harpy-0.2: Harpy/CodeGenMonad.hs
{-# OPTIONS -cpp #-}
--------------------------------------------------------------------------
-- |
-- Module : CodeGenMonad
-- Copyright : (c) 2006-2007 Martin Grabmueller and Dirk Kleeblatt
-- License : GPL
--
-- Maintainer : {magr,klee}@cs.tu-berlin.de
-- Stability : provisional
-- Portability : portable (but generated code non-portable)
--
-- Monad for generating x86 machine code at runtime.
--
-- This is a combined reader-state-exception monad which handles all
-- the details of handling code buffers, emitting binary data,
-- relocation etc.
--
-- All the code generation functions in module "Harpy.X86CodeGen"
-- live in this monad and use its error reporting facilities as well
-- as the internal state maintained by the monad. The user state is
-- independent from the internal state and may be used by
-- higher-level code generation libraries to maintain their own
-- state across code generation operations.
--
--------------------------------------------------------------------------
module Harpy.CodeGenMonad(
-- * Types
CodeGen,
RelocKind(..),
ErrMsg,
Reloc,
Label,
FixupKind(..),
CodeGenConfig(..),
defaultCodeGenConfig,
-- * Functions
-- ** General code generator monad operations
failCodeGen,
-- ** Accessing code generation internals
getEntryPoint,
getCodeOffset,
getBasePtr,
getCodeBufferList,
-- ** Access to user state and environment
setState,
getState,
getEnv,
withEnv,
-- ** Label management
newLabel,
setLabel,
defineLabel,
(@@),
emitFixup,
labelAddress,
emitRelocInfo,
-- ** Code emission
emit8,
emit8At,
peek8At,
emit32,
emit32At,
checkBufferSize,
ensureBufferSize,
-- ** Executing code generation
runCodeGen,
runCodeGenWithConfig,
-- ** Calling generated functions
callDecl,
-- ** Interface to disassembler
disassemble
) where
import qualified Harpy.X86Disassembler as Dis
import Control.Monad
import Text.PrettyPrint.HughesPJ
import Text.Printf
import Data.Word
import qualified Data.Map as Map
import Foreign
import System.Cmd
import System.IO
import Control.Monad.Trans
import Language.Haskell.TH.Syntax
-- | An error message produced by a code generation operation.
type ErrMsg = Doc
-- | The code generation monad, a combined reader-state-exception
-- monad.
newtype CodeGen e s a = CodeGen ((e, CodeGenEnv) -> (s, CodeGenState) -> IO ((s, CodeGenState), Either ErrMsg a))
-- | Configuration of the code generator.
data CodeGenConfig = CodeGenConfig { codeBufferSize :: Int -- ^ Size of individual code buffer blocks.
}
-- | Internal state of the code generator
data CodeGenState = CodeGenState { buffer :: Ptr Word8,
bufferList :: [(Ptr Word8, Int)],
firstBuffer :: Ptr Word8,
bufferOfs :: Int,
bufferSize :: Int,
relocEntries :: [Reloc],
nextLabel :: Int,
definedLabels :: Map.Map Int (Ptr Word8, Int),
pendingFixups :: Map.Map Int [FixupEntry],
config :: CodeGenConfig}
data FixupKind = Fixup8
| Fixup16
| Fixup32
| Fixup32Absolute
deriving (Show)
data FixupEntry = FixupEntry { fueBuffer :: Ptr Word8,
fueOfs :: Int,
fueKind :: FixupKind }
data CodeGenEnv = CodeGenEnv { tailContext :: Bool }
deriving (Show)
-- | Kind of relocation, for example PC-relative
data RelocKind = RelocPCRel -- ^ PC-relative relocation
| RelocAbsolute -- ^ Absolute address
deriving (Show)
-- | Relocation entry
data Reloc = Reloc { offset :: Int,
-- ^ offset in code block which needs relocation
kind :: RelocKind,
-- ^ kind of relocation
address :: FunPtr ()
-- ^ target address
}
deriving (Show)
-- | Label
data Label = Label Int
unCg :: CodeGen e s a -> ((e, CodeGenEnv) -> (s, CodeGenState) -> IO ((s, CodeGenState), Either ErrMsg a))
unCg (CodeGen a) = a
instance Monad (CodeGen e s) where
return x = cgReturn x
fail err = cgFail err
m >>= k = cgBind m k
-- {-# INLINE cgReturn #-}
cgReturn x = CodeGen (\_env state -> return (state, Right x))
-- {-# INLINE cgFail #-}
cgFail err = CodeGen (\_env state -> return (state, Left (text err)))
-- {-# INLINE cgBind #-}
cgBind m k = CodeGen (\env state ->
do r1 <- unCg m env state
case r1 of
(state', Left err) -> return (state', Left err)
(state', Right v) -> unCg (k v) env state')
-- | Abort code generation with the given error message.
failCodeGen :: Doc -> CodeGen e s a
failCodeGen d = CodeGen (\_env state -> return (state, Left d))
instance MonadIO (CodeGen e s) where
liftIO st = CodeGen (\_env state -> do { r <- st; return (state, Right r) })
emptyCodeGenState :: CodeGenState
emptyCodeGenState = CodeGenState { buffer = undefined,
bufferList = [],
firstBuffer = undefined,
bufferOfs = 0,
bufferSize = 0,
relocEntries = [],
nextLabel = 0,
definedLabels = Map.empty,
pendingFixups = Map.empty,
config = defaultCodeGenConfig}
defaultCodeGenConfig :: CodeGenConfig
defaultCodeGenConfig = CodeGenConfig { codeBufferSize = defaultCodeBufferSize }
defaultCodeBufferSize :: Int
defaultCodeBufferSize = 128
-- | Execute code generation, given a user environment and state.
-- The result is a tuple of the resulting user state and either an
-- error message (when code generation failed) or the result of the
-- code generation.
runCodeGen :: CodeGen e s a -> e -> s -> IO (s, Either ErrMsg a)
runCodeGen cg uenv ustate =
runCodeGenWithConfig cg uenv ustate defaultCodeGenConfig
runCodeGenWithConfig :: CodeGen e s a -> e -> s -> CodeGenConfig -> IO (s, Either ErrMsg a)
runCodeGenWithConfig (CodeGen cg) uenv ustate conf =
do let initSize = codeBufferSize conf
arr <- mallocBytes initSize
let env = CodeGenEnv {tailContext = True}
let state = emptyCodeGenState{buffer = arr,
bufferList = [],
firstBuffer = arr,
bufferSize = initSize,
config = conf}
((ustate', _), res) <- cg (uenv, env) (ustate, state)
return (ustate', res)
-- | Check whether the code buffer has room for at least the given
-- number of bytes. This should be called by code generators
-- whenever it cannot be guaranteed that the code buffer is large
-- enough to hold all the generated code. Lets the code generation
-- monad fail when the buffer overflows.
checkBufferSize :: Int -> CodeGen e s ()
checkBufferSize needed =
do state <- getInternalState
unless (bufferOfs state + needed <= bufferSize state)
(failCodeGen (text "code generation buffer overflow: needed additional" <+>
int needed <+> text "bytes (offset =" <+>
int (bufferOfs state) <>
text ", buffer size =" <+>
int (bufferSize state) <> text ")"))
-- | Make sure that the code buffer has room for at least the given
-- number of bytes. This should be called by code generators
-- whenever it cannot be guaranteed that the code buffer is large
-- enough to hold all the generated code. Creates a new buffer and
-- places a jump to the new buffer when there is not sufficient space
-- available
ensureBufferSize :: Int -> CodeGen e s ()
ensureBufferSize needed =
do state <- getInternalState
unless (bufferOfs state + needed + 5 <= bufferSize state)
(do let incrSize = max (needed + 16)
(codeBufferSize (config state))
arr <- liftIO $ mallocBytes incrSize
ofs <- getCodeOffset
let buf = buffer state
disp :: Int
disp = arr `minusPtr` (buf `plusPtr` ofs) - 5
emit8 0xe9
emit32 (fromIntegral disp)
st <- getInternalState
setInternalState st{buffer = arr, bufferList = bufferList st ++ [(buffer st, bufferOfs st)], bufferOfs = 0})
-- | Return a pointer to the beginning of the first code buffer, which
-- is normally the entry point to the generated code.
getEntryPoint :: CodeGen e s (Ptr Word8)
getEntryPoint =
CodeGen (\ env (ustate, state) ->
return $ ((ustate, state), Right (firstBuffer state)))
-- | Return the current offset in the code buffer, e.g. the offset
-- at which the next instruction will be emitted.
getCodeOffset :: CodeGen e s Int
getCodeOffset =
CodeGen (\ env (ustate, state) ->
return $ ((ustate, state), Right (bufferOfs state)))
-- | Set the user state to the given value.
setState :: s -> CodeGen e s ()
setState st =
CodeGen (\ env (_, state) ->
return $ ((st, state), Right ()))
-- | Return the current user state.
getState :: CodeGen e s s
getState =
CodeGen (\ env (ustate, state) ->
return $ ((ustate, state), Right (ustate)))
-- | Return the current user environment.
getEnv :: CodeGen e s e
getEnv =
CodeGen (\ (uenv, env) state ->
return $ (state, Right uenv))
-- | Set the environment to the given value and execute the given
-- code generation in this environment.
withEnv :: e -> CodeGen e s r -> CodeGen e s r
withEnv e (CodeGen cg) =
CodeGen (\ (_, env) state ->
cg (e, env) state)
-- | Set the user state to the given value.
setInternalState :: CodeGenState -> CodeGen e s ()
setInternalState st =
CodeGen (\ env (ustate, _) ->
return $ ((ustate, st), Right ()))
-- | Return the current user state.
getInternalState :: CodeGen e s CodeGenState
getInternalState =
CodeGen (\ env (ustate, state) ->
return $ ((ustate, state), Right (state)))
-- | Return the pointer to the start of the code buffer.
-- {-# INLINE getBasePtr #-}
getBasePtr :: CodeGen e s (Ptr Word8)
getBasePtr =
CodeGen (\ env (ustate, state) ->
return $ ((ustate, state), Right (buffer state)))
-- | Return a list of all code buffers and their respective size
-- (i.e., actually used space for code, not allocated size).
getCodeBufferList :: CodeGen e s [(Ptr Word8, Int)]
getCodeBufferList = do st <- getInternalState
return $ bufferList st ++ [(buffer st, bufferOfs st)]
-- | Generate a new label to be used with the label operations
-- 'emitRelocInfo', 'emitFixup' and 'defineLabel'.
newLabel :: CodeGen e s Label
newLabel =
do state <- getInternalState
let lab = nextLabel state
setInternalState state{nextLabel = lab + 1}
return (Label lab)
-- | Generate a new label and define it at once
setLabel :: CodeGen e s Label
setLabel =
do l <- newLabel
defineLabel l
return l
-- | Emit a relocation entry for the given offset, relocation kind
-- and target address.
emitRelocInfo :: Int -> RelocKind -> FunPtr a -> CodeGen e s ()
emitRelocInfo ofs kind addr =
CodeGen (\ env (ustate, state) ->
do let newState = state{relocEntries =
Reloc{offset = ofs,
kind = kind,
address = castFunPtr addr} :
(relocEntries state)}
return $ ((ustate, newState), Right ()))
-- | Emit a byte value to the code buffer.
-- {-# INLINE emit8 #-}
emit8 :: Word8 -> CodeGen e s ()
emit8 op =
CodeGen (\ env (ustate, state) ->
do let buf = buffer state
ptr = bufferOfs state
pokeByteOff buf ptr op
return $ ((ustate, state{bufferOfs = ptr + 1}), Right ()))
-- | Store a byte value at the given offset into the code buffer.
-- {-# INLINE emit8At #-}
emit8At :: Int -> Word8 -> CodeGen e s ()
emit8At pos op =
CodeGen (\ env (ustate, state) ->
do let buf = buffer state
pokeByteOff buf pos op
return $ ((ustate, state), Right ()))
-- | Return the byte value at the given offset in the code buffer.
-- {-# INLINE peek8At #-}
peek8At :: Int -> CodeGen e s Word8
peek8At pos =
CodeGen (\ env (ustate, state) ->
do let buf = buffer state
b <- peekByteOff buf pos
return $ ((ustate, state), Right b))
-- | Like 'emit8', but for a 32-bit value.
-- {-# INLINE emit32 #-}
emit32 :: Word32 -> CodeGen e s ()
emit32 op =
CodeGen (\ env (ustate, state) ->
do let buf = buffer state
ptr = bufferOfs state
pokeByteOff buf ptr op
return $ ((ustate, state{bufferOfs = ptr + 4}), Right ()))
-- | Like 'emit8At', but for a 32-bit value.
-- {-# INLINE emit32At #-}
emit32At :: Int -> Word32 -> CodeGen e s ()
emit32At pos op =
CodeGen (\ env (ustate, state) ->
do let buf = buffer state
pokeByteOff buf pos op
return $ ((ustate, state), Right ()))
-- | Emit a label at the current offset in the code buffer. All
-- references to the label will be relocated to this offset.
defineLabel :: Label -> CodeGen e s ()
defineLabel (Label lab) =
do state <- getInternalState
case Map.lookup lab (pendingFixups state) of
Just fixups -> do mapM_ (performFixup (buffer state) (bufferOfs state)) fixups
setInternalState state{pendingFixups = Map.delete lab (pendingFixups state)}
Nothing -> return ()
state <- getInternalState
setInternalState state{definedLabels = Map.insert lab (buffer state, bufferOfs state) (definedLabels state)}
performFixup :: Ptr Word8 -> Int -> FixupEntry -> CodeGen e s ()
performFixup labBuf labOfs (FixupEntry{fueBuffer = buf, fueOfs = ofs, fueKind = kind}) =
do let diff = (labBuf `plusPtr` labOfs) `minusPtr` (buf `plusPtr` (ofs + 4))
liftIO $ case kind of
Fixup8 -> pokeByteOff buf ofs (fromIntegral diff :: Word8)
Fixup16 -> pokeByteOff buf ofs (fromIntegral diff :: Word16)
Fixup32 -> pokeByteOff buf ofs (fromIntegral diff :: Word32)
Fixup32Absolute -> pokeByteOff buf ofs (fromIntegral (ptrToWordPtr (labBuf `plusPtr` labOfs)) :: Word32)
return ()
(@@) :: Label -> CodeGen e s a -> CodeGen e s a
(@@) lab gen = do defineLabel lab
gen
-- | Emit a fixup entry for the given label at the current offset in
-- the code buffer (unless the label is already defined).
-- The instruction at this offset will
-- be patched to target the address associated with this label when
-- it is defined later.
emitFixup :: Label -> Int -> FixupKind -> CodeGen e s ()
emitFixup (Label lab) ofs kind =
do state <- getInternalState
let base = buffer state
ptr = bufferOfs state
case Map.lookup lab (definedLabels state) of
Just (labBuf, labOfs) -> performFixup labBuf labOfs (FixupEntry{fueBuffer = base,
fueOfs = ptr + ofs,
fueKind = kind})
Nothing -> setInternalState state{pendingFixups = Map.insertWith (++) lab [FixupEntry{fueBuffer = base,
fueOfs = ptr + ofs,
fueKind = kind}]
(pendingFixups state)}
-- | Return the address of a label, fail if the label is not yet defined.
labelAddress :: Label -> CodeGen e s (Ptr a)
labelAddress (Label lab) = do
state <- getInternalState
case Map.lookup lab (definedLabels state) of
Just (labBuf, labOfs) -> return $ plusPtr labBuf labOfs
Nothing -> fail $ "Label " ++ show lab ++ " not yet defined"
-- | Disassemble all code buffers.
disassemble :: CodeGen e s [Dis.Instruction]
disassemble = do
s <- getInternalState
let buffers = bufferList s
r <- mapM (\ (buffer, length) -> do
r <- liftIO $ Dis.disassembleBlock buffer length
case r of
Left err -> cgFail $ show err
Right instr -> return instr
) $ buffers ++ [(buffer s, bufferOfs s)]
return $ concat r
#ifndef __HADDOCK__
callDecl :: String -> Q Type -> Q [Dec]
callDecl ns qt = do
t0 <- qt
let (tvars, cxt, t) = case t0 of
ForallT vs c t -> (vs, c, t)
_ -> ([], [], t0)
let name = mkName ns
let funptr = AppT (ConT $ mkName "FunPtr") t
let ioresult = addIO t
let ty = AppT (AppT ArrowT funptr) ioresult
dynName <- newName "conv"
let dyn = ForeignD $ ImportF CCall Safe "dynamic" dynName $ ForallT tvars cxt ty
vs <- mkArgs t
cbody <- [| CodeGen (\env (ustate, state) ->
do let code = firstBuffer state
res <- liftIO $ $(do
c <- newName "c"
cast <- [|castPtrToFunPtr|]
let f = AppE (VarE dynName)
(AppE cast
(VarE c))
return $ LamE [VarP c] $ foldl AppE f $ map VarE vs
) code
return $ ((ustate, state), Right res))|]
let call = ValD (VarP name) (NormalB $ LamE (map VarP vs) cbody) []
return [ dyn, call ]
mkArgs (AppT (AppT ArrowT _from) to) = do
v <- newName "v"
vs <- mkArgs to
return $ v : vs
mkArgs _ = return []
addIO (AppT t@(AppT ArrowT _from) to) = AppT t $ addIO to
addIO t = AppT (ConT $ mkName "IO") t
#else
-- | Declare a stub function to call the code buffer. Arguments are the name
-- of the generated function, and the type the code buffer is supposed to have.
-- The type argument can be given using the [t| ... |] notation of Template Haskell.
-- Allowed types are the legal types for FFI functions.
callDecl :: String -> Q Type -> Q [Dec]
#endif