{- (c) The University of Glasgow 2006 (c) The GRASP/AQUA Project, Glasgow University, 1998 -} {-# LANGUAGE CPP, DeriveDataTypeable, ScopedTypeVariables #-} {-# LANGUAGE TypeApplications #-} {-# LANGUAGE MagicHash #-} {-# LANGUAGE AllowAmbiguousTypes #-} {-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-} -- | Core literals module GHC.Types.Literal ( -- * Main data type Literal(..) -- Exported to ParseIface , LitNumType(..) -- ** Creating Literals , mkLitInt, mkLitIntWrap, mkLitIntWrapC, mkLitIntUnchecked , mkLitWord, mkLitWordWrap, mkLitWordWrapC , mkLitInt8, mkLitInt8Wrap , mkLitWord8, mkLitWord8Wrap , mkLitInt16, mkLitInt16Wrap , mkLitWord16, mkLitWord16Wrap , mkLitInt32, mkLitInt32Wrap , mkLitWord32, mkLitWord32Wrap , mkLitInt64, mkLitInt64Wrap , mkLitWord64, mkLitWord64Wrap , mkLitFloat, mkLitDouble , mkLitChar, mkLitString , mkLitInteger, mkLitNatural , mkLitNumber, mkLitNumberWrap -- ** Operations on Literals , literalType , absentLiteralOf , pprLiteral , litNumIsSigned , litNumCheckRange , litNumWrap , litNumCoerce , litNumNarrow , litNumBitSize , isMinBound , isMaxBound -- ** Predicates on Literals and their contents , litIsDupable, litIsTrivial, litIsLifted , inCharRange , isZeroLit, isOneLit , litFitsInChar , litValue, mapLitValue , isLitValue_maybe -- ** Coercions , narrowInt8Lit, narrowInt16Lit, narrowInt32Lit, narrowInt64Lit , narrowWord8Lit, narrowWord16Lit, narrowWord32Lit, narrowWord64Lit , extendIntLit, extendWordLit , charToIntLit, intToCharLit , floatToIntLit, intToFloatLit, doubleToIntLit, intToDoubleLit , nullAddrLit, floatToDoubleLit, doubleToFloatLit , rubbishLit, isRubbishLit ) where #include "HsVersions.h" import GHC.Prelude import GHC.Builtin.Types.Prim import {-# SOURCE #-} GHC.Builtin.Types import GHC.Builtin.Names import GHC.Core.Type import GHC.Core.TyCon import GHC.Utils.Outputable import GHC.Data.FastString import GHC.Types.Basic import GHC.Utils.Binary import GHC.Settings.Constants import GHC.Platform import GHC.Types.Unique.FM import GHC.Utils.Misc import GHC.Utils.Panic import Data.ByteString (ByteString) import Data.Int import Data.Word import Data.Char import Data.Data ( Data ) import GHC.Exts import Numeric ( fromRat ) {- ************************************************************************ * * \subsection{Literals} * * ************************************************************************ -} -- | So-called 'Literal's are one of: -- -- * An unboxed numeric literal or floating-point literal 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' in the 'LitNumber' -- constructor is actually in the (possibly target-dependent) range. -- The mkLit{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 ('LitLabel') -- -- * A 'LitRubbish' to be used in place of values of 'UnliftedRep' -- (i.e. 'MutVar#') when the value is never used. -- -- * A character -- * A string -- * The NULL pointer -- data Literal = LitChar Char -- ^ @Char#@ - at least 31 bits. Create with -- 'mkLitChar' | LitNumber !LitNumType !Integer -- ^ Any numeric literal that can be -- internally represented with an Integer. | LitString !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 'mkLitString' | LitNullAddr -- ^ The @NULL@ pointer, the only pointer value -- that can be represented as a Literal. Create -- with 'nullAddrLit' | LitRubbish Bool -- ^ A nonsense value; always boxed, but -- True <=> lifted, False <=> unlifted -- Used when a binding is absent. -- See Note [Rubbish literals] | LitFloat Rational -- ^ @Float#@. Create with 'mkLitFloat' | LitDouble Rational -- ^ @Double#@. Create with 'mkLitDouble' | LitLabel 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. -- -- 3) Flag indicating whether the symbol -- references a function or a data deriving Data -- | Numeric literal type data LitNumType = LitNumInteger -- ^ @Integer@ (see Note [BigNum literals]) | LitNumNatural -- ^ @Natural@ (see Note [BigNum literals]) | LitNumInt -- ^ @Int#@ - according to target machine | LitNumInt8 -- ^ @Int8#@ - exactly 8 bits | LitNumInt16 -- ^ @Int16#@ - exactly 16 bits | LitNumInt32 -- ^ @Int32#@ - exactly 32 bits | LitNumInt64 -- ^ @Int64#@ - exactly 64 bits | LitNumWord -- ^ @Word#@ - according to target machine | LitNumWord8 -- ^ @Word8#@ - exactly 8 bits | LitNumWord16 -- ^ @Word16#@ - exactly 16 bits | LitNumWord32 -- ^ @Word32#@ - exactly 32 bits | LitNumWord64 -- ^ @Word64#@ - exactly 64 bits deriving (Data,Enum,Eq,Ord) -- | Indicate if a numeric literal type supports negative numbers litNumIsSigned :: LitNumType -> Bool litNumIsSigned nt = case nt of LitNumInteger -> True LitNumNatural -> False LitNumInt -> True LitNumInt8 -> True LitNumInt16 -> True LitNumInt32 -> True LitNumInt64 -> True LitNumWord -> False LitNumWord8 -> False LitNumWord16 -> False LitNumWord32 -> False LitNumWord64 -> False -- | Number of bits litNumBitSize :: Platform -> LitNumType -> Maybe Word litNumBitSize platform nt = case nt of LitNumInteger -> Nothing LitNumNatural -> Nothing LitNumInt -> Just (fromIntegral (platformWordSizeInBits platform)) LitNumInt8 -> Just 8 LitNumInt16 -> Just 16 LitNumInt32 -> Just 32 LitNumInt64 -> Just 64 LitNumWord -> Just (fromIntegral (platformWordSizeInBits platform)) LitNumWord8 -> Just 8 LitNumWord16 -> Just 16 LitNumWord32 -> Just 32 LitNumWord64 -> Just 64 instance Binary LitNumType where put_ bh numTyp = putByte bh (fromIntegral (fromEnum numTyp)) get bh = do h <- getByte bh return (toEnum (fromIntegral h)) {- Note [BigNum literals] ~~~~~~~~~~~~~~~~~~~~~~ GHC supports 2 kinds of arbitrary precision integers (a.k.a BigNum): * Natural: natural represented as a Word# or as a BigNat * Integer: integer represented a an Int# or as a BigNat (Integer's constructors indicate the sign) BigNum literal instances are removed from Core during the CorePrep phase. They are replaced with expression to build them at runtime from machine literals (Word#, Int#, etc.) or from a list of Word#s. Note [String literals] ~~~~~~~~~~~~~~~~~~~~~~ String literals are UTF-8 encoded and stored into ByteStrings in the following ASTs: Haskell, Core, Stg, Cmm. TH can also emit ByteString based string literals with the BytesPrimL constructor (see #14741). It wasn't true before as [Word8] was used in Cmm AST and in TH which was quite bad for performance with large strings (see #16198 and #14741). To include string literals into output objects, the assembler code generator has to embed the UTF-8 encoded binary blob. See Note [Embedding large binary blobs] for more details. -} instance Binary Literal where put_ bh (LitChar aa) = do putByte bh 0; put_ bh aa put_ bh (LitString ab) = do putByte bh 1; put_ bh ab put_ bh (LitNullAddr) = putByte bh 2 put_ bh (LitFloat ah) = do putByte bh 3; put_ bh ah put_ bh (LitDouble ai) = do putByte bh 4; put_ bh ai put_ bh (LitLabel aj mb fod) = do putByte bh 5 put_ bh aj put_ bh mb put_ bh fod put_ bh (LitNumber nt i) = do putByte bh 6 put_ bh nt put_ bh i put_ bh (LitRubbish b) = do putByte bh 7; put_ bh b get bh = do h <- getByte bh case h of 0 -> do aa <- get bh return (LitChar aa) 1 -> do ab <- get bh return (LitString ab) 2 -> return (LitNullAddr) 3 -> do ah <- get bh return (LitFloat ah) 4 -> do ai <- get bh return (LitDouble ai) 5 -> do aj <- get bh mb <- get bh fod <- get bh return (LitLabel aj mb fod) 6 -> do nt <- get bh i <- get bh return (LitNumber nt i) _ -> do b <- get bh return (LitRubbish b) instance Outputable Literal where ppr = pprLiteral id instance Eq Literal where a == b = compare a b == EQ -- | Needed for the @Ord@ instance of 'AltCon', which in turn is needed in -- 'GHC.Data.TrieMap.CoreMap'. instance Ord Literal where compare = cmpLit {- 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. -} -- | Make a literal number using wrapping semantics if the value is out of -- bound. mkLitNumberWrap :: Platform -> LitNumType -> Integer -> Literal mkLitNumberWrap platform nt i = case nt of LitNumInt -> case platformWordSize platform of PW4 -> wrap @Int32 PW8 -> wrap @Int64 LitNumWord -> case platformWordSize platform of PW4 -> wrap @Word32 PW8 -> wrap @Word64 LitNumInt8 -> wrap @Int8 LitNumInt16 -> wrap @Int16 LitNumInt32 -> wrap @Int32 LitNumInt64 -> wrap @Int64 LitNumWord8 -> wrap @Word8 LitNumWord16 -> wrap @Word16 LitNumWord32 -> wrap @Word32 LitNumWord64 -> wrap @Word64 LitNumInteger -> LitNumber nt i LitNumNatural | i < 0 -> panic "mkLitNumberWrap: trying to create a negative Natural" | otherwise -> LitNumber nt i where wrap :: forall a. (Integral a, Num a) => Literal wrap = LitNumber nt (toInteger (fromIntegral i :: a)) -- | Wrap a literal number according to its type using wrapping semantics. litNumWrap :: Platform -> Literal -> Literal litNumWrap platform (LitNumber nt i) = mkLitNumberWrap platform nt i litNumWrap _ l = pprPanic "litNumWrap" (ppr l) -- | Coerce a literal number into another using wrapping semantics. litNumCoerce :: LitNumType -> Platform -> Literal -> Literal litNumCoerce pt platform (LitNumber _nt i) = mkLitNumberWrap platform pt i litNumCoerce _ _ l = pprPanic "litNumWrapCoerce: not a number" (ppr l) -- | Narrow a literal number by converting it into another number type and then -- converting it back to its original type. litNumNarrow :: LitNumType -> Platform -> Literal -> Literal litNumNarrow pt platform (LitNumber nt i) = case mkLitNumberWrap platform pt i of LitNumber _ j -> mkLitNumberWrap platform nt j l -> pprPanic "litNumNarrow: got invalid literal" (ppr l) litNumNarrow _ _ l = pprPanic "litNumNarrow: invalid literal" (ppr l) -- | Check that a given number is in the range of a numeric literal litNumCheckRange :: Platform -> LitNumType -> Integer -> Bool litNumCheckRange platform nt i = case nt of LitNumInt -> platformInIntRange platform i LitNumWord -> platformInWordRange platform i LitNumInt8 -> inBoundedRange @Int8 i LitNumInt16 -> inBoundedRange @Int16 i LitNumInt32 -> inBoundedRange @Int32 i LitNumInt64 -> inBoundedRange @Int64 i LitNumWord8 -> inBoundedRange @Word8 i LitNumWord16 -> inBoundedRange @Word16 i LitNumWord32 -> inBoundedRange @Word32 i LitNumWord64 -> inBoundedRange @Word64 i LitNumNatural -> i >= 0 LitNumInteger -> True -- | Create a numeric 'Literal' of the given type mkLitNumber :: Platform -> LitNumType -> Integer -> Literal mkLitNumber platform nt i = ASSERT2(litNumCheckRange platform nt i, integer i) (LitNumber nt i) -- | Creates a 'Literal' of type @Int#@ mkLitInt :: Platform -> Integer -> Literal mkLitInt platform x = ASSERT2( platformInIntRange platform x, integer x ) (mkLitIntUnchecked 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] mkLitIntWrap :: Platform -> Integer -> Literal mkLitIntWrap platform i = mkLitNumberWrap platform LitNumInt i -- | Creates a 'Literal' of type @Int#@ without checking its range. mkLitIntUnchecked :: Integer -> Literal mkLitIntUnchecked i = LitNumber LitNumInt i -- | Creates a 'Literal' of type @Int#@, as well as a 'Bool'ean flag indicating -- overflow. That is, if the argument is out of the (target-dependent) range -- the argument is wrapped and the overflow flag will be set. -- See Note [Word/Int underflow/overflow] mkLitIntWrapC :: Platform -> Integer -> (Literal, Bool) mkLitIntWrapC platform i = (n, i /= i') where n@(LitNumber _ i') = mkLitIntWrap platform i -- | Creates a 'Literal' of type @Word#@ mkLitWord :: Platform -> Integer -> Literal mkLitWord platform x = ASSERT2( platformInWordRange platform x, integer x ) (mkLitWordUnchecked 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] mkLitWordWrap :: Platform -> Integer -> Literal mkLitWordWrap platform i = mkLitNumberWrap platform LitNumWord i -- | Creates a 'Literal' of type @Word#@ without checking its range. mkLitWordUnchecked :: Integer -> Literal mkLitWordUnchecked i = LitNumber LitNumWord i -- | Creates a 'Literal' of type @Word#@, as well as a 'Bool'ean flag indicating -- carry. That is, if the argument is out of the (target-dependent) range -- the argument is wrapped and the carry flag will be set. -- See Note [Word/Int underflow/overflow] mkLitWordWrapC :: Platform -> Integer -> (Literal, Bool) mkLitWordWrapC platform i = (n, i /= i') where n@(LitNumber _ i') = mkLitWordWrap platform i -- | Creates a 'Literal' of type @Int8#@ mkLitInt8 :: Integer -> Literal mkLitInt8 x = ASSERT2( inBoundedRange @Int8 x, integer x ) (mkLitInt8Unchecked x) -- | Creates a 'Literal' of type @Int8#@. -- If the argument is out of the range, it is wrapped. mkLitInt8Wrap :: Integer -> Literal mkLitInt8Wrap i = mkLitInt8Unchecked (toInteger (fromIntegral i :: Int8)) -- | Creates a 'Literal' of type @Int8#@ without checking its range. mkLitInt8Unchecked :: Integer -> Literal mkLitInt8Unchecked i = LitNumber LitNumInt8 i -- | Creates a 'Literal' of type @Word8#@ mkLitWord8 :: Integer -> Literal mkLitWord8 x = ASSERT2( inBoundedRange @Word8 x, integer x ) (mkLitWord8Unchecked x) -- | Creates a 'Literal' of type @Word8#@. -- If the argument is out of the range, it is wrapped. mkLitWord8Wrap :: Integer -> Literal mkLitWord8Wrap i = mkLitWord8Unchecked (toInteger (fromIntegral i :: Word8)) -- | Creates a 'Literal' of type @Word8#@ without checking its range. mkLitWord8Unchecked :: Integer -> Literal mkLitWord8Unchecked i = LitNumber LitNumWord8 i -- | Creates a 'Literal' of type @Int16#@ mkLitInt16 :: Integer -> Literal mkLitInt16 x = ASSERT2( inBoundedRange @Int16 x, integer x ) (mkLitInt16Unchecked x) -- | Creates a 'Literal' of type @Int16#@. -- If the argument is out of the range, it is wrapped. mkLitInt16Wrap :: Integer -> Literal mkLitInt16Wrap i = mkLitInt16Unchecked (toInteger (fromIntegral i :: Int16)) -- | Creates a 'Literal' of type @Int16#@ without checking its range. mkLitInt16Unchecked :: Integer -> Literal mkLitInt16Unchecked i = LitNumber LitNumInt16 i -- | Creates a 'Literal' of type @Word16#@ mkLitWord16 :: Integer -> Literal mkLitWord16 x = ASSERT2( inBoundedRange @Word16 x, integer x ) (mkLitWord16Unchecked x) -- | Creates a 'Literal' of type @Word16#@. -- If the argument is out of the range, it is wrapped. mkLitWord16Wrap :: Integer -> Literal mkLitWord16Wrap i = mkLitWord16Unchecked (toInteger (fromIntegral i :: Word16)) -- | Creates a 'Literal' of type @Word16#@ without checking its range. mkLitWord16Unchecked :: Integer -> Literal mkLitWord16Unchecked i = LitNumber LitNumWord16 i -- | Creates a 'Literal' of type @Int32#@ mkLitInt32 :: Integer -> Literal mkLitInt32 x = ASSERT2( inBoundedRange @Int32 x, integer x ) (mkLitInt32Unchecked x) -- | Creates a 'Literal' of type @Int32#@. -- If the argument is out of the range, it is wrapped. mkLitInt32Wrap :: Integer -> Literal mkLitInt32Wrap i = mkLitInt32Unchecked (toInteger (fromIntegral i :: Int32)) -- | Creates a 'Literal' of type @Int32#@ without checking its range. mkLitInt32Unchecked :: Integer -> Literal mkLitInt32Unchecked i = LitNumber LitNumInt32 i -- | Creates