September 2022 - ghc-devs

GHC compiler perf CI
by Simon Peyton Jones 11 Sep '22

11 Sep '22

Dear devs I used to use the build *x86_64-linux-deb10-int_native-validate* as the place to look for compiler/bytes-allocated changes in perf/compiler. But now it doesn't show those results any more, only runtime/bytes-allocated in perf/should_run. - Should we not run perf/compiler in every build? - Why has it gone from the build above - Which build should I look at to see perf/compiler data Thanks Simon

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When do we get loads/stores with volatile semantics (if we get them at all)?
by Travis Whitaker 10 Sep '22

10 Sep '22

Hello Haskell Friends, Recently I noticed some strange behavior in a program that uses peek/poke to manipulate memory mapped hardware registers, that smells a lot like missing volatile semantics to me. It hadn’t occurred to me that peek/poke might not have volatile semantics (they return an IO, and that IO has to happen, right?), but naturally once they’re lowered all such bets are off. This made me wonder: - Do we have a type like #Addr whose loads/stores have volatile semantics? - Do we have any primops with volatile semantics at all? - Are there any tricks one could use to get volatile semantics out of base’s peek/poke functions? Poking around, I’m afraid the answer to all three of these is “no.” If so, I’d be very interested in contributing volatile load/store primops and working out some way to make them easily available from Foreign.Storable. Does no such thing currently exist or am I missing something? Thanks for all your ongoing efforts, Travis

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Unix library apparently broken
by Simon Peyton Jones 07 Sep '22

07 Sep '22

My !8750 builds are failing in the Unix library with the "pattern match is redundant" message below. And indeed the pattern match is redundant. Here's the .hs version of the file unpackRLimit :: CRLim -> ResourceLimit unpackRLimit (18446744073709551615) = ResourceLimitInfinity {-# LINE 101 "libraries/unix/System/Posix/Resource.hsc" #-} unpackRLimit other {-# LINE 103 "libraries/unix/System/Posix/Resource.hsc" #-} | ((18446744073709551615) :: CRLim) /= (18446744073709551615) && {-# LINE 104 "libraries/unix/System/Posix/Resource.hsc" #-} other == (18446744073709551615) = ResourceLimitUnknown {-# LINE 105 "libraries/unix/System/Posix/Resource.hsc" #-} {-# LINE 106 "libraries/unix/System/Posix/Resource.hsc" #-} {-# LINE 107 "libraries/unix/System/Posix/Resource.hsc" #-} | ((18446744073709551615) :: CRLim) /= (18446744073709551615) && {-# LINE 108 "libraries/unix/System/Posix/Resource.hsc" #-} other == (18446744073709551615) = ResourceLimitUnknown {-# LINE 109 "libraries/unix/System/Posix/Resource.hsc" #-} {-# LINE 110 "libraries/unix/System/Posix/Resource.hsc" #-} | otherwise = ResourceLimit (fromIntegral other) The red line means that the blue lines will fail. So the warning looks correct. But it's stopping my CI from working. I have no idea why this doesn't happen in HEAD. Can anyone help? Thanks Simon Command line: _build/stage0/bin/aarch64-linux-gnu-ghc -Wall -Wcompat -fdiagnostics-color=never -dynamic-too -hisuf hi -osuf o -hcsuf hc -static -hide-all-packages -no-user-package-db '-package-env -' '-package-db _build/stage1/lib/package.conf.d' '-this-unit-id unix-2.7.2.2' '-package-id base-4.17.0.0' '-package-id bytestring-0.11.3.1' '-package-id time-1.12.2' -i -i/builds/ghc/ghc/_build/stage1/libraries/unix/build -i/builds/ghc/ghc/_build/stage1/libraries/unix/build/autogen -i/builds/ghc/ghc/libraries/unix -Irts/include -I_build/stage1/libraries/unix/build -I_build/stage1/libraries/unix/build/include -Ilibraries/unix/include -I/builds/ghc/ghc/_build/stage1/lib/aarch64-linux-ghc-9.5.20220906/time-1.12.2/include -I/builds/ghc/ghc/_build/stage1/lib/aarch64-linux-ghc-9.5.20220906/bytestring-0.11.3.1/include -I/builds/ghc/ghc/_build/stage1/lib/aarch64-linux-ghc-9.5.20220906/base-4.17.0.0/include -I/builds/ghc/ghc/_build/stage1/lib/aarch64-linux-ghc-9.5.20220906/ghc-bignum-1.3/include -I/builds/ghc/ghc/_build/stage1/lib/aarch64-linux-ghc-9.5.20220906/rts-1.0.2/include -optP-include -optP_build/stage1/libraries/unix/build/autogen/cabal_macros.h -outputdir _build/stage1/libraries/unix/build -Wnoncanonical-monad-instances -optc-Wno-error=inline -optP-Wno-nonportable-include-path -c _build/stage1/libraries/unix/build/System/Posix/Resource.hs -o _build/stage1/libraries/unix/build/System/Posix/Resource.o -fllvm-fill-undef-with-garbage -dno-debug-output -Wall -XHaskell2010 -no-global-package-db -package-db=/builds/ghc/ghc/_build/stage1/lib/package.conf.d -ghcversion-file=rts/include/ghcversion.h -ghcversion-file=rts/include/ghcversion.h -O -Wno-deprecated-flags -Werror -dlint ===> Command failed with error code: 1 libraries/unix/System/Posix/Resource.hsc:107:7: error: [-Woverlapping-patterns, -Werror=overlapping-patterns] Pattern match is redundant In an equation for ‘unpackRLimit’: unpackRLimit other | ((18446744073709551615) :: CRLim) /= (18446744073709551615) && other == (18446744073709551615) = ... | 107 | | ((#const RLIM_SAVED_CUR) :: CRLim) /= (#const RLIM_INFINITY) && | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^...

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possible regression in GHC 9.2.4: hang in simplifier (?) when building a test executable
by Doug Burke 07 Sep '22

07 Sep '22

I have a test executable which will build with ghc 9.2.3 (and many older versions) but which appears to hang with GHC 9.2.4. I have exhausted what little I know of in debugging this, so any help in identifying the problem would be appreciated. Unfortunately it's a relatively large application, so the following reproducer requires some time/disk space. Thanks fo ryour time, Doug ----------------------------------------------------------------------------------------------------------------- I am on a linux machine (ubuntu 22.04) and have seen this with builds either with stack or nix. % git clone https://gitlab.com/dburke/swish temp % cd temp % git rev-parse HEAD 09c92e0fbbea9be86cac5c8e273e1d5915a9eeae Added to get the timings, but it's not strictly necessary: % sed -i -e "s/-Wall /-Wall -ddump-timings /" swish.cabal First a check of a successful build (with stack, GHC 9.0.2): % stack test --resolver lts-19.22 :test-rdfproof ... wait a while [2 of 2] Compiling Main *** Parser [Main]: Parser [Main]: alloc=27576560 time=8.702 *** Renamer/typechecker [Main]: Renamer/typechecker [Main]: alloc=61957416 time=85.052 *** Desugar [Main]: Desugar [Main]: alloc=19485576 time=16.095 *** Simplifier [Main]: Simplifier [Main]: alloc=1024590752 time=937.479 *** Specialise [Main]: Specialise [Main]: alloc=49779464 time=30.480 *** Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = False}) [Main]: Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = False}) [Main]: alloc=243444904 time=287.934 *** Simplifier [Main]: Simplifier [Main]: alloc=959971736 time=844.707 *** Simplifier [Main]: Simplifier [Main]: alloc=816465992 time=727.244 *** Simplifier [Main]: Simplifier [Main]: alloc=914290184 time=835.805 Float inwards [Main]: alloc=17448 time=0.007 Called arity analysis [Main]: alloc=19288 time=0.008 *** Float inwards [Main]: *** Called arity analysis [Main]: *** Simplifier [Main]: *** Demand analysis [Main]: Simplifier [Main]: alloc=492772800 time=396.191 Demand analysis [Main]: alloc=435384136 time=234.248 *** Constructed Product Result analysis [Main]: Constructed Product Result analysis [Main]: alloc=67395816 time=27.498 *** Worker Wrapper binds [Main]: Worker Wrapper binds [Main]: alloc=10456160 time=10.538 *** Simplifier [Main]: Simplifier [Main]: alloc=675869616 time=624.538 Exitification transformation [Main]: alloc=20416 time=0.007 *** Exitification transformation [Main]: *** Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = True}) [Main]: Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = True}) [Main]: alloc=212059304 time=172.872 Common sub-expression [Main]: alloc=18768 time=0.008 Float inwards [Main]: alloc=17448 time=0.006 *** Common sub-expression [Main]: *** Float inwards [Main]: *** Simplifier [Main]: Simplifier [Main]: alloc=430634768 time=397.868 *** Demand analysis [Main]: Demand analysis [Main]: alloc=144629272 time=70.451 *** CoreTidy [Main]: CoreTidy [Main]: alloc=48438688 time=44.112 *** CorePrep [Main]: *** CodeGen [Main]: CorePrep [Main]: alloc=15032 time=0.012 CodeGen [Main]: alloc=1738308168 time=1051.197 *** systool:as: systool:as: alloc=118376 time=0.481 *** initializing unit database: initializing unit database: alloc=15393080 time=21.985 *** initializing unit database: initializing unit database: alloc=3745512 time=2.507 *** Chasing dependencies: *** systool:cpp: systool:cpp: alloc=213016 time=0.552 Chasing dependencies: alloc=11345152 time=5.353 Linking .stack-work/dist/x86_64-linux-tinfo6/Cabal-3.4.1.0/build/test-rdfproof/test-rdfproof ... ... ... then it goes on to run the test ... With 9.2.4 it will not build % ... similar to above but with some information about the versions not ... fully tested with stack ... *** Parser [Main]: Parser [Main]: alloc=24346008 time=8.730 *** Renamer/typechecker [Main]: Renamer/typechecker [Main]: alloc=58415776 time=44.077 *** Desugar [Main]: Desugar [Main]: alloc=22148416 time=15.693 *** Simplifier [Main]: Simplifier [Main]: alloc=651048904 time=530.123 *** Specialise [Main]: Specialise [Main]: alloc=44412080 time=31.885 *** Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = False}) [Main]: Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = False}) [Main]: alloc=207753368 time=259.238 *** Simplifier [Main]: Simplifier [Main]: alloc=599788216 time=548.107 *** Simplifier [Main]: Simplifier [Main]: alloc=562910904 time=474.847 *** Simplifier [Main]: Simplifier [Main]: alloc=725093584 time=643.255 Float inwards [Main]: alloc=23720 time=0.011 Called arity analysis [Main]: alloc=25856 time=0.012 *** Float inwards [Main]: *** Called arity analysis [Main]: *** Simplifier [Main]: At this point it just makes my laptop fan spin faster wit h one of my CPUs pegged at 100%, but it never seems to print anything more. For those that prefer nix, you can try the following which shows the same behavior (these are using the same mangled cabal file to get the timings): % nix-shell --argstr compiler ghc923 % cabal test