summaryrefslogtreecommitdiff
path: root/compiler/cmm/OldCmmLint.hs
blob: 5dd32098925f8a1400d23a59c8afb64dd8c0e450 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
-----------------------------------------------------------------------------
--
-- (c) The University of Glasgow 2004-2006
--
-- CmmLint: checking the correctness of Cmm statements and expressions
--
-----------------------------------------------------------------------------

{-# OPTIONS -fno-warn-tabs #-}
-- The above warning supression flag is a temporary kludge.
-- While working on this module you are encouraged to remove it and
-- detab the module (please do the detabbing in a separate patch). See
--     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#TabsvsSpaces
-- for details

module OldCmmLint (
  cmmLint, cmmLintTop
  ) where

import BlockId
import OldCmm
import CLabel
import Outputable
import OldPprCmm()
import FastString
import DynFlags

import Data.Maybe

-- -----------------------------------------------------------------------------
-- Exported entry points:

cmmLint :: (Outputable d, Outputable h)
        => DynFlags -> GenCmmGroup d h (ListGraph CmmStmt) -> Maybe SDoc
cmmLint dflags tops = runCmmLint dflags (mapM_ (lintCmmDecl dflags)) tops

cmmLintTop :: (Outputable d, Outputable h)
           => DynFlags -> GenCmmDecl d h (ListGraph CmmStmt) -> Maybe SDoc
cmmLintTop dflags top = runCmmLint dflags (lintCmmDecl dflags) top

runCmmLint :: Outputable a
           => DynFlags -> (a -> CmmLint b) -> a -> Maybe SDoc
runCmmLint _ l p =
   case unCL (l p) of
   Left err -> Just (vcat [ptext $ sLit ("Cmm lint error:"),
                           nest 2 err,
                           ptext $ sLit ("Program was:"),
                           nest 2 (ppr p)])
   Right _  -> Nothing

lintCmmDecl :: DynFlags -> (GenCmmDecl h i (ListGraph CmmStmt)) -> CmmLint ()
lintCmmDecl dflags (CmmProc _ lbl (ListGraph blocks))
  = addLintInfo (text "in proc " <> pprCLabel platform lbl) $
        let labels = foldl (\s b -> setInsert (blockId b) s) setEmpty blocks
        in  mapM_ (lintCmmBlock dflags labels) blocks
    where platform = targetPlatform dflags

lintCmmDecl _ (CmmData {})
  = return ()

lintCmmBlock :: DynFlags -> BlockSet -> GenBasicBlock CmmStmt -> CmmLint ()
lintCmmBlock dflags labels (BasicBlock id stmts)
  = addLintInfo (text "in basic block " <> ppr id) $
	mapM_ (lintCmmStmt dflags labels) stmts

-- -----------------------------------------------------------------------------
-- lintCmmExpr

-- Checks whether a CmmExpr is "type-correct", and check for obvious-looking
-- byte/word mismatches.

lintCmmExpr :: DynFlags -> CmmExpr -> CmmLint CmmType
lintCmmExpr dflags (CmmLoad expr rep) = do
  _ <- lintCmmExpr dflags 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 dflags expr@(CmmMachOp op args) = do
  tys <- mapM (lintCmmExpr dflags) args
  if map (typeWidth . cmmExprType dflags) args == machOpArgReps dflags op
  	then cmmCheckMachOp dflags op args tys
	else cmmLintMachOpErr expr (map (cmmExprType dflags) args) (machOpArgReps dflags op)
lintCmmExpr dflags (CmmRegOff reg offset)
  = lintCmmExpr dflags (CmmMachOp (MO_Add rep)
		[CmmReg reg, CmmLit (CmmInt (fromIntegral offset) rep)])
  where rep = typeWidth (cmmRegType dflags reg)
lintCmmExpr dflags expr =
  return (cmmExprType dflags expr)

-- Check for some common byte/word mismatches (eg. Sp + 1)
cmmCheckMachOp   :: DynFlags -> MachOp -> [CmmExpr] -> [CmmType] -> CmmLint CmmType
cmmCheckMachOp dflags op [lit@(CmmLit (CmmInt { })), reg@(CmmReg _)] tys
  = cmmCheckMachOp dflags op [reg, lit] tys
cmmCheckMachOp dflags op _ tys
  = return (machOpResultType dflags 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 dflags) /= 0
  = cmmLintDubiousWordOffset e
_cmmCheckWordAddress e@(CmmMachOp op [CmmLit (CmmInt i _), arg])
  | isOffsetOp op && notNodeReg arg && i `rem` fromIntegral (wORD_SIZE dflags) /= 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
-}

lintCmmStmt :: DynFlags -> BlockSet -> CmmStmt -> CmmLint ()
lintCmmStmt dflags labels = lint
    where lint (CmmNop) = return ()
          lint (CmmComment {}) = return ()
          lint stmt@(CmmAssign reg expr) = do
            erep <- lintCmmExpr dflags expr
            let reg_ty = cmmRegType dflags reg
            if (erep `cmmEqType_ignoring_ptrhood` reg_ty)
                then return ()
                else cmmLintAssignErr stmt erep reg_ty
          lint (CmmStore l r) = do
            _ <- lintCmmExpr dflags l
            _ <- lintCmmExpr dflags r
            return ()
          lint (CmmCall target _res args _) =
              do lintTarget dflags labels target
                 mapM_ (lintCmmExpr dflags . hintlessCmm) args
          lint (CmmCondBranch e id) = checkTarget id >> lintCmmExpr dflags e >> checkCond dflags e
          lint (CmmSwitch e branches) = do
            mapM_ checkTarget $ catMaybes branches
            erep <- lintCmmExpr dflags e
            if (erep `cmmEqType_ignoring_ptrhood` bWord dflags)
              then return ()
              else cmmLintErr (text "switch scrutinee is not a word: " <> ppr e <>
                               text " :: " <> ppr erep)
          lint (CmmJump e _) = lintCmmExpr dflags e >> return ()
          lint (CmmReturn) = return ()
          lint (CmmBranch id)    = checkTarget id
          checkTarget id = if setMember id labels then return ()
                           else cmmLintErr (text "Branch to nonexistent id" <+> ppr id)

lintTarget :: DynFlags -> BlockSet -> CmmCallTarget -> CmmLint ()
lintTarget dflags _      (CmmCallee e _) = do _ <- lintCmmExpr dflags e
                                              return ()
lintTarget _      _      (CmmPrim _ Nothing) = return ()
lintTarget dflags labels (CmmPrim _ (Just stmts))
    = mapM_ (lintCmmStmt dflags labels) stmts


checkCond :: DynFlags -> CmmExpr -> CmmLint ()
checkCond _      (CmmMachOp mop _) | isComparisonMachOp mop = return ()
checkCond dflags (CmmLit (CmmInt x t)) | x == 0 || x == 1, t == wordWidth dflags = return () -- constant values
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 -> [CmmType] -> [Width] -> CmmLint a
cmmLintMachOpErr expr argsRep opExpectsRep
     = cmmLintErr (text "in MachOp application: " $$ 
					nest 2 (ppr expr) $$
				        (text "op is expecting: " <+> ppr opExpectsRep) $$
					(text "arguments provide: " <+> ppr argsRep))

cmmLintAssignErr :: CmmStmt -> CmmType -> CmmType -> CmmLint a
cmmLintAssignErr stmt e_ty r_ty
  = cmmLintErr (text "in assignment: " $$ 
		nest 2 (vcat [ppr stmt, 
			      text "Reg ty:" <+> ppr r_ty,
			      text "Rhs ty:" <+> ppr e_ty]))
			 
					

{-
cmmLintDubiousWordOffset :: CmmExpr -> CmmLint a
cmmLintDubiousWordOffset expr
   = cmmLintErr (text "offset is not a multiple of words: " $$
			nest 2 (ppr expr))
-}