CmmLint.hs 4.82 KB
Newer Older
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
-----------------------------------------------------------------------------
--
-- CmmLint: checking the correctness of Cmm statements and expressions
--
-- (c) The University of Glasgow 2004
--
-----------------------------------------------------------------------------

module CmmLint (
  cmmLint, cmmLintTop
  ) where

#include "HsVersions.h"

import Cmm
import CLabel		( pprCLabel )
import MachOp
import Outputable
import PprCmm
import Unique		( getUnique )
import Constants	( wORD_SIZE )

import Monad		( when )

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

cmmLint :: Cmm -> Maybe SDoc
cmmLint (Cmm tops) = runCmmLint $ mapM_ lintCmmTop tops

cmmLintTop :: CmmTop -> 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 _info lbl _args 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
lintCmmExpr (CmmRegOff reg offset)
  = lintCmmExpr (CmmMachOp (MO_Add rep) 
		[CmmReg reg, CmmLit (CmmInt (fromIntegral offset) rep)])
  where rep = cmmRegRep reg
71 72 73
lintCmmExpr lit@(CmmLit (CmmInt _ rep))
  | isFloatingRep rep
  = cmmLintErr (text "integer literal with floating MachRep: " <> ppr lit)
74 75 76 77 78 79 80 81 82
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]
83 84 85 86
cmmCheckMachOp op@(MO_U_Conv from to) args
  | isFloatingRep from || isFloatingRep to
  = cmmLintErr (text "unsigned conversion from/to floating rep: " 
		<> ppr (CmmMachOp op args))
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
cmmCheckMachOp op args
  = return (resultRepOfMachOp op)

isWordOffsetReg (CmmGlobal Sp) = True
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 && i `rem` fromIntegral wORD_SIZE /= 0
  = cmmLintDubiousWordOffset e
cmmCheckWordAddress e@(CmmMachOp op [CmmLit (CmmInt i _), arg])
  | isOffsetOp op && i `rem` fromIntegral wORD_SIZE /= 0
  = cmmLintDubiousWordOffset e
cmmCheckWordAddress _
  = return ()


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 _vols) = mapM_ (lintCmmExpr.fst) args
lintCmmStmt (CmmCondBranch e _id)   = lintCmmExpr e >> return ()
lintCmmStmt (CmmSwitch e _branches) = lintCmmExpr e >> return ()
lintCmmStmt (CmmJump e _args)       = lintCmmExpr e >> return ()
lintCmmStmt _other 		    = return ()

-- -----------------------------------------------------------------------------
-- 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 -> CmmLint a
cmmLintMachOpErr expr = cmmLintErr (text "in MachOp application: " $$ 
					nest 2 (pprExpr expr))

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))