test-rdfproof ... [2 of 2] Compiling Main ( tests/RDFProofTest.hs, /home/dburke/rdf/temp/dist-newstyle/build/x86_64-linux/ghc-9.2.3/swish-0.10.2.0/t/test-rdfproof/build/test-rdfproof/test-rdfproof-tmp/Main.o ) *** Parser [Main]: Parser [Main]: alloc=25233912 time=9.910 *** Renamer/typechecker [Main]: Renamer/typechecker [Main]: alloc=57027880 time=45.911 *** Desugar [Main]: Desugar [Main]: alloc=21808096 time=54.569 *** Simplifier [Main]: Simplifier [Main]: alloc=936319072 time=880.189 *** Specialise [Main]: Specialise [Main]: alloc=41599784 time=23.425 *** Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = False}) [Main]: Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = False}) [Main]: alloc=204955224 time=226.189 *** Simplifier [Main]: Simplifier [Main]: alloc=610153728 time=654.735 *** Simplifier [Main]: Simplifier [Main]: alloc=566346328 time=549.298 *** Simplifier [Main]: Simplifier [Main]: alloc=801330080 time=802.428 *** Float inwards [Main]: Float inwards [Main]: alloc=23160 time=0.012 *** Called arity analysis [Main]: Called arity analysis [Main]: alloc=25296 time=0.013 *** Simplifier [Main]: Simplifier [Main]: alloc=423629864 time=320.611 *** Demand analysis [Main]: Demand analysis [Main]: alloc=253018800 time=175.884 *** Constructed Product Result analysis [Main]: Constructed Product Result analysis [Main]: alloc=74681224 time=28.675 *** Worker Wrapper binds [Main]: Worker Wrapper binds [Main]: alloc=8622264 time=7.070 *** Simplifier [Main]: Simplifier [Main]: alloc=598294440 time=554.802 *** Exitification transformation [Main]: Exitification transformation [Main]: alloc=26712 time=0.013 *** Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = True}) [Main]: Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = True}) [Main]: alloc=179540608 time=226.938 *** Common sub-expression [Main]: Common sub-expression [Main]: alloc=24800 time=0.014 *** Float inwards [Main]: Float inwards [Main]: alloc=23168 time=0.010 *** Simplifier [Main]: Simplifier [Main]: alloc=382679152 time=318.224 *** Demand analysis [Main]: Demand analysis [Main]: alloc=84192056 time=50.989 *** CoreTidy [Main]: CoreTidy [Main]: alloc=45347360 time=44.571 *** CorePrep [Main]: CorePrep [Main]: alloc=34753448 time=10.917 *** CoreToStg [Main]: CoreToStg [Main]: alloc=108293568 time=114.768 *** CodeGen [Main]: CodeGen [Main]: alloc=1475393208 time=858.854 *** WriteIface [/home/dburke/rdf/temp/dist-newstyle/build/x86_64-linux/ghc-9.2.3/swish-0.10.2.0/t/test-rdfproof/build/test-rdfproof/test-rdfproof-tmp/Main.hi]: WriteIface [/home/dburke/rdf/temp/dist-newstyle/build/x86_64-linux/ghc-9.2.3/swish-0.10.2.0/t/test-rdfproof/build/test-rdfproof/test-rdfproof-tmp/Main.hi]: alloc=3732816 time=3.044 *** systool:as: systool:as: alloc=132384 time=0.456 *** initializing unit database: initializing unit database: alloc=7386016 time=4.306 *** initializing unit database: initializing unit database: alloc=4000384 time=12.125 *** Chasing dependencies: *** systool:cpp: systool:cpp: alloc=313896 time=0.486 Chasing dependencies: alloc=12822240 time=6.459 Linking /home/dburke/rdf/temp/dist-newstyle/build/x86_64-linux/ghc-9.2.3/swish-0.10.2.0/t/test-rdfproof/build/test-rdfproof/test-rdfproof ... ... versus % nix-shell --argstr compiler ghc924 cabal test test-rdfproof Warning: The package list for 'hackage.haskell.org' is 20 days old. Run 'cabal update' to get the latest list of available packages. Resolving dependencies... Build profile: -w ghc-9.2.4 -O1 In order, the following will be built (use -v for more details): - swish-0.10.2.0 (test:test-rdfproof) (first run) Preprocessing test suite 'test-rdfproof' for swish-0.10.2.0.. Building test suite 'test-rdfproof' for swish-0.10.2.0.. *** initializing unit database: initializing unit database: alloc=7389248 time=4.462 *** initializing unit database: initializing unit database: alloc=4001312 time=11.664 *** Chasing dependencies: *** systool:cpp: systool:cpp: alloc=319464 time=0.481 Chasing dependencies: alloc=12861208 time=6.331 [2 of 2] Compiling Main ( tests/RDFProofTest.hs, /home/dburke/rdf/temp/dist-newstyle/build/x86_64-linux/ghc-9.2.4/swish-0.10.2.0/t/test-rdfproof/build/test-rdfproof/test-rdfproof-tmp/Main.o ) *** Parser [Main]: Parser [Main]: alloc=25236056 time=23.982 *** Renamer/typechecker [Main]: Renamer/typechecker [Main]: alloc=101830968 time=97.529 *** Desugar [Main]: Desugar [Main]: alloc=24617072 time=19.187 *** Simplifier [Main]: Simplifier [Main]: alloc=665051592 time=558.078 *** Specialise [Main]: Specialise [Main]: alloc=44894576 time=30.341 *** Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = False}) [Main]: Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = False}) [Main]: alloc=208060752 time=245.458 *** Simplifier [Main]: Simplifier [Main]: alloc=602721856 time=555.073 *** Simplifier [Main]: Simplifier [Main]: alloc=563887832 time=529.865 *** Simplifier [Main]: Simplifier [Main]: alloc=727381840 time=606.367 *** Float inwards [Main]: Float inwards [Main]: alloc=23720 time=0.012 *** Called arity analysis [Main]: Called arity analysis [Main]: alloc=25848 time=0.012 *** Simplifier [Main]: which again hangs

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Updating haddock
by Simon Peyton Jones 06 Sep '22

06 Sep '22

Dear devs I'm working on !8750, which has some knock-on changes that are needed on the Haddock repo. So - in the main repo I have wip/T21623 - in the utils/haddock repo have branch wip/spj-T21623 Periodically I need to rebase on master. Question: what is the Blessed Sequence of Commands that I should use to push the right changes to haddock? I think it is something like: 1. In the main GHC repo, on branch wip/T21623 1. git fetch 2. git rebase origin/master 2. In utils/haddock, 1. identify the set of patches P1..Pn between the trunk and my haddock tip, the changes that I need to haddock. 2. Somehow check out the haddock commit K that corresponds to origin/master 3. Apply P1..Pn on top of K 4. Force-push to origin/wip/spj-T21623 3. Move to the main GHC repo 1. git add utils/haddock 2. Create a patch for that change 3. Push to main repo But I am not sure how to do step 2.2, nor what is an efficient way to do 2.3. I would welcome very precise instructions. Thank you! Simon

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Tags
by Simon Peyton Jones 06 Sep '22

06 Sep '22

I love emacs' tags-query-replace function, which allows me to do a search-and-replace across an entire repo. But to do that I need a TAGS file that, at least, lists all the Hsakell files in GHC. What is the approved way to construct a TAGS file for a bunch of Haskell modules? Is this documented anywhere? Thanks Simon

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CI failures
by Simon Peyton Jones 06 Sep '22

06 Sep '22

Matthew, Ben, Bryan CI is failing in in "lint-ci-config".. See https://gitlab.haskell.org/ghc/ghc/-/merge_requests/8916 or https://gitlab.haskell.org/ghc/ghc/-/merge_requests/7847 What's up? Simon

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