diff options
Diffstat (limited to 'compiler/GHC/Driver/Backend.hs')
| -rw-r--r-- | compiler/GHC/Driver/Backend.hs | 56 |
1 files changed, 35 insertions, 21 deletions
diff --git a/compiler/GHC/Driver/Backend.hs b/compiler/GHC/Driver/Backend.hs index 2642a2a9af..9f37f6c62a 100644 --- a/compiler/GHC/Driver/Backend.hs +++ b/compiler/GHC/Driver/Backend.hs @@ -1,8 +1,11 @@ {-# LANGUAGE MultiWayIf #-} +{-# LANGUAGE PatternSynonyms #-} -- | Code generation backends module GHC.Driver.Backend - ( Backend (..) + ( Backend + , pattern NoBackend + , ActualBackend (..) , platformDefaultBackend , platformNcgSupported , backendProducesObject @@ -19,7 +22,7 @@ import GHC.Platform -- (producing machine code, producing ByteCode for the interpreter) and -- supporting different platforms. -- -data Backend +data ActualBackend = NCG -- ^ Native code generator backend. -- -- Compiles Cmm code into textual assembler, then relies on @@ -72,19 +75,30 @@ data Backend -- -- See "GHC.StgToByteCode" + deriving (Eq,Ord,Show,Read) - | NoBackend -- ^ No code generated. - -- - -- Use this to disable code generation. It is particularly - -- useful when GHC is used as a library for other purpose - -- than generating code (e.g. to generate documentation with - -- Haddock) or when the user requested it (via -fno-code) for - -- some reason. +-- | Sometimes we have a backend, and sometimes we do not. +-- +-- Not inlining 'Nothing' into 'ActualBackend' will help lead towards things +-- like e.g. +-- +-- - Building for multiple backends at once, where we would switch from +-- 'Maybe ActualBackend' to 'Set ActualBackend', not 'Set (Maybe +-- ActualBackend)'. +-- +-- - Ensuring all backends can write to files. That would mean byte code can be +-- written to a file (#21034), which makes 'ActualBackend' much more uniform. +-- Conversely it's hard to imagine it would ever make sense for 'NoBackend' to +-- write to a file! +type Backend = Maybe ActualBackend - deriving (Eq,Ord,Show,Read) +{-# COMPLETE NoBackend, Just #-} + +pattern NoBackend :: Backend +pattern NoBackend = Nothing -- | Default backend to use for the given platform. -platformDefaultBackend :: Platform -> Backend +platformDefaultBackend :: Platform -> ActualBackend platformDefaultBackend platform = if | platformUnregisterised platform -> ViaC | platformNcgSupported platform -> NCG @@ -108,11 +122,11 @@ platformNcgSupported platform = if -- | Will this backend produce an object file on the disk? backendProducesObject :: Backend -> Bool -backendProducesObject ViaC = True -backendProducesObject NCG = True -backendProducesObject LLVM = True -backendProducesObject Interpreter = False -backendProducesObject NoBackend = False +backendProducesObject (Just ViaC) = True +backendProducesObject (Just NCG) = True +backendProducesObject (Just LLVM) = True +backendProducesObject (Just Interpreter) = False +backendProducesObject NoBackend = False -- | Does this backend retain *all* top-level bindings for a module, -- rather than just the exported bindings, in the TypeEnv and compiled @@ -124,8 +138,8 @@ backendProducesObject NoBackend = False -- When no backend is used we also do it, so that Haddock can get access to the -- GlobalRdrEnv for a module after typechecking it. backendRetainsAllBindings :: Backend -> Bool -backendRetainsAllBindings Interpreter = True -backendRetainsAllBindings NoBackend = True -backendRetainsAllBindings ViaC = False -backendRetainsAllBindings NCG = False -backendRetainsAllBindings LLVM = False +backendRetainsAllBindings NoBackend = True +backendRetainsAllBindings (Just Interpreter) = True +backendRetainsAllBindings (Just ViaC) = False +backendRetainsAllBindings (Just NCG) = False +backendRetainsAllBindings (Just LLVM) = False |