Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC

Commits:

• d5d940b3
  by Matthew Pickering at 2025-12-07T03:58:31-05:00

  ci: Try using multi repl in ghc-in-ghci test
  
  This should be quite a bit faster than the ./hadrian/ghci command as it
  doesn't properly build all the dependencies.
  

• f6cbfed3
  by Rodrigo Mesquita at 2025-12-07T03:58:32-05:00

  Stack.Decode: Don't error on bitmap size 0
  
  A RET_BCO may have a bitmap with no payload.
  In that case, the bitmap = 0.
  
  One can observe this by using -ddump-bcos and interpreting
  
  ```
  main = pure ()
  ```
  
  Observe, for instance, that the BCO for this main function has size 0:
  
  ```
  ProtoBCO Main.main#0:
     \u []
         break<main:Main,0>() GHC.Internal.Base.pure
                                  GHC.Internal.Base.$fApplicativeIO GHC.Internal.Tuple.()
     bitmap:  0 []
     BRK_FUN <breakarray> main:Main 0 <cc>
     PACK     () 0
     PUSH_G   GHC.Internal.Base.$fApplicativeIO
     PUSH_APPLY_PP
     PUSH_G   GHC.Internal.Base.pure
     ENTER
  ```
  
  Perhaps we never tried to decode a stack in which a BCO like this was
  present. However, for the debugger, we want to decode stacks of threads
  stopped at breakpoints, and these kind of BCOs do get on a stack under
  e.g. `stg_apply_interp_info` frames.
  
  See the accompanying test in the next commit for an example to trigger
  the bug this commit fixes.
  
  Fixes #26640
  

• d844061d
  by Rodrigo Mesquita at 2025-12-07T03:58:32-05:00

  Add test for #26640
  

6 changed files:

• .gitlab-ci.yml
• libraries/ghc-internal/src/GHC/Internal/Stack/Decode.hs
• + testsuite/tests/bytecode/T26640.hs
• + testsuite/tests/bytecode/T26640.script
• + testsuite/tests/bytecode/T26640.stdout
• testsuite/tests/bytecode/all.T

Changes:

     # workaround for docker permissions

     - sudo chown ghc:ghc -R .

   variables:

-    GHC_FLAGS: -Werror

+    GHC_FLAGS: -Werror -Wwarn=unused-imports

   tags:

     - x86_64-linux

   script:

     - "echo '  ghc-options: -Werror'  >> hadrian/cabal.project.local"

     # Load ghc-in-ghci then immediately exit and check the modules loaded

     - export CORES="$(mk/detect-cpu-count.sh)"

-    - echo ":q" | HADRIAN_ARGS=-j$CORES hadrian/ghci -j$CORES | tail -n2 | grep "Ok,"

+    - echo ":q" | HADRIAN_ARGS=-j$CORES hadrian/ghci-multi -j$CORES | tail -n2 | grep "Ok,"

   after_script:

     - .gitlab/ci.sh save_cache

     - cat ci_timings.txt

     cWordArrayToList ptr size = mapM (peekElemOff ptr) [0 .. (size - 1)]

     usedBitmapWords :: Int -> Int

-    usedBitmapWords 0 = error "Invalid large bitmap size 0."

+    usedBitmapWords 0 = 0

     usedBitmapWords size = (size `div` fromIntegral wORD_SIZE_IN_BITS) + 1

     bitmapWordsPointerness :: Word -> [Word] -> [Pointerness]

+-- Main.hs

+module Main where

+main = pure ()

+

+:l T26640

+:break 3

+main

+import GHC.Conc

+import GHC.Stack.CloneStack

+() <- mapM_ (\ix -> do !_ <- decode =<< cloneThreadStack ix; return ()) =<< listThreads

+Breakpoint 0 activated at T26640.hs:3:8-14

+Stopped in Main.main, T26640.hs:3:8-14

+_result :: IO () = _

 test('T26565', extra_files(["T26565.hs"]), ghci_script, ['T26565.script'])

 test('T23973', extra_files(["T23973.hs"]), ghci_script, ['T23973.script'])

+test('T26640', extra_files(["T26640.hs"]), ghci_script, ['T26640.script'])

 # Nullary data constructors

 test('T26216', extra_files(["T26216_aux.hs"]), ghci_script, ['T26216.script'])