harpy-0.4: Harpy/CodeGenMonad.hs
{-# OPTIONS -cpp #-}
--------------------------------------------------------------------------
-- |
-- Module: Harpy.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 library user can pass a user environment and user state through
-- the monad. This 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,
ErrMsg,
RelocKind(..),
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,
newNamedLabel,
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 Numeric
import Data.List
import qualified Data.Map as Map
import Foreign
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. There are currently two
-- configuration options. The first is the number fo bytes to use for
-- allocating code buffers (the first as well as additional buffers
-- created in calls to 'ensureBufferSize'. The second allows to pass
-- in a pre-allocated code buffer and its size. When this option is
-- used, Harpy does not perform any code buffer resizing (calls to
-- 'ensureBufferSize' will be equivalent to calls to
-- 'checkBufferSize').
data CodeGenConfig = CodeGenConfig {
codeBufferSize :: Int, -- ^ Size of individual code buffer blocks.
customCodeBuffer :: Maybe (Ptr Word8, Int) -- ^ Code buffer passed in.
}
-- | Internal state of the code generator
data CodeGenState = CodeGenState {
buffer :: Ptr Word8, -- ^ Pointer to current code buffer.
bufferList :: [(Ptr Word8, Int)], -- ^ List of all other code buffers.
firstBuffer :: Ptr Word8, -- ^ Pointer to first buffer.
bufferOfs :: Int, -- ^ Current offset into buffer where next instruction will be stored.
bufferSize :: Int, -- ^ Size of current buffer.
relocEntries :: [Reloc], -- ^ List of all emitted relocation entries.
nextLabel :: Int, -- ^ Counter for generating labels.
definedLabels :: Map.Map Int (Ptr Word8, Int, String), -- ^ Map of already defined labels.
pendingFixups :: Map.Map Int [FixupEntry], -- ^ Map of labels which have been referenced, but not defined.
config :: CodeGenConfig -- ^ Configuration record.
}
data FixupEntry = FixupEntry {
fueBuffer :: Ptr Word8,
fueOfs :: Int,
fueKind :: FixupKind
}
-- | Kind of a fixup entry. When a label is emitted with
-- 'defineLabel', all prior references to this label must be fixed
-- up. This data type tells how to perform the fixup operation.
data FixupKind = Fixup8 -- ^ 8-bit relative reference
| Fixup16 -- ^ 16-bit relative reference
| Fixup32 -- ^ 32-bit relative reference
| Fixup32Absolute -- ^ 32-bit absolute reference
deriving (Show)
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 String
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
cgReturn :: a -> CodeGen e s a
cgReturn x = CodeGen (\_env state -> return (state, Right x))
cgFail :: String -> CodeGen e s a
cgFail err = CodeGen (\_env state -> return (state, Left (text err)))
cgBind :: CodeGen e s a -> (a -> CodeGen e s a1) -> CodeGen e s a1
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}
-- | Default code generation configuration. The code buffer size is
-- set to 4KB, and code buffer management is automatic. This value is
-- intended to be used with record update syntax, for example:
--
-- > runCodeGenWithConfig ... defaultCodeGenConfig{codeBufferSize = 128} ...
defaultCodeGenConfig :: CodeGenConfig
defaultCodeGenConfig = CodeGenConfig { codeBufferSize = defaultCodeBufferSize,
customCodeBuffer = Nothing }
defaultCodeBufferSize :: Int
defaultCodeBufferSize = 4096
-- | 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. This function runs 'runCodeGenWithConfig' with a
-- sensible default configuration.
runCodeGen :: CodeGen e s a -> e -> s -> IO (s, Either ErrMsg a)
runCodeGen cg uenv ustate =
runCodeGenWithConfig cg uenv ustate defaultCodeGenConfig
-- | Like 'runCodeGen', but allows more control over the code
-- generation process. In addition to a code generator and a user
-- environment and state, a code generation configuration must be
-- provided. A code generation configuration allows control over the
-- allocation of code buffers, for example.
runCodeGenWithConfig :: CodeGen e s a -> e -> s -> CodeGenConfig -> IO (s, Either ErrMsg a)
runCodeGenWithConfig (CodeGen cg) uenv ustate conf =
do (buf, sze) <- case customCodeBuffer conf of
Nothing -> do let initSize = codeBufferSize conf
arr <- mallocBytes initSize
return (arr, initSize)
Just (buf, sze) -> return (buf, sze)
let env = CodeGenEnv {tailContext = True}
let state = emptyCodeGenState{buffer = buf,
bufferList = [],
firstBuffer = buf,
bufferSize = sze,
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.
--
-- /Note:/ Starting with version 0.4, Harpy automatically checks for
-- buffer overflow, so you do not need to call this function anymore.
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. When code generation was invoked with a pre-defined
-- code buffer, code generation is aborted on overflow.
--
-- /Note:/ Starting with version 0.4, Harpy automatically checks for
-- buffer overflow, so you do not need to call this function anymore.
ensureBufferSize :: Int -> CodeGen e s ()
ensureBufferSize needed =
do state <- getInternalState
case (customCodeBuffer (config state)) of
Nothing ->
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 -- FIXME: Machine dependent!
emit32 (fromIntegral disp)
st <- getInternalState
setInternalState st{buffer = arr, bufferList = bufferList st ++ [(buffer st, bufferOfs st)], bufferOfs = 0})
Just (_, _) -> checkBufferSize needed
-- | 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 (\ _ (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 (\ _ (ustate, state) ->
return $ ((ustate, state), Right (bufferOfs state)))
-- | Set the user state to the given value.
setState :: s -> CodeGen e s ()
setState st =
CodeGen (\ _ (_, state) ->
return $ ((st, state), Right ()))
-- | Return the current user state.
getState :: CodeGen e s s
getState =
CodeGen (\ _ (ustate, state) ->
return $ ((ustate, state), Right (ustate)))
-- | Return the current user environment.
getEnv :: CodeGen e s e
getEnv =
CodeGen (\ (uenv, _) 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 (\ _ (ustate, _) ->
return $ ((ustate, st), Right ()))
-- | Return the current user state.
getInternalState :: CodeGen e s CodeGenState
getInternalState =
CodeGen (\ _ (ustate, state) ->
return $ ((ustate, state), Right (state)))
-- | Return the pointer to the start of the code buffer.
getBasePtr :: CodeGen e s (Ptr Word8)
getBasePtr =
CodeGen (\ _ (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
-- '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 to be used with the label operations
-- 'emitFixup' and 'defineLabel'. The given name is used for
-- diagnostic purposes, and will appear in the disassembly.
newNamedLabel :: String -> CodeGen e s Label
newNamedLabel name =
do state <- getInternalState
let lab = nextLabel state
setInternalState state{nextLabel = lab + 1}
return (Label lab name)
-- | 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 knd addr =
do state <- getInternalState
setInternalState state{relocEntries =
Reloc{offset = ofs,
kind = knd,
address = castFunPtr addr} :
(relocEntries state)}
-- | Emit a byte value to the code buffer.
emit8 :: Word8 -> CodeGen e s ()
emit8 op =
CodeGen (\ _ (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.
emit8At :: Int -> Word8 -> CodeGen e s ()
emit8At pos op =
CodeGen (\ _ (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.
peek8At :: Int -> CodeGen e s Word8
peek8At pos =
CodeGen (\ _ (ustate, state) ->
do let buf = buffer state
b <- peekByteOff buf pos
return $ ((ustate, state), Right b))
-- | Like 'emit8', but for a 32-bit value.
emit32 :: Word32 -> CodeGen e s ()
emit32 op =
CodeGen (\ _ (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.
emit32At :: Int -> Word32 -> CodeGen e s ()
emit32At pos op =
CodeGen (\ _ (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 name) =
do state <- getInternalState
case Map.lookup lab (definedLabels state) of
Just _ -> failCodeGen $ text "duplicate definition of label" <+>
int lab
_ -> return ()
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 ()
state1 <- getInternalState
setInternalState state1{definedLabels = Map.insert lab (buffer state1, bufferOfs state1, name) (definedLabels state1)}
performFixup :: Ptr Word8 -> Int -> FixupEntry -> CodeGen e s ()
performFixup labBuf labOfs (FixupEntry{fueBuffer = buf, fueOfs = ofs, fueKind = knd}) =
do let diff = (labBuf `plusPtr` labOfs) `minusPtr` (buf `plusPtr` (ofs + 4))
liftIO $ case knd 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 ()
-- | This operator gives neat syntax for defining labels. When @l@ is a label, the code
--
-- > l @@ mov eax ebx
--
-- associates the label l with the following @mov@ instruction.
(@@) :: 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 knd =
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 = knd})
Nothing -> setInternalState state{pendingFixups = Map.insertWith (++) lab [FixupEntry{fueBuffer = base,
fueOfs = ptr + ofs,
fueKind = knd}]
(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 name) = do
state <- getInternalState
case Map.lookup lab (definedLabels state) of
Just (labBuf, labOfs, _) -> return $ plusPtr labBuf labOfs
Nothing -> fail $ "Label " ++ show lab ++ "(" ++ name ++ ") not yet defined"
-- | Disassemble all code buffers. The result is a list of
-- disassembled instructions which can be converted to strings using
-- the 'Dis.showIntel' or 'Dis.showAtt' functions from module
-- "Harpy.X86Disassembler".
disassemble :: CodeGen e s [Dis.Instruction]
disassemble = do
s <- getInternalState
let buffers = bufferList s
r <- mapM (\ (buff, len) -> do
r <- liftIO $ Dis.disassembleBlock buff len
case r of
Left err -> cgFail $ show err
Right instr -> return instr
) $ buffers ++ [(buffer s, bufferOfs s)]
r' <- insertLabels (concat r)
return r'
where insertLabels :: [Dis.Instruction] -> CodeGen e s [Dis.Instruction]
insertLabels = liftM concat . mapM ins
ins :: Dis.Instruction -> CodeGen e s [Dis.Instruction]
ins i@(Dis.BadInstruction{}) = return [i]
ins i@(Dis.PseudoInstruction{}) = return [i]
ins i@(Dis.Instruction{Dis.address = addr}) =
do state <- getInternalState
let labs = Map.toList (definedLabels state)
lab = find (\ (_, (buf, ofs, _)) -> fromIntegral (ptrToWordPtr (buf `plusPtr` ofs)) == addr) labs
case lab of
Nothing -> return [i]
Just (l, (buf, ofs, name)) -> return [Dis.PseudoInstruction addr
(case name of
"" ->
"label " ++ show l ++
" [" ++
hex32 (fromIntegral (ptrToWordPtr (buf `plusPtr` ofs))) ++
"]"
_ -> name ++ ": [" ++
hex32 (fromIntegral (ptrToWordPtr (buf `plusPtr` ofs))) ++
"]"),
i]
hex32 :: Int -> String
hex32 i =
let w :: Word32
w = fromIntegral i
s = showHex w ""
in take (8 - length s) (repeat '0') ++ s
#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