June 2018 - ghc-tickets

[GHC] #13233: typePrimRep panic while compiling GHC with profiling
by GHC 20 Sep '18

20 Sep '18

#13233: typePrimRep panic while compiling GHC with profiling -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I am seeing this panic while compiling GHC stage2, {{{ ghc-stage1: panic! (the 'impossible' happened) (GHC version 8.1.20170124 for x86_64-unknown-linux): runtimeRepPrimRep typePrimRep (a :: TYPE k0) k0 Call stack: ?callStack, called at compiler/utils/Util.hs:1352:50 in ghc:Util prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1166:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1170:37 in ghc:Outputable pprPanic, called at compiler/simplStg/RepType.hs:360:5 in ghc:RepType Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug <<ghc: 1038844096 bytes, 158 GCs, 21564561/73278928 avg/max bytes residency (8 samples), 148M in use, 0.000 INIT (0.000 elapsed), 1.113 MUT (1.125 elapsed), 0.935 GC (0.940 elapsed) :ghc>> compiler/ghc.mk:582: recipe for target 'compiler/stage2/build/StgCmmMonad.p_o' failed }}} This appears to be due to my enabling of profiling. `build.mk` contains, {{{ BuildFlavour=prof ifneq "$(BuildFlavour)" "" include mk/flavours/$(BuildFlavour).mk endif HADDOCK_DOCS=YES compiler_HC_OPTS += -fprof-auto-exported }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13233> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14941: Switching direct type family application to EqPred (~) prevents inlining in code using vector (10x slowdown)
by GHC 20 Sep '18

20 Sep '18

#14941: Switching direct type family application to EqPred (~) prevents inlining in code using vector (10x slowdown) -------------------------------------+------------------------------------- Reporter: nh2 | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Runtime Unknown/Multiple | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{#!hs selectVectorDestructive2 :: (PrimMonad m, VG.Vector v e, Ord e, Show e, VG.Mutable v ~ vm) => Int -> v e -> vm (PrimState m) e -> Int -> Int -> m () -- slow selectVectorDestructive2 :: (PrimMonad m, VG.Vector v e, Ord e, Show e) => Int -> v e -> VG.Mutable v (PrimState m) e -> Int -> Int -> m () -- fast }}} These two functions are identical except one has `VG.Mutable v ~ vm` as a constraint, the other one has it in the type signature right of the `=>`. The second function is 10x faster. I would expect them to be equally fast. The code of the functions is identical, I change only the type declaration. The slowness happens because with the first function, inlining of primitives like `unsafeRead` does not happen, and thus also it boxes the `Int#`s back to `Int`s when calling `unsafeRead`. In particular, in `-ddump-simpl`, the slow version has {{{#!hs $wpartitionLoop2_rgEy :: forall (m :: * -> *) (vm :: * -> * -> *) e. (PrimMonad m, MVector vm e, Ord e) => vm (PrimState m) e -> GHC.Prim.Int# -> e -> GHC.Prim.Int# -> GHC.Prim.Int# -> GHC.Prim.Int# -> m Int $wpartitionLoop2_rgEy = \... -> let { endIndex_a7Ay :: Int ... endIndex_a7Ay = GHC.Types.I# ww2_sfZn } in ... (VGM.basicUnsafeRead ... endIndex_a7Ay) ... }}} while the fast version has {{{#!hs $w$spartitionLoop2_rgUN :: GHC.Prim.Int# -> GHC.Prim.Int# -> GHC.Prim.MutableByteArray# GHC.Prim.RealWorld -> GHC.Prim.Int# -> GHC.Prim.Int# -> GHC.Prim.Int# -> GHC.Prim.Int# -> GHC.Prim.Int# -> GHC.Prim.State# GHC.Prim.RealWorld -> (# GHC.Prim.State# GHC.Prim.RealWorld, Int #) ... $spartitionLoop2_rgUP :: VG.Mutable VU.Vector (PrimState IO) Int -> Int -> Int -> Int -> Int -> Int -> GHC.Prim.State# GHC.Prim.RealWorld -> (# GHC.Prim.State# GHC.Prim.RealWorld, Int #) }}} So with `VG.Mutable v (PrimState m) e` in the type signature, GHC managed to inline + specialise it all the way down to concrete types (`VUM.MVector`, `IO`, and `Int` as the element type), and consequently inline `basicUnsafeRead` on unboxed `Int#`. But with `VG.Mutable v ~ vm`, ghc keeps `vm (PrimState m) e` all the way, passes around dictionaries, thus eventually cannot inline `basicUnsafeRead` and re-packs already unboxed values, like `endIndex_a7Ay = GHC.Types.I# ww2_sfZn`, before passing them into the non-inlined call of `basicUnsafeRead`, thus making a tight loop allocate that normally wouldn't allocate. Why might rewriting the type signature in such a trivial way make this happen? ---- I have tested this on GHC 8.0.2, GHC 8.2.2, and GHC 8.5 HEAD commit cc4677c36ee. Reproducer: * https://github.com/nh2/haskell-quickselect-median-of- medians/blob/0efd6293e779fda2d864ec3d75329fb16b8af6d9/Main.hs#L506 * Running instructions are [https://github.com/nh2/haskell-quickselect- median-of-medians/commit/7a49d673990dfaebdb0ba837c3fbbaae0455dba0 in this commit message]; for short: `stack exec -- ghc -O --make Main.hs -rtsopts -ddump-simpl -dsuppress-coercions -fforce-recomp -ddump-to-file -fno-full- laziness && ./Main +RTS -sstderr` * For that file, I have pregenerated `-dverbose-core2core` output here: https://github.com/nh2/haskell-quickselect-median-of- medians/tree/0efd6293e779fda2d864ec3d75329fb16b8af6d9/slowness-analysis * I originally just wanted to write a fast median-of-medians implementation on ZuriHac 2017, but got totally derailed by this performance problem. The version of it that I link here is a total mess because of me mauling it to track down this performance issue. Trying to increase `-funfolding-use-threshold` or `-funfolding-keeness- factor` did not change the situation. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14941> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11295: Figure out what LLVM passes are fruitful
by GHC 19 Sep '18

19 Sep '18

#11295: Figure out what LLVM passes are fruitful -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 (LLVM) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Builds using GHC's LLVM backend are currently substantially slower than GHC's own native code generator. There are a few possible reasons for this, 1. the cost of forking processes and serializing/parsing LLVM's intermediate representation 2. the cost of the more powerful optimizations responsible for LLVM's (hopefully) better code generation 3. the cost of redundant optimizations overlapping effort already expended by GHC Given that some architecture (e.g. ARM) are only supported by LLVM and therefore suffer considerably at the hand of our slow builds, we should try to reduce # -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11295> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14329: GHC 8.2.1 segfaults while bootstrapping master
by GHC 19 Sep '18

19 Sep '18

#14329: GHC 8.2.1 segfaults while bootstrapping master -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.2.2 Component: Compiler | Version: 8.2.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Earlier this week the Linux/amd64 Harbormaster started failing somewhat reliably during validation. It seems the stage0 compiler (GHC 8.2.1) often fails with a segmentation fault. This seems to have started with ef26182e2014b0a2a029ae466a4b121bf235e4e4 although I suspect this isn't causal. I was able to capture a core dump of the crashing stage0 compiler which implicates the allocator, {{{ Reading symbols from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/ghc...(no debugging symbols found)...done. [New LWP 25151] [New LWP 25160] [New LWP 25156] [New LWP 25158] [New LWP 25157] [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". Core was generated by `/opt/ghc/8.2.1/lib/ghc-8.2.1/bin/ghc -B/opt/ghc/8.2.1/lib/ghc-8.2.1 -hisuf hi -'. Program terminated with signal SIGSEGV, Segmentation fault. #0 0x00007f836aaa2c90 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so [Current thread is 1 (Thread 0x7f83711b5340 (LWP 25151))] (gdb) bt #0 0x00007f836aaa2c90 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so #1 0x00007f836aaa3211 in allocGroupOnNode () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so #2 0x00007f836aa9dd41 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so #3 0x00007f836aa9deb9 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so #4 0x00007f836aa82a39 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so #5 0x00007f836aa7fc06 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so #6 0x00007f836aa9d461 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so #7 0x00007f836aaa423a in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so #8 0x00007f836aaa4b3c in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so #9 0x00007f836aa8bbc8 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so #10 0x00007f836aa8c912 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so #11 0x00007f836aa8da01 in scheduleWaitThread () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so #12 0x00007f836aa99fae in hs_main () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so #13 0x0000000000427038 in ?? () #14 0x00007f83694fd2b1 in __libc_start_main (main=0x426fd0, argc=119, argv=0x7fffcfee8078, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffcfee8068) at ../csu/libc- start.c:291 #15 0x0000000000427069 in ?? () }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14329> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12100: GHC 8.0.1 build segmentation fault in haddock
by GHC 19 Sep '18

19 Sep '18

#12100: GHC 8.0.1 build segmentation fault in haddock -------------------------------------+------------------------------------- Reporter: ilovezfs | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: MacOS X Architecture: | Type of failure: Building GHC Unknown/Multiple | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Skylake iMac OS X 10.11.5. Xcode 7.3.1. march=native. This happens each time I attempt to build 8.0.1. The release candidates were not affected: {{{ "inplace/bin/ghc-stage2" -hisuf dyn_hi -osuf dyn_o -hcsuf dyn_hc -fPIC -dynamic -H32m -O -Wall -hide-all-packages -i -iutils/haddock/driver -iutils/haddock/haddock-api/src -iutils/haddock/haddock- library/vendor/attoparsec-0.12.1.1 -iutils/haddock/haddock-library/src -iutils/haddock/dist/build -iutils/haddock/dist/build/autogen -Iutils/haddock/dist/build -Iutils/haddock/dist/build/autogen -optP- DIN_GHC_TREE -optP-include -optPutils/haddock/dist/build/autogen/cabal_macros.h -package-id Cabal-1.24.0.0 -package-id array-0.5.1.1 -package-id base-4.9.0.0 -package-id bytestring-0.10.8.1 -package-id containers-0.5.7.1 -package-id deepseq-1.4.2.0 -package-id directory-1.2.6.2 -package-id filepath-1.4.1.0 -package-id ghc-8.0.1 -package-id ghc-boot-8.0.1 -package-id transformers-0.5.2.0 -package-id xhtml-3000.2.1 -funbox-strict-fields -Wall -fwarn-tabs -O2 -threaded -XHaskell2010 -no-user-package-db -rtsopts -Wno-unused-imports -Wno-deprecations -Wnoncanonical-monad- instances -odir utils/haddock/dist/build -hidir utils/haddock/dist/build -stubdir utils/haddock/dist/build -c utils/haddock/haddock- library/src/Documentation/Haddock/Types.hs -o utils/haddock/dist/build/Documentation/Haddock/Types.dyn_o "inplace/bin/ghc-stage2" -hisuf dyn_hi -osuf dyn_o -hcsuf dyn_hc -fPIC -dynamic -H32m -O -Wall -hide-all-packages -i -iutils/haddock/driver -iutils/haddock/haddock-api/src -iutils/haddock/haddock- library/vendor/attoparsec-0.12.1.1 -iutils/haddock/haddock-library/src -iutils/haddock/dist/build -iutils/haddock/dist/build/autogen -Iutils/haddock/dist/build -Iutils/haddock/dist/build/autogen -optP- DIN_GHC_TREE -optP-include -optPutils/haddock/dist/build/autogen/cabal_macros.h -package-id Cabal-1.24.0.0 -package-id array-0.5.1.1 -package-id base-4.9.0.0 -package-id bytestring-0.10.8.1 -package-id containers-0.5.7.1 -package-id deepseq-1.4.2.0 -package-id directory-1.2.6.2 -package-id filepath-1.4.1.0 -package-id ghc-8.0.1 -package-id ghc-boot-8.0.1 -package-id transformers-0.5.2.0 -package-id xhtml-3000.2.1 -funbox-strict-fields -Wall -fwarn-tabs -O2 -threaded -XHaskell2010 -no-user-package-db -rtsopts -Wno-unused-imports -Wno-deprecations -Wnoncanonical-monad- instances -odir utils/haddock/dist/build -hidir utils/haddock/dist/build -stubdir utils/haddock/dist/build -c utils/haddock/dist/build/autogen/Paths_haddock.hs -o utils/haddock/dist/build/Paths_haddock.dyn_o "inplace/bin/ghc-stage2" -hisuf dyn_hi -osuf dyn_o -hcsuf dyn_hc -fPIC -dynamic -H32m -O -Wall -hide-all-packages -i -iutils/haddock/driver -iutils/haddock/haddock-api/src -iutils/haddock/haddock- library/vendor/attoparsec-0.12.1.1 -iutils/haddock/haddock-library/src -iutils/haddock/dist/build -iutils/haddock/dist/build/autogen -Iutils/haddock/dist/build -Iutils/haddock/dist/build/autogen -optP- DIN_GHC_TREE -optP-include -optPutils/haddock/dist/build/autogen/cabal_macros.h -package-id Cabal-1.24.0.0 -package-id array-0.5.1.1 -package-id base-4.9.0.0 -package-id bytestring-0.10.8.1 -package-id containers-0.5.7.1 -package-id deepseq-1.4.2.0 -package-id directory-1.2.6.2 -package-id filepath-1.4.1.0 -package-id ghc-8.0.1 -package-id ghc-boot-8.0.1 -package-id transformers-0.5.2.0 -package-id xhtml-3000.2.1 -funbox-strict-fields -Wall -fwarn-tabs -O2 -threaded -XHaskell2010 -no-user-package-db -rtsopts -Wno-unused-imports -Wno-deprecations -Wnoncanonical-monad- instances -odir utils/haddock/dist/build -hidir utils/haddock/dist/build -stubdir utils/haddock/dist/build -c utils/haddock/haddock- library/src/Documentation/Haddock/Utf8.hs -o utils/haddock/dist/build/Documentation/Haddock/Utf8.dyn_o make[1]: *** [utils/haddock/dist/build/Haddock/Backends/Hyperlinker/Types.dyn_o] Segmentation fault: 11 make[1]: *** Waiting for unfinished jobs.... make[1]: *** [utils/haddock/dist/build/Documentation/Haddock/Types.dyn_o] Segmentation fault: 11 make[1]: *** [utils/haddock/dist/build/Haddock/GhcUtils.dyn_o] Segmentation fault: 11 make[1]: *** [utils/haddock/dist/build/Paths_haddock.dyn_o] Segmentation fault: 11 make[1]: *** [utils/haddock/dist/build/ResponseFile.dyn_o] Segmentation fault: 11 make: *** [all] Error 2 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12100> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13279: Check known-key lists
by GHC 19 Sep '18

19 Sep '18

#13279: Check known-key lists -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I noticed that `fmap` (for example) has a known key {{{#!hs fmapName = varQual gHC_BASE (fsLit "fmap") fmapClassOpKey fmapClassOpKey = mkPreludeMiscIdUnique 173 }}} but its `RdrName` doesn't refer to it. {{{#!hs fmap_RDR = varQual_RDR gHC_BASE (fsLit "fmap") }}} Is there a reason for this? If not, it seems likely that we could get a bit of a speed-up by using `fmapName` here. We may also consider making `liftA2` known-key for `Traversable` deriving. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13279> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11284: Lambda-lifting fails in simple Text example
by GHC 18 Sep '18

18 Sep '18

#11284: Lambda-lifting fails in simple Text example -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Consider the example, {{{#!hs import Data.Char (isSpace) import Data.List (foldl') import GHC.Exts (build) import qualified Data.Text as T longestWord :: T.Text -> Int longestWord t = foldl' max 0 $ map T.length $ fusedWords t fusedWords :: T.Text -> [T.Text] fusedWords t0 = build $ \cons nil -> let go !t | T.null t = nil | otherwise = let (w, rest) = T.span (not . isSpace) t in cons w (go $ T.dropWhile isSpace rest) in go t0 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11284> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10859: Generated Eq instance associates && wrongly
by GHC 18 Sep '18

18 Sep '18

#10859: Generated Eq instance associates && wrongly -------------------------------------+------------------------------------- Reporter: nomeata | Owner: simonpj Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 7.10.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #10858 Differential Revisions: | -------------------------------------+------------------------------------- Currently, we derive this code for `(==)`: {{{ (==) (ImportDecl a1_acXi a2_acXj a3_acXk a4_acXl a5_acXm a6_acXn a7_acXo a8_acXp) (ImportDecl b1_acXq b2_acXr b3_acXs b4_acXt b5_acXu b6_acXv b7_acXw b8_acXx) = (((((((((a1_acXi == b1_acXq)) && ((a2_acXj == b2_acXr))) && ((a3_acXk == b3_acXs))) && ((a4_acXl == b4_acXt))) && ((a5_acXm == b5_acXu))) && ((a6_acXn == b6_acXv))) && ((a7_acXo == b7_acXw))) && ((a8_acXp == b8_acXx))) }}} To me this looks wrongly associated: Since `&&` is strict in the left but lazy in the right argument, shouldn’t this be associated the other way around? The compiler might clean it up later, but why not produce it correctly right away? The culprit is this line: {{{ = foldl1 and_Expr (zipWith3Equal "nested_eq" nested_eq tys as bs) }}} and I was just about to change that ot `foldr1`, but then I did some git- archeology and found that Simon changed that deliberately from `foldr1` to `foldl1` in changeset:8de16184643ea3c2f9f30b5eaed18db6ef247760. Simon, do you still recall what you were thinking when you applied this commit ... 18½years ago? :-) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10859> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15208: GHC 8.4 fails to build on Debian armel (softfloat)
by GHC 18 Sep '18

18 Sep '18

#15208: GHC 8.4 fails to build on Debian armel (softfloat) --------------------------------+--------------------------------- Reporter: clint | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 Keywords: | Operating System: Linux Architecture: arm | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: --------------------------------+--------------------------------- This seems intentional but on the other hand the error message says "Please report this as a GHC bug" {{{ "inplace/bin/ghc-stage1" -static -H32m -O -lffi -optl-pthread -optl-B/usr/bin/ld.gold -Wall -Iincludes -Iincludes/dist -Iincludes /dist-derivedconstants/header -Iincludes/dist-ghcconstants/header -Irts -Irts/dist/build -DCOMPILING_RTS -this-unit-id rts -optc-DNOSMP -dcmm-lint -i -irts -irts/dist/build -Irts/dist/build -irts/dist/build/./autogen -Irts/dist/build/./autogen -O2 -Wcpp-undef -Wnoncanonical- monad-instances -c rts/StgStartup.cmm -o rts/dist/build/StgStartup.o "inplace/bin/ghc-stage1" -static -H32m -O -lffi -optl-pthread -optl-B/usr/bin/ld.gold -Wall -Iincludes -Iincludes/dist -Iincludes /dist-derivedconstants/header -Iincludes/dist-ghcconstants/header -Irts -Irts/dist/build -DCOMPILING_RTS -this-unit-id rts -optc-DNOSMP -dcmm-lint -i -irts -irts/dist/build -Irts/dist/build -irts/dist/build/./autogen -Irts/dist/build/./autogen -O2 -Wcpp-undef -Wnoncanonical- monad-instances -c rts/PrimOps.cmm -o rts/dist/build/PrimOps.o "inplace/bin/ghc-stage1" -static -H32m -O -lffi -optl-pthread -optl-B/usr/bin/ld.gold -Wall -Iincludes -Iincludes/dist -Iincludes /dist-derivedconstants/header -Iincludes/dist-ghcconstants/header -Irts -Irts/dist/build -DCOMPILING_RTS -this-unit-id rts -optc-DNOSMP -dcmm-lint -i -irts -irts/dist/build -Irts/dist/build -irts/dist/build/./autogen -Irts/dist/build/./autogen -O2 -Wcpp-undef -Wnoncanonical- monad-instances -c rts/Updates.cmm -o rts/dist/build/Updates.o ghc-stage1: panic! (the 'impossible' happened) (GHC version 8.4.3 for arm-unknown-linux): Failed to lookup the datalayout for armv7l-unknown-linux-gnueabi; available targets: ["i386-unknown-windows","i686-unknown-windows","x86_64 -unknown-windows","arm-unknown-linux-gnueabihf","armv6-unknown-linux- gnueabihf","armv6l-unknown-linux-gnueabihf","armv7-unknown-linux-gnueabihf ","armv7a-unknown-linux-gnueabi","armv7l-unknown-linux-gnueabihf","aarch64 -unknown-linux-gnu","aarch64-unknown-linux","i386-unknown-linux-gnu","i386 -unknown-linux","x86_64-unknown-linux-gnu","x86_64-unknown-linux","armv7 -unknown-linux-androideabi","aarch64-unknown-linux-android","arm-unknown- nto-qnx-eabi","i386-apple-darwin","x86_64-apple-darwin","armv7-apple- ios","aarch64-apple-ios","i386-apple-ios","x86_64-apple-ios"] CallStack (from HasCallStack): error, called at compiler/llvmGen/LlvmCodeGen.hs:96:24 in ghc:LlvmCodeGen Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug rts/ghc.mk:295: recipe for target 'rts/dist/build/StgStartup.o' failed make[3]: *** [rts/dist/build/StgStartup.o] Error 1 make[3]: *** Waiting for unfinished jobs.... ghc-stage1: panic! (the 'impossible' happened) (GHC version 8.4.3 for arm-unknown-linux): Failed to lookup the datalayout for armv7l-unknown-linux-gnueabi; available targets: ["i386-unknown-windows","i686-unknown-windows","x86_64 -unknown-windows","arm-unknown-linux-gnueabihf","armv6-unknown-linux- gnueabihf","armv6l-unknown-linux-gnueabihf","armv7-unknown-linux-gnueabihf ","armv7a-unknown-linux-gnueabi","armv7l-unknown-linux-gnueabihf","aarch64 -unknown-linux-gnu","aarch64-unknown-linux","i386-unknown-linux-gnu","i386 -unknown-linux","x86_64-unknown-linux-gnu","x86_64-unknown-linux","armv7 -unknown-linux-androideabi","aarch64-unknown-linux-android","arm-unknown- nto-qnx-eabi","i386-apple-darwin","x86_64-apple-darwin","armv7-apple- ios","aarch64-apple-ios","i386-apple-ios","x86_64-apple-ios"] CallStack (from HasCallStack): error, called at compiler/llvmGen/LlvmCodeGen.hs:96:24 in ghc:LlvmCodeGen Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug rts/ghc.mk:295: recipe for target 'rts/dist/build/Updates.o' failed make[3]: *** [rts/dist/build/Updates.o] Error 1 ghc-stage1: panic! (the 'impossible' happened) (GHC version 8.4.3 for arm-unknown-linux): Failed to lookup the datalayout for armv7l-unknown-linux-gnueabi; available targets: ["i386-unknown-windows","i686-unknown-windows","x86_64 -unknown-windows","arm-unknown-linux-gnueabihf","armv6-unknown-linux- gnueabihf","armv6l-unknown-linux-gnueabihf","armv7-unknown-linux-gnueabihf ","armv7a-unknown-linux-gnueabi","armv7l-unknown-linux-gnueabihf","aarch64 -unknown-linux-gnu","aarch64-unknown-linux","i386-unknown-linux-gnu","i386 -unknown-linux","x86_64-unknown-linux-gnu","x86_64-unknown-linux","armv7 -unknown-linux-androideabi","aarch64-unknown-linux-android","arm-unknown- nto-qnx-eabi","i386-apple-darwin","x86_64-apple-darwin","armv7-apple- ios","aarch64-apple-ios","i386-apple-ios","x86_64-apple-ios"] CallStack (from HasCallStack): error, called at compiler/llvmGen/LlvmCodeGen.hs:96:24 in ghc:LlvmCodeGen Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug rts/ghc.mk:295: recipe for target 'rts/dist/build/PrimOps.o' failed }}} https://buildd.debian.org/status/fetch.php?pkg=ghc&arch=armel&ver=8.4.3-1&s… -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15208> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13617: Segfault in Windows GHCi involving C code compiled with -O4
by GHC 17 Sep '18

17 Sep '18

#13617: Segfault in Windows GHCi involving C code compiled with -O4 ----------------------------------------+------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.0.2 Keywords: | Operating System: Windows Architecture: Unknown/Multiple | Type of failure: GHCi crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+------------------------------- This is a very elusive bug that I noticed when running an `hmatrix` example under GHCi on Windows. Luckily, this example can be reduced down to a couple of `.hs` files and a single `.c` file (with no other Haskell or C dependencies). Unfortunately, I can't quite figure out a way to reproduce this bug without `cabal`, so I've put the source code at https://github.com/RyanGlScott/hmatrix-segfault. You can reproduce this bug by doing the following: {{{ $ git clone https://github.com/RyanGlScott/hmatrix-segfault $ git reset 2bfe38f964fca64dd776993c89ec59d35fb368a5 $ cd hmatrix-segfault/ $ cabal install $ runghc exe/Main.hs Access violation in generated code when reading ffffffffffffffff }}} Running `Main.hs` in GHCi crashes, whereas compiling it works: {{{ $ ghc exe/Main.hs $ ./exe/Main.exe [1,1,1,1,1,1,1,1,1,1,1,1] }}} I've reproduced this with GHC 7.10.3, 8.0.2, and 8.2.1-rc1. There are a couple of things that appear to be necessary to trigger the segfault: 1. You need to have `-O4` under `cc-options` in `hmatrix-segfault.cabal`. 2. You need to define the [https://github.com/RyanGlScott/hmatrix- segfault/blob/2bfe38f964fca64dd776993c89ec59d35fb368a5/src/Internal/Vectorized.hs#L38 FunCodeS] datatype. Removing either of these things causes the program to work again under GHCi. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13617> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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