%
\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 ( getIdUnfolding )
-import Const ( mkMachInt, mkMachWord, Literal(..), Con(..) )
+import Id ( mkWildId )
+import Literal ( Literal(..), isLitLitLit, mkMachInt, mkMachWord
+ , literalType
+ , word2IntLit, int2WordLit, char2IntLit, int2CharLit
+ , float2IntLit, int2FloatLit, double2IntLit, int2DoubleLit
+ , addr2IntLit, int2AddrLit, float2DoubleLit, double2FloatLit
+ )
import PrimOp ( PrimOp(..), primOpOcc )
-import TysWiredIn ( trueDataCon, falseDataCon )
-import TyCon ( tyConDataCons, isEnumerationTyCon, isNewTyCon )
-import DataCon ( dataConTag, dataConTyCon, fIRST_TAG )
-import CoreUnfold ( maybeUnfoldingTemplate )
-import CoreUtils ( exprIsValue, cheapEqExpr )
+import TysWiredIn ( trueDataConId, falseDataConId )
+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 ( unpackCStringFoldrName, unpackCStringFoldrIdKey, hasKey )
+import Name ( Name )
+import Bits ( Bits(..) )
+import Word ( Word64 )
import Outputable
-
-#if __GLASGOW_HASKELL__ >= 404
-import GlaExts ( fromInt )
-#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
- -- Int2WordOp -- SIGH: these two cause trouble in unfoldery
- -- Int2AddrOp -- as we can't distinguish unsigned literals in interfaces (ToDo?)
primop_rule SeqOp = seqRule
primop_rule TagToEnumOp = tagToEnumRule
primop_rule DataToTagOp = dataToTagRule
- -- Addr operations
- primop_rule Addr2IntOp = oneLit (addr2IntOp op_name)
-
- -- Char operations
- primop_rule OrdOp = oneLit (chrOp op_name)
-
- -- Int/Word operations
- primop_rule IntAddOp = twoLits (intOp2 (+) op_name)
- primop_rule IntSubOp = twoLits (intOp2 (-) op_name)
- primop_rule IntMulOp = twoLits (intOp2 (*) op_name)
+ -- Int operations
+ primop_rule IntAddOp = twoLits (intOp2 (+) op_name)
+ primop_rule IntSubOp = twoLits (intOp2 (-) op_name)
+ primop_rule IntMulOp = twoLits (intOp2 (*) op_name)
primop_rule IntQuotOp = twoLits (intOp2Z quot op_name)
primop_rule IntRemOp = twoLits (intOp2Z rem op_name)
- primop_rule IntNegOp = oneLit (negOp op_name)
+ primop_rule IntNegOp = oneLit (negOp op_name)
+
+ -- 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
- primop_rule ChrOp = oneLit (intCoerce (mkCharVal . chr) op_name)
- primop_rule Int2FloatOp = oneLit (intCoerce mkFloatVal op_name)
- primop_rule Int2DoubleOp = oneLit (intCoerce mkDoubleVal op_name)
- primop_rule Word2IntOp = oneLit (intCoerce mkIntVal op_name)
- primop_rule Int2WordOp = oneLit (intCoerce mkWordVal op_name)
+ -- coercions
+ primop_rule Word2IntOp = oneLit (litCoerce word2IntLit op_name)
+ primop_rule Int2WordOp = oneLit (litCoerce int2WordLit op_name)
+ primop_rule OrdOp = oneLit (litCoerce char2IntLit op_name)
+ primop_rule ChrOp = oneLit (litCoerce int2CharLit op_name)
+ primop_rule Float2IntOp = oneLit (litCoerce float2IntLit op_name)
+ primop_rule Int2FloatOp = oneLit (litCoerce int2FloatLit op_name)
+ primop_rule Double2IntOp = oneLit (litCoerce double2IntLit op_name)
+ primop_rule Int2DoubleOp = oneLit (litCoerce int2DoubleLit op_name)
+ primop_rule Addr2IntOp = oneLit (litCoerce addr2IntLit op_name)
+ primop_rule Int2AddrOp = oneLit (litCoerce int2AddrLit op_name)
+ -- SUP: Not sure what the standard says about precision in the following 2 cases
+ primop_rule Float2DoubleOp = oneLit (litCoerce float2DoubleLit op_name)
+ primop_rule Double2FloatOp = oneLit (litCoerce double2FloatLit op_name)
-- Float
primop_rule FloatAddOp = twoLits (floatOp2 (+) op_name)
primop_rule DoubleSubOp = twoLits (doubleOp2 (-) op_name)
primop_rule DoubleMulOp = twoLits (doubleOp2 (*) op_name)
primop_rule DoubleDivOp = twoLits (doubleOp2Z (/) op_name)
+ primop_rule DoubleNegOp = oneLit (negOp op_name)
-- Relational operators
- primop_rule IntEqOp = relop (==) op_name `or_rule` litVar True op_name_case
- primop_rule IntNeOp = relop (/=) op_name `or_rule` litVar False op_name_case
- primop_rule CharEqOp = relop (==) op_name `or_rule` litVar True op_name_case
- primop_rule CharNeOp = relop (/=) op_name `or_rule` litVar False op_name_case
-
- primop_rule IntGtOp = relop (>) op_name
- primop_rule IntGeOp = relop (>=) op_name
- primop_rule IntLeOp = relop (<=) op_name
- primop_rule IntLtOp = relop (<) op_name
-
- primop_rule CharGtOp = relop (>) op_name
- primop_rule CharGeOp = relop (>=) op_name
- primop_rule CharLeOp = relop (<=) op_name
- primop_rule CharLtOp = relop (<) op_name
-
- primop_rule FloatGtOp = relop (>) op_name
- primop_rule FloatGeOp = relop (>=) op_name
- primop_rule FloatLeOp = relop (<=) op_name
- primop_rule FloatLtOp = relop (<) op_name
- primop_rule FloatEqOp = relop (==) op_name
- primop_rule FloatNeOp = relop (/=) op_name
-
- primop_rule DoubleGtOp = relop (>) op_name
- primop_rule DoubleGeOp = relop (>=) op_name
- primop_rule DoubleLeOp = relop (<=) op_name
- primop_rule DoubleLtOp = relop (<) op_name
- primop_rule DoubleEqOp = relop (==) op_name
- primop_rule DoubleNeOp = relop (/=) op_name
-
- primop_rule WordGtOp = relop (>) op_name
- primop_rule WordGeOp = relop (>=) op_name
- primop_rule WordLeOp = relop (<=) op_name
- primop_rule WordLtOp = relop (<) op_name
- primop_rule WordEqOp = relop (==) op_name
- primop_rule WordNeOp = relop (/=) op_name
+ primop_rule IntEqOp = relop (==) `or_rule` litEq True op_name_case
+ primop_rule IntNeOp = relop (/=) `or_rule` litEq False op_name_case
+ primop_rule CharEqOp = relop (==) `or_rule` litEq True op_name_case
+ primop_rule CharNeOp = relop (/=) `or_rule` litEq False op_name_case
+
+ primop_rule IntGtOp = relop (>)
+ primop_rule IntGeOp = relop (>=)
+ primop_rule IntLeOp = relop (<=)
+ primop_rule IntLtOp = relop (<)
+
+ primop_rule CharGtOp = relop (>)
+ primop_rule CharGeOp = relop (>=)
+ primop_rule CharLeOp = relop (<=)
+ primop_rule CharLtOp = relop (<)
+
+ primop_rule FloatGtOp = relop (>)
+ primop_rule FloatGeOp = relop (>=)
+ primop_rule FloatLeOp = relop (<=)
+ primop_rule FloatLtOp = relop (<)
+ primop_rule FloatEqOp = relop (==)
+ primop_rule FloatNeOp = relop (/=)
+
+ primop_rule DoubleGtOp = relop (>)
+ primop_rule DoubleGeOp = relop (>=)
+ primop_rule DoubleLeOp = relop (<=)
+ primop_rule DoubleLtOp = relop (<)
+ primop_rule DoubleEqOp = relop (==)
+ primop_rule DoubleNeOp = relop (/=)
+
+ primop_rule WordGtOp = relop (>)
+ primop_rule WordGeOp = relop (>=)
+ primop_rule WordLeOp = relop (<=)
+ primop_rule WordLtOp = relop (<)
+ primop_rule WordEqOp = relop (==)
+ primop_rule WordNeOp = relop (/=)
primop_rule other = \args -> Nothing
+
+
+ relop cmp = twoLits (cmpOp (\ord -> ord `cmp` EQ) op_name)
+ -- Cunning. cmpOp compares the values to give an Ordering.
+ -- It applies its argument to that ordering value to turn
+ -- the ordering into a boolean value. (`cmp` EQ) is just the job.
\end{code}
%************************************************************************
%* *
%************************************************************************
+ IMPORTANT NOTE
+
+In all these operations we might find a LitLit as an operand; that's
+why we have the catch-all Nothing case.
+
\begin{code}
--------------------------
-intCoerce :: Num a => (a -> CoreExpr) -> RuleName -> Literal -> Maybe (RuleName, CoreExpr)
-intCoerce fn name (MachInt i _) = Just (name, fn (fromInteger i))
+litCoerce :: (Literal -> Literal) -> RuleName -> Literal -> Maybe (RuleName, CoreExpr)
+litCoerce fn name lit | isLitLitLit lit = Nothing
+ | otherwise = Just (name, Lit (fn lit))
--------------------------
-relop cmp name = twoLits (\l1 l2 -> Just (name, if l1 `cmp` l2 then trueVal else falseVal))
+cmpOp :: (Ordering -> Bool) -> FAST_STRING -> Literal -> Literal -> Maybe (RuleName, CoreExpr)
+cmpOp cmp name l1 l2
+ = go l1 l2
+ where
+ done res | cmp res = Just (name, trueVal)
+ | otherwise = Just (name, falseVal)
+
+ -- These compares are at different types
+ go (MachChar i1) (MachChar i2) = done (i1 `compare` i2)
+ go (MachInt i1) (MachInt i2) = done (i1 `compare` i2)
+ go (MachInt64 i1) (MachInt64 i2) = done (i1 `compare` i2)
+ go (MachWord i1) (MachWord i2) = done (i1 `compare` i2)
+ go (MachWord64 i1) (MachWord64 i2) = done (i1 `compare` i2)
+ go (MachFloat i1) (MachFloat i2) = done (i1 `compare` i2)
+ go (MachDouble i1) (MachDouble i2) = done (i1 `compare` i2)
+ go l1 l2 = Nothing
--------------------------
+
negOp name (MachFloat f) = Just (name, mkFloatVal (-f))
negOp name (MachDouble d) = Just (name, mkDoubleVal (-d))
-negOp name (MachInt i _) = Just (name, mkIntVal (-i))
+negOp name l@(MachInt i) = intResult name (-i)
+negOp name l = Nothing
-chrOp name (MachChar c) = Just (name, mkIntVal (fromInt (ord c)))
+--------------------------
+intOp2 op name l1@(MachInt i1) l2@(MachInt i2)
+ = intResult name (i1 `op` i2)
+intOp2 op name l1 l2 = Nothing -- Could find LitLit
-addr2IntOp name (MachAddr i) = Just (name, mkIntVal i)
+intOp2Z op name (MachInt i1) (MachInt i2)
+ | i2 /= 0 = Just (name, mkIntVal (i1 `op` i2))
+intOp2Z op name l1 l2 = Nothing -- LitLit or zero dividend
--------------------------
-intOp2 op name l1@(MachInt i1 s1) l2@(MachInt i2 s2)
- | (result > fromInt maxInt) || (result < fromInt minInt)
- -- Better tell the user that we've overflowed...
- -- ..not that it stops us from actually folding!
- = pprTrace "Warning:" (text "Integer overflow in expression: " <>
- ppr name <+> ppr l1 <+> ppr l2) $
- Just (name, mkIntVal result)
-
- | otherwise
- = ASSERT( s1 && s2 ) -- Both should be signed
- Just (name, mkIntVal result)
- where
- result = i1 `op` i2
-
-intOp2Z op name (MachInt i1 s1) (MachInt i2 s2)
- | i2 == 0 = Nothing -- Don't do it if the dividend < 0
- | otherwise = Just (name, mkIntVal (i1 `op` i2))
+-- Integer is not an instance of Bits, so we operate on Word64
+wordBitOp2 op name l1@(MachWord w1) l2@(MachWord 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)
+ | w2 /= 0 = Just (name, mkWordVal (w1 `op` w2))
+wordOp2Z op name l1 l2 = Nothing -- LitLit or zero dividend
--------------------------
floatOp2 op name (MachFloat f1) (MachFloat f2)
= Just (name, mkFloatVal (f1 `op` f2))
+floatOp2 op name l1 l2 = Nothing
floatOp2Z op name (MachFloat f1) (MachFloat f2)
- | f1 /= 0 = Just (name, mkFloatVal (f1 `op` f2))
- | otherwise = Nothing
-
+ | f2 /= 0 = Just (name, mkFloatVal (f1 `op` f2))
+floatOp2Z op name l1 l2 = Nothing
--------------------------
doubleOp2 op name (MachDouble f1) (MachDouble f2)
= Just (name, mkDoubleVal (f1 `op` f2))
+doubleOp2 op name l1 l2 = Nothing
doubleOp2Z op name (MachDouble f1) (MachDouble f2)
- | f1 /= 0 = Just (name, mkDoubleVal (f1 `op` f2))
- | otherwise = Nothing
+ | f2 /= 0 = Just (name, mkDoubleVal (f1 `op` f2))
+doubleOp2Z op name l1 l2 = Nothing
--------------------------
-- m -> e2
-- (modulo the usual precautions to avoid duplicating e1)
-litVar :: Bool -- True <=> equality, False <=> inequality
+litEq :: Bool -- True <=> equality, False <=> inequality
-> RuleName
-> RuleFun
-litVar is_eq name [Con (Literal lit) _, Var var] = do_lit_var is_eq name lit var
-litVar is_eq name [Var var, Con (Literal lit) _] = do_lit_var is_eq name lit var
-litVar is_eq name other = Nothing
-
-do_lit_var is_eq name lit var
- = Just (name, Case (Var var) var [(Literal lit, [], val_if_eq),
- (DEFAULT, [], val_if_neq)])
+litEq is_eq name [Lit lit, expr] = do_lit_eq is_eq name lit expr
+litEq is_eq name [expr, Lit lit] = do_lit_eq is_eq name lit expr
+litEq is_eq name other = Nothing
+
+do_lit_eq is_eq name lit expr
+ = Just (name, Case expr (mkWildId (literalType lit))
+ [(LitAlt lit, [], val_if_eq),
+ (DEFAULT, [], val_if_neq)])
where
val_if_eq | is_eq = trueVal
| otherwise = falseVal
val_if_neq | is_eq = falseVal
| otherwise = trueVal
+
+-- 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 [Con (Literal l1) _, Con (Literal l2) _] = rule l1 l2
-twoLits rule other = Nothing
+twoLits rule [Lit l1, Lit l2] = rule (convFloating l1) (convFloating l2)
+twoLits rule other = Nothing
oneLit :: (Literal -> Maybe (RuleName, CoreExpr)) -> RuleFun
-oneLit rule [Con (Literal l1) _] = rule l1
-oneLit rule other = Nothing
-
-
-trueVal = Con (DataCon trueDataCon) []
-falseVal = Con (DataCon falseDataCon) []
-mkIntVal i = Con (Literal (mkMachInt i)) []
-mkCharVal c = Con (Literal (MachChar c)) []
-mkWordVal w = Con (Literal (mkMachWord w)) []
-mkFloatVal f = Con (Literal (MachFloat f)) []
-mkDoubleVal d = Con (Literal (MachDouble d)) []
+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)
+mkFloatVal f = Lit (convFloating (MachFloat f))
+mkDoubleVal d = Lit (convFloating (MachDouble d))
\end{code}
\begin{code}
-tagToEnumRule [Type ty, Con (Literal (MachInt i _)) _]
+tagToEnumRule [Type ty, Lit (MachInt i)]
= ASSERT( isEnumerationTyCon tycon )
- Just (SLIT("TagToEnum"), Con (DataCon 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}
dataToTagRule [_, val_arg]
- = case val_arg of
- Con (DataCon dc) _ -> yes dc
- Var x -> case maybeUnfoldingTemplate (getIdUnfolding x) of
- Just (Con (DataCon dc) _) -> yes dc
- other -> Nothing
- other -> Nothing
- where
- yes dc = ASSERT( not (isNewTyCon (dataConTyCon dc)) )
- Just (SLIT("DataToTag"),
- mkIntVal (toInteger (dataConTag dc - fIRST_TAG)))
+ = case exprIsConApp_maybe val_arg of
+ Just (dc,_) -> ASSERT( not (isNewTyCon (dataConTyCon dc)) )
+ Just (SLIT("DataToTag"),
+ mkIntVal (toInteger (dataConTag dc - fIRST_TAG)))
+
+ other -> Nothing
dataToTagRule other = Nothing
\end{code}
%************************************************************************
\begin{code}
-builtinRules :: [ProtoCoreRule]
+builtinRules :: [(Name, CoreRule)]
+-- Rules for non-primops that can't be expressed using a RULE pragma
builtinRules
- = [ ProtoCoreRule False unpackCStringFoldrId
- (BuiltinRule match_append_lit_str)
+ = [ (unpackCStringFoldrName, BuiltinRule match_append_lit_str)
]
--- unpack "foo" c (unpack "baz" c n) = unpack "foobaz" c n
+-- The rule is this:
+-- unpackFoldrCString# "foo" c (unpackFoldrCString# "baz" c n) = unpackFoldrCString# "foobaz" c n
match_append_lit_str [Type ty1,
- Con (Literal (MachStr s1)) [],
+ Lit (MachStr s1),
c1,
Var unpk `App` Type ty2
- `App` Con (Literal (MachStr s2)) []
+ `App` Lit (MachStr s2)
`App` c2
`App` n
]
- | unpk == unpackCStringFoldrId &&
+ | unpk `hasKey` unpackCStringFoldrIdKey &&
c1 `cheapEqExpr` c2
= ASSERT( ty1 == ty2 )
Just (SLIT("AppendLitString"),
Var unpk `App` Type ty1
- `App` Con (Literal (MachStr (s1 _APPEND_ s2))) []
+ `App` Lit (MachStr (s1 _APPEND_ s2))
`App` c1
`App` n)
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