{-# LANGUAGE
  TemplateHaskell,
  MultiParamTypeClasses
  #-}
module LLVM.General.Internal.PassManager where

import qualified Language.Haskell.TH as TH

import Control.Exception
import Control.Monad hiding (forM_)
import Control.Monad.IO.Class
import Control.Applicative

import Control.Monad.AnyCont

import Data.Word
import Data.Foldable (forM_)
import Foreign.C (CString)
import Foreign.Ptr

import qualified LLVM.General.Internal.FFI.PassManager as FFI
import qualified LLVM.General.Internal.FFI.Transforms as FFI

import LLVM.General.Internal.Module
import LLVM.General.Internal.Target
import LLVM.General.Internal.Coding
import LLVM.General.Internal.DataLayout
import LLVM.General.Transforms

import LLVM.General.AST.DataLayout

-- | <http://llvm.org/doxygen/classllvm_1_1PassManager.html>
-- Note: a PassManager does substantive behind-the-scenes work, arranging for the
-- results of various analyses to be available as needed by transform passes, shared
-- as possible.
newtype PassManager = PassManager (Ptr FFI.PassManager)

-- | There are different ways to get a 'PassManager'. This type embodies them.
data PassSetSpec
  -- | a 'PassSetSpec' is a lower-level, detailed specification of a set of passes. It
  -- allows fine-grained control of what passes are to be run when, and the specification
  -- of passes not available through 'CuratedPassSetSpec'.
  = PassSetSpec {
      transforms :: [Pass],
      dataLayout :: Maybe DataLayout,
      targetLibraryInfo :: Maybe TargetLibraryInfo,
      targetLowering :: Maybe TargetLowering
    }
  -- | This type is a high-level specification of a set of passes. It uses the same
  -- collection of passes chosen by the LLVM team in the command line tool 'opt'.  The fields
  -- of this spec are much like typical compiler command-line flags - e.g. -O\<n\>, etc.
  | CuratedPassSetSpec {
      optLevel :: Maybe Word,
      sizeLevel :: Maybe Word,
      unitAtATime :: Maybe Bool,
      simplifyLibCalls :: Maybe Bool,
      useInlinerWithThreshold :: Maybe Word
    }

-- | Helper to make a curated 'PassSetSpec'
defaultCuratedPassSetSpec = CuratedPassSetSpec {
  optLevel = Nothing,
  sizeLevel = Nothing,
  unitAtATime = Nothing,
  simplifyLibCalls = Nothing,
  useInlinerWithThreshold = Nothing
}

-- | an empty 'PassSetSpec'
defaultPassSetSpec = PassSetSpec {
  transforms = [],
  dataLayout = Nothing,
  targetLibraryInfo = Nothing,
  targetLowering = Nothing
}

instance (Monad m, MonadAnyCont IO m) => EncodeM m GCOVVersion CString where
  encodeM (GCOVVersion cs@[_,_,_,_]) = encodeM cs

createPassManager :: PassSetSpec -> IO (Ptr FFI.PassManager)
createPassManager pss = flip runAnyContT return $ do
  pm <- liftIO $ FFI.createPassManager
  case pss of
    s@CuratedPassSetSpec {} -> liftIO $ do
      bracket FFI.passManagerBuilderCreate FFI.passManagerBuilderDispose $ \b -> do
        let handleOption g m = forM_ (m s) (g b <=< encodeM) 
        handleOption FFI.passManagerBuilderSetOptLevel optLevel
        handleOption FFI.passManagerBuilderSetSizeLevel sizeLevel
        handleOption FFI.passManagerBuilderSetDisableUnitAtATime (liftM not . unitAtATime)
        handleOption FFI.passManagerBuilderSetDisableSimplifyLibCalls (liftM not . simplifyLibCalls)
        handleOption FFI.passManagerBuilderUseInlinerWithThreshold useInlinerWithThreshold
        FFI.passManagerBuilderPopulateModulePassManager b pm
    PassSetSpec ps dl tli tl' -> do
      let tl = maybe nullPtr (\(TargetLowering tl) -> tl) tl'
      forM_ tli $ \(TargetLibraryInfo tli) -> do
        liftIO $ FFI.addTargetLibraryInfoPass pm tli
      forM_ dl $ \dl -> liftIO $ withFFIDataLayout dl $ FFI.addDataLayoutPass pm 
      forM_ ps $ \p -> $(
        do
          TH.TyConI (TH.DataD _ _ _ cons _) <- TH.reify ''Pass
          TH.caseE [| p |] $ flip map cons $ \con -> do
            let
              (n, fns) = case con of
                            TH.RecC n fs -> (n, [ TH.nameBase fn | (fn, _, _) <- fs ])
                            TH.NormalC n [] -> (n, [])
              actions = 
                [ TH.bindS (TH.varP . TH.mkName $ fn) [| encodeM $(TH.dyn fn) |] | fn <- fns ]
                ++ [
                 TH.noBindS [|
                   liftIO $(
                     foldl1 TH.appE
                     (map TH.dyn $
                        ["FFI.add" ++ TH.nameBase n ++ "Pass", "pm"]
                        ++ ["tl" | FFI.needsTargetLowering (TH.nameBase n)]
                        ++ fns)
                    )
                   |]
                 ]
            TH.match (TH.conP n $ map (TH.varP . TH.mkName) fns) (TH.normalB (TH.doE actions)) []
       )
  return pm

-- | bracket the creation of a 'PassManager'
withPassManager :: PassSetSpec -> (PassManager -> IO a) -> IO a
withPassManager s = bracket (createPassManager s) FFI.disposePassManager . (. PassManager)

-- | run the passes in a 'PassManager' on a 'Module', modifying the 'Module'.
runPassManager :: PassManager -> Module -> IO Bool
runPassManager (PassManager p) (Module m) = toEnum . fromIntegral <$> FFI.runPassManager p m