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Re: [GHC] #2867: Make a way to tell GHC that a pragma name should be "recognised"
by GHC 03 Aug '14

03 Aug '14

#2867: Make a way to tell GHC that a pragma name should be "recognised" -------------------------------------+------------------------------------- Reporter: igloo | Owner: Type: feature | Status: new request | Milestone: 7.10.1 Priority: lowest | Version: 6.10.1 Component: Compiler | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by agdfrnd): * owner: agdfrnd => -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2867#comment:14> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2867: Make a way to tell GHC that a pragma name should be "recognised"
by GHC 03 Aug '14

03 Aug '14

#2867: Make a way to tell GHC that a pragma name should be "recognised" -------------------------------------+------------------------------------- Reporter: igloo | Owner: agdfrnd Type: feature | Status: new request | Milestone: 7.10.1 Priority: lowest | Version: 6.10.1 Component: Compiler | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by agdfrnd): * owner: => agdfrnd * failure: => None/Unknown * type: bug => feature request -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2867#comment:13> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8880: Configured gcc not used for some build steps
by GHC 03 Aug '14

03 Aug '14

#8880: Configured gcc not used for some build steps ------------------------------------+------------------------------------- Reporter: tibbe | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 7.9 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- The gcc passed to `./configure --with-gcc` isn't used for all gcc invocations, leadings to warnings (and potentially problems) on OS X where the default gcc is llvm. Here's an example, the call to `gcc -E` doesn't use my configure gcc, `/usr/local/bin/gcc-4.9`: {{{ sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.o|" -e "1s|^|rts/|" -e "1s|rts/|rts/dist/build/|" -e "1s|dist/build/dist/build|dist/build|g" -e "s|/Users/tibbe/src/ghc/||g" rts/dist/build/.depend-v-dyn-l-debug-thr- thr_debug-thr_l-debug_dyn-thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.bit >> rts/dist/build/.depend-v-dyn-l-debug-thr-thr_debug-thr_l-debug_dyn- thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.tmp && sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.dyn_o|" -e "1s|^|rts/|" -e "1s|rts/|rts/dist/build/|" -e "1s|dist/build/dist/build|dist/build|g" -e "s|/Users/tibbe/src/ghc/||g" rts/dist/build/.depend-v-dyn-l-debug-thr- thr_debug-thr_l-debug_dyn-thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.bit >> rts/dist/build/.depend-v-dyn-l-debug-thr-thr_debug-thr_l-debug_dyn- thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.tmp && sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.l_o|" -e "1s|^|rts/|" -e "1s|rts/|rts/dist/build/|" -e "1s|dist/build/dist/build|dist/build|g" -e "s|/Users/tibbe/src/ghc/||g" rts/dist/build/.depend-v-dyn-l-debug-thr- thr_debug-thr_l-debug_dyn-thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.bit >> rts/dist/build/.depend-v-dyn-l-debug-thr-thr_debug-thr_l-debug_dyn- thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.tmp && sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.debug_o|" -e "1s|^|rts/|" -e "1s|rts/|rts/dist/build/|" -e "1s|dist/build/dist/build|dist/build|g" -e "s|/Users/tibbe/src/ghc/||g" rts/dist/build/.depend-v-dyn-l-debug-thr- thr_debug-thr_l-debug_dyn-thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.bit >> rts/dist/build/.depend-v-dyn-l-debug-thr-thr_debug-thr_l-debug_dyn- thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.tmp && sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.thr_o|" -e "1s|^|rts/|" -e "1s|rts/|rts/dist/build/|" -e "1s|dist/build/dist/build|dist/build|g" -e "s|/Users/tibbe/src/ghc/||g" rts/dist/build/.depend-v-dyn-l-debug-thr- thr_debug-thr_l-debug_dyn-thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.bit >> rts/dist/build/.depend-v-dyn-l-debug-thr-thr_debug-thr_l-debug_dyn- thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.tmp && sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.thr_debug_o|" -e "1s|^|rts/|" -e "1s|rts/|rts/dist/build/|" -e "1s|dist/build/dist/build|dist/build|g" -e "s|/Users/tibbe/src/ghc/||g" rts/dist/build/.depend-v-dyn-l-debug-thr- thr_debug-thr_l-debug_dyn-thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.bit >> rts/dist/build/.depend-v-dyn-l-debug-thr-thr_debug-thr_l-debug_dyn- thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.tmp && sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.thr_l_o|" -e "1s|^|rts/|" -e "1s|rts/|rts/dist/build/|" -e "1s|dist/build/dist/build|dist/build|g" -e "s|/Users/tibbe/src/ghc/||g" rts/dist/build/.depend-v-dyn-l-debug-thr- thr_debug-thr_l-debug_dyn-thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.bit >> rts/dist/build/.depend-v-dyn-l-debug-thr-thr_debug-thr_l-debug_dyn- thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.tmp && sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.debug_dyn_o|" -e "1s|^|rts/|" -e "1s|rts/|rts/dist/build/|" -e "1s|dist/build/dist/build|dist/build|g" -e "s|/Users/tibbe/src/ghc/||g" rts/dist/build/.depend-v-dyn-l-debug-thr- thr_debug-thr_l-debug_dyn-thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.bit >> rts/dist/build/.depend-v-dyn-l-debug-thr-thr_debug-thr_l-debug_dyn- thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.tmp && sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.thr_dyn_o|" -e "1s|^|rts/|" -e "1s|rts/|rts/dist/build/|" -e "1s|dist/build/dist/build|dist/build|g" -e "s|/Users/tibbe/src/ghc/||g" rts/dist/build/.depend-v-dyn-l-debug-thr- thr_debug-thr_l-debug_dyn-thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.bit >> rts/dist/build/.depend-v-dyn-l-debug-thr-thr_debug-thr_l-debug_dyn- thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.tmp && sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.thr_debug_dyn_o|" -e "1s|^|rts/|" -e "1s|rts/|rts/dist/build/|" -e "1s|dist/build/dist/build|dist/build|g" -e "s|/Users/tibbe/src/ghc/||g" rts/dist/build/.depend-v-dyn-l-debug-thr- thr_debug-thr_l-debug_dyn-thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.bit >> rts/dist/build/.depend-v-dyn-l-debug-thr-thr_debug-thr_l-debug_dyn- thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.tmp && sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.l_dyn_o|" -e "1s|^|rts/|" -e "1s|rts/|rts/dist/build/|" -e "1s|dist/build/dist/build|dist/build|g" -e "s|/Users/tibbe/src/ghc/||g" rts/dist/build/.depend-v-dyn-l-debug-thr- thr_debug-thr_l-debug_dyn-thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.bit >> rts/dist/build/.depend-v-dyn-l-debug-thr-thr_debug-thr_l-debug_dyn- thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.tmp && sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.thr_l_dyn_o|" -e "1s|^|rts/|" -e "1s|rts/|rts/dist/build/|" -e "1s|dist/build/dist/build|dist/build|g" -e "s|/Users/tibbe/src/ghc/||g" rts/dist/build/.depend-v-dyn-l-debug-thr- thr_debug-thr_l-debug_dyn-thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.bit >> rts/dist/build/.depend-v-dyn-l-debug-thr-thr_debug-thr_l-debug_dyn- thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.tmp && true gcc -E -m64 -DPROFILING -DTHREADED_RTS -DDEBUG -Irts/dist/build -m64 -fno-stack-protector -Wall -Wextra -Wstrict-prototypes -Wmissing- prototypes -Wmissing-declarations -Winline -Waggregate-return -Wpointer- arith -Wmissing-noreturn -Wnested-externs -Wredundant-decls -Iincludes -Iincludes/dist -Iincludes/dist-derivedconstants/header -Iincludes/dist- ghcconstants/header -Irts -Irts/dist/build -DCOMPILING_RTS -fno-strict- aliasing -fno-common -DDTRACE -O2 -fomit-frame-pointer -DRtsWay=\"rts_v\" -Wno-strict-prototypes -MM -x c rts/WSDeque.c -MF rts/dist/build/.depend-v-dyn-l-debug-thr-thr_debug-thr_l-debug_dyn- thr_dyn-thr_debug_dyn-l_dyn-thr_l_dyn.c_asm.bit no checking for sigaction... In file included from rts/WSDeque.c:44: In file included from rts/RtsUtils.h:12: rts/BeginPrivate.h:9:13: warning: unknown pragma ignored [-Wunknown- pragmas] #pragma GCC visibility push(hidden) ^ In file included from rts/WSDeque.c:44: In file included from rts/RtsUtils.h:48: rts/EndPrivate.h:2:13: warning: unknown pragma ignored [-Wunknown-pragmas] #pragma GCC visibility pop ^ 2 warnings generated. }}} I can't quite tell from which part of the build this is. Looks RTS related. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8880> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9397: Probable fix: add an INLINE[n] or NOINLINE[n] pragma confused?
by GHC 03 Aug '14

