I'm observing a few different runtime errors. I'm not sure if they're because of different bugs so I'm filing one ticket for now. The reproduce with GHC HEAD: ``` prog001 git:(master) $ ghc-stage2 Mult.hs -prof -fprof-auto -fforce-recomp -threaded [1 of 7] Compiling Stream ( Stream.hs, Stream.o ) [2 of 7] Compiling Converter ( Converter.hs, Converter.o ) [3 of 7] Compiling Thread ( Thread.hs, Thread.o ) [4 of 7] Compiling Utilities ( Utilities.hs, Utilities.o ) [5 of 7] Compiling Trit ( Trit.hs, Trit.o ) [6 of 7] Compiling Arithmetic ( Arithmetic.hs, Arithmetic.o ) [7 of 7] Compiling Main ( Mult.hs, Mult.o ) Linking Mult ... prog001 git:(master) $ ./Mult +RTS -N2 Mult: internal error: scavenge_one: strange object 624722688 (GHC version 8.7.20180809 for x86_64_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug zsh: abort (core dumped) ./Mult +RTS -N2 prog001 git:(master) $ ./Mult +RTS -N2 Mult: internal error: scavenge_stack: weird activation record found on stack: 0 (GHC version 8.7.20180821 for x86_64_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug zsh: abort (core dumped) ./Mult +RTS -N2 prog001 git:(master) $ ./Mult +RTS -N2 zsh: segmentation fault (core dumped) ./Mult +RTS -N2 ``` It's very easy to trigger other kind of panics in `concprog001`, just try different compile and runtime flag combinations. Note that for the examples below you'll need debug + profiling or debug + profiling + threaded runtimes, which are not built by default. To build those apply this patch: ``` diff --git a/mk/config.mk.in b/mk/config.mk.in index 11050120d4..f083abad22 100644 --- a/mk/config.mk.in +++ b/mk/config.mk.in @@ -297,6 +297,7 @@ GhcRTSWays=l # Usually want the debug version GhcRTSWays += debug +GhcRTSWays += thr_debug_p debug_p # We always have the threaded versions, but note that SMP support may be disabled # (see GhcWithSMP). diff --git a/rts/ghc.mk b/rts/ghc.mk index 532c9aa175..ff3f18f30c 100644 --- a/rts/ghc.mk +++ b/rts/ghc.mk @@ -329,7 +329,6 @@ WARNING_OPTS += -Wstrict-prototypes WARNING_OPTS += -Wmissing-prototypes WARNING_OPTS += -Wmissing-declarations WARNING_OPTS += -Winline -WARNING_OPTS += -Waggregate-return WARNING_OPTS += -Wpointer-arith WARNING_OPTS += -Wmissing-noreturn WARNING_OPTS += -Wnested-externs ``` Examples: ``` prog001 git:(master) $ ghc-stage2 Mult.hs -prof -fprof-auto -fforce-recomp -debug [1 of 7] Compiling Stream ( Stream.hs, Stream.o ) [2 of 7] Compiling Converter ( Converter.hs, Converter.o ) [3 of 7] Compiling Thread ( Thread.hs, Thread.o ) [4 of 7] Compiling Utilities ( Utilities.hs, Utilities.o ) [5 of 7] Compiling Trit ( Trit.hs, Trit.o ) [6 of 7] Compiling Arithmetic ( Arithmetic.hs, Arithmetic.o ) [7 of 7] Compiling Main ( Mult.hs, Mult.o ) Linking Mult ... prog001 git:(master) $ ./Mult +RTS -DS Mult: internal error: ASSERTION FAILED: file rts/sm/Sanity.c, line 210 (GHC version 8.7.20180809 for x86_64_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug zsh: abort (core dumped) ./Mult +RTS -DS ``` (I tried to fix this in [D5051](https://phabricator.haskell.org/D5051) but it's causing a segfault in test `T11108` when run with profiling. Not sure what the problem is yet.) Another way: ``` prog001 git:(master) $ ghc-stage2 Mult.hs -prof -fprof-auto -fforce-recomp -threaded [1 of 7] Compiling Stream ( Stream.hs, Stream.o ) [2 of 7] Compiling Converter ( Converter.hs, Converter.o ) [3 of 7] Compiling Thread ( Thread.hs, Thread.o ) [4 of 7] Compiling Utilities ( Utilities.hs, Utilities.o ) [5 of 7] Compiling Trit ( Trit.hs, Trit.o ) [6 of 7] Compiling Arithmetic ( Arithmetic.hs, Arithmetic.o ) [7 of 7] Compiling Main ( Mult.hs, Mult.o ) Linking Mult ... prog001 git:(master) $ ./Mult +RTS -N2 zsh: segmentation fault (core dumped) ./Mult +RTS -N2 ``` Yet another way: ``` prog001 git:(master) $ ghc-stage2 Mult.hs -prof -fprof-auto -fforce-recomp -threaded -debug [1 of 7] Compiling Stream ( Stream.hs, Stream.o ) [2 of 7] Compiling Converter ( Converter.hs, Converter.o ) [3 of 7] Compiling Thread ( Thread.hs, Thread.o ) [4 of 7] Compiling Utilities ( Utilities.hs, Utilities.o ) [5 of 7] Compiling Trit ( Trit.hs, Trit.o ) [6 of 7] Compiling Arithmetic ( Arithmetic.hs, Arithmetic.o ) [7 of 7] Compiling Main ( Mult.hs, Mult.o ) Linking Mult ... prog001 git:(master) $ ./Mult +RTS -N2 Mult: internal error: invalid closure, info=0x947edc (GHC version 8.7.20180809 for x86_64_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug zsh: abort (core dumped) ./Mult +RTS -N2 ``` \~\~It seems to work fine when not compiled for profiling so marking this bug as a profiler bug.\~\~ This program fails sanity checks with non-threaded and non-profiling runtime too: ``` prog001 git:(master) $ ghc-stage2 Mult.hs -fforce-recomp -debug -rtsopts [1 of 7] Compiling Stream ( Stream.hs, Stream.o ) [2 of 7] Compiling Converter ( Converter.hs, Converter.o ) [3 of 7] Compiling Thread ( Thread.hs, Thread.o ) [4 of 7] Compiling Utilities ( Utilities.hs, Utilities.o ) [5 of 7] Compiling Trit ( Trit.hs, Trit.o ) [6 of 7] Compiling Arithmetic ( Arithmetic.hs, Arithmetic.o ) [7 of 7] Compiling Main ( Mult.hs, Mult.o ) Linking Mult ... prog001 git:(master) $ ./Mult +RTS -DS Mult: internal error: checkClosure: stack frame (GHC version 8.7.20180821 for x86_64_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug zsh: abort (core dumped) ./Mult +RTS -DS ```