#13960: Ticks exhausted with 8.0.2 -------------------------------------+------------------------------------- Reporter: tom-bop | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 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 bgamari): In general it is expected that some modules will occasionally need to have the tick limit bumped in order to compile. Afterall, the simplifier tick mechanism is merely a heuristic. In your case it sounds like this is a rather small and simple program, which makes the failure a bit more surprising. However, it's hard to tell without seeing actual code. It would be quite helpful if you could try to reduce the problem down to a something that you can share. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13960#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#13960: Ticks exhausted with 8.0.2 -------------------------------------+------------------------------------- Reporter: tom-bop | Owner: (none) Type: bug | Status: infoneeded Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 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 bgamari): So it looks like the issue here is that `Query`'s `fromString` instance inlines: {{{ Inlining done: Database.PostgreSQL.Simple.Types.$fIsStringQuery_g Inlined fn: \ (x [Occ=Once] :: GHC.Base.String) -> let { cs :: Data.ByteString.Lazy.Internal.ByteString [LclId] cs = Data.ByteString.Builder.toLazyByteString (src src Data.ByteString.Builder.Prim.primMapListBounded @ GHC.Types.Char (src Data.ByteString.Builder.Prim.charUtf8) (src x)) } in src src Data.ByteString.Lazy.toStrict_goLen0 (src cs) cs }}} We then eventually inline `primMapListBounded`, which is itself a very large function. The simplifier is then force to crunch through all of this. The most surprising part of all of this is that in the end the `Builder` essentially iterates over the list produced by `unpackCString# "query"#` and painstakingly fills the target buffer byte-by-byte. Surely something has gone terribly wrong here. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13960#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#13960: Ticks exhausted with 8.0.2 -------------------------------------+------------------------------------- Reporter: tom-bop | Owner: (none) Type: bug | Status: infoneeded Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 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 tom-bop): I've updated the repro case to not depend on the postgresql-simple library: Broken.hs: {{{ #!haskell {-# LANGUAGE OverloadedStrings #-} module Broken (breaks) where import Data.ByteString import Data.ByteString.Builder import Data.ByteString.Lazy (toStrict) import Data.String (IsString(..)) newtype Query = Query ByteString toByteString :: Builder -> ByteString toByteString x = toStrict (toLazyByteString x) instance IsString Query where fromString = Query . toByteString . stringUtf8 breaks :: [(Query, Query)] breaks = [ ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") ] }}} broken.cabal: {{{ name: broken version: 0.1.0.0 build-type: Simple cabal-version: >=1.10 library exposed-modules: Broken other-extensions: OverloadedStrings build-depends: base , bytestring , bytestring-builder default-language: Haskell2010 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13960#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#13960: Ticks exhausted with 8.0.2 -------------------------------------+------------------------------------- Reporter: tom-bop | Owner: (none) Type: bug | Status: infoneeded Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 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: | -------------------------------------+------------------------------------- Description changed by tom-bop: Old description:

**Update**: I've been able to provide a much simpler test case for this error:

Broken.hs:

{{{ #!haskell {-# LANGUAGE OverloadedStrings #-}

module Broken (breaks) where

import Database.PostgreSQL.Simple.Types (Query)

breaks :: [(Query, Query)] breaks = [ ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") ] }}}

broken.cabal:

{{{ name: broken version: 0.1.0.0 build-type: Simple cabal-version: >=1.10

library exposed-modules: Broken other-extensions: OverloadedStrings build-depends: base -- >=4.9 && <4.10 , postgresql-simple -- >=0.5 && <0.6 default-language: Haskell2010 }}}

`cabal install broken.cabal` results in:

{{{ ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): Simplifier ticks exhausted When trying UnfoldingDone ord To increase the limit, use -fsimpl-tick-factor=N (default 100) If you need to do this, let GHC HQ know, and what factor you needed To see detailed counts use -ddump-simpl-stats Total ticks: 20731

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

----

----

**Older info:**

~~This is unfortunately a closed-source codebase I'm experiencing this with, but we get a GHC panic with a small/not-doing-anything-crazy codebase:~~

{{{

ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): Simplifier ticks exhausted When trying RuleFired Class op return To increase the limit, use -fsimpl-tick-factor=N (default 100) If you need to do this, let GHC HQ know, and what factor you needed To see detailed counts use -ddump-simpl-stats Total ticks: 118123

}}}

When upping to `-fsimpl-tick-factor=150`, the error is a little different:

{{{ ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): Simplifier ticks exhausted When trying UnfoldingDone $ To increase the limit, use -fsimpl-tick-factor=N (default 100) If you need to do this, let GHC HQ know, and what factor you needed To see detailed counts use -ddump-simpl-stats Total ticks: 177190 }}}

Upping to 200 makes the issue go away.

We're building with

`ghc-options: -fhpc`

Before each build, we remove all .tix files and the .hpc directory

At the point this error fires, we're compiling the 6th module of 9. The first 6 modules to compile only have a total of 635 lines of code.

To address issues I've seen in other similar tickets: - There are no recursive module imports - We don't use any `{-# INLINE #-}` or similar pragmas - There is no Template Haskell other than a `makeLenses ''App` for a small Snaplet. - We don't have any "very"/exponentially recursive code - We don't use any unboxed tuples (there *is* ST code in a module that's compiled, but not the one ghc panics on) - We don't use type families - We don't use TypeRep or Typeable - We don't use Generic

When this error occurs, it fails on a module which has very little code in it. It's mainly a list of ~200-300 Query[0] values, using OverloadedStrings. I notice Query's `mappend`, which we use, is `INLINE`d.

Please let me know if I can provide more detail!

[0] http://hackage.haskell.org/package/postgresql-simple-0.5.3.0/docs /Database-PostgreSQL-Simple-Types.html#t:Query

New description: **Update 2**: repro case with fewer dependencies: Broken.hs: {{{ #!haskell {-# LANGUAGE OverloadedStrings #-} module Broken (breaks) where import Data.ByteString import Data.ByteString.Builder import Data.ByteString.Lazy (toStrict) import Data.String (IsString(..)) newtype Query = Query ByteString toByteString :: Builder -> ByteString toByteString x = toStrict (toLazyByteString x) instance IsString Query where fromString = Query . toByteString . stringUtf8 breaks :: [(Query, Query)] breaks = [ ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") ] }}} broken.cabal: {{{ name: broken version: 0.1.0.0 build-type: Simple cabal-version: >=1.10 library exposed-modules: Broken other-extensions: OverloadedStrings build-depends: base , bytestring , bytestring-builder default-language: Haskell2010 }}} Errors with: {{{ ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): Simplifier ticks exhausted When trying UnfoldingDone pokeN_a1Db To increase the limit, use -fsimpl-tick-factor=N (default 100) If you need to do this, let GHC HQ know, and what factor you needed To see detailed counts use -ddump-simpl-stats Total ticks: 22484 }}} ---- ---- **Update 1**: I've been able to provide a much simpler test case for this error: Broken.hs: {{{ #!haskell {-# LANGUAGE OverloadedStrings #-} module Broken (breaks) where import Database.PostgreSQL.Simple.Types (Query) breaks :: [(Query, Query)] breaks = [ ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") , ("query", "query") ] }}} broken.cabal: {{{ name: broken version: 0.1.0.0 build-type: Simple cabal-version: >=1.10 library exposed-modules: Broken other-extensions: OverloadedStrings build-depends: base -- >=4.9 && <4.10 , postgresql-simple -- >=0.5 && <0.6 default-language: Haskell2010 }}} `cabal install broken.cabal` results in: {{{ ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): Simplifier ticks exhausted When trying UnfoldingDone ord To increase the limit, use -fsimpl-tick-factor=N (default 100) If you need to do this, let GHC HQ know, and what factor you needed To see detailed counts use -ddump-simpl-stats Total ticks: 20731 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} ---- ---- **Older info:** ~~This is unfortunately a closed-source codebase I'm experiencing this with, but we get a GHC panic with a small/not-doing-anything-crazy codebase:~~ {{{ ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): Simplifier ticks exhausted When trying RuleFired Class op return To increase the limit, use -fsimpl-tick-factor=N (default 100) If you need to do this, let GHC HQ know, and what factor you needed To see detailed counts use -ddump-simpl-stats Total ticks: 118123 }}} When upping to `-fsimpl-tick-factor=150`, the error is a little different: {{{ ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): Simplifier ticks exhausted When trying UnfoldingDone $ To increase the limit, use -fsimpl-tick-factor=N (default 100) If you need to do this, let GHC HQ know, and what factor you needed To see detailed counts use -ddump-simpl-stats Total ticks: 177190 }}} Upping to 200 makes the issue go away. We're building with `ghc-options: -fhpc` Before each build, we remove all .tix files and the .hpc directory At the point this error fires, we're compiling the 6th module of 9. The first 6 modules to compile only have a total of 635 lines of code. To address issues I've seen in other similar tickets: - There are no recursive module imports - We don't use any `{-# INLINE #-}` or similar pragmas - There is no Template Haskell other than a `makeLenses ''App` for a small Snaplet. - We don't have any "very"/exponentially recursive code - We don't use any unboxed tuples (there *is* ST code in a module that's compiled, but not the one ghc panics on) - We don't use type families - We don't use TypeRep or Typeable - We don't use Generic When this error occurs, it fails on a module which has very little code in it. It's mainly a list of ~200-300 Query[0] values, using OverloadedStrings. I notice Query's `mappend`, which we use, is `INLINE`d. Please let me know if I can provide more detail! [0] http://hackage.haskell.org/package/postgresql-simple-0.5.3.0/docs /Database-PostgreSQL-Simple-Types.html#t:Query -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13960#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#13960: Ticks exhausted with 8.0.2 -------------------------------------+------------------------------------- Reporter: tom-bop | Owner: (none) Type: bug | Status: infoneeded Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #11312 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * related: => #11312 Comment: #11312 has previously suggested that we introduce a distinct `String#` primitive type (potentially with a fixed length). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13960#comment:13 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#13960: Ticks exhausted with 8.0.2 -------------------------------------+------------------------------------- Reporter: tom-bop | Owner: (none) Type: bug | Status: upstream Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #11312 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: infoneeded => upstream Comment: At this point we are waiting on `bytestring` upstream. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13960#comment:15 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler