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|
-----------------------------------------------------------------------------
--
-- (c) The University of Glasgow 2011
--
-- CmmLint: checking the correctness of Cmm statements and expressions
--
-----------------------------------------------------------------------------
{-# LANGUAGE GADTs #-}
module CmmLint (
cmmLint, cmmLintDecl, cmmLintGraph
) where
import Hoopl
import Cmm
import CmmUtils
import PprCmm ()
import BlockId
import FastString
import CLabel
import Platform
import Outputable
import Constants
import Data.Maybe
-- Things to check:
-- - invariant on CmmBlock in CmmExpr (see comment there)
-- - check for branches to blocks that don't exist
-- - check types
-- -----------------------------------------------------------------------------
-- Exported entry points:
cmmLint :: (PlatformOutputable d, PlatformOutputable h)
=> Platform -> GenCmmGroup d h CmmGraph -> Maybe SDoc
cmmLint platform tops = runCmmLint platform (mapM_ lintCmmDecl) tops
cmmLintDecl :: (PlatformOutputable d, PlatformOutputable h)
=> Platform -> GenCmmDecl d h CmmGraph -> Maybe SDoc
cmmLintDecl platform top = runCmmLint platform lintCmmDecl top
cmmLintGraph :: Platform -> CmmGraph -> Maybe SDoc
cmmLintGraph platform g = runCmmLint platform lintCmmGraph g
runCmmLint :: PlatformOutputable a
=> Platform -> (a -> CmmLint b) -> a -> Maybe SDoc
runCmmLint platform l p =
case unCL (l p) platform of
Left err -> Just (vcat [ptext $ sLit ("Cmm lint error:"),
nest 2 err,
ptext $ sLit ("Program was:"),
nest 2 (pprPlatform platform p)])
Right _ -> Nothing
lintCmmDecl :: GenCmmDecl h i CmmGraph -> CmmLint ()
lintCmmDecl (CmmProc _ lbl g)
= addLintInfo (\platform -> text "in proc " <> pprCLabel platform lbl) $
lintCmmGraph g
lintCmmDecl (CmmData {})
= return ()
lintCmmGraph :: CmmGraph -> CmmLint ()
lintCmmGraph g = mapM_ (lintCmmBlock labels) blocks
where
blocks = toBlockList g
labels = setFromList (map entryLabel blocks)
lintCmmBlock :: BlockSet -> CmmBlock -> CmmLint ()
lintCmmBlock labels block
= addLintInfo (\_ -> text "in basic block " <> ppr (entryLabel block)) $ do
let (_, middle, last) = blockSplit block
mapM_ lintCmmMiddle (blockToList middle)
lintCmmLast labels last
-- -----------------------------------------------------------------------------
-- lintCmmExpr
-- Checks whether a CmmExpr is "type-correct", and check for obvious-looking
-- byte/word mismatches.
lintCmmExpr :: CmmExpr -> CmmLint CmmType
lintCmmExpr (CmmLoad expr rep) = do
_ <- lintCmmExpr expr
-- Disabled, if we have the inlining phase before the lint phase,
-- we can have funny offsets due to pointer tagging. -- EZY
-- when (widthInBytes (typeWidth rep) >= wORD_SIZE) $
-- cmmCheckWordAddress expr
return rep
lintCmmExpr expr@(CmmMachOp op args) = do
tys <- mapM lintCmmExpr args
if map (typeWidth . cmmExprType) args == machOpArgReps op
then cmmCheckMachOp op args tys
else cmmLintMachOpErr expr (map cmmExprType args) (machOpArgReps op)
lintCmmExpr (CmmRegOff reg offset)
= lintCmmExpr (CmmMachOp (MO_Add rep)
[CmmReg reg, CmmLit (CmmInt (fromIntegral offset) rep)])
where rep = typeWidth (cmmRegType reg)
lintCmmExpr expr =
return (cmmExprType expr)
-- Check for some common byte/word mismatches (eg. Sp + 1)
cmmCheckMachOp :: MachOp -> [CmmExpr] -> [CmmType] -> CmmLint CmmType
cmmCheckMachOp op [lit@(CmmLit (CmmInt { })), reg@(CmmReg _)] tys
= cmmCheckMachOp op [reg, lit] tys
cmmCheckMachOp op _ tys
= return (machOpResultType op tys)
isOffsetOp :: MachOp -> Bool
isOffsetOp (MO_Add _) = True
isOffsetOp (MO_Sub _) = True
isOffsetOp _ = False
-- This expression should be an address from which a word can be loaded:
-- check for funny-looking sub-word offsets.
_cmmCheckWordAddress :: CmmExpr -> CmmLint ()
_cmmCheckWordAddress e@(CmmMachOp op [arg, CmmLit (CmmInt i _)])
| isOffsetOp op && notNodeReg arg && i `rem` fromIntegral wORD_SIZE /= 0
= cmmLintDubiousWordOffset e
_cmmCheckWordAddress e@(CmmMachOp op [CmmLit (CmmInt i _), arg])
| isOffsetOp op && notNodeReg arg && i `rem` fromIntegral wORD_SIZE /= 0
= cmmLintDubiousWordOffset e
_cmmCheckWordAddress _
= return ()
-- No warnings for unaligned arithmetic with the node register,
-- which is used to extract fields from tagged constructor closures.
notNodeReg :: CmmExpr -> Bool
notNodeReg (CmmReg reg) | reg == nodeReg = False
notNodeReg _ = True
lintCmmMiddle :: CmmNode O O -> CmmLint ()
lintCmmMiddle node = case node of
CmmComment _ -> return ()
CmmAssign reg expr -> do
erep <- lintCmmExpr expr
let reg_ty = cmmRegType reg
if (erep `cmmEqType_ignoring_ptrhood` reg_ty)
then return ()
else cmmLintAssignErr (CmmAssign reg expr) erep reg_ty
CmmStore l r -> do
_ <- lintCmmExpr l
_ <- lintCmmExpr r
return ()
CmmUnsafeForeignCall target _formals actuals -> do
lintTarget target
mapM_ lintCmmExpr actuals
lintCmmLast :: BlockSet -> CmmNode O C -> CmmLint ()
lintCmmLast labels node = case node of
CmmBranch id -> checkTarget id
CmmCondBranch e t f -> do
mapM_ checkTarget [t,f]
_ <- lintCmmExpr e
checkCond e
CmmSwitch e branches -> do
mapM_ checkTarget $ catMaybes branches
erep <- lintCmmExpr e
if (erep `cmmEqType_ignoring_ptrhood` bWord)
then return ()
else cmmLintErr (\platform ->
text "switch scrutinee is not a word: " <>
pprPlatform platform e <>
text " :: " <> ppr erep)
CmmCall { cml_target = target, cml_cont = cont } -> do
_ <- lintCmmExpr target
maybe (return ()) checkTarget cont
CmmForeignCall tgt _ args succ _ _ -> do
lintTarget tgt
mapM_ lintCmmExpr args
checkTarget succ
where
checkTarget id
| setMember id labels = return ()
| otherwise = cmmLintErr (\_ -> text "Branch to nonexistent id" <+> ppr id)
lintTarget :: ForeignTarget -> CmmLint ()
lintTarget (ForeignTarget e _) = lintCmmExpr e >> return ()
lintTarget (PrimTarget {}) = return ()
checkCond :: CmmExpr -> CmmLint ()
checkCond (CmmMachOp mop _) | isComparisonMachOp mop = return ()
checkCond (CmmLit (CmmInt x t)) | x == 0 || x == 1, t == wordWidth = return () -- constant values
checkCond expr
= cmmLintErr (\platform -> hang (text "expression is not a conditional:") 2
(pprPlatform platform expr))
-- -----------------------------------------------------------------------------
-- CmmLint monad
-- just a basic error monad:
newtype CmmLint a = CmmLint { unCL :: Platform -> Either SDoc a }
instance Monad CmmLint where
CmmLint m >>= k = CmmLint $ \p -> case m p of
Left e -> Left e
Right a -> unCL (k a) p
return a = CmmLint (\_ -> Right a)
cmmLintErr :: (Platform -> SDoc) -> CmmLint a
cmmLintErr msg = CmmLint (\p -> Left (msg p))
addLintInfo :: (Platform -> SDoc) -> CmmLint a -> CmmLint a
addLintInfo info thing = CmmLint $ \p ->
case unCL thing p of
Left err -> Left (hang (info p) 2 err)
Right a -> Right a
cmmLintMachOpErr :: CmmExpr -> [CmmType] -> [Width] -> CmmLint a
cmmLintMachOpErr expr argsRep opExpectsRep
= cmmLintErr (\platform -> text "in MachOp application: " $$
nest 2 (pprPlatform platform expr) $$
(text "op is expecting: " <+> ppr opExpectsRep) $$
(text "arguments provide: " <+> ppr argsRep))
cmmLintAssignErr :: CmmNode e x -> CmmType -> CmmType -> CmmLint a
cmmLintAssignErr stmt e_ty r_ty
= cmmLintErr (\platform -> text "in assignment: " $$
nest 2 (vcat [pprPlatform platform stmt,
text "Reg ty:" <+> ppr r_ty,
text "Rhs ty:" <+> ppr e_ty]))
cmmLintDubiousWordOffset :: CmmExpr -> CmmLint a
cmmLintDubiousWordOffset expr
= cmmLintErr (\platform -> text "offset is not a multiple of words: " $$
nest 2 (pprPlatform platform expr))
|
