`opt` is the LLVM optimizer, not part of GHC. If it's exiting with exit code -11 that's almost certainly due to a segfault, which in turn is almost certainly due to it running out of memory, seeing as you're building on an ARM system and the source file contains a 72KB-long list
#13062: `opt' failed in phase `LLVM Optimiser'. (Exit code: -11) -------------------------------------+------------------------------------- Reporter: 2bdkid | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (LLVM) | Version: 8.0.1 Resolution: | Keywords: LLVM | Optimiser -11 Operating System: Linux | Architecture: arm Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by 2bdkid): Replying to [comment:1 rwbarton]: literal. How much RAM does your build system have? This is a Raspberry Pi 2 and it only has 1GB of ram. Is there any documentation for opt exit codes? I can't find any through Google -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13062#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler