{- (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 \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. -} {-# LANGUAGE CPP, RankNTypes #-} {-# OPTIONS_GHC -optc-DNON_POSIX_SOURCE #-} module PrelRules ( primOpRules , builtinRules , caseRules ) where #include "HsVersions.h" #include "MachDeps.h" import {-# SOURCE #-} MkId ( mkPrimOpId, magicDictId ) import CoreSyn import MkCore import Id import Literal import CoreOpt ( exprIsLiteral_maybe ) import PrimOp ( PrimOp(..), tagToEnumKey ) import TysWiredIn import TysPrim import TyCon ( tyConDataCons_maybe, isEnumerationTyCon, isNewTyCon, unwrapNewTyCon_maybe ) import DataCon ( dataConTag, dataConTyCon, dataConWorkId ) import CoreUtils ( cheapEqExpr, exprIsHNF ) import CoreUnfold ( exprIsConApp_maybe ) import Type import OccName ( occNameFS ) import PrelNames import Maybes ( orElse ) import Name ( Name, nameOccName ) import Outputable import FastString import BasicTypes import DynFlags import Platform import Util import Coercion (mkUnbranchedAxInstCo,mkSymCo,Role(..)) import Control.Applicative ( Alternative(..) ) import Control.Monad #if __GLASGOW_HASKELL__ > 710 import qualified Control.Monad.Fail as MonadFail #endif import Data.Bits as Bits import qualified Data.ByteString as BS import Data.Int import Data.Ratio import Data.Word {- Note [Constant folding] ~~~~~~~~~~~~~~~~~~~~~~~ primOpRules generates a rewrite rule for each primop These rules do what is often called "constant folding" E.g. the rules for +# might say 4 +# 5 = 9 Well, of course you'd need a lot of rules if you did it like that, so we use a BuiltinRule instead, so that we can match in any two literal values. So the rule is really more like (Lit x) +# (Lit y) = Lit (x+#y) where the (+#) on the rhs is done at compile time That is why these rules are built in here. -} primOpRules :: Name -> PrimOp -> Maybe CoreRule -- ToDo: something for integer-shift ops? -- NotOp primOpRules nm TagToEnumOp = mkPrimOpRule nm 2 [ tagToEnumRule ] primOpRules nm DataToTagOp = mkPrimOpRule nm 2 [ dataToTagRule ] -- Int operations primOpRules nm IntAddOp = mkPrimOpRule nm 2 [ binaryLit (intOp2 (+)) , identityDynFlags zeroi ] primOpRules nm IntSubOp = mkPrimOpRule nm 2 [ binaryLit (intOp2 (-)) , rightIdentityDynFlags zeroi , equalArgs >> retLit zeroi ] primOpRules nm IntMulOp = mkPrimOpRule nm 2 [ binaryLit (intOp2 (*)) , zeroElem zeroi , identityDynFlags onei ] primOpRules nm IntQuotOp = mkPrimOpRule nm 2 [ nonZeroLit 1 >> binaryLit (intOp2 quot) , leftZero zeroi , rightIdentityDynFlags onei , equalArgs >> retLit onei ] primOpRules nm IntRemOp = mkPrimOpRule nm 2 [ nonZeroLit 1 >> binaryLit (intOp2 rem) , leftZero zeroi , do l <- getLiteral 1 dflags <- getDynFlags guard (l == onei dflags) retLit zeroi , equalArgs >> retLit zeroi , equalArgs >> retLit zeroi ] primOpRules nm AndIOp = mkPrimOpRule nm 2 [ binaryLit (intOp2 (.&.)) , idempotent , zeroElem zeroi ] primOpRules nm OrIOp = mkPrimOpRule nm 2 [ binaryLit (intOp2 (.|.)) , idempotent , identityDynFlags zeroi ] primOpRules nm XorIOp = mkPrimOpRule nm 2 [ binaryLit (intOp2 xor) , identityDynFlags zeroi , equalArgs >> retLit zeroi ] primOpRules nm NotIOp = mkPrimOpRule nm 1 [ unaryLit complementOp , inversePrimOp NotIOp ] primOpRules nm IntNegOp = mkPrimOpRule nm 1 [ unaryLit negOp , inversePrimOp IntNegOp ] primOpRules nm ISllOp = mkPrimOpRule nm 2 [ binaryLit (intOp2 Bits.shiftL) , rightIdentityDynFlags zeroi ] primOpRules nm ISraOp = mkPrimOpRule nm 2 [ binaryLit (intOp2 Bits.shiftR) , rightIdentityDynFlags zeroi ] primOpRules nm ISrlOp = mkPrimOpRule nm 2 [ binaryLit (intOp2' shiftRightLogical) , rightIdentityDynFlags zeroi ] -- Word operations primOpRules nm WordAddOp = mkPrimOpRule nm 2 [ binaryLit (wordOp2 (+)) , identityDynFlags zerow ] primOpRules nm WordSubOp = mkPrimOpRule nm 2 [ binaryLit (wordOp2 (-)) , rightIdentityDynFlags zerow , equalArgs >> retLit zerow ] primOpRules nm WordMulOp = mkPrimOpRule nm 2 [ binaryLit (wordOp2 (*)) , identityDynFlags onew ] primOpRules nm WordQuotOp = mkPrimOpRule nm 2 [ nonZeroLit 1 >> binaryLit (wordOp2 quot) , rightIdentityDynFlags onew ] primOpRules nm WordRemOp = mkPrimOpRule nm 2 [ nonZeroLit 1 >> binaryLit (wordOp2 rem) , leftZero zerow , do l <- getLiteral 1 dflags <- getDynFlags guard (l == onew dflags) retLit zerow , equalArgs >> retLit zerow ] primOpRules nm AndOp = mkPrimOpRule nm 2 [ binaryLit (wordOp2 (.&.)) , idempotent , zeroElem zerow ] primOpRules nm OrOp = mkPrimOpRule nm 2 [ binaryLit (wordOp2 (.|.)) , idempotent , identityDynFlags zerow ] primOpRules nm XorOp = mkPrimOpRule nm 2 [ binaryLit (wordOp2 xor) , identityDynFlags zerow , equalArgs >> retLit zerow ] primOpRules nm NotOp = mkPrimOpRule nm 1 [ unaryLit complementOp , inversePrimOp NotOp ] primOpRules nm SllOp = mkPrimOpRule nm 2 [ wordShiftRule (const Bits.shiftL) ] primOpRules nm SrlOp = mkPrimOpRule nm 2 [ wordShiftRule shiftRightLogical ] -- coercions primOpRules nm Word2IntOp = mkPrimOpRule nm 1 [ liftLitDynFlags word2IntLit , inversePrimOp Int2WordOp ] primOpRules nm Int2WordOp = mkPrimOpRule nm 1 [ liftLitDynFlags int2WordLit , inversePrimOp Word2IntOp ] primOpRules nm Narrow8IntOp = mkPrimOpRule nm 1 [ liftLit narrow8IntLit , subsumedByPrimOp Narrow8IntOp , Narrow8IntOp `subsumesPrimOp` Narrow16IntOp , Narrow8IntOp `subsumesPrimOp` Narrow32IntOp ] primOpRules nm Narrow16IntOp = mkPrimOpRule nm 1 [ liftLit narrow16IntLit , subsumedByPrimOp Narrow8IntOp , subsumedByPrimOp Narrow16IntOp , Narrow16IntOp `subsumesPrimOp` Narrow32IntOp ] primOpRules nm Narrow32IntOp = mkPrimOpRule nm 1 [ liftLit narrow32IntLit , subsumedByPrimOp Narrow8IntOp , subsumedByPrimOp Narrow16IntOp , subsumedByPrimOp Narrow32IntOp , removeOp32 ] primOpRules nm Narrow8WordOp = mkPrimOpRule nm 1 [ liftLit narrow8WordLit , subsumedByPrimOp Narrow8WordOp , Narrow8WordOp `subsumesPrimOp` Narrow16WordOp , Narrow8WordOp `subsumesPrimOp` Narrow32WordOp ] primOpRules nm Narrow16WordOp = mkPrimOpRule nm 1 [ liftLit narrow16WordLit , subsumedByPrimOp Narrow8WordOp , subsumedByPrimOp Narrow16WordOp , Narrow16WordOp `subsumesPrimOp` Narrow32WordOp ] primOpRules nm Narrow32WordOp = mkPrimOpRule nm 1 [ liftLit narrow32WordLit , subsumedByPrimOp Narrow8WordOp , subsumedByPrimOp Narrow16WordOp , subsumedByPrimOp Narrow32WordOp , removeOp32 ] primOpRules nm OrdOp = mkPrimOpRule nm 1 [ liftLit char2IntLit , inversePrimOp ChrOp ] primOpRules nm ChrOp = mkPrimOpRule nm 1 [ do [Lit lit] <- getArgs guard (litFitsInChar lit) liftLit int2CharLit , inversePrimOp OrdOp ] primOpRules nm Float2IntOp = mkPrimOpRule nm 1 [ liftLit float2IntLit ] primOpRules nm Int2FloatOp = mkPrimOpRule nm 1 [ liftLit int2FloatLit ] primOpRules nm Double2IntOp = mkPrimOpRule nm 1 [ liftLit double2IntLit ] primOpRules nm Int2DoubleOp = mkPrimOpRule nm 1 [ liftLit int2DoubleLit ] -- SUP: Not sure what the standard says about precision in the following 2 cases primOpRules nm Float2DoubleOp = mkPrimOpRule nm 1 [ liftLit float2DoubleLit ] primOpRules nm Double2FloatOp = mkPrimOpRule nm 1 [ liftLit double2FloatLit ] -- Float primOpRules nm FloatAddOp = mkPrimOpRule nm 2 [ binaryLit (floatOp2 (+)) , identity zerof ] primOpRules nm FloatSubOp = mkPrimOpRule nm 2 [ binaryLit (floatOp2 (-)) , rightIdentity zerof ] primOpRules nm FloatMulOp = mkPrimOpRule nm 2 [ binaryLit (floatOp2 (*)) , identity onef , strengthReduction twof FloatAddOp ] -- zeroElem zerof doesn't hold because of NaN primOpRules nm FloatDivOp = mkPrimOpRule nm 2 [ guardFloatDiv >> binaryLit (floatOp2 (/)) , rightIdentity onef ] primOpRules nm FloatNegOp = mkPrimOpRule nm 1 [ unaryLit negOp , inversePrimOp FloatNegOp ] -- Double primOpRules nm DoubleAddOp = mkPrimOpRule nm 2 [ binaryLit (doubleOp2 (+)) , identity zerod ] primOpRules nm DoubleSubOp = mkPrimOpRule nm 2 [ binaryLit (doubleOp2 (-)) , rightIdentity zerod ] primOpRules nm DoubleMulOp = mkPrimOpRule nm 2 [ binaryLit (doubleOp2 (*)) , identity oned , strengthReduction twod DoubleAddOp ] -- zeroElem zerod doesn't hold because of NaN primOpRules nm DoubleDivOp = mkPrimOpRule nm 2 [ guardDoubleDiv >> binaryLit (doubleOp2 (/)) , rightIdentity oned ] primOpRules nm DoubleNegOp = mkPrimOpRule nm 1 [ unaryLit negOp , inversePrimOp DoubleNegOp ] -- Relational operators primOpRules nm IntEqOp = mkRelOpRule nm (==) [ litEq True ] primOpRules nm IntNeOp = mkRelOpRule nm (/=) [ litEq False ] primOpRules nm CharEqOp = mkRelOpRule nm (==) [ litEq True ] primOpRules nm CharNeOp = mkRelOpRule nm (/=) [ litEq False ] primOpRules nm IntGtOp = mkRelOpRule nm (>) [ boundsCmp Gt ] primOpRules nm IntGeOp = mkRelOpRule nm (>=) [ boundsCmp Ge ] primOpRules nm IntLeOp = mkRelOpRule nm (<=) [ boundsCmp Le ] primOpRules nm IntLtOp = mkRelOpRule nm (<) [ boundsCmp Lt ] primOpRules nm CharGtOp = mkRelOpRule nm (>) [ boundsCmp Gt ] primOpRules nm CharGeOp = mkRelOpRule nm (>=) [ boundsCmp Ge ] primOpRules nm CharLeOp = mkRelOpRule nm (<=) [ boundsCmp Le ] primOpRules nm CharLtOp = mkRelOpRule nm (<) [ boundsCmp Lt ] primOpRules nm FloatGtOp = mkFloatingRelOpRule nm (>) primOpRules nm FloatGeOp = mkFloatingRelOpRule nm (>=) primOpRules nm FloatLeOp = mkFloatingRelOpRule nm (<=) primOpRules nm FloatLtOp = mkFloatingRelOpRule nm (<) primOpRules nm FloatEqOp = mkFloatingRelOpRule nm (==) primOpRules nm FloatNeOp = mkFloatingRelOpRule nm (/=) primOpRules nm DoubleGtOp = mkFloatingRelOpRule nm (>) primOpRules nm DoubleGeOp = mkFloatingRelOpRule nm (>=) primOpRules nm DoubleLeOp = mkFloatingRelOpRule nm (<=) primOpRules nm DoubleLtOp = mkFloatingRelOpRule nm (<) primOpRules nm DoubleEqOp = mkFloatingRelOpRule nm (==) primOpRules nm DoubleNeOp = mkFloatingRelOpRule nm (/=) primOpRules nm WordGtOp = mkRelOpRule nm (>) [ boundsCmp Gt ] primOpRules nm WordGeOp = mkRelOpRule nm (>=) [ boundsCmp Ge ] primOpRules nm WordLeOp = mkRelOpRule nm (<=) [ boundsCmp Le ] primOpRules nm WordLtOp = mkRelOpRule nm (<) [ boundsCmp Lt ] primOpRules nm WordEqOp = mkRelOpRule nm (==) [ litEq True ] primOpRules nm WordNeOp = mkRelOpRule nm (/=) [ litEq False ] primOpRules nm AddrAddOp = mkPrimOpRule nm 2 [ rightIdentityDynFlags zeroi ] primOpRules nm SeqOp = mkPrimOpRule nm 4 [ seqRule ] primOpRules nm SparkOp = mkPrimOpRule nm 4 [ sparkRule ] primOpRules _ _ = Nothing {- ************************************************************************ * * \subsection{Doing the business} * * ************************************************************************ -} -- useful shorthands mkPrimOpRule :: Name -> Int -> [RuleM CoreExpr] -> Maybe CoreRule mkPrimOpRule nm arity rules = Just $ mkBasicRule nm arity (msum rules) mkRelOpRule :: Name -> (forall a . Ord a => a -> a -> Bool) -> [RuleM CoreExpr] -> Maybe CoreRule mkRelOpRule nm cmp extra = mkPrimOpRule nm 2 $ binaryCmpLit cmp : equal_rule : extra where -- x `cmp` x does not depend on x, so -- compute it for the arbitrary value 'True' -- and use that result equal_rule = do { equalArgs ; dflags <- getDynFlags ; return (if cmp True True then trueValInt dflags else falseValInt dflags) } {- Note [Rules for floating-point comparisons] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We need different rules for floating-point values because for floats it is not true that x = x (for NaNs); so we do not want the equal_rule rule that mkRelOpRule uses. Note also that, in the case of equality/inequality, we do /not/ want to switch to a case-expression. For example, we do not want to convert case (eqFloat# x 3.8#) of True -> this False -> that to case x of 3.8#::Float# -> this _ -> that See Trac #9238. Reason: comparing floating-point values for equality delicate, and we don't want to implement that delicacy in the code for case expressions. So we make it an invariant of Core that a case expression never scrutinises a Float# or Double#. This transformation is what the litEq rule does; see Note [The litEq rule: converting equality to case]. So we /refrain/ from using litEq for mkFloatingRelOpRule. -} mkFloatingRelOpRule :: Name -> (forall a . Ord a => a -> a -> Bool) -> Maybe CoreRule -- See Note [Rules for floating-point comparisons] mkFloatingRelOpRule nm cmp = mkPrimOpRule nm 2 [binaryCmpLit cmp] -- common constants zeroi, onei, zerow, onew :: DynFlags -> Literal zeroi dflags = mkMachInt dflags 0 onei dflags = mkMachInt dflags 1 zerow dflags = mkMachWord dflags 0 onew dflags = mkMachWord dflags 1 zerof, onef, twof, zerod, oned, twod :: Literal zerof = mkMachFloat 0.0 onef = mkMachFloat 1.0 twof = mkMachFloat 2.0 zerod = mkMachDouble 0.0 oned = mkMachDouble 1.0 twod = mkMachDouble 2.0 cmpOp :: DynFlags -> (forall a . Ord a => a -> a -> Bool) -> Literal -> Literal -> Maybe CoreExpr cmpOp dflags cmp = go where done True = Just $ trueValInt dflags done False = Just $ falseValInt dflags -- These compares are at different types go (MachChar i1) (MachChar i2) = done (i1 `cmp` i2) go (MachInt i1) (MachInt i2) = done (i1 `cmp` i2) go (MachInt64 i1) (MachInt64 i2) = done (i1 `cmp` i2) go (MachWord i1) (MachWord i2) = done (i1 `cmp` i2) go (MachWord64 i1) (MachWord64 i2) = done (i1 `cmp` i2) go (MachFloat i1) (MachFloat i2) = done (i1 `cmp` i2) go (MachDouble i1) (MachDouble i2) = done (i1 `cmp` i2) go _ _ = Nothing -------------------------- negOp :: DynFlags -> Literal -> Maybe CoreExpr -- Negate negOp _ (MachFloat 0.0) = Nothing -- can't represent -0.0 as a Rational negOp dflags (MachFloat f) = Just (mkFloatVal dflags (-f)) negOp _ (MachDouble 0.0) = Nothing negOp dflags (MachDouble d) = Just (mkDoubleVal dflags (-d)) negOp dflags (MachInt i) = intResult dflags (-i) negOp _ _ = Nothing complementOp :: DynFlags -> Literal -> Maybe CoreExpr -- Binary complement complementOp dflags (MachWord i) = wordResult dflags (complement i) complementOp dflags (MachInt i) = intResult dflags (complement i) complementOp _ _ = Nothing -------------------------- intOp2 :: (Integral a, Integral b) => (a -> b -> Integer) -> DynFlags -> Literal -> Literal -> Maybe CoreExpr intOp2 = intOp2' . const intOp2' :: (Integral a, Integral b) => (DynFlags -> a -> b -> Integer) -> DynFlags -> Literal -> Literal -> Maybe CoreExpr intOp2' op dflags (MachInt i1) (MachInt i2) = let o = op dflags in intResult dflags (fromInteger i1 `o` fromInteger i2) intOp2' _ _ _ _ = Nothing -- Could find LitLit shiftRightLogical :: DynFlags -> Integer -> Int -> Integer -- Shift right, putting zeros in rather than sign-propagating as Bits.shiftR would do -- Do this by converting to Word and back. Obviously this won't work for big -- values, but its ok as we use it here shiftRightLogical dflags x n | wordSizeInBits dflags == 32 = fromIntegral (fromInteger x `shiftR` n :: Word32) | wordSizeInBits dflags == 64 = fromIntegral (fromInteger x `shiftR` n :: Word64) | otherwise = panic "shiftRightLogical: unsupported word size" -------------------------- retLit :: (DynFlags -> Literal) -> RuleM CoreExpr retLit l = do dflags <- getDynFlags return $ Lit $ l dflags wordOp2 :: (Integral a, Integral b) => (a -> b -> Integer) -> DynFlags -> Literal -> Literal -> Maybe CoreExpr wordOp2 op dflags (MachWord w1) (MachWord w2) = wordResult dflags (fromInteger w1 `op` fromInteger w2) wordOp2 _ _ _ _ = Nothing -- Could find LitLit wordShiftRule :: (DynFlags -> Integer -> Int -> Integer) -> RuleM CoreExpr -- Shifts take an Int; hence third arg of op is Int -- See Note [Guarding against silly shifts] wordShiftRule shift_op = do { dflags <- getDynFlags ; [e1, Lit (MachInt shift_len)] <- getArgs ; case e1 of _ | shift_len == 0 -> return e1 | shift_len < 0 || wordSizeInBits dflags < shift_len -> return (mkRuntimeErrorApp rUNTIME_ERROR_ID wordPrimTy ("Bad shift length" ++ show shift_len)) Lit (MachWord x) -> let op = shift_op dflags in liftMaybe $ wordResult dflags (x `op` fromInteger shift_len) -- Do the shift at type Integer, but shift length is Int _ -> mzero } wordSizeInBits :: DynFlags -> Integer wordSizeInBits dflags = toInteger (platformWordSize (targetPlatform dflags) `shiftL` 3) -------------------------- floatOp2 :: (Rational -> Rational -> Rational) -> DynFlags -> Literal -> Literal -> Maybe (Expr CoreBndr) floatOp2 op dflags (MachFloat f1) (MachFloat f2) = Just (mkFloatVal dflags (f1 `op` f2)) floatOp2 _ _ _ _ = Nothing -------------------------- doubleOp2 :: (Rational -> Rational -> Rational) -> DynFlags -> Literal -> Literal -> Maybe (Expr CoreBndr) doubleOp2 op dflags (MachDouble f1) (MachDouble f2) = Just (mkDoubleVal dflags (f1 `op` f2)) doubleOp2 _ _ _ _ = Nothing -------------------------- {- Note [The litEq rule: converting equality to case] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This stuff turns n ==# 3# into case n of 3# -> True m -> False This is a Good Thing, because it allows case-of case things to happen, and case-default absorption to happen. For example: if (n ==# 3#) || (n ==# 4#) then e1 else e2 will transform to case n of 3# -> e1 4# -> e1 m -> e2 (modulo the usual precautions to avoid duplicating e1) -} litEq :: Bool -- True <=> equality, False <=> inequality -> RuleM CoreExpr litEq is_eq = msum [ do [Lit lit, expr] <- getArgs dflags <- getDynFlags do_lit_eq dflags lit expr , do [expr, Lit lit] <- getArgs dflags <- getDynFlags do_lit_eq dflags lit expr ] where do_lit_eq dflags lit expr = do guard (not (litIsLifted lit)) return (mkWildCase expr (literalType lit) intPrimTy [(DEFAULT, [], val_if_neq), (LitAlt lit, [], val_if_eq)]) where val_if_eq | is_eq = trueValInt dflags | otherwise = falseValInt dflags val_if_neq | is_eq = falseValInt dflags | otherwise = trueValInt dflags -- | Check if there is comparison with minBound or maxBound, that is -- always true or false. For instance, an Int cannot be smaller than its -- minBound, so we can replace such comparison with False. boundsCmp :: Comparison -> RuleM CoreExpr boundsCmp op = do dflags <- getDynFlags [a, b] <- getArgs liftMaybe $ mkRuleFn dflags op a b data Comparison = Gt | Ge | Lt | Le mkRuleFn :: DynFlags -> Comparison -> CoreExpr -> CoreExpr -> Maybe CoreExpr mkRuleFn dflags Gt (Lit lit) _ | isMinBound dflags lit = Just $ falseValInt dflags mkRuleFn dflags Le (Lit lit) _ | isMinBound dflags lit = Just $ trueValInt dflags mkRuleFn dflags Ge _ (Lit lit) | isMinBound dflags lit = Just $ trueValInt dflags mkRuleFn dflags Lt _ (Lit lit) | isMinBound dflags lit = Just $ falseValInt dflags mkRuleFn dflags Ge (Lit lit) _ | isMaxBound dflags lit = Just $ trueValInt dflags mkRuleFn dflags Lt (Lit lit) _ | isMaxBound dflags lit = Just $ falseValInt dflags mkRuleFn dflags Gt _ (Lit lit) | isMaxBound dflags lit = Just $ falseValInt dflags mkRuleFn dflags Le _ (Lit lit) | isMaxBound dflags lit = Just $ trueValInt dflags mkRuleFn _ _ _ _ = Nothing isMinBound :: DynFlags -> Literal -> Bool isMinBound _ (MachChar c) = c == minBound isMinBound dflags (MachInt i) = i == tARGET_MIN_INT dflags isMinBound _ (MachInt64 i) = i == toInteger (minBound :: Int64) isMinBound _ (MachWord i) = i == 0 isMinBound _ (MachWord64 i) = i == 0 isMinBound _ _ = False isMaxBound :: DynFlags -> Literal -> Bool isMaxBound _ (MachChar c) = c == maxBound isMaxBound dflags (MachInt i) = i == tARGET_MAX_INT dflags isMaxBound _ (MachInt64 i) = i == toInteger (maxBound :: Int64) isMaxBound dflags (MachWord i) = i == tARGET_MAX_WORD dflags isMaxBound _ (MachWord64 i) = i == toInteger (maxBound :: Word64) isMaxBound _ _ = False -- Note [Word/Int underflow/overflow] -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -- -- According to the Haskell Report 2010 (Sections 18.1 and 23.1 about signed and -- unsigned integral types): "All arithmetic is performed modulo 2^n, where n is -- the number of bits in the type." -- -- GHC stores Word# and Int# constant values as Integer. Core optimizations such -- as constant folding must ensure that the Integer value remains in the valid -- target Word/Int range (see #13172). The following functions are used to -- ensure this. -- -- 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)) -- doesn't yield a warning. Instead we simply squash the value into the *target* -- Int/Word range. -- | Ensure the given Integer is in the target Int range intResult' :: DynFlags -> Integer -> Integer intResult' dflags result = case platformWordSize (targetPlatform dflags) of 4 -> toInteger (fromInteger result :: Int32) 8 -> toInteger (fromInteger result :: Int64) w -> panic ("intResult: Unknown platformWordSize: " ++ show w) -- | Ensure the given Integer is in the target Word range wordResult' :: DynFlags -> Integer -> Integer wordResult' dflags result = case platformWordSize (targetPlatform dflags) of 4 -> toInteger (fromInteger result :: Word32) 8 -> toInteger (fromInteger result :: Word64) w -> panic ("wordResult: Unknown platformWordSize: " ++ show w) -- | Create an Int literal expression while ensuring the given Integer is in the -- target Int range intResult :: DynFlags -> Integer -> Maybe CoreExpr intResult dflags result = Just (mkIntVal dflags (intResult' dflags result)) -- | Create a Word literal expression while ensuring the given Integer is in the -- target Word range wordResult :: DynFlags -> Integer -> Maybe CoreExpr wordResult dflags result = Just (mkWordVal dflags (wordResult' dflags result)) inversePrimOp :: PrimOp -> RuleM CoreExpr inversePrimOp primop = do [Var primop_id `App` e] <- getArgs matchPrimOpId primop primop_id return e subsumesPrimOp :: PrimOp -> PrimOp -> RuleM CoreExpr this `subsumesPrimOp` that = do [Var primop_id `App` e] <- getArgs matchPrimOpId that primop_id return (Var (mkPrimOpId this) `App` e) subsumedByPrimOp :: PrimOp -> RuleM CoreExpr subsumedByPrimOp primop = do [e@(Var primop_id `App` _)] <- getArgs matchPrimOpId primop primop_id return e idempotent :: RuleM CoreExpr idempotent = do [e1, e2] <- getArgs guard $ cheapEqExpr e1 e2 return e1 {- Note [Guarding against silly shifts] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider this code: import Data.Bits( (.|.), shiftL ) chunkToBitmap :: [Bool] -> Word32 chunkToBitmap chunk = foldr (.|.) 0 [ 1 `shiftL` n | (True,n) <- zip chunk [0..] ] This optimises to: Shift.$wgo = \ (w_sCS :: GHC.Prim.Int#) (w1_sCT :: [GHC.Types.Bool]) -> case w1_sCT of _ { [] -> 0##; : x_aAW xs_aAX -> case x_aAW of _ { GHC.Types.False -> case w_sCS of wild2_Xh { __DEFAULT -> Shift.$wgo (GHC.Prim.+# wild2_Xh 1) xs_aAX; 9223372036854775807 -> 0## }; GHC.Types.True -> case GHC.Prim.>=# w_sCS 64 of _ { GHC.Types.False -> case w_sCS of wild3_Xh { __DEFAULT -> case Shift.$wgo (GHC.Prim.+# wild3_Xh 1) xs_aAX of ww_sCW { __DEFAULT -> GHC.Prim.or# (GHC.Prim.narrow32Word# (GHC.Prim.uncheckedShiftL# 1## wild3_Xh)) ww_sCW }; 9223372036854775807 -> GHC.Prim.narrow32Word# !!!!--> (GHC.Prim.uncheckedShiftL# 1## 9223372036854775807) }; GHC.Types.True -> case w_sCS of wild3_Xh { __DEFAULT -> Shift.$wgo (GHC.Prim.+# wild3_Xh 1) xs_aAX; 9223372036854775807 -> 0## } } } } Note the massive shift on line "!!!!". It can't happen, because we've checked that w < 64, but the optimiser didn't spot that. We DO NO want to constant-fold this! Moreover, if the programmer writes (n `uncheckedShiftL` 9223372036854775807), we can't constant fold it, but if it gets to the assember we get Error: operand type mismatch for `shl' So the best thing to do is to rewrite the shift with a call to error, when the second arg is stupid. ************************************************************************ * * \subsection{Vaguely generic functions} * * ************************************************************************ -} mkBasicRule :: Name -> Int -> RuleM CoreExpr -> CoreRule -- Gives the Rule the same name as the primop itself mkBasicRule op_name n_args rm = BuiltinRule { ru_name = occNameFS (nameOccName op_name), ru_fn = op_name, ru_nargs = n_args, ru_try = \ dflags in_scope _ -> runRuleM rm dflags in_scope } newtype RuleM r = RuleM { runRuleM :: DynFlags -> InScopeEnv -> [CoreExpr] -> Maybe r } instance Functor RuleM where fmap = liftM instance Applicative RuleM where pure x = RuleM $ \_ _ _ -> Just x (<*>) = ap instance Monad RuleM where RuleM f >>= g = RuleM $ \dflags iu e -> case f dflags iu e of Nothing -> Nothing Just r -> runRuleM (g r) dflags iu e fail _ = mzero #if __GLASGOW_HASKELL__ > 710 instance MonadFail.MonadFail RuleM where fail _ = mzero #endif instance Alternative RuleM where empty = RuleM $ \_ _ _ -> Nothing RuleM f1 <|> RuleM f2 = RuleM $ \dflags iu args -> f1 dflags iu args <|> f2 dflags iu args instance MonadPlus RuleM instance HasDynFlags RuleM where getDynFlags = RuleM $ \dflags _ _ -> Just dflags liftMaybe :: Maybe a -> RuleM a liftMaybe Nothing = mzero liftMaybe (Just x) = return x liftLit :: (Literal -> Literal) -> RuleM CoreExpr liftLit f = liftLitDynFlags (const f) liftLitDynFlags :: (DynFlags -> Literal -> Literal) -> RuleM CoreExpr liftLitDynFlags f = do dflags <- getDynFlags [Lit lit] <- getArgs return $ Lit (f dflags lit) removeOp32 :: RuleM CoreExpr removeOp32 = do dflags <- getDynFlags if wordSizeInBits dflags == 32 then do [e] <- getArgs return e else mzero getArgs :: RuleM [CoreExpr] getArgs = RuleM $ \_ _ args -> Just args getInScopeEnv :: RuleM InScopeEnv getInScopeEnv = RuleM $ \_ iu _ -> Just iu -- return the n-th argument of this rule, if it is a literal -- argument indices start from 0 getLiteral :: Int -> RuleM Literal getLiteral n = RuleM $ \_ _ exprs -> case drop n exprs of (Lit l:_) -> Just l _ -> Nothing unaryLit :: (DynFlags -> Literal -> Maybe CoreExpr) -> RuleM CoreExpr unaryLit op = do dflags <- getDynFlags [Lit l] <- getArgs liftMaybe $ op dflags (convFloating dflags l) binaryLit :: (DynFlags -> Literal -> Literal -> Maybe CoreExpr) -> RuleM CoreExpr binaryLit op = do dflags <- getDynFlags [Lit l1, Lit l2] <- getArgs liftMaybe $ op dflags (convFloating dflags l1) (convFloating dflags l2) binaryCmpLit :: (forall a . Ord a => a -> a -> Bool) -> RuleM CoreExpr binaryCmpLit op = do dflags <- getDynFlags binaryLit (\_ -> cmpOp dflags op) leftIdentity :: Literal -> RuleM CoreExpr leftIdentity id_lit = leftIdentityDynFlags (const id_lit) rightIdentity :: Literal -> RuleM CoreExpr rightIdentity id_lit = rightIdentityDynFlags (const id_lit) identity :: Literal -> RuleM CoreExpr identity lit = leftIdentity lit `mplus` rightIdentity lit leftIdentityDynFlags :: (DynFlags -> Literal) -> RuleM CoreExpr leftIdentityDynFlags id_lit = do dflags <- getDynFlags [Lit l1, e2] <- getArgs guard $ l1 == id_lit dflags return e2 rightIdentityDynFlags :: (DynFlags -> Literal) -> RuleM CoreExpr rightIdentityDynFlags id_lit = do dflags <- getDynFlags [e1, Lit l2] <- getArgs guard $ l2 == id_lit dflags return e1 identityDynFlags :: (DynFlags -> Literal) -> RuleM CoreExpr identityDynFlags lit = leftIdentityDynFlags lit `mplus` rightIdentityDynFlags lit leftZero :: (DynFlags -> Literal) -> RuleM CoreExpr leftZero zero = do dflags <- getDynFlags [Lit l1, _] <- getArgs guard $ l1 == zero dflags return $ Lit l1 rightZero :: (DynFlags -> Literal) -> RuleM CoreExpr rightZero zero = do dflags <- getDynFlags [_, Lit l2] <- getArgs guard $ l2 == zero dflags return $ Lit l2 zeroElem :: (DynFlags -> Literal) -> RuleM CoreExpr zeroElem lit = leftZero lit `mplus` rightZero lit equalArgs :: RuleM () equalArgs = do [e1, e2] <- getArgs guard $ e1 `cheapEqExpr` e2 nonZeroLit :: Int -> RuleM () nonZeroLit n = getLiteral n >>= guard . not . isZeroLit -- 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 :: DynFlags -> Literal -> Literal convFloating dflags (MachFloat f) | not (gopt Opt_ExcessPrecision dflags) = MachFloat (toRational (fromRational f :: Float )) convFloating dflags (MachDouble d) | not (gopt Opt_ExcessPrecision dflags) = MachDouble (toRational (fromRational d :: Double)) convFloating _ l = l guardFloatDiv :: RuleM () guardFloatDiv = do [Lit (MachFloat f1), Lit (MachFloat f2)] <- getArgs guard $ (f1 /=0 || f2 > 0) -- see Note [negative zero] && f2 /= 0 -- avoid NaN and Infinity/-Infinity guardDoubleDiv :: RuleM () guardDoubleDiv = do [Lit (MachDouble d1), Lit (MachDouble d2)] <- getArgs guard $ (d1 /=0 || d2 > 0) -- see Note [negative zero] && d2 /= 0 -- avoid NaN and Infinity/-Infinity -- Note [negative zero] Avoid (0 / -d), otherwise 0/(-1) reduces to -- zero, but we might want to preserve the negative zero here which -- is representable in Float/Double but not in (normalised) -- Rational. (#3676) Perhaps we should generate (0 :% (-1)) instead? strengthReduction :: Literal -> PrimOp -> RuleM CoreExpr strengthReduction two_lit add_op = do -- Note [Strength reduction] arg <- msum [ do [arg, Lit mult_lit] <- getArgs guard (mult_lit == two_lit) return arg , do [Lit mult_lit, arg] <- getArgs guard (mult_lit == two_lit) return arg ] return $ Var (mkPrimOpId add_op) `App` arg `App` arg -- Note [Strength reduction] -- ~~~~~~~~~~~~~~~~~~~~~~~~~ -- -- This rule turns floating point multiplications of the form 2.0 * x and -- x * 2.0 into x + x addition, because addition costs less than multiplication. -- See #7116 -- Note [What's true and false] -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -- -- trueValInt and falseValInt represent true and false values returned by -- comparison primops for Char, Int, Word, Integer, Double, Float and Addr. -- True is represented as an unboxed 1# literal, while false is represented -- as 0# literal. -- We still need Bool data constructors (True and False) to use in a rule -- for constant folding of equal Strings trueValInt, falseValInt :: DynFlags -> Expr CoreBndr trueValInt dflags = Lit $ onei dflags -- see Note [What's true and false] falseValInt dflags = Lit $ zeroi dflags trueValBool, falseValBool :: Expr CoreBndr trueValBool = Var trueDataConId -- see Note [What's true and false] falseValBool = Var falseDataConId ltVal, eqVal, gtVal :: Expr CoreBndr ltVal = Var ltDataConId eqVal = Var eqDataConId gtVal = Var gtDataConId mkIntVal :: DynFlags -> Integer -> Expr CoreBndr mkIntVal dflags i = Lit (mkMachInt dflags i) mkWordVal :: DynFlags -> Integer -> Expr CoreBndr mkWordVal dflags w = Lit (mkMachWord dflags w) mkFloatVal :: DynFlags -> Rational -> Expr CoreBndr mkFloatVal dflags f = Lit (convFloating dflags (MachFloat f)) mkDoubleVal :: DynFlags -> Rational -> Expr CoreBndr mkDoubleVal dflags d = Lit (convFloating dflags (MachDouble d)) matchPrimOpId :: PrimOp -> Id -> RuleM () matchPrimOpId op id = do op' <- liftMaybe $ isPrimOpId_maybe id guard $ op == op' {- ************************************************************************ * * \subsection{Special rules for seq, tagToEnum, dataToTag} * * ************************************************************************ Note [tagToEnum#] ~~~~~~~~~~~~~~~~~ Nasty check to ensure that tagToEnum# is applied to a type that is an enumeration TyCon. Unification may refine the type later, but this check won't see that, alas. It's crude but it works. Here's are two cases that should fail f :: forall a. a f = tagToEnum# 0 -- Can't do tagToEnum# at a type variable g :: Int g = tagToEnum# 0 -- Int is not an enumeration We used to make this check in the type inference engine, but it's quite ugly to do so, because the delayed constraint solving means that we don't really know what's going on until the end. It's very much a corner case because we don't expect the user to call tagToEnum# at all; we merely generate calls in derived instances of Enum. So we compromise: a rewrite rule rewrites a bad instance of tagToEnum# to an error call, and emits a warning. -} tagToEnumRule :: RuleM CoreExpr -- If data T a = A | B | C -- then tag2Enum# (T ty) 2# --> B ty tagToEnumRule = do [Type ty, Lit (MachInt i)] <- getArgs case splitTyConApp_maybe ty of Just (tycon, tc_args) | isEnumerationTyCon tycon -> do let tag = fromInteger i correct_tag dc = (dataConTag dc - fIRST_TAG) == tag (dc:rest) <- return $ filter correct_tag (tyConDataCons_maybe tycon `orElse` []) ASSERT(null rest) return () return $ mkTyApps (Var (dataConWorkId dc)) tc_args -- See Note [tagToEnum#] _ -> WARN( True, text "tagToEnum# on non-enumeration type" <+> ppr ty ) return $ mkRuntimeErrorApp rUNTIME_ERROR_ID ty "tagToEnum# on non-enumeration type" {- For dataToTag#, we can reduce if either (a) the argument is a constructor (b) the argument is a variable whose unfolding is a known constructor -} dataToTagRule :: RuleM CoreExpr dataToTagRule = a `mplus` b where a = do [Type ty1, Var tag_to_enum `App` Type ty2 `App` tag] <- getArgs guard $ tag_to_enum `hasKey` tagToEnumKey guard $ ty1 `eqType` ty2 return tag -- dataToTag (tagToEnum x) ==> x b = do dflags <- getDynFlags [_, val_arg] <- getArgs in_scope <- getInScopeEnv (dc,_,_) <- liftMaybe $ exprIsConApp_maybe in_scope val_arg ASSERT( not (isNewTyCon (dataConTyCon dc)) ) return () return $ mkIntVal dflags (toInteger (dataConTag dc - fIRST_TAG)) {- ************************************************************************ * * \subsection{Rules for seq# and spark#} * * ************************************************************************ -} -- seq# :: forall a s . a -> State# s -> (# State# s, a #) seqRule :: RuleM CoreExpr seqRule = do [Type ty_a, Type ty_s, a, s] <- getArgs guard $ exprIsHNF a return $ mkCoreUbxTup [mkStatePrimTy ty_s, ty_a] [s, a] -- spark# :: forall a s . a -> State# s -> (# State# s, a #) sparkRule :: RuleM CoreExpr sparkRule = seqRule -- reduce on HNF, just the same -- XXX perhaps we shouldn't do this, because a spark eliminated by -- this rule won't be counted as a dud at runtime? {- ************************************************************************ * * \subsection{Built in rules} * * ************************************************************************ Note [Scoping for Builtin rules] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When compiling a (base-package) module that defines one of the functions mentioned in the RHS of a built-in rule, there's a danger that we'll see f = ...(eq String x).... ....and lower down... eqString = ... Then a rewrite would give f = ...(eqString x)... ....and lower down... eqString = ... and lo, eqString is not in scope. This only really matters when we get to code generation. With -O we do a GlomBinds step that does a new SCC analysis on the whole set of bindings, which sorts out the dependency. Without -O we don't do any rule rewriting so again we are fine. (This whole thing doesn't show up for non-built-in rules because their dependencies are explicit.) -} builtinRules :: [CoreRule] -- Rules for non-primops that can't be expressed using a RULE pragma builtinRules = [BuiltinRule { ru_name = fsLit "AppendLitString", ru_fn = unpackCStringFoldrName, ru_nargs = 4, ru_try = match_append_lit }, BuiltinRule { ru_name = fsLit "EqString", ru_fn = eqStringName, ru_nargs = 2, ru_try = match_eq_string }, BuiltinRule { ru_name = fsLit "Inline", ru_fn = inlineIdName, ru_nargs = 2, ru_try = \_ _ _ -> match_inline }, BuiltinRule { ru_name = fsLit "MagicDict", ru_fn = idName magicDictId, ru_nargs = 4, ru_try = \_ _ _ -> match_magicDict }, mkBasicRule divIntName 2 $ msum [ nonZeroLit 1 >> binaryLit (intOp2 div) , leftZero zeroi , do [arg, Lit (MachInt d)] <- getArgs Just n <- return $ exactLog2 d dflags <- getDynFlags return $ Var (mkPrimOpId ISraOp) `App` arg `App` mkIntVal dflags n ], mkBasicRule modIntName 2 $ msum [ nonZeroLit 1 >> binaryLit (intOp2 mod) , leftZero zeroi , do [arg, Lit (MachInt d)] <- getArgs Just _ <- return $ exactLog2 d dflags <- getDynFlags return $ Var (mkPrimOpId AndIOp) `App` arg `App` mkIntVal dflags (d - 1) ] ] ++ builtinIntegerRules builtinIntegerRules :: [CoreRule] builtinIntegerRules = [rule_IntToInteger "smallInteger" smallIntegerName, rule_WordToInteger "wordToInteger" wordToIntegerName, rule_Int64ToInteger "int64ToInteger" int64ToIntegerName, rule_Word64ToInteger "word64ToInteger" word64ToIntegerName, rule_convert "integerToWord" integerToWordName mkWordLitWord, rule_convert "integerToInt" integerToIntName mkIntLitInt, rule_convert "integerToWord64" integerToWord64Name (\_ -> mkWord64LitWord64), rule_convert "integerToInt64" integerToInt64Name (\_ -> mkInt64LitInt64), rule_binop "plusInteger" plusIntegerName (+), rule_binop "minusInteger" minusIntegerName (-), rule_binop "timesInteger" timesIntegerName (*), rule_unop "negateInteger" negateIntegerName negate, rule_binop_Prim "eqInteger#" eqIntegerPrimName (==), rule_binop_Prim "neqInteger#" neqIntegerPrimName (/=), rule_unop "absInteger" absIntegerName abs, rule_unop "signumInteger" signumIntegerName signum, rule_binop_Prim "leInteger#" leIntegerPrimName (<=), rule_binop_Prim "gtInteger#" gtIntegerPrimName (>), rule_binop_Prim "ltInteger#" ltIntegerPrimName (<), rule_binop_Prim "geInteger#" geIntegerPrimName (>=), rule_binop_Ordering "compareInteger" compareIntegerName compare, rule_encodeFloat "encodeFloatInteger" encodeFloatIntegerName mkFloatLitFloat, rule_convert "floatFromInteger" floatFromIntegerName (\_ -> mkFloatLitFloat), rule_encodeFloat "encodeDoubleInteger" encodeDoubleIntegerName mkDoubleLitDouble, rule_decodeDouble "decodeDoubleInteger" decodeDoubleIntegerName, rule_convert "doubleFromInteger" doubleFromIntegerName (\_ -> mkDoubleLitDouble), rule_rationalTo "rationalToFloat" rationalToFloatName mkFloatExpr, rule_rationalTo "rationalToDouble" rationalToDoubleName mkDoubleExpr, rule_binop "gcdInteger" gcdIntegerName gcd, rule_binop "lcmInteger" lcmIntegerName lcm, rule_binop "andInteger" andIntegerName (.&.), rule_binop "orInteger" orIntegerName (.|.), rule_binop "xorInteger" xorIntegerName xor, rule_unop "complementInteger" complementIntegerName complement, rule_Int_binop "shiftLInteger" shiftLIntegerName shiftL, rule_Int_binop "shiftRInteger" shiftRIntegerName shiftR, rule_bitInteger "bitInteger" bitIntegerName, -- See Note [Integer division constant folding] in libraries/base/GHC/Real.hs rule_divop_one "quotInteger" quotIntegerName quot, rule_divop_one "remInteger" remIntegerName rem, rule_divop_one "divInteger" divIntegerName div, rule_divop_one "modInteger" modIntegerName mod, rule_divop_both "divModInteger" divModIntegerName divMod, rule_divop_both "quotRemInteger" quotRemIntegerName quotRem, -- These rules below don't actually have to be built in, but if we -- put them in the Haskell source then we'd have to duplicate them -- between all Integer implementations rule_XToIntegerToX "smallIntegerToInt" integerToIntName smallIntegerName, rule_XToIntegerToX "wordToIntegerToWord" integerToWordName wordToIntegerName, rule_XToIntegerToX "int64ToIntegerToInt64" integerToInt64Name int64ToIntegerName, rule_XToIntegerToX "word64ToIntegerToWord64" integerToWord64Name word64ToIntegerName, rule_smallIntegerTo "smallIntegerToWord" integerToWordName Int2WordOp, rule_smallIntegerTo "smallIntegerToFloat" floatFromIntegerName Int2FloatOp, rule_smallIntegerTo "smallIntegerToDouble" doubleFromIntegerName Int2DoubleOp ] where rule_convert str name convert = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 1, ru_try = match_Integer_convert convert } rule_IntToInteger str name = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 1, ru_try = match_IntToInteger } rule_WordToInteger str name = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 1, ru_try = match_WordToInteger } rule_Int64ToInteger str name = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 1, ru_try = match_Int64ToInteger } rule_Word64ToInteger str name = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 1, ru_try = match_Word64ToInteger } rule_unop str name op = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 1, ru_try = match_Integer_unop op } rule_bitInteger str name = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 1, ru_try = match_IntToInteger_unop (bit . fromIntegral) } rule_binop str name op = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 2, ru_try = match_Integer_binop op } rule_divop_both str name op = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 2, ru_try = match_Integer_divop_both op } rule_divop_one str name op = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 2, ru_try = match_Integer_divop_one op } rule_Int_binop str name op = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 2, ru_try = match_Integer_Int_binop op } rule_binop_Prim str name op = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 2, ru_try = match_Integer_binop_Prim op } rule_binop_Ordering str name op = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 2, ru_try = match_Integer_binop_Ordering op } rule_encodeFloat str name op = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 2, ru_try = match_Integer_Int_encodeFloat op } rule_decodeDouble str name = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 1, ru_try = match_decodeDouble } rule_XToIntegerToX str name toIntegerName = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 1, ru_try = match_XToIntegerToX toIntegerName } rule_smallIntegerTo str name primOp = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 1, ru_try = match_smallIntegerTo primOp } rule_rationalTo str name mkLit = BuiltinRule { ru_name = fsLit str, ru_fn = name, ru_nargs = 2, ru_try = match_rationalTo mkLit } --------------------------------------------------- -- The rule is this: -- unpackFoldrCString# "foo" c (unpackFoldrCString# "baz" c n) -- = unpackFoldrCString# "foobaz" c n match_append_lit :: RuleFun match_append_lit _ id_unf _ [ Type ty1 , lit1 , c1 , Var unpk `App` Type ty2 `App` lit2 `App` c2 `App` n ] | unpk `hasKey` unpackCStringFoldrIdKey && c1 `cheapEqExpr` c2 , Just (MachStr s1) <- exprIsLiteral_maybe id_unf lit1 , Just (MachStr s2) <- exprIsLiteral_maybe id_unf lit2 = ASSERT( ty1 `eqType` ty2 ) Just (Var unpk `App` Type ty1 `App` Lit (MachStr (s1 `BS.append` s2)) `App` c1 `App` n) match_append_lit _ _ _ _ = Nothing --------------------------------------------------- -- The rule is this: -- eqString (unpackCString# (Lit s1)) (unpackCString# (Lit s2) = s1==s2 match_eq_string :: RuleFun match_eq_string _ id_unf _ [Var unpk1 `App` lit1, Var unpk2 `App` lit2] | unpk1 `hasKey` unpackCStringIdKey , unpk2 `hasKey` unpackCStringIdKey , Just (MachStr s1) <- exprIsLiteral_maybe id_unf lit1 , Just (MachStr s2) <- exprIsLiteral_maybe id_unf lit2 = Just (if s1 == s2 then trueValBool else falseValBool) match_eq_string _ _ _ _ = Nothing --------------------------------------------------- -- The rule is this: -- inline f_ty (f a b c) = a b c -- (if f has an unfolding, EVEN if it's a loop breaker) -- -- It's important to allow the argument to 'inline' to have args itself -- (a) because its more forgiving to allow the programmer to write -- inline f a b c -- or inline (f a b c) -- (b) because a polymorphic f wll get a type argument that the -- programmer can't avoid -- -- Also, don't forget about 'inline's type argument! match_inline :: [Expr CoreBndr] -> Maybe (Expr CoreBndr) match_inline (Type _ : e : _) | (Var f, args1) <- collectArgs e, Just unf <- maybeUnfoldingTemplate (realIdUnfolding f) -- Ignore the IdUnfoldingFun here! = Just (mkApps unf args1) match_inline _ = Nothing -- See Note [magicDictId magic] in `basicTypes/MkId.hs` -- for a description of what is going on here. match_magicDict :: [Expr CoreBndr] -> Maybe (Expr CoreBndr) match_magicDict [Type _, Var wrap `App` Type a `App` Type _ `App` f, x, y ] | Just (fieldTy, _) <- splitFunTy_maybe $ dropForAlls $ idType wrap , Just (dictTy, _) <- splitFunTy_maybe fieldTy , Just dictTc <- tyConAppTyCon_maybe dictTy , Just (_,_,co) <- unwrapNewTyCon_maybe dictTc = Just $ f `App` Cast x (mkSymCo (mkUnbranchedAxInstCo Representational co [a] [])) `App` y match_magicDict _ = Nothing ------------------------------------------------- -- Integer rules -- smallInteger (79::Int#) = 79::Integer -- wordToInteger (79::Word#) = 79::Integer -- Similarly Int64, Word64 match_IntToInteger :: RuleFun match_IntToInteger = match_IntToInteger_unop id match_WordToInteger :: RuleFun match_WordToInteger _ id_unf id [xl] | Just (MachWord x) <- exprIsLiteral_maybe id_unf xl = case splitFunTy_maybe (idType id) of Just (_, integerTy) -> Just (Lit (LitInteger x integerTy)) _ -> panic "match_WordToInteger: Id has the wrong type" match_WordToInteger _ _ _ _ = Nothing match_Int64ToInteger :: RuleFun match_Int64ToInteger _ id_unf id [xl] | Just (MachInt64 x) <- exprIsLiteral_maybe id_unf xl = case splitFunTy_maybe (idType id) of Just (_, integerTy) -> Just (Lit (LitInteger x integerTy)) _ -> panic "match_Int64ToInteger: Id has the wrong type" match_Int64ToInteger _ _ _ _ = Nothing match_Word64ToInteger :: RuleFun match_Word64ToInteger _ id_unf id [xl] | Just (MachWord64 x) <- exprIsLiteral_maybe id_unf xl = case splitFunTy_maybe (idType id) of Just (_, integerTy) -> Just (Lit (LitInteger x integerTy)) _ -> panic "match_Word64ToInteger: Id has the wrong type" match_Word64ToInteger _ _ _ _ = Nothing ------------------------------------------------- match_Integer_convert :: Num a => (DynFlags -> a -> Expr CoreBndr) -> RuleFun match_Integer_convert convert dflags id_unf _ [xl] | Just (LitInteger x _) <- exprIsLiteral_maybe id_unf xl = Just (convert dflags (fromInteger x)) match_Integer_convert _ _ _ _ _ = Nothing match_Integer_unop :: (Integer -> Integer) -> RuleFun match_Integer_unop unop _ id_unf _ [xl] | Just (LitInteger x i) <- exprIsLiteral_maybe id_unf xl = Just (Lit (LitInteger (unop x) i)) match_Integer_unop _ _ _ _ _ = Nothing {- Note [Rewriting bitInteger] For most types the bitInteger operation can be implemented in terms of shifts. The integer-gmp package, however, can do substantially better than this if allowed to provide its own implementation. However, in so doing it previously lost constant-folding (see Trac #8832). The bitInteger rule above provides constant folding specifically for this function. There is, however, a bit of trickiness here when it comes to ranges. While the AST encodes all integers (even MachInts) as Integers, `bit` expects the bit index to be given as an Int. Hence we coerce to an Int in the rule definition. This will behave a bit funny for constants larger than the word size, but the user should expect some funniness given that they will have at very least ignored a warning in this case. -} match_IntToInteger_unop :: (Integer -> Integer) -> RuleFun match_IntToInteger_unop unop _ id_unf fn [xl] | Just (MachInt x) <- exprIsLiteral_maybe id_unf xl = case splitFunTy_maybe (idType fn) of Just (_, integerTy) -> Just (Lit (LitInteger (unop x) integerTy)) _ -> panic "match_IntToInteger_unop: Id has the wrong type" match_IntToInteger_unop _ _ _ _ _ = Nothing match_Integer_binop :: (Integer -> Integer -> Integer) -> RuleFun match_Integer_binop binop _ id_unf _ [xl,yl] | Just (LitInteger x i) <- exprIsLiteral_maybe id_unf xl , Just (LitInteger y _) <- exprIsLiteral_maybe id_unf yl = Just (Lit (LitInteger (x `binop` y) i)) match_Integer_binop _ _ _ _ _ = Nothing -- This helper is used for the quotRem and divMod functions match_Integer_divop_both :: (Integer -> Integer -> (Integer, Integer)) -> RuleFun match_Integer_divop_both divop _ id_unf _ [xl,yl] | Just (LitInteger x t) <- exprIsLiteral_maybe id_unf xl , Just (LitInteger y _) <- exprIsLiteral_maybe id_unf yl , y /= 0 , (r,s) <- x `divop` y = Just $ mkCoreUbxTup [t,t] [Lit (LitInteger r t), Lit (LitInteger s t)] match_Integer_divop_both _ _ _ _ _ = Nothing -- This helper is used for the quot and rem functions match_Integer_divop_one :: (Integer -> Integer -> Integer) -> RuleFun match_Integer_divop_one divop _ id_unf _ [xl,yl] | Just (LitInteger x i) <- exprIsLiteral_maybe id_unf xl , Just (LitInteger y _) <- exprIsLiteral_maybe id_unf yl , y /= 0 = Just (Lit (LitInteger (x `divop` y) i)) match_Integer_divop_one _ _ _ _ _ = Nothing match_Integer_Int_binop :: (Integer -> Int -> Integer) -> RuleFun match_Integer_Int_binop binop _ id_unf _ [xl,yl] | Just (LitInteger x i) <- exprIsLiteral_maybe id_unf xl , Just (MachInt y) <- exprIsLiteral_maybe id_unf yl = Just (Lit (LitInteger (x `binop` fromIntegral y) i)) match_Integer_Int_binop _ _ _ _ _ = Nothing match_Integer_binop_Prim :: (Integer -> Integer -> Bool) -> RuleFun match_Integer_binop_Prim binop dflags id_unf _ [xl, yl] | Just (LitInteger x _) <- exprIsLiteral_maybe id_unf xl , Just (LitInteger y _) <- exprIsLiteral_maybe id_unf yl = Just (if x `binop` y then trueValInt dflags else falseValInt dflags) match_Integer_binop_Prim _ _ _ _ _ = Nothing match_Integer_binop_Ordering :: (Integer -> Integer -> Ordering) -> RuleFun match_Integer_binop_Ordering binop _ id_unf _ [xl, yl] | Just (LitInteger x _) <- exprIsLiteral_maybe id_unf xl , Just (LitInteger y _) <- exprIsLiteral_maybe id_unf yl = Just $ case x `binop` y of LT -> ltVal EQ -> eqVal GT -> gtVal match_Integer_binop_Ordering _ _ _ _ _ = Nothing match_Integer_Int_encodeFloat :: RealFloat a => (a -> Expr CoreBndr) -> RuleFun match_Integer_Int_encodeFloat mkLit _ id_unf _ [xl,yl] | Just (LitInteger x _) <- exprIsLiteral_maybe id_unf xl , Just (MachInt y) <- exprIsLiteral_maybe id_unf yl = Just (mkLit $ encodeFloat x (fromInteger y)) match_Integer_Int_encodeFloat _ _ _ _ _ = Nothing --------------------------------------------------- -- constant folding for Float/Double -- -- This turns -- rationalToFloat n d -- into a literal Float, and similarly for Doubles. -- -- it's important to not match d == 0, because that may represent a -- literal "0/0" or similar, and we can't produce a literal value for -- NaN or +-Inf match_rationalTo :: RealFloat a => (a -> Expr CoreBndr) -> RuleFun match_rationalTo mkLit _ id_unf _ [xl, yl] | Just (LitInteger x _) <- exprIsLiteral_maybe id_unf xl , Just (LitInteger y _) <- exprIsLiteral_maybe id_unf yl , y /= 0 = Just (mkLit (fromRational (x % y))) match_rationalTo _ _ _ _ _ = Nothing match_decodeDouble :: RuleFun match_decodeDouble _ id_unf fn [xl] | Just (MachDouble x) <- exprIsLiteral_maybe id_unf xl = case splitFunTy_maybe (idType fn) of Just (_, res) | Just [_lev1, _lev2, integerTy, intHashTy] <- tyConAppArgs_maybe res -> case decodeFloat (fromRational x :: Double) of (y, z) -> Just $ mkCoreUbxTup [integerTy, intHashTy] [Lit (LitInteger y integerTy), Lit (MachInt (toInteger z))] _ -> pprPanic "match_decodeDouble: Id has the wrong type" (ppr fn <+> dcolon <+> ppr (idType fn)) match_decodeDouble _ _ _ _ = Nothing match_XToIntegerToX :: Name -> RuleFun match_XToIntegerToX n _ _ _ [App (Var x) y] | idName x == n = Just y match_XToIntegerToX _ _ _ _ _ = Nothing match_smallIntegerTo :: PrimOp -> RuleFun match_smallIntegerTo primOp _ _ _ [App (Var x) y] | idName x == smallIntegerName = Just $ App (Var (mkPrimOpId primOp)) y match_smallIntegerTo _ _ _ _ _ = Nothing -------------------------------------------------------- -- Constant folding through case-expressions -- -- cf Scrutinee Constant Folding in simplCore/SimplUtils -------------------------------------------------------- -- | Match the scrutinee of a case and potentially return a new scrutinee and a -- function to apply to each literal alternative. caseRules :: DynFlags -> CoreExpr -> Maybe (CoreExpr, Integer -> Integer) caseRules dflags scrut = case scrut of -- We need to call wordResult' and intResult' to ensure that the literal -- alternatives remain in Word/Int target ranges (cf Note [Word/Int -- underflow/overflow] and #13172). -- v `op` x# App (App (Var f) v) (Lit l) | Just op <- isPrimOpId_maybe f , Just x <- isLitValue_maybe l -> case op of WordAddOp -> Just (v, \y -> wordResult' dflags $ y-x ) IntAddOp -> Just (v, \y -> intResult' dflags $ y-x ) WordSubOp -> Just (v, \y -> wordResult' dflags $ y+x ) IntSubOp -> Just (v, \y -> intResult' dflags $ y+x ) XorOp -> Just (v, \y -> wordResult' dflags $ y `xor` x) XorIOp -> Just (v, \y -> intResult' dflags $ y `xor` x) _ -> Nothing -- x# `op` v App (App (Var f) (Lit l)) v | Just op <- isPrimOpId_maybe f , Just x <- isLitValue_maybe l -> case op of WordAddOp -> Just (v, \y -> wordResult' dflags $ y-x ) IntAddOp -> Just (v, \y -> intResult' dflags $ y-x ) WordSubOp -> Just (v, \y -> wordResult' dflags $ x-y ) IntSubOp -> Just (v, \y -> intResult' dflags $ x-y ) XorOp -> Just (v, \y -> wordResult' dflags $ y `xor` x) XorIOp -> Just (v, \y -> intResult' dflags $ y `xor` x) _ -> Nothing -- op v App (Var f) v | Just op <- isPrimOpId_maybe f -> case op of NotOp -> Just (v, \y -> wordResult' dflags $ complement y) NotIOp -> Just (v, \y -> intResult' dflags $ complement y) IntNegOp -> Just (v, \y -> intResult' dflags $ negate y ) _ -> Nothing _ -> Nothing