03 Aug '14

#9397: Probable fix: add an INLINE[n] or NOINLINE[n] pragma confused? -------------------------------------+------------------------------------- Reporter: jrp | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Build System | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Incorrect Blocked By: | warning at compile-time Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Building ghc HEAD using 7.8.3 under OS X results in the following warnings: {{{ "inplace/bin/ghc-stage1" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -package-name binary-0.7.1.0 -hide-all-packages -i -ilibraries/binary/src -ilibraries/binary/dist-install/build -ilibraries/binary/dist- install/build/autogen -Ilibraries/binary/dist-install/build -Ilibraries/binary/dist-install/build/autogen -Ilibraries/binary/. -optP-DGENERICS -optP-include -optPlibraries/binary/dist- install/build/autogen/cabal_macros.h -package array-0.5.0.0 -package base-4.7.1.0 -package bytestring-0.10.4.0 -package containers-0.5.5.1 -O2 -Wall -fliberate-case-threshold=1000 -XHaskell98 -O2 -no-user-package-db -rtsopts -odir libraries/binary/dist-install/build -hidir libraries/binary/dist-install/build -stubdir libraries/binary/dist- install/build -split-objs -dynamic-too -c libraries/binary/src/Data/Binary/Get/Internal.hs -o libraries/binary/dist- install/build/Data/Binary/Get/Internal.o -dyno libraries/binary/dist- install/build/Data/Binary/Get/Internal.dyn_o libraries/binary/src/Data/Binary/Get/Internal.hs:314:1: Warning: Rule "<$> to <*>" may never fire because ‘<$>’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma on ‘<$>’ "inplace/bin/ghc-stage1" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -package-name binary-0.7.1.0 -hide-all-packages -i -ilibraries/binary/src -ilibraries/binary/dist-install/build -ilibraries/binary/dist- install/build/autogen -Ilibraries/binary/dist-install/build -Ilibraries/binary/dist-install/build/autogen -Ilibraries/binary/. -optP-DGENERICS -optP-include -optPlibraries/binary/dist- install/build/autogen/cabal_macros.h -package array-0.5.0.0 -package base-4.7.1.0 -package bytestring-0.10.4.0 -package containers-0.5.5.1 -O2 -Wall -fliberate-case-threshold=1000 -XHaskell98 -O2 -no-user-package-db -rtsopts -odir libraries/binary/dist-install/build -hidir libraries/binary/dist-install/build -stubdir libraries/binary/dist- install/build -split-objs -dynamic-too -c libraries/binary/src/Data/Binary/Get.hs -o libraries/binary/dist- install/build/Data/Binary/Get.o -dyno libraries/binary/dist- install/build/Data/Binary/Get.dyn_o libraries/binary/src/Data/Binary/Get.hs:416:1: Warning: Rule "getWord8/readN" may never fire because ‘getWord8’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma on ‘getWord8’ libraries/binary/src/Data/Binary/Get.hs:417:1: Warning: Rule "getWord16be/readN" may never fire because ‘getWord16be’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma on ‘getWord16be’ libraries/binary/src/Data/Binary/Get.hs:418:1: Warning: Rule "getWord16le/readN" may never fire because ‘getWord16le’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma on ‘getWord16le’ libraries/binary/src/Data/Binary/Get.hs:419:1: Warning: Rule "getWord32be/readN" may never fire because ‘getWord32be’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma on ‘getWord32be’ libraries/binary/src/Data/Binary/Get.hs:420:1: Warning: Rule "getWord32le/readN" may never fire because ‘getWord32le’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma on ‘getWord32le’ libraries/binary/src/Data/Binary/Get.hs:421:1: Warning: Rule "getWord64be/readN" may never fire because ‘getWord64be’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma on ‘getWord64be’ libraries/binary/src/Data/Binary/Get.hs:422:1: Warning: Rule "getWord64le/readN" may never fire because ‘getWord64le’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma on ‘getWord64le’ }}} Not sure what the probable fix is suggesting as the functions that are pointed are already marked as INLINE. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9397> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8331: GHC fails to apply {-# SPECIALIZE #-} for dubious reasons
by GHC 01 Aug '14