a 'Literal' of type @Word32#@ mkLitWord32 :: Integer -> Literal mkLitWord32 x = ASSERT2( inBoundedRange @Word32 x, integer x ) (mkLitWord32Unchecked x) -- | Creates a 'Literal' of type @Word32#@. -- If the argument is out of the range, it is wrapped. mkLitWord32Wrap :: Integer -> Literal mkLitWord32Wrap i = mkLitWord32Unchecked (toInteger (fromIntegral i :: Word32)) -- | Creates a 'Literal' of type @Word32#@ without checking its range. mkLitWord32Unchecked :: Integer -> Literal mkLitWord32Unchecked i = LitNumber LitNumWord32 i -- | Creates a 'Literal' of type @Int64#@ mkLitInt64 :: Integer -> Literal mkLitInt64 x = ASSERT2( inBoundedRange @Int64 x, integer x ) (mkLitInt64Unchecked x) -- | Creates a 'Literal' of type @Int64#@. -- If the argument is out of the range, it is wrapped. mkLitInt64Wrap :: Integer -> Literal mkLitInt64Wrap i = mkLitInt64Unchecked (toInteger (fromIntegral i :: Int64)) -- | Creates a 'Literal' of type @Int64#@ without checking its range. mkLitInt64Unchecked :: Integer -> Literal mkLitInt64Unchecked i = LitNumber LitNumInt64 i -- | Creates a 'Literal' of type @Word64#@ mkLitWord64 :: Integer -> Literal mkLitWord64 x = ASSERT2( inBoundedRange @Word64 x, integer x ) (mkLitWord64Unchecked x) -- | Creates a 'Literal' of type @Word64#@. -- If the argument is out of the range, it is wrapped. mkLitWord64Wrap :: Integer -> Literal mkLitWord64Wrap i = mkLitWord64Unchecked (toInteger (fromIntegral i :: Word64)) -- | Creates a 'Literal' of type @Word64#@ without checking its range. mkLitWord64Unchecked :: Integer -> Literal mkLitWord64Unchecked i = LitNumber LitNumWord64 i -- | Creates a 'Literal' of type @Float#@ mkLitFloat :: Rational -> Literal mkLitFloat = LitFloat -- | Creates a 'Literal' of type @Double#@ mkLitDouble :: Rational -> Literal mkLitDouble = LitDouble -- | Creates a 'Literal' of type @Char#@ mkLitChar :: Char -> Literal mkLitChar = LitChar -- | 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@ mkLitString :: String -> Literal -- stored UTF-8 encoded mkLitString s = LitString (bytesFS $ mkFastString s) mkLitInteger :: Integer -> Literal mkLitInteger x = LitNumber LitNumInteger x mkLitNatural :: Integer -> Literal mkLitNatural x = ASSERT2( inNaturalRange x, integer x ) (LitNumber LitNumNatural x) inNaturalRange :: Integer -> Bool inNaturalRange x = x >= 0 inBoundedRange :: forall a. (Bounded a, Integral a) => Integer -> Bool inBoundedRange x = x >= toInteger (minBound :: a) && x <= toInteger (maxBound :: a) isMinBound :: Platform -> Literal -> Bool isMinBound _ (LitChar c) = c == minBound isMinBound platform (LitNumber nt i) = case nt of LitNumInt -> i == platformMinInt platform LitNumInt8 -> i == toInteger (minBound :: Int8) LitNumInt16 -> i == toInteger (minBound :: Int16) LitNumInt32 -> i == toInteger (minBound :: Int32) LitNumInt64 -> i == toInteger (minBound :: Int64) LitNumWord -> i == 0 LitNumWord8 -> i == 0 LitNumWord16 -> i == 0 LitNumWord32 -> i == 0 LitNumWord64 -> i == 0 LitNumNatural -> i == 0 LitNumInteger -> False isMinBound _ _ = False isMaxBound :: Platform -> Literal -> Bool isMaxBound _ (LitChar c) = c == maxBound isMaxBound platform (LitNumber nt i) = case nt of LitNumInt -> i == platformMaxInt platform LitNumInt8 -> i == toInteger (maxBound :: Int8) LitNumInt16 -> i == toInteger (maxBound :: Int16) LitNumInt32 -> i == toInteger (maxBound :: Int32) LitNumInt64 -> i == toInteger (maxBound :: Int64) LitNumWord -> i == platformMaxWord platform LitNumWord8 -> i == toInteger (maxBound :: Word8) LitNumWord16 -> i == toInteger (maxBound :: Word16) LitNumWord32 -> i == toInteger (maxBound :: Word32) LitNumWord64 -> i == toInteger (maxBound :: Word64) LitNumNatural -> False LitNumInteger -> False isMaxBound _ _ = False 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 (LitNumber _ 0) = True isZeroLit (LitFloat 0) = True isZeroLit (LitDouble 0) = True isZeroLit _ = False -- | Tests whether the literal represents a one of whatever type it is isOneLit :: Literal -> Bool isOneLit (LitNumber _ 1) = True isOneLit (LitFloat 1) = True isOneLit (LitDouble 1) = True isOneLit _ = False -- | Returns the 'Integer' contained in the 'Literal', for when that makes -- sense, i.e. for 'Char', 'Int', 'Word', 'LitInteger' and 'LitNatural'. 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' and numbers. isLitValue_maybe :: Literal -> Maybe Integer isLitValue_maybe (LitChar c) = Just $ toInteger $ ord c isLitValue_maybe (LitNumber _ 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' and numbers. -- 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 :: Platform -> (Integer -> Integer) -> Literal -> Literal mapLitValue _ f (LitChar c) = mkLitChar (fchar c) where fchar = chr . fromInteger . f . toInteger . ord mapLitValue platform f (LitNumber nt i) = mkLitNumberWrap platform nt (f i) mapLitValue _ _ l = pprPanic "mapLitValue" (ppr l) {- Coercions ~~~~~~~~~ -} charToIntLit, intToCharLit, floatToIntLit, intToFloatLit, doubleToIntLit, intToDoubleLit, floatToDoubleLit, doubleToFloatLit :: Literal -> Literal -- | Narrow a literal number (unchecked result range) narrowLit' :: forall a. Integral a => LitNumType -> Literal -> Literal narrowLit' nt' (LitNumber _ i) = LitNumber nt' (toInteger (fromInteger i :: a)) narrowLit' _ l = pprPanic "narrowLit" (ppr l) narrowInt8Lit, narrowInt16Lit, narrowInt32Lit, narrowInt64Lit, narrowWord8Lit, narrowWord16Lit, narrowWord32Lit, narrowWord64Lit :: Literal -> Literal narrowInt8Lit = narrowLit' @Int8 LitNumInt8 narrowInt16Lit = narrowLit' @Int16 LitNumInt16 narrowInt32Lit = narrowLit' @Int32 LitNumInt32 narrowInt64Lit = narrowLit' @Int64 LitNumInt64 narrowWord8Lit = narrowLit' @Word8 LitNumWord8 narrowWord16Lit = narrowLit' @Word16 LitNumWord16 narrowWord32Lit = narrowLit' @Word32 LitNumWord32 narrowWord64Lit = narrowLit' @Word64 LitNumWord64 -- | Extend a fixed-width literal (e.g. 'Int16#') to a word-sized literal (e.g. -- 'Int#'). extendWordLit, extendIntLit :: Platform -> Literal -> Literal extendWordLit platform (LitNumber _nt i) = mkLitWord platform i extendWordLit _platform l = pprPanic "extendWordLit" (ppr l) extendIntLit platform (LitNumber _nt i) = mkLitInt platform i extendIntLit _platform l = pprPanic "extendIntLit" (ppr l) charToIntLit (LitChar c) = mkLitIntUnchecked (toInteger (ord c)) charToIntLit l = pprPanic "charToIntLit" (ppr l) intToCharLit (LitNumber _ i) = LitChar (chr (fromInteger i)) intToCharLit l = pprPanic "intToCharLit" (ppr l) floatToIntLit (LitFloat f) = mkLitIntUnchecked (truncate f) floatToIntLit l = pprPanic "floatToIntLit" (ppr l) intToFloatLit (LitNumber _ i) = LitFloat (fromInteger i) intToFloatLit l = pprPanic "intToFloatLit" (ppr l) doubleToIntLit (LitDouble f) = mkLitIntUnchecked (truncate f) doubleToIntLit l = pprPanic "doubleToIntLit" (ppr l) intToDoubleLit (LitNumber _ i) = LitDouble (fromInteger i) intToDoubleLit l = pprPanic "intToDoubleLit" (ppr l) floatToDoubleLit (LitFloat f) = LitDouble f floatToDoubleLit l = pprPanic "floatToDoubleLit" (ppr l) doubleToFloatLit (LitDouble d) = LitFloat d doubleToFloatLit l = pprPanic "doubleToFloatLit" (ppr l) nullAddrLit :: Literal nullAddrLit = LitNullAddr -- | A rubbish literal; see Note [Rubbish literals] rubbishLit :: Bool -> Literal rubbishLit is_lifted = LitRubbish is_lifted isRubbishLit :: Literal -> Bool isRubbishLit (LitRubbish {}) = True isRubbishLit _ = False {- 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. GHC.Core.Utils.exprIsTrivial litIsTrivial (LitString _) = False litIsTrivial (LitNumber nt _) = case nt of LitNumInteger -> False LitNumNatural -> False LitNumInt -> True LitNumInt8 -> True LitNumInt16 -> True LitNumInt32 -> True LitNumInt64 -> True LitNumWord -> True LitNumWord8 -> True LitNumWord16 -> True LitNumWord32 -> True LitNumWord64 -> True litIsTrivial _ = True -- | True if code space does not go bad if we duplicate this literal litIsDupable :: Platform -> Literal -> Bool -- c.f. GHC.Core.Utils.exprIsDupable litIsDupable platform x = case x of (LitNumber nt i) -> case nt of LitNumInteger -> platformInIntRange platform i LitNumNatural -> platformInWordRange platform i LitNumInt -> True LitNumInt8 -> True LitNumInt16 -> True LitNumInt32 -> True LitNumInt64 -> True LitNumWord -> True LitNumWord8 -> True LitNumWord16 -> True LitNumWord32 -> True LitNumWord64 -> True (LitString _) -> False _ -> True litFitsInChar :: Literal -> Bool litFitsInChar (LitNumber _ i) = i >= toInteger (ord minBound) && i <= toInteger (ord maxBound) litFitsInChar _ = False litIsLifted :: Literal -> Bool litIsLifted (LitNumber nt _) = case nt of LitNumInteger -> True LitNumNatural -> True LitNumInt -> False LitNumInt8 -> False LitNumInt16 -> False LitNumInt32 -> False LitNumInt64 -> False LitNumWord -> False LitNumWord8 -> False LitNumWord16 -> False LitNumWord32 -> False LitNumWord64 -> False litIsLifted _ = False {- Types ~~~~~ -} -- | Find the Haskell 'Type' the literal occupies literalType :: Literal -> Type literalType LitNullAddr = addrPrimTy literalType (LitChar _) = charPrimTy literalType (LitString _) = addrPrimTy literalType (LitFloat _) = floatPrimTy literalType (LitDouble _) = doublePrimTy literalType (LitLabel _ _ _) = addrPrimTy literalType (LitNumber lt _) = case lt of LitNumInteger -> integerTy LitNumNatural -> naturalTy LitNumInt -> intPrimTy LitNumInt8 -> int8PrimTy LitNumInt16 -> int16PrimTy LitNumInt32 -> int32PrimTy LitNumInt64 -> int64PrimTy LitNumWord -> wordPrimTy LitNumWord8 -> word8PrimTy LitNumWord16 -> word16PrimTy LitNumWord32 -> word32PrimTy LitNumWord64 -> word64PrimTy literalType (LitRubbish is_lifted) = mkForAllTy a Inferred (mkTyVarTy a) where -- See Note [Rubbish literals] a | is_lifted = alphaTyVar | otherwise = alphaTyVarUnliftedRep absentLiteralOf :: TyCon -> Maybe Literal -- Return a literal of the appropriate primitive -- TyCon, to use as a placeholder when it doesn't matter -- Rubbish literals are handled in GHC.Core.Opt.WorkWrap.Utils, because -- 1. Looking at the TyCon is not enough, we need the actual type -- 2. This would need to return a type application to a literal absentLiteralOf tc = lookupUFM absent_lits tc -- We do not use TyConEnv here to avoid import cycles. absent_lits :: UniqFM TyCon Literal absent_lits = listToUFM_Directly -- Explicitly construct the mape from the known -- keys of these tyCons. [ (addrPrimTyConKey, LitNullAddr) , (charPrimTyConKey, LitChar 'x') , (intPrimTyConKey, mkLitIntUnchecked 0) , (int8PrimTyConKey, mkLitInt8Unchecked 0) , (int16PrimTyConKey, mkLitInt16Unchecked 0) , (int32PrimTyConKey, mkLitInt32Unchecked 0) , (int64PrimTyConKey, mkLitInt64Unchecked 0) , (wordPrimTyConKey, mkLitWordUnchecked 0) , (word8PrimTyConKey, mkLitWord8Unchecked 0) , (word16PrimTyConKey, mkLitWord16Unchecked 0) , (word32PrimTyConKey, mkLitWord32Unchecked 0) , (word64PrimTyConKey, mkLitWord64Unchecked 0) , (floatPrimTyConKey, LitFloat 0) , (doublePrimTyConKey, LitDouble 0) ] {- Comparison ~~~~~~~~~~ -} cmpLit :: Literal -> Literal -> Ordering cmpLit (LitChar a) (LitChar b) = a `compare` b cmpLit (LitString a) (LitString b) = a `compare` b cmpLit (LitNullAddr) (LitNullAddr) = EQ cmpLit (LitFloat a) (LitFloat b) = a `compare` b cmpLit (LitDouble a) (LitDouble b) = a `compare` b cmpLit (LitLabel a _ _) (LitLabel b _ _) = a `lexicalCompareFS` b cmpLit (LitNumber nt1 a) (LitNumber nt2 b) = (nt1 `compare` nt2) `mappend` (a `compare` b) cmpLit (LitRubbish b1) (LitRubbish b2) = b1 `compare` b2 cmpLit lit1 lit2 | isTrue# (dataToTag# lit1 <# dataToTag# lit2) = LT | otherwise = GT {- Printing ~~~~~~~~ * See Note [Printing of literals in Core] -} pprLiteral :: (SDoc -> SDoc) -> Literal -> SDoc pprLiteral _ (LitChar c) = pprPrimChar c pprLiteral _ (LitString s) = pprHsBytes s pprLiteral _ (LitNullAddr) = text "__NULL" pprLiteral _ (LitFloat f) = float (fromRat f) <> primFloatSuffix pprLiteral _ (LitDouble d) = double (fromRat d) <> primDoubleSuffix pprLiteral add_par (LitNumber nt i) = case nt of LitNumInteger -> pprIntegerVal add_par i LitNumNatural -> pprIntegerVal add_par i LitNumInt -> pprPrimInt i LitNumInt8 -> pprPrimInt8 i LitNumInt16 -> pprPrimInt16 i LitNumInt32 -> pprPrimInt32 i LitNumInt64 -> pprPrimInt64 i LitNumWord -> pprPrimWord i LitNumWord8 -> pprPrimWord8 i LitNumWord16 -> pprPrimWord16 i LitNumWord32 -> pprPrimWord32 i LitNumWord64 -> pprPrimWord64 i pprLiteral add_par (LitLabel 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)) pprLiteral _ (LitRubbish is_lifted) = text "__RUBBISH" <> parens (if is_lifted then text "lifted" else text "unlifted") 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 (`LitLabel`), 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) ------- ------- ---------------------- LitChar 'a'# LitString "aaa"# LitNullAddr "__NULL" LitInt -1# LitIntN -1#N LitWord 1## LitWordN 1##N LitFloat -1.0# LitDouble -1.0## LitInteger -1 (-1) LitLabel "__label" ... ("__label" ...) LitRubbish "__RUBBISH" Note [Rubbish literals] ~~~~~~~~~~~~~~~~~~~~~~~ During worker/wrapper after demand analysis, where an argument is unused (absent) we do the following w/w split (supposing that y is absent): f x y z = e ===> f x y z = $wf x z $wf x z = let y = in e Usually the binding for y is ultimately optimised away, and even if not it should never be evaluated -- but that's the way the w/w split starts off. What is ? * For lifted values can be a call to 'error'. * For primitive types like Int# or Word# we can use any random value of that type. * But what about /unlifted/ but /boxed/ types like MutVar# or Array#? Or /lifted/ but /strict/ values, such as a field of a strict data constructor. For these we use LitRubbish. See Note [Absent errors] in GHC.Core.Opt.WorkWrap.Utils.hs The literal (LitRubbish is_lifted) has type LitRubbish :: forall (a :: TYPE LiftedRep). a if is_lifted LitRubbish :: forall (a :: TYPE UnliftedRep). a otherwise So we might see a w/w split like $wf x z = let y :: Array# Int = (LitRubbish False) @(Array# Int) in e Here are the moving parts, but see also Note [Absent errors] in GHC.Core.Opt.WorkWrap.Utils * We define LitRubbish as a constructor in GHC.Types.Literal.Literal * It is given its polymorphic type by Literal.literalType * GHC.Core.Opt.WorkWrap.Utils.mk_absent_let introduces a LitRubbish for absent arguments of boxed, unlifted type; or boxed, lifted arguments of strict data constructors. * In CoreToSTG we convert (RubishLit @t) to just (). STG is untyped, so this will work OK for both lifted and unlifted (but boxed) values. The important thing is that it is a heap pointer, which the garbage collector can follow if it encounters it. We considered maintaining LitRubbish in STG, and lowering it in the code generators, but it seems simpler to do it once and for all in CoreToSTG. In GHC.ByteCode.Asm we just lower it as a 0 literal, because it's all boxed to the host GC anyway. -}