    {-# LANGUAGE GeneralizedNewtypeDeriving #-}

    -- | Free regs map for i386
    module GHC.CmmToAsm.Reg.Linear.X86 where

    import GHC.Prelude

    import GHC.CmmToAsm.X86.Regs
    import GHC.Platform.Reg.Class
    import GHC.Platform.Reg
    import GHC.Utils.Panic
    import GHC.Platform
    import GHC.Utils.Outputable

    import Data.Word

    newtype FreeRegs = FreeRegs Word32
        deriving (RegNo -> FreeRegs -> ShowS
    [FreeRegs] -> ShowS
    FreeRegs -> String
    forall a.
    (RegNo -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
    showList :: [FreeRegs] -> ShowS
    $cshowList :: [FreeRegs] -> ShowS
    show :: FreeRegs -> String
    $cshow :: FreeRegs -> String
    showsPrec :: RegNo -> FreeRegs -> ShowS
    $cshowsPrec :: RegNo -> FreeRegs -> ShowS
    Show,FreeRegs -> SDoc
    forall a. (a -> SDoc) -> Outputable a
    ppr :: FreeRegs -> SDoc
    $cppr :: FreeRegs -> SDoc
    Outputable)

    noFreeRegs :: FreeRegs
