Skip to content

GitLab

  • Projects
  • Groups
  • Snippets
  • Help
    • Loading...
  • Help
    • Help
    • Support
    • Community forum
    • Submit feedback
  • Sign in / Register
GHC
GHC
  • Project overview
    • Project overview
    • Details
    • Activity
    • Releases
  • Repository
    • Repository
    • Files
    • Commits
    • Branches
    • Tags
    • Contributors
    • Graph
    • Compare
    • Locked Files
  • Issues 4,251
    • Issues 4,251
    • List
    • Boards
    • Labels
    • Service Desk
    • Milestones
    • Iterations
  • Merge Requests 398
    • Merge Requests 398
  • Requirements
    • Requirements
    • List
  • CI / CD
    • CI / CD
    • Pipelines
    • Jobs
    • Schedules
  • Security & Compliance
    • Security & Compliance
    • Dependency List
    • License Compliance
  • Operations
    • Operations
    • Incidents
    • Environments
  • Analytics
    • Analytics
    • CI / CD
    • Code Review
    • Insights
    • Issue
    • Repository
    • Value Stream
  • Wiki
    • Wiki
  • Snippets
    • Snippets
  • Members
    • Members
  • Collapse sidebar
  • Activity
  • Graph
  • Create a new issue
  • Jobs
  • Commits
  • Issue Boards
  • Glasgow Haskell Compiler
  • GHCGHC
  • Issues
  • #6078

Closed
Open
Opened May 04, 2012 by SimonMeier@trac-SimonMeier

GHC panic encountered for unlifted let bindings

The following code block makes GHC panic:

{-# LANGUAGE BangPatterns #-}
module GhcPanic where

import GHC.Ptr
import Foreign 

-- Occurred in a really low-level bytestring decoder implementation.
{-# INLINE byteStringSlice #-}
byteStringSlice len = \fpbuf ip0 ipe s0 ->
    let ip1p@(Ptr ip1) = Ptr ip0 `plusPtr` len
    -- Note that the panic goes away if we use a bang-pattern as follows
    -- let !ip1p@(Ptr ip1) = Ptr ip0 `plusPtr` len
    in  ip1p

The panic output is

ghc-7.4.1 GhcPanic.hs                                                           
[1 of 1] Compiling GhcPanic         ( GhcPanic.hs, GhcPanic.o )
ghc: panic! (the 'impossible' happened)
  (GHC version 7.4.1 for x86_64-unknown-linux):
        dsLet: unlifted
    AbsBinds
    [( t{tv acU} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} )]
    []
    [( ip1p{v acI} [lid] :: forall ( t{tv acU} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} ).
                            base:GHC.Ptr.Ptr{tc 33A}
                              ( t{tv acU} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} ) ) <= ( ip1p{v acK} [lid] :: base:GHC.Ptr.Ptr{tc 33A}
                                                                                                                  ( t{tv acU} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} ) )
       /\(@ ( t{tv acW} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} )).
       (<>) @ ( t{tv acW} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} ),
     ( ip1{v acJ} [lid] :: ghc-prim:GHC.Prim.Addr#{(w) tc 33} ) <= ( ip1{v acP} [lid] :: ghc-prim:GHC.Prim.Addr#{(w) tc 33} )
       (<>)
       @ (ghc-prim:GHC.Prim.Any{(w) tc 31N}
            ghc-prim:GHC.Prim.*{(w) tc 34d})]
      ( ip1p{v acI} [lid] :: forall ( t{tv acU} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} ).
                             base:GHC.Ptr.Ptr{tc 33A}
                               ( t{tv acU} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} ) )
        :: forall ( t{tv acU} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} ).
           base:GHC.Ptr.Ptr{tc 33A}
             ( t{tv acU} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} )
      [LclId]
      ( ip1{v acJ} [lid] :: ghc-prim:GHC.Prim.Addr#{(w) tc 33} )
        :: ghc-prim:GHC.Prim.Addr#{(w) tc 33}
      [LclId]
      {GhcPanic.hs:10:9-46}
      {GhcPanic.hs:10:9-22}
      {GhcPanic.hs:10:9-12}
      ( ip1p{v acK} [lid] :: base:GHC.Ptr.Ptr{tc 33A}
                               ( t{tv acU} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} ) )@({GhcPanic.hs:10:15-21}
                                                                                        {GhcPanic.hs:10:15-17}
                                                                                        base:GHC.Ptr.Ptr{d r3C}{EvBinds{}} ((( ip1{v acP} [lid] :: ghc-prim:GHC.Prim.Addr#{(w) tc 33} )
                                                                                                                               :: ghc-prim:GHC.Prim.Addr#{(w) tc 33})))
        = {GhcPanic.hs:10:26-46}
          {GhcPanic.hs:10:34-42}
          (base:GHC.Ptr.plusPtr{v r3E})
          @ (ghc-prim:GHC.Prim.Any{(w) tc 31N}
               ghc-prim:GHC.Prim.*{(w) tc 34d})
          @ ( t{tv acU} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} )
            ((base:GHC.Ptr.Ptr{v r39})
             @ (ghc-prim:GHC.Prim.Any{(w) tc 31N}
                  ghc-prim:GHC.Prim.*{(w) tc 34d})
               ip0{v acF})
            len{v acD}
    EvBinds{}
    ( ip1p{v acI} [lid] :: forall ( t{tv acU} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} ).
                           base:GHC.Ptr.Ptr{tc 33A}
                             ( t{tv acU} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} ) )
      @ ( t{tv ad5} [sk] :: ghc-prim:GHC.Prim.*{(w) tc 34d} )

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

It might be that its an instance of #4498 (closed).

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
Assignee
Assign to
None
Milestone
None
Assign milestone
Time tracking
None
Due date
None
Reference: ghc/ghc#6078