GHC.Core.Opt.Monad

Types used in core-to-core passes

data FloatOutSwitches

Constructors

FloatOutSwitches

Fields

• floatOutLambdas :: Maybe Int

  Just n = float lambdas to top level, if doing so will abstract over n or fewer value variables Nothing = float all lambdas to top level, regardless of how many free variables Just 0 is the vanilla case: float a lambda iff it has no free vars

• floatOutConstants :: Bool

  True = float constants to top level, even if they do not escape a lambda

• floatOutOverSatApps :: Bool

  True = float out over-saturated applications based on arity information. See Note [Floating over-saturated applications] in GHC.Core.Opt.SetLevels

• floatToTopLevelOnly :: Bool

  Allow floating to the top level only.

Instances

Outputable FloatOutSwitches

Defined in GHC.Core.Opt.Monad

Methods

ppr :: FloatOutSwitches -> SDoc

The monad

data CoreM a

The monad used by Core-to-Core passes to register simplification statistics. Also used to have common state (in the form of UniqueSupply) for generating Uniques.

Instances

MonadIO CoreM

Defined in GHC.Core.Opt.Monad

Methods

liftIO :: IO a -> CoreM a

Alternative CoreM

Defined in GHC.Core.Opt.Monad

Methods

empty :: CoreM a

(<|>) :: CoreM a -> CoreM a -> CoreM a

some :: CoreM a -> CoreM [a]

many :: CoreM a -> CoreM [a]

Applicative CoreM

Defined in GHC.Core.Opt.Monad

Methods

pure :: a -> CoreM a

(<*>) :: CoreM (a -> b) -> CoreM a -> CoreM b

liftA2 :: (a -> b -> c) -> CoreM a -> CoreM b -> CoreM c

(*>) :: CoreM a -> CoreM b -> CoreM b

(<*) :: CoreM a -> CoreM b -> CoreM a

Functor CoreM

Defined in GHC.Core.Opt.Monad

Methods

fmap :: (a -> b) -> CoreM a -> CoreM b

(<$) :: a -> CoreM b -> CoreM a

Monad CoreM

Defined in GHC.Core.Opt.Monad

Methods

(>>=) :: CoreM a -> (a -> CoreM b) -> CoreM b

(>>) :: CoreM a -> CoreM b -> CoreM b

return :: a -> CoreM a

MonadPlus CoreM

Defined in GHC.Core.Opt.Monad

Methods

mzero :: CoreM a

mplus :: CoreM a -> CoreM a -> CoreM a

HasDynFlags CoreM

Defined in GHC.Core.Opt.Monad

Methods

getDynFlags :: CoreM DynFlags

MonadUnique CoreM

Defined in GHC.Core.Opt.Monad

Methods

getUniqueSupplyM :: CoreM UniqSupply

getUniqueM :: CoreM Unique

getUniquesM :: CoreM [Unique]

HasModule CoreM

Defined in GHC.Core.Opt.Monad

Methods

getModule :: CoreM Module

HasLogger CoreM

Defined in GHC.Core.Opt.Monad

Methods

getLogger :: CoreM Logger

runCoreM

Arguments

:: HscEnv

-> RuleBase

-> Char

Mask

-> Module

-> NamePprCtx

-> SrcSpan

-> CoreM a

-> IO (a, SimplCount)

mapDynFlagsCoreM :: (DynFlags -> DynFlags) -> CoreM a -> CoreM a

Adjust the dyn flags passed to the argument action

dropSimplCount :: CoreM a -> CoreM a

Drop the single count of the argument action so it doesn't effect the total.

Reading from the monad

getHscEnv :: CoreM HscEnv

getModule :: HasModule m => m Module

initRuleEnv :: ModGuts -> CoreM RuleEnv

getExternalRuleBase :: CoreM RuleBase

getDynFlags :: HasDynFlags m => m DynFlags

getPackageFamInstEnv :: CoreM PackageFamInstEnv

getInteractiveContext :: CoreM InteractiveContext

getUniqMask :: CoreM Char

getNamePprCtx :: CoreM NamePprCtx

getSrcSpanM :: CoreM SrcSpan

Writing to the monad

addSimplCount :: SimplCount -> CoreM ()

Lifting into the monad

liftIO :: MonadIO m => IO a -> m a

Lift a computation from the IO monad. This allows us to run IO computations in any monadic stack, so long as it supports these kinds of operations (i.e. IO is the base monad for the stack).

Example

import Control.Monad.Trans.State -- from the "transformers" library

printState :: Show s => StateT s IO ()
printState = do
  state <- get
  liftIO $ print state

Had we omitted liftIO, we would have ended up with this error:

• Couldn't match type ‘IO’ with ‘StateT s IO’
 Expected type: StateT s IO ()
   Actual type: IO ()

The important part here is the mismatch between StateT s IO () and IO ().

Luckily, we know of a function that takes an IO a and returns an (m a): liftIO, enabling us to run the program and see the expected results:

> evalStateT printState "hello"
"hello"

> evalStateT printState 3
3

liftIOWithCount :: IO (SimplCount, a) -> CoreM a

Lift an IO operation into CoreM while consuming its SimplCount

Dealing with annotations

getAnnotations :: Typeable a => ([Word8] -> a) -> ModGuts -> CoreM (ModuleEnv [a], NameEnv [a])

Get all annotations of a given type. This happens lazily, that is no deserialization will take place until the [a] is actually demanded and the [a] can also be empty (the UniqFM is not filtered).

This should be done once at the start of a Core-to-Core pass that uses annotations.

See Note [Annotations]

getFirstAnnotations :: Typeable a => ([Word8] -> a) -> ModGuts -> CoreM (ModuleEnv a, NameEnv a)

Get at most one annotation of a given type per annotatable item.

Screen output

putMsg :: SDoc -> CoreM ()

Output a message to the screen

putMsgS :: String -> CoreM ()

Output a String message to the screen

errorMsg :: SDoc -> CoreM ()

Output an error to the screen. Does not cause the compiler to die.

msg :: MessageClass -> SDoc -> CoreM ()

fatalErrorMsg :: SDoc -> CoreM ()

Output a fatal error to the screen. Does not cause the compiler to die.

fatalErrorMsgS :: String -> CoreM ()

Output a fatal error to the screen. Does not cause the compiler to die.

debugTraceMsg :: SDoc -> CoreM ()

Outputs a debugging message at verbosity level of -v or higher

debugTraceMsgS :: String -> CoreM ()

Output a string debugging message at verbosity level of -v or higher