECIALISE instance AdditiveGroup (Piecewise Scale Double) #-}`. That SPECIALIZE instance pragma, and the `INLINE negateV` pragma, both seem required to trigger this. I haven't attempted to simplify the definition of `^+^` at all, I'll continue with that tomorrow. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8892#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#8892: Ghc panics (variable not found) ---------------------------------------+----------------------------------- Reporter: jwlato | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.1-rc2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time crash | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: ---------------------------------------+----------------------------------- Comment (by Simon Peyton Jones ): In [changeset:"87bbc69c40d36046492d754c8d7ff02c3be6ce43/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="87bbc69c40d36046492d754c8d7ff02c3be6ce43" Make sure we occurrence-analyse unfoldings (fixes Trac #8892) For DFunUnfoldings we were failing to occurrence-analyse the unfolding, and that meant that a loop breaker wasn't marked as such, which in turn meant it was inlined away when it still had occurrence sites. See Note [Occurrrence analysis of unfoldings] in CoreUnfold. This is a pretty long-standing bug, happily nailed by John Lato. }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8892#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#8892: Ghc panics (variable not found) ---------------------------------------+----------------------------------- Reporter: jwlato | Owner: Type: bug | Status: closed Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: 7.8.1-rc2 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time crash | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: ---------------------------------------+----------------------------------- Changes (by thoughtpolice): * status: merge => closed * resolution: => fixed * milestone: => 7.8.1 Comment: Merged. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8892#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler