%
\section[ConFold]{Constant Folder}
+Conceptually, constant folding should be parameterized with the kind
+of target machine to get identical behaviour during compilation time
+and runtime. We cheat a little bit here...
+
ToDo:
check boundaries before folding, e.g. we can fold the Float addition
(i1 + i2) only if it results in a valid Float.
#include "HsVersions.h"
import CoreSyn
-import Rules ( ProtoCoreRule(..) )
-import Id ( idUnfolding, mkWildId, isDataConId_maybe )
+import Id ( mkWildId )
import Literal ( Literal(..), isLitLitLit, mkMachInt, mkMachWord
, inIntRange, inWordRange, literalType
, word2IntLit, int2WordLit, char2IntLit, int2CharLit
, float2IntLit, int2FloatLit, double2IntLit, int2DoubleLit
, addr2IntLit, int2AddrLit, float2DoubleLit, double2FloatLit
)
+import RdrName ( RdrName )
import PrimOp ( PrimOp(..), primOpOcc )
import TysWiredIn ( trueDataConId, falseDataConId )
-import TyCon ( tyConDataCons, isEnumerationTyCon, isNewTyCon )
-import DataCon ( DataCon, dataConTag, dataConRepArity, dataConTyCon, dataConId, fIRST_TAG )
-import CoreUnfold ( maybeUnfoldingTemplate )
+import TyCon ( tyConDataConsIfAvailable, isEnumerationTyCon, isNewTyCon )
+import DataCon ( dataConTag, dataConTyCon, dataConId, fIRST_TAG )
import CoreUtils ( exprIsValue, cheapEqExpr, exprIsConApp_maybe )
import Type ( splitTyConApp_maybe )
import OccName ( occNameUserString)
-import ThinAir ( unpackCStringFoldrId )
-import Maybes ( maybeToBool )
-import Char ( ord, chr )
+import PrelNames ( unpackCStringFoldr_RDR )
+import Unique ( unpackCStringFoldrIdKey, hasKey )
import Bits ( Bits(..) )
-import PrelAddr ( wordToInt )
import Word ( Word64 )
import Outputable
-
-#if __GLASGOW_HASKELL__ > 404
-import PrelAddr ( intToWord )
-#else
-import PrelAddr ( Word(..) )
-import PrelGHC ( int2Word# )
-intToWord :: Int -> Word
-intToWord (I# i#) = W# (int2Word# i#)
-#endif
+import CmdLineOpts ( opt_SimplExcessPrecision )
\end{code}
-
\begin{code}
primOpRule :: PrimOp -> CoreRule
primOpRule op
= BuiltinRule (primop_rule op)
where
op_name = _PK_ (occNameUserString (primOpOcc op))
- op_name_case = op_name _APPEND_ SLIT("case")
+ op_name_case = op_name _APPEND_ SLIT("->case")
-- ToDo: something for integer-shift ops?
-- NotOp
-- Word operations
primop_rule WordQuotOp = twoLits (wordOp2Z quot op_name)
primop_rule WordRemOp = twoLits (wordOp2Z rem op_name)
+#if __GLASGOW_HASKELL__ >= 407
primop_rule AndOp = twoLits (wordBitOp2 (.&.) op_name)
primop_rule OrOp = twoLits (wordBitOp2 (.|.) op_name)
primop_rule XorOp = twoLits (wordBitOp2 xor op_name)
+#endif
-- coercions
primop_rule Word2IntOp = oneLit (litCoerce word2IntLit op_name)
negOp name (MachFloat f) = Just (name, mkFloatVal (-f))
negOp name (MachDouble d) = Just (name, mkDoubleVal (-d))
-negOp name l@(MachInt i) = intResult name (ppr l) (-i)
+negOp name l@(MachInt i) = intResult name (-i)
negOp name l = Nothing
--------------------------
intOp2 op name l1@(MachInt i1) l2@(MachInt i2)
- = intResult name (ppr l1 <+> ppr l2) (i1 `op` i2)
+ = intResult name (i1 `op` i2)
intOp2 op name l1 l2 = Nothing -- Could find LitLit
intOp2Z op name (MachInt i1) (MachInt i2)
--------------------------
-- Integer is not an instance of Bits, so we operate on Word64
wordBitOp2 op name l1@(MachWord w1) l2@(MachWord w2)
- = wordResult name (ppr l1 <+> ppr l2)
- ((fromIntegral::Word64->Integer) (fromIntegral w1 `op` fromIntegral w2))
+ = Just (name, mkWordVal ((fromIntegral::Word64->Integer) (fromIntegral w1 `op` fromIntegral w2)))
wordBitOp2 op name l1 l2 = Nothing -- Could find LitLit
wordOp2Z op name (MachWord w1) (MachWord w2)
floatOp2 op name l1 l2 = Nothing
floatOp2Z op name (MachFloat f1) (MachFloat f2)
- | f1 /= 0 = Just (name, mkFloatVal (f1 `op` f2))
+ | f2 /= 0 = Just (name, mkFloatVal (f1 `op` f2))
floatOp2Z op name l1 l2 = Nothing
--------------------------
doubleOp2 op name l1 l2 = Nothing
doubleOp2Z op name (MachDouble f1) (MachDouble f2)
- | f1 /= 0 = Just (name, mkDoubleVal (f1 `op` f2))
+ | f2 /= 0 = Just (name, mkDoubleVal (f1 `op` f2))
doubleOp2Z op name l1 l2 = Nothing
val_if_neq | is_eq = falseVal
| otherwise = trueVal
--- TODO: Merge intResult/wordResult
-intResult name pp_args result
- | not (inIntRange result)
- -- Better tell the user that we've overflowed...
- -- ..not that it stops us from actually folding!
-
- = pprTrace "Warning:" (text "Integer overflow in:" <+> ppr name <+> pp_args)
- Just (name, mkIntVal (squashInt result))
-
- | otherwise
- = Just (name, mkIntVal result)
-
-wordResult name pp_args result
- | not (inWordRange result)
- -- Better tell the user that we've overflowed...
- -- ..not that it stops us from actually folding!
-
- = pprTrace "Warning:" (text "Word overflow in:" <+> ppr name <+> pp_args)
- Just (name, mkWordVal (squashInt result))
-
- | otherwise
- = Just (name, mkWordVal result)
-
-squashInt :: Integer -> Integer -- Squash into Int range
-squashInt i = toInteger ((fromInteger i)::Int)
+-- Note that we *don't* warn the user about overflow. It's not done at
+-- runtime either, and compilation of completely harmless things like
+-- ((124076834 :: Word32) + (2147483647 :: Word32))
+-- would yield a warning. Instead we simply squash the value into the
+-- Int range, but not in a way suitable for cross-compiling... :-(
+intResult :: RuleName -> Integer -> Maybe (RuleName, CoreExpr)
+intResult name result
+ = Just (name, mkIntVal (toInteger ((fromInteger result)::Int)))
\end{code}
type RuleFun = [CoreExpr] -> Maybe (RuleName, CoreExpr)
or_rule :: RuleFun -> RuleFun -> RuleFun
-or_rule r1 r2 args = case r1 args of
- Just stuff -> Just stuff
- Nothing -> r2 args
+or_rule r1 r2 args = maybe (r2 args) Just (r1 args) -- i.e.: r1 args `mplus` r2 args
twoLits :: (Literal -> Literal -> Maybe (RuleName, CoreExpr)) -> RuleFun
-twoLits rule [Lit l1, Lit l2] = rule l1 l2
+twoLits rule [Lit l1, Lit l2] = rule (convFloating l1) (convFloating l2)
twoLits rule other = Nothing
oneLit :: (Literal -> Maybe (RuleName, CoreExpr)) -> RuleFun
-oneLit rule [Lit l1] = rule l1
+oneLit rule [Lit l1] = rule (convFloating l1)
oneLit rule other = Nothing
+-- When excess precision is not requested, cut down the precision of the
+-- Rational value to that of Float/Double. We confuse host architecture
+-- and target architecture here, but it's convenient (and wrong :-).
+convFloating :: Literal -> Literal
+convFloating (MachFloat f) | not opt_SimplExcessPrecision =
+ MachFloat (toRational ((fromRational f) :: Float ))
+convFloating (MachDouble d) | not opt_SimplExcessPrecision =
+ MachDouble (toRational ((fromRational d) :: Double))
+convFloating l = l
+
trueVal = Var trueDataConId
falseVal = Var falseDataConId
mkIntVal i = Lit (mkMachInt i)
mkWordVal w = Lit (mkMachWord w)
mkCharVal c = Lit (MachChar c)
-mkFloatVal f = Lit (MachFloat f)
-mkDoubleVal d = Lit (MachDouble d)
+mkFloatVal f = Lit (convFloating (MachFloat f))
+mkDoubleVal d = Lit (convFloating (MachDouble d))
\end{code}
\begin{code}
tagToEnumRule [Type ty, Lit (MachInt i)]
= ASSERT( isEnumerationTyCon tycon )
- Just (SLIT("TagToEnum"), Var (dataConId dc))
+ case filter correct_tag (tyConDataConsIfAvailable tycon) of
+
+
+ [] -> Nothing -- Abstract type
+ (dc:rest) -> ASSERT( null rest )
+ Just (SLIT("TagToEnum"), Var (dataConId dc))
where
+ correct_tag dc = (dataConTag dc - fIRST_TAG) == tag
tag = fromInteger i
- constrs = tyConDataCons tycon
- (dc:_) = [ dc | dc <- constrs, tag == dataConTag dc - fIRST_TAG ]
(Just (tycon,_)) = splitTyConApp_maybe ty
tagToEnumRule other = Nothing
%************************************************************************
\begin{code}
-builtinRules :: [ProtoCoreRule]
+builtinRules :: [(RdrName, CoreRule)]
-- Rules for non-primops that can't be expressed using a RULE pragma
builtinRules
- = [ ProtoCoreRule False unpackCStringFoldrId
- (BuiltinRule match_append_lit_str)
+ = [ (unpackCStringFoldr_RDR, BuiltinRule match_append_lit_str)
]
--- unpack "foo" c (unpack "baz" c n) = unpack "foobaz" c n
+-- unpackFoldrCString# "foo" c (unpackFoldrCString# "baz" c n) = unpackFoldrCString# "foobaz" c n
match_append_lit_str [Type ty1,
Lit (MachStr s1),
`App` c2
`App` n
]
- | unpk == unpackCStringFoldrId &&
+ | unpk `hasKey` unpackCStringFoldrIdKey &&
c1 `cheapEqExpr` c2
= ASSERT( ty1 == ty2 )
Just (SLIT("AppendLitString"),
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