ghc-9.2.2: GHC/Types/Literal.hs
{-
(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
, convertToIntLit, convertToWordLit
, 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@ => @\<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 or narrow a fixed-width literal (e.g. 'Int16#') to a target
-- word-sized literal ('Int#' or 'Word#'). Narrowing can only happen on 32-bit
-- architectures when we convert a 64-bit literal into a 32-bit one.
convertToWordLit, convertToIntLit :: Platform -> Literal -> Literal
convertToWordLit platform (LitNumber _nt i) = mkLitWordWrap platform i
convertToWordLit _platform l = pprPanic "convertToWordLit" (ppr l)
convertToIntLit platform (LitNumber _nt i) = mkLitIntWrap platform i
convertToIntLit _platform l = pprPanic "convertToIntLit" (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 = <absent value>
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 <absent value>?
* For lifted values <absent value> 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.
-}