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{-# OPTIONS_GHC -w #-}
-- The above warning supression flag is a temporary kludge.
-- While working on this module you are encouraged to remove it and fix
-- any warnings in the module. See
-- http://hackage.haskell.org/trac/ghc/wiki/WorkingConventions#Warnings
-- for details
-----------------------------------------------------------------------------
--
-- (c) The University of Glasgow 2004-2006
--
-- CmmLint: checking the correctness of Cmm statements and expressions
--
-----------------------------------------------------------------------------
module CmmLint (
cmmLint, cmmLintTop
) where
#include "HsVersions.h"
import Cmm
import CLabel
import MachOp
import Outputable
import PprCmm
import Unique
import Constants
import Control.Monad
-- -----------------------------------------------------------------------------
-- Exported entry points:
cmmLint :: GenCmm d h CmmStmt -> Maybe SDoc
cmmLint (Cmm tops) = runCmmLint $ mapM_ lintCmmTop tops
cmmLintTop :: GenCmmTop d h CmmStmt -> Maybe SDoc
cmmLintTop top = runCmmLint $ lintCmmTop top
runCmmLint :: CmmLint a -> Maybe SDoc
runCmmLint l =
case unCL l of
Left err -> Just (ptext SLIT("Cmm lint error:") $$ nest 2 err)
Right _ -> Nothing
lintCmmTop (CmmProc _ lbl _ blocks)
= addLintInfo (text "in proc " <> pprCLabel lbl) $
mapM_ lintCmmBlock blocks
lintCmmTop _other
= return ()
lintCmmBlock (BasicBlock id stmts)
= addLintInfo (text "in basic block " <> ppr (getUnique id)) $
mapM_ lintCmmStmt stmts
-- -----------------------------------------------------------------------------
-- lintCmmExpr
-- Checks whether a CmmExpr is "type-correct", and check for obvious-looking
-- byte/word mismatches.
lintCmmExpr :: CmmExpr -> CmmLint MachRep
lintCmmExpr (CmmLoad expr rep) = do
lintCmmExpr expr
when (machRepByteWidth rep >= wORD_SIZE) $
cmmCheckWordAddress expr
return rep
lintCmmExpr expr@(CmmMachOp op args) = do
mapM_ lintCmmExpr args
if map cmmExprRep args == machOpArgReps op
then cmmCheckMachOp op args
else cmmLintMachOpErr expr (map cmmExprRep args) (machOpArgReps op)
lintCmmExpr (CmmRegOff reg offset)
= lintCmmExpr (CmmMachOp (MO_Add rep)
[CmmReg reg, CmmLit (CmmInt (fromIntegral offset) rep)])
where rep = cmmRegRep reg
lintCmmExpr lit@(CmmLit (CmmInt _ rep))
| isFloatingRep rep
= cmmLintErr (text "integer literal with floating MachRep: " <> ppr lit)
lintCmmExpr expr =
return (cmmExprRep expr)
-- Check for some common byte/word mismatches (eg. Sp + 1)
cmmCheckMachOp op args@[CmmReg reg, CmmLit (CmmInt i _)]
| isWordOffsetReg reg && isOffsetOp op && i `rem` fromIntegral wORD_SIZE /= 0
= cmmLintDubiousWordOffset (CmmMachOp op args)
cmmCheckMachOp op [lit@(CmmLit (CmmInt i _)), reg@(CmmReg _)]
= cmmCheckMachOp op [reg, lit]
cmmCheckMachOp op@(MO_U_Conv from to) args
| isFloatingRep from || isFloatingRep to
= cmmLintErr (text "unsigned conversion from/to floating rep: "
<> ppr (CmmMachOp op args))
cmmCheckMachOp op args
= return (resultRepOfMachOp op)
isWordOffsetReg (CmmGlobal Sp) = True
-- No warnings for unaligned arithmetic, which is used to tag dynamic constructor closures.
--isWordOffsetReg (CmmGlobal Hp) = True
isWordOffsetReg _ = False
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 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 (CmmReg reg) | reg == nodeReg = False
notNodeReg _ = True
lintCmmStmt :: CmmStmt -> CmmLint ()
lintCmmStmt stmt@(CmmAssign reg expr) = do
erep <- lintCmmExpr expr
if (erep == cmmRegRep reg)
then return ()
else cmmLintAssignErr stmt
lintCmmStmt (CmmStore l r) = do
lintCmmExpr l
lintCmmExpr r
return ()
lintCmmStmt (CmmCall _target _res args _ _) = mapM_ (lintCmmExpr.fst) args
lintCmmStmt (CmmCondBranch e _id) = lintCmmExpr e >> checkCond e >> return ()
lintCmmStmt (CmmSwitch e _branches) = do
erep <- lintCmmExpr e
if (erep == wordRep)
then return ()
else cmmLintErr (text "switch scrutinee is not a word: " <> ppr e)
lintCmmStmt (CmmJump e _args) = lintCmmExpr e >> return ()
lintCmmStmt _other = return ()
checkCond (CmmMachOp mop _) | isComparisonMachOp mop = return ()
checkCond expr = cmmLintErr (hang (text "expression is not a conditional:") 2
(ppr expr))
-- -----------------------------------------------------------------------------
-- CmmLint monad
-- just a basic error monad:
newtype CmmLint a = CmmLint { unCL :: Either SDoc a }
instance Monad CmmLint where
CmmLint m >>= k = CmmLint $ case m of
Left e -> Left e
Right a -> unCL (k a)
return a = CmmLint (Right a)
cmmLintErr :: SDoc -> CmmLint a
cmmLintErr msg = CmmLint (Left msg)
addLintInfo :: SDoc -> CmmLint a -> CmmLint a
addLintInfo info thing = CmmLint $
case unCL thing of
Left err -> Left (hang info 2 err)
Right a -> Right a
cmmLintMachOpErr :: CmmExpr -> [MachRep] -> [MachRep] -> CmmLint a
cmmLintMachOpErr expr argsRep opExpectsRep
= cmmLintErr (text "in MachOp application: " $$
nest 2 (pprExpr expr) $$
(text "op is expecting: " <+> ppr opExpectsRep) $$
(text "arguments provide: " <+> ppr argsRep))
cmmLintAssignErr :: CmmStmt -> CmmLint a
cmmLintAssignErr stmt = cmmLintErr (text "in assignment: " $$
nest 2 (pprStmt stmt))
cmmLintDubiousWordOffset :: CmmExpr -> CmmLint a
cmmLintDubiousWordOffset expr
= cmmLintErr (text "offset is not a multiple of words: " $$
nest 2 (pprExpr expr))
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