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| author | Sylvain Henry <sylvain@haskus.fr> | 2020-04-22 11:23:31 +0200 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2020-05-09 21:46:38 -0400 |
| commit | 951c1fb03d80094c8b0d9bcc463d86fa71695b3a (patch) | |
| tree | 28a03e1ad9256c5038a0351c806910e9b7ef5aef /libraries/ghc-prim | |
| parent | ea86360f21e8c9812acba8dc1bc2a54fef700ece (diff) | |
| download | haskell-951c1fb03d80094c8b0d9bcc463d86fa71695b3a.tar.gz | |
Fix unboxed-sums GC ptr-slot rubbish value (#17791)
This patch allows boot libraries to use unboxed sums without implicitly
depending on `base` package because of `absentSumFieldError`.
See updated Note [aBSENT_SUM_FIELD_ERROR_ID] in GHC.Core.Make
Diffstat (limited to 'libraries/ghc-prim')
| -rw-r--r-- | libraries/ghc-prim/GHC/Prim/Panic.hs | 45 | ||||
| -rw-r--r-- | libraries/ghc-prim/ghc-prim.cabal | 1 |
2 files changed, 46 insertions, 0 deletions
diff --git a/libraries/ghc-prim/GHC/Prim/Panic.hs b/libraries/ghc-prim/GHC/Prim/Panic.hs new file mode 100644 index 0000000000..8dd8f03530 --- /dev/null +++ b/libraries/ghc-prim/GHC/Prim/Panic.hs @@ -0,0 +1,45 @@ +{-# LANGUAGE GHCForeignImportPrim #-} +{-# LANGUAGE UnliftedFFITypes #-} +{-# LANGUAGE MagicHash #-} +{-# LANGUAGE UnboxedTuples #-} +{-# LANGUAGE NoImplicitPrelude #-} +{-# LANGUAGE EmptyCase #-} + +-- | Primitive panics. +module GHC.Prim.Panic + ( absentSumFieldError + , panicError + ) +where + +import GHC.Prim +import GHC.Magic + +default () -- Double and Integer aren't available yet + +-- `stg_panic#` never returns but it can't just return `State# RealWorld` so we +-- indicate that it returns `Void#` too to make the compiler happy. +foreign import prim "stg_paniczh" panic# :: Addr# -> State# RealWorld -> (# State# RealWorld, Void# #) + +-- | Display the CString whose address is given as an argument and exit. +panicError :: Addr# -> a +panicError errmsg = + runRW# (\s -> + case panic# errmsg s of + (# _, _ #) -> -- This bottom is unreachable but we can't + -- use an empty case lest the pattern match + -- checker squawks. + let x = x in x) + +-- | Closure introduced by GHC.Stg.Unarise for unused unboxed sum fields. +-- +-- See Note [aBSENT_SUM_FIELD_ERROR_ID] in GHC.Core.Make +absentSumFieldError :: a +absentSumFieldError = panicError "entered absent sum field!"# + +-- GHC.Core.Make.aBSENT_SUM_FIELD_ERROR_ID gives absentSumFieldError a bottoming +-- demand signature. But if we ever inlined it (to a call to panicError) we'd +-- lose that information. Should not happen because absentSumFieldError is only +-- introduced in Stg.Unarise, long after inlining has stopped, but it seems +-- more direct simply to give it a NOINLINE pragma +{-# NOINLINE absentSumFieldError #-} diff --git a/libraries/ghc-prim/ghc-prim.cabal b/libraries/ghc-prim/ghc-prim.cabal index 040eb43b27..607f24df99 100644 --- a/libraries/ghc-prim/ghc-prim.cabal +++ b/libraries/ghc-prim/ghc-prim.cabal @@ -46,6 +46,7 @@ Library GHC.IntWord64 GHC.Magic GHC.Prim.Ext + GHC.Prim.Panic GHC.PrimopWrappers GHC.Tuple GHC.Types |