01 Aug '14

#8331: GHC fails to apply {-# SPECIALIZE #-} for dubious reasons -------------------------+------------------------------------------------- Reporter: | Owner: blitzcode | Status: new Type: bug | Milestone: Priority: | Version: 7.6.3 normal | Operating System: Unknown/Multiple Component: | Type of failure: Incorrect warning at Compiler | compile-time Keywords: | Test Case: Architecture: | Blocking: Unknown/Multiple | Difficulty: | Unknown | Blocked By: | Related Tickets: | -------------------------+------------------------------------------------- I encountered a 'RULE left-hand side too complicated to desugar' warning when trying to reduce some typeclass overhead through a SPECIALIZE pragma. The change I had to make to my program to make the warning go away seems rather strange, so I thought it might be worth reporting as a bug. This is the small test case I wrote to understand the problem better: {{{ {-# LANGUAGE FlexibleInstances, RankNTypes #-} module Main (main) where import Control.Monad import Control.Monad.Reader import Control.Monad.ST import Control.Applicative class (Applicative m, {- Functor m ,-} Monad m) => MonadAbstractIOST m where addstuff :: Int -> m Int type ReaderST s = ReaderT (Int) (ST s) instance MonadAbstractIOST (ReaderST s) where addstuff a = return . (a +) =<< ask runAbstractST :: (forall s. ReaderST s a) -> a runAbstractST f = runST $ runReaderT f 99 {-# SPECIALIZE INLINE useAbstractMonad :: ReaderST s Int #-} useAbstractMonad :: MonadAbstractIOST m => m Int useAbstractMonad = foldM (\a b -> a `seq` return . (a +) =<< (addstuff b)) 0 [1..50000000] -- useConcreteMonad :: ReaderST s Int -- useConcreteMonad = foldM (\a b -> a `seq` return . (a +) =<< (addstuff b)) 0 [1..50000000] main :: IO () main = do let st = runAbstractST useAbstractMonad putStrLn . show $ st }}} The use case here is simply having a library of functions which are abstracted from the underlying implementation of state (Reader / IO, Reader / ST, etc.) and operate on it with a small set of typeclass functions. This has very severe runtime overhead (~5x) compared to using the actual transformer stack directly, so a SPECIALIZE pragma seemed a good idea. The simple program above works as expected, but the warning appears as soon as the 'Functor' superclass is commented back in. It seems to me this should make no difference as Functor is already a superclass of Applicative. It was still there simply by oversight. I think SPECIALIZE should not fail in this case, and if it does, it would be really helpful to have a better error message. 'Too complicated' does not help in tracking down what needs to be changed for the specialization to happen, and given how harsh the overhead is otherwise, this is quite painful. In any case, once the specialization is applied in my actual program, the following error appears: {{{ ghc: panic! (the 'impossible' happened) (GHC version 7.6.3 for i386-apple-darwin): Simplifier ticks exhausted When trying UnfoldingDone a_saCf{v} [lid] 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: 66169 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} It seems like I need a -fsimpl-tick-factor of 450-500 for the compilation to succeed, resulting in a ~3x increase in binary size and a ~4x increase in compile time. The resulting code at least seems to benefit from the specialization as expected. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8331> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9325: mod73 output file needs to be reordered
by GHC 01 Aug '14

01 Aug '14

#9325: mod73 output file needs to be reordered -------------------------------------+------------------------------------- Reporter: jrp | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Test Suite | Version: 7.8.3 Keywords: mod73 | Differential Revisions: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Difficulty: Unknown Test Case: mod73 | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------- The correct output from the mod73 test needs to be reordered in HEAD: {{{ =====> mod73(normal) 1610 of 4044 [0, 0, 0] cd ./module && '/Users/jrp/Projects/ghc/inplace/bin/ghc-stage2' -fforce- recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c mod73.hs >mod73.comp.stderr 2>&1 Actual stderr output differs from expected: --- ./module/mod73.stderr 2014-07-16 21:21:57.000000000 +0100 +++ ./module/mod73.comp.stderr 2014-07-17 20:15:54.000000000 +0100 @@ -2,6 +2,6 @@ mod73.hs:3:7: Not in scope: ‘Prelude.g’ Perhaps you meant one of these: - data constructor ‘Prelude.LT’ (imported from Prelude), + data constructor ‘Prelude.GT’ (imported from Prelude), data constructor ‘Prelude.EQ’ (imported from Prelude), - data constructor ‘Prelude.GT’ (imported from Prelude) + data constructor ‘Prelude.LT’ (imported from Prelude) *** unexpected failure for mod73(normal) Unexpected results from: TEST="mod73" }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9325> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9380: ghc generates seemingly incorrect code
by GHC 31 Jul '14

31 Jul '14

#9380: ghc generates seemingly incorrect code -------------------------------------+------------------------------------- Reporter: qnikst | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Incorrect Blocked By: | result at runtime Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- GHC generates a wrong code for the case-match on GADT with polymorphic type, here is a minimal example attached, expected results are 'A' in all test cases (this is case for ghc-HEAD), however in: test0 - result is missing as matches are removed from code (according to core) test1 - returns A as expected test2 - output 'o_O' without any checks -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9380> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9387: LLVM backend: redundant code for functions calling themselves
by GHC 31 Jul '14

31 Jul '14

#9387: LLVM backend: redundant code for functions calling themselves -----------------------------------+--------------------------------------- Reporter: jmoy | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (LLVM) | Version: 7.6.3 Keywords: | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -----------------------------------+--------------------------------------- It seems that the LLVM backed does not recognize when a function calls itself. As a result it generates redundant load and store instructions. I am compiling the following simple recursive Fibonacci function {{{ fib::Int->Int fib n = loop n 0 1 where loop !n !a !b = if n==1 then a else loop (n-1) b (a+b) }}} I am attaching the files produced by {{{ ghc -c -O3 -fllvm -ddump-stg -ddump-cmm -ddump-llvm -ddump-to-file Fib.hs }}} I rename the generated LLVM file with a `.ll` extension and run `llc -O3` on it to generate the attached `.s` file (LLVM version 3.4.2). The actual work gets done in `Fib_zdwloop_info`. It begins as: {{{ Fib_zdwloop_info: # @Fib_zdwloop_info # BB#0: # %css pushq %rax movq %r13, (%rsp) movq %rbp, -8(%rsp) movq %r12, -16(%rsp) movq %rbx, -24(%rsp) movq %r14, -32(%rsp) movq %rsi, -40(%rsp) movq %rdi, -48(%rsp) movq %r8, -56(%rsp) movq %r9, -64(%rsp) movq %r15, -72(%rsp) movss %xmm1, -76(%rsp) movss %xmm2, -80(%rsp) movss %xmm3, -84(%rsp) movss %xmm4, -88(%rsp) movsd %xmm5, -96(%rsp) movsd %xmm6, -104(%rsp) }}} Later on when the function makes a recursive call to itself the code generated is {{{ movq -8(%rsp), %rbp movq -16(%rsp), %r12 movq -24(%rsp), %rbx movq -32(%rsp), %r14 movq -40(%rsp), %rsi movq -72(%rsp), %r15 popq %rax jmp Fib_zdwloop_info # TAILCALL }}} Given that the values are being loaded from the stack to the registers in the second excerpt, it is redundant to re-store the same values into the stack at the entry of the function. It seems to me that this is happening because LLVM uses a general function call instruction to translate a function calling itself. I was wondering if it is possible to recognize this special case in the LLVM backed or earlier so that instead of a function call we can translate this as the LLVM level as a jump to some point after the function entry. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9387> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1620: ModBreaks.modBreaks_array not initialised
by GHC 31 Jul '14

31 Jul '14

#1620: ModBreaks.modBreaks_array not initialised -------------------------------------+------------------------------------- Reporter: guest | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: GHCi | Version: 7.8.2 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: | Blocked By: None/Unknown | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by rwbarton): * version: 7.8.3 => 7.8.2 * milestone: => 7.10.1 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1620#comment:6> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1620: ModBreaks.modBreaks_array not initialised (was: Bug in debugger 6.7.20070817)
by GHC 31 Jul '14

31 Jul '14

#1620: ModBreaks.modBreaks_array not initialised -------------------------------------+------------------------------------- Reporter: guest | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.8.3 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: | Blocked By: None/Unknown | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by rwbarton): * status: closed => new * version: 6.7 => 7.8.3 * resolution: fixed => -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1620#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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