{- (c) The University of Glasgow 2006 (c) The GRASP/AQUA Project, Glasgow University, 1998 \section[Literal]{@Literal@: Machine literals (unboxed, of course)} -} {-# LANGUAGE CPP, DeriveDataTypeable #-} module Literal ( -- * Main data type Literal(..) -- Exported to ParseIface -- ** Creating Literals , mkMachInt, mkMachIntWrap , mkMachWord, mkMachWordWrap , mkMachInt64, mkMachInt64Wrap , mkMachWord64, mkMachWord64Wrap , mkMachFloat, mkMachDouble , mkMachChar, mkMachString , mkLitInteger -- ** Operations on Literals , literalType , absentLiteralOf , pprLiteral -- ** Predicates on Literals and their contents , litIsDupable, litIsTrivial, litIsLifted , inIntRange, inWordRange, tARGET_MAX_INT, inCharRange , isZeroLit , litFitsInChar , litValue, isLitValue, isLitValue_maybe, mapLitValue -- ** Coercions , word2IntLit, int2WordLit , narrow8IntLit, narrow16IntLit, narrow32IntLit , narrow8WordLit, narrow16WordLit, narrow32WordLit , char2IntLit, int2CharLit , float2IntLit, int2FloatLit, double2IntLit, int2DoubleLit , nullAddrLit, float2DoubleLit, double2FloatLit ) where #include "HsVersions.h" import GhcPrelude import TysPrim import PrelNames import Type import TyCon import Outputable import FastString import BasicTypes import Binary import Constants import DynFlags import Platform import UniqFM import Util import Data.ByteString (ByteString) import Data.Int import Data.Word import Data.Char import Data.Maybe ( isJust ) import Data.Data ( Data ) import Numeric ( fromRat ) {- ************************************************************************ * * \subsection{Literals} * * ************************************************************************ -} -- | So-called 'Literal's are one of: -- -- * An unboxed (/machine/) literal ('MachInt', 'MachFloat', etc.), -- which is presumed to be surrounded by appropriate constructors -- (@Int#@, etc.), so that the overall thing makes sense. -- -- We maintain the invariant that the 'Integer' the Mach{Int,Word}* -- constructors are actually in the (possibly target-dependent) range. -- The mkMach{Int,Word}*Wrap smart constructors ensure this by applying -- the target machine's wrapping semantics. Use these in situations -- where you know the wrapping semantics are correct. -- -- * The literal derived from the label mentioned in a \"foreign label\" -- declaration ('MachLabel') data Literal = ------------------ -- First the primitive guys MachChar Char -- ^ @Char#@ - at least 31 bits. Create with 'mkMachChar' | MachStr ByteString -- ^ A string-literal: stored and emitted -- UTF-8 encoded, we'll arrange to decode it -- at runtime. Also emitted with a @'\0'@ -- terminator. Create with 'mkMachString' | MachNullAddr -- ^ The @NULL@ pointer, the only pointer value -- that can be represented as a Literal. Create -- with 'nullAddrLit' | MachInt Integer -- ^ @Int#@ - according to target machine | MachInt64 Integer -- ^ @Int64#@ - exactly 64 bits | MachWord Integer -- ^ @Word#@ - according to target machine | MachWord64 Integer -- ^ @Word64#@ - exactly 64 bits | MachFloat Rational -- ^ @Float#@. Create with 'mkMachFloat' | MachDouble Rational -- ^ @Double#@. Create with 'mkMachDouble' | MachLabel FastString (Maybe Int) FunctionOrData -- ^ A label literal. Parameters: -- -- 1) The name of the symbol mentioned in the declaration -- -- 2) The size (in bytes) of the arguments -- the label expects. Only applicable with -- @stdcall@ labels. @Just x@ => @\@ will -- be appended to label name when emitting assembly. | LitInteger Integer Type -- ^ Integer literals -- See Note [Integer literals] deriving Data {- Note [Integer literals] ~~~~~~~~~~~~~~~~~~~~~~~ An Integer literal is represented using, well, an Integer, to make it easier to write RULEs for them. They also contain the Integer type, so that e.g. literalType can return the right Type for them. They only get converted into real Core, mkInteger [c1, c2, .., cn] during the CorePrep phase, although TidyPgm looks ahead at what the core will be, so that it can see whether it involves CAFs. When we initally build an Integer literal, notably when deserialising it from an interface file (see the Binary instance below), we don't have convenient access to the mkInteger Id. So we just use an error thunk, and fill in the real Id when we do tcIfaceLit in TcIface. Binary instance -} instance Binary Literal where put_ bh (MachChar aa) = do putByte bh 0; put_ bh aa put_ bh (MachStr ab) = do putByte bh 1; put_ bh ab put_ bh (MachNullAddr) = do putByte bh 2 put_ bh (MachInt ad) = do putByte bh 3; put_ bh ad put_ bh (MachInt64 ae) = do putByte bh 4; put_ bh ae put_ bh (MachWord af) = do putByte bh 5; put_ bh af put_ bh (MachWord64 ag) = do putByte bh 6; put_ bh ag put_ bh (MachFloat ah) = do putByte bh 7; put_ bh ah put_ bh (MachDouble ai) = do putByte bh 8; put_ bh ai put_ bh (MachLabel aj mb fod) = do putByte bh 9 put_ bh aj put_ bh mb put_ bh fod put_ bh (LitInteger i _) = do putByte bh 10; put_ bh i get bh = do h <- getByte bh case h of 0 -> do aa <- get bh return (MachChar aa) 1 -> do ab <- get bh return (MachStr ab) 2 -> do return (MachNullAddr) 3 -> do ad <- get bh return (MachInt ad) 4 -> do ae <- get bh return (MachInt64 ae) 5 -> do af <- get bh return (MachWord af) 6 -> do ag <- get bh return (MachWord64 ag) 7 -> do ah <- get bh return (MachFloat ah) 8 -> do ai <- get bh return (MachDouble ai) 9 -> do aj <- get bh mb <- get bh fod <- get bh return (MachLabel aj mb fod) _ -> do i <- get bh -- See Note [Integer literals] return $ mkLitInteger i (panic "Evaluated the place holder for mkInteger") instance Outputable Literal where ppr lit = pprLiteral (\d -> d) lit instance Eq Literal where a == b = case (a `compare` b) of { EQ -> True; _ -> False } a /= b = case (a `compare` b) of { EQ -> False; _ -> True } instance Ord Literal where a <= b = case (a `compare` b) of { LT -> True; EQ -> True; GT -> False } a < b = case (a `compare` b) of { LT -> True; EQ -> False; GT -> False } a >= b = case (a `compare` b) of { LT -> False; EQ -> True; GT -> True } a > b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True } compare a b = cmpLit a b {- Construction ~~~~~~~~~~~~ -} {- 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. -} -- | Creates a 'Literal' of type @Int#@ mkMachInt :: DynFlags -> Integer -> Literal mkMachInt dflags x = ASSERT2( inIntRange dflags x, integer x ) MachInt x -- | Creates a 'Literal' of type @Int#@. -- If the argument is out of the (target-dependent) range, it is wrapped. -- See Note [Word/Int underflow/overflow] mkMachIntWrap :: DynFlags -> Integer -> Literal mkMachIntWrap dflags i = MachInt $ case platformWordSize (targetPlatform dflags) of 4 -> toInteger (fromIntegral i :: Int32) 8 -> toInteger (fromIntegral i :: Int64) w -> panic ("toIntRange: Unknown platformWordSize: " ++ show w) -- | Creates a 'Literal' of type @Word#@ mkMachWord :: DynFlags -> Integer -> Literal mkMachWord dflags x = ASSERT2( inWordRange dflags x, integer x ) MachWord x -- | Creates a 'Literal' of type @Word#@. -- If the argument is out of the (target-dependent) range, it is wrapped. -- See Note [Word/Int underflow/overflow] mkMachWordWrap :: DynFlags -> Integer -> Literal mkMachWordWrap dflags i = MachWord $ case platformWordSize (targetPlatform dflags) of 4 -> toInteger (fromInteger i :: Word32) 8 -> toInteger (fromInteger i :: Word64) w -> panic ("toWordRange: Unknown platformWordSize: " ++ show w) -- | Creates a 'Literal' of type @Int64#@ mkMachInt64 :: Integer -> Literal mkMachInt64 x = ASSERT2( inInt64Range x, integer x ) MachInt64 x -- | Creates a 'Literal' of type @Int64#@. -- If the argument is out of the range, it is wrapped. mkMachInt64Wrap :: Integer -> Literal mkMachInt64Wrap i = MachInt64 (toInteger (fromIntegral i :: Int64)) -- | Creates a 'Literal' of type @Word64#@ mkMachWord64 :: Integer -> Literal mkMachWord64 x = ASSERT2( inWord64Range x, integer x ) MachWord64 x -- | Creates a 'Literal' of type @Word64#@. -- If the argument is out of the range, it is wrapped. mkMachWord64Wrap :: Integer -> Literal mkMachWord64Wrap i = MachWord64 (toInteger (fromIntegral i :: Word64)) -- | Creates a 'Literal' of type @Float#@ mkMachFloat :: Rational -> Literal mkMachFloat = MachFloat -- | Creates a 'Literal' of type @Double#@ mkMachDouble :: Rational -> Literal mkMachDouble = MachDouble -- | Creates a 'Literal' of type @Char#@ mkMachChar :: Char -> Literal mkMachChar = MachChar -- | Creates a 'Literal' of type @Addr#@, which is appropriate for passing to -- e.g. some of the \"error\" functions in GHC.Err such as @GHC.Err.runtimeError@ mkMachString :: String -> Literal -- stored UTF-8 encoded mkMachString s = MachStr (fastStringToByteString $ mkFastString s) mkLitInteger :: Integer -> Type -> Literal mkLitInteger = LitInteger inIntRange, inWordRange :: DynFlags -> Integer -> Bool inIntRange dflags x = x >= tARGET_MIN_INT dflags && x <= tARGET_MAX_INT dflags inWordRange dflags x = x >= 0 && x <= tARGET_MAX_WORD dflags inInt64Range, inWord64Range :: Integer -> Bool inInt64Range x = x >= toInteger (minBound :: Int64) && x <= toInteger (maxBound :: Int64) inWord64Range x = x >= toInteger (minBound :: Word64) && x <= toInteger (maxBound :: Word64) inCharRange :: Char -> Bool inCharRange c = c >= '\0' && c <= chr tARGET_MAX_CHAR -- | Tests whether the literal represents a zero of whatever type it is isZeroLit :: Literal -> Bool isZeroLit (MachInt 0) = True isZeroLit (MachInt64 0) = True isZeroLit (MachWord 0) = True isZeroLit (MachWord64 0) = True isZeroLit (MachFloat 0) = True isZeroLit (MachDouble 0) = True isZeroLit _ = False -- | Returns the 'Integer' contained in the 'Literal', for when that makes -- sense, i.e. for 'Char', 'Int', 'Word' and 'LitInteger'. litValue :: Literal -> Integer litValue l = case isLitValue_maybe l of Just x -> x Nothing -> pprPanic "litValue" (ppr l) -- | Returns the 'Integer' contained in the 'Literal', for when that makes -- sense, i.e. for 'Char', 'Int', 'Word' and 'LitInteger'. isLitValue_maybe :: Literal -> Maybe Integer isLitValue_maybe (MachChar c) = Just $ toInteger $ ord c isLitValue_maybe (MachInt i) = Just i isLitValue_maybe (MachInt64 i) = Just i isLitValue_maybe (MachWord i) = Just i isLitValue_maybe (MachWord64 i) = Just i isLitValue_maybe (LitInteger i _) = Just i isLitValue_maybe _ = Nothing -- | Apply a function to the 'Integer' contained in the 'Literal', for when that -- makes sense, e.g. for 'Char', 'Int', 'Word' and 'LitInteger'. For -- fixed-size integral literals, the result will be wrapped in -- accordance with the semantics of the target type. -- See Note [Word/Int underflow/overflow] mapLitValue :: DynFlags -> (Integer -> Integer) -> Literal -> Literal mapLitValue _ f (MachChar c) = mkMachChar (fchar c) where fchar = chr . fromInteger . f . toInteger . ord mapLitValue dflags f (MachInt i) = mkMachIntWrap dflags (f i) mapLitValue _ f (MachInt64 i) = mkMachInt64Wrap (f i) mapLitValue dflags f (MachWord i) = mkMachWordWrap dflags (f i) mapLitValue _ f (MachWord64 i) = mkMachWord64Wrap (f i) mapLitValue _ f (LitInteger i t) = mkLitInteger (f i) t mapLitValue _ _ l = pprPanic "mapLitValue" (ppr l) -- | Indicate if the `Literal` contains an 'Integer' value, e.g. 'Char', -- 'Int', 'Word' and 'LitInteger'. isLitValue :: Literal -> Bool isLitValue = isJust . isLitValue_maybe {- Coercions ~~~~~~~~~ -} narrow8IntLit, narrow16IntLit, narrow32IntLit, narrow8WordLit, narrow16WordLit, narrow32WordLit, char2IntLit, int2CharLit, float2IntLit, int2FloatLit, double2IntLit, int2DoubleLit, float2DoubleLit, double2FloatLit :: Literal -> Literal word2IntLit, int2WordLit :: DynFlags -> Literal -> Literal word2IntLit dflags (MachWord w) | w > tARGET_MAX_INT dflags = MachInt (w - tARGET_MAX_WORD dflags - 1) | otherwise = MachInt w word2IntLit _ l = pprPanic "word2IntLit" (ppr l) int2WordLit dflags (MachInt i) | i < 0 = MachWord (1 + tARGET_MAX_WORD dflags + i) -- (-1) ---> tARGET_MAX_WORD | otherwise = MachWord i int2WordLit _ l = pprPanic "int2WordLit" (ppr l) narrow8IntLit (MachInt i) = MachInt (toInteger (fromInteger i :: Int8)) narrow8IntLit l = pprPanic "narrow8IntLit" (ppr l) narrow16IntLit (MachInt i) = MachInt (toInteger (fromInteger i :: Int16)) narrow16IntLit l = pprPanic "narrow16IntLit" (ppr l) narrow32IntLit (MachInt i) = MachInt (toInteger (fromInteger i :: Int32)) narrow32IntLit l = pprPanic "narrow32IntLit" (ppr l) narrow8WordLit (MachWord w) = MachWord (toInteger (fromInteger w :: Word8)) narrow8WordLit l = pprPanic "narrow8WordLit" (ppr l) narrow16WordLit (MachWord w) = MachWord (toInteger (fromInteger w :: Word16)) narrow16WordLit l = pprPanic "narrow16WordLit" (ppr l) narrow32WordLit (MachWord w) = MachWord (toInteger (fromInteger w :: Word32)) narrow32WordLit l = pprPanic "narrow32WordLit" (ppr l) char2IntLit (MachChar c) = MachInt (toInteger (ord c)) char2IntLit l = pprPanic "char2IntLit" (ppr l) int2CharLit (MachInt i) = MachChar (chr (fromInteger i)) int2CharLit l = pprPanic "int2CharLit" (ppr l) float2IntLit (MachFloat f) = MachInt (truncate f) float2IntLit l = pprPanic "float2IntLit" (ppr l) int2FloatLit (MachInt i) = MachFloat (fromInteger i) int2FloatLit l = pprPanic "int2FloatLit" (ppr l) double2IntLit (MachDouble f) = MachInt (truncate f) double2IntLit l = pprPanic "double2IntLit" (ppr l) int2DoubleLit (MachInt i) = MachDouble (fromInteger i) int2DoubleLit l = pprPanic "int2DoubleLit" (ppr l) float2DoubleLit (MachFloat f) = MachDouble f float2DoubleLit l = pprPanic "float2DoubleLit" (ppr l) double2FloatLit (MachDouble d) = MachFloat d double2FloatLit l = pprPanic "double2FloatLit" (ppr l) nullAddrLit :: Literal nullAddrLit = MachNullAddr {- Predicates ~~~~~~~~~~ -} -- | True if there is absolutely no penalty to duplicating the literal. -- False principally of strings. -- -- "Why?", you say? I'm glad you asked. Well, for one duplicating strings would -- blow up code sizes. Not only this, it's also unsafe. -- -- Consider a program that wants to traverse a string. One way it might do this -- is to first compute the Addr# pointing to the end of the string, and then, -- starting from the beginning, bump a pointer using eqAddr# to determine the -- end. For instance, -- -- @ -- -- Given pointers to the start and end of a string, count how many zeros -- -- the string contains. -- countZeros :: Addr# -> Addr# -> -> Int -- countZeros start end = go start 0 -- where -- go off n -- | off `addrEq#` end = n -- | otherwise = go (off `plusAddr#` 1) n' -- where n' | isTrue# (indexInt8OffAddr# off 0# ==# 0#) = n + 1 -- | otherwise = n -- @ -- -- Consider what happens if we considered strings to be trivial (and therefore -- duplicable) and emitted a call like @countZeros "hello"# ("hello"# -- `plusAddr`# 5)@. The beginning and end pointers do not belong to the same -- string, meaning that an iteration like the above would blow up terribly. -- This is what happened in #12757. -- -- Ultimately the solution here is to make primitive strings a bit more -- structured, ensuring that the compiler can't inline in ways that will break -- user code. One approach to this is described in #8472. litIsTrivial :: Literal -> Bool -- c.f. CoreUtils.exprIsTrivial litIsTrivial (MachStr _) = False litIsTrivial (LitInteger {}) = False litIsTrivial _ = True -- | True if code space does not go bad if we duplicate this literal -- Currently we treat it just like 'litIsTrivial' litIsDupable :: DynFlags -> Literal -> Bool -- c.f. CoreUtils.exprIsDupable litIsDupable _ (MachStr _) = False litIsDupable dflags (LitInteger i _) = inIntRange dflags i litIsDupable _ _ = True litFitsInChar :: Literal -> Bool litFitsInChar (MachInt i) = i >= toInteger (ord minBound) && i <= toInteger (ord maxBound) litFitsInChar _ = False litIsLifted :: Literal -> Bool litIsLifted (LitInteger {}) = True litIsLifted _ = False {- Types ~~~~~ -} -- | Find the Haskell 'Type' the literal occupies literalType :: Literal -> Type literalType MachNullAddr = addrPrimTy literalType (MachChar _) = charPrimTy literalType (MachStr _) = addrPrimTy literalType (MachInt _) = intPrimTy literalType (MachWord _) = wordPrimTy literalType (MachInt64 _) = int64PrimTy literalType (MachWord64 _) = word64PrimTy literalType (MachFloat _) = floatPrimTy literalType (MachDouble _) = doublePrimTy literalType (MachLabel _ _ _) = addrPrimTy literalType (LitInteger _ t) = t absentLiteralOf :: TyCon -> Maybe Literal -- Return a literal of the appropriate primitive -- TyCon, to use as a placeholder when it doesn't matter absentLiteralOf tc = lookupUFM absent_lits (tyConName tc) absent_lits :: UniqFM Literal absent_lits = listToUFM [ (addrPrimTyConKey, MachNullAddr) , (charPrimTyConKey, MachChar 'x') , (intPrimTyConKey, MachInt 0) , (int64PrimTyConKey, MachInt64 0) , (floatPrimTyConKey, MachFloat 0) , (doublePrimTyConKey, MachDouble 0) , (wordPrimTyConKey, MachWord 0) , (word64PrimTyConKey, MachWord64 0) ] {- Comparison ~~~~~~~~~~ -} cmpLit :: Literal -> Literal -> Ordering cmpLit (MachChar a) (MachChar b) = a `compare` b cmpLit (MachStr a) (MachStr b) = a `compare` b cmpLit (MachNullAddr) (MachNullAddr) = EQ cmpLit (MachInt a) (MachInt b) = a `compare` b cmpLit (MachWord a) (MachWord b) = a `compare` b cmpLit (MachInt64 a) (MachInt64 b) = a `compare` b cmpLit (MachWord64 a) (MachWord64 b) = a `compare` b cmpLit (MachFloat a) (MachFloat b) = a `compare` b cmpLit (MachDouble a) (MachDouble b) = a `compare` b cmpLit (MachLabel a _ _) (MachLabel b _ _) = a `compare` b cmpLit (LitInteger a _) (LitInteger b _) = a `compare` b cmpLit lit1 lit2 | litTag lit1 < litTag lit2 = LT | otherwise = GT litTag :: Literal -> Int litTag (MachChar _) = 1 litTag (MachStr _) = 2 litTag (MachNullAddr) = 3 litTag (MachInt _) = 4 litTag (MachWord _) = 5 litTag (MachInt64 _) = 6 litTag (MachWord64 _) = 7 litTag (MachFloat _) = 8 litTag (MachDouble _) = 9 litTag (MachLabel _ _ _) = 10 litTag (LitInteger {}) = 11 {- Printing ~~~~~~~~ * See Note [Printing of literals in Core] -} pprLiteral :: (SDoc -> SDoc) -> Literal -> SDoc pprLiteral _ (MachChar c) = pprPrimChar c pprLiteral _ (MachStr s) = pprHsBytes s pprLiteral _ (MachNullAddr) = text "__NULL" pprLiteral _ (MachInt i) = pprPrimInt i pprLiteral _ (MachInt64 i) = pprPrimInt64 i pprLiteral _ (MachWord w) = pprPrimWord w pprLiteral _ (MachWord64 w) = pprPrimWord64 w pprLiteral _ (MachFloat f) = float (fromRat f) <> primFloatSuffix pprLiteral _ (MachDouble d) = double (fromRat d) <> primDoubleSuffix pprLiteral add_par (LitInteger i _) = pprIntegerVal add_par i pprLiteral add_par (MachLabel l mb fod) = add_par (text "__label" <+> b <+> ppr fod) where b = case mb of Nothing -> pprHsString l Just x -> doubleQuotes (text (unpackFS l ++ '@':show x)) pprIntegerVal :: (SDoc -> SDoc) -> Integer -> SDoc -- See Note [Printing of literals in Core]. pprIntegerVal add_par i | i < 0 = add_par (integer i) | otherwise = integer i {- Note [Printing of literals in Core] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The function `add_par` is used to wrap parenthesis around negative integers (`LitInteger`) and labels (`MachLabel`), if they occur in a context requiring an atomic thing (for example function application). Although not all Core literals would be valid Haskell, we are trying to stay as close as possible to Haskell syntax in the printing of Core, to make it easier for a Haskell user to read Core. To that end: * We do print parenthesis around negative `LitInteger`, because we print `LitInteger` using plain number literals (no prefix or suffix), and plain number literals in Haskell require parenthesis in contexts like function application (i.e. `1 - -1` is not valid Haskell). * We don't print parenthesis around other (negative) literals, because they aren't needed in GHC/Haskell either (i.e. `1# -# -1#` is accepted by GHC's parser). Literal Output Output if context requires an atom (if different) ------- ------- ---------------------- MachChar 'a'# MachStr "aaa"# MachNullAddr "__NULL" MachInt -1# MachInt64 -1L# MachWord 1## MachWord64 1L## MachFloat -1.0# MachDouble -1.0## LitInteger -1 (-1) MachLabel "__label" ... ("__label" ...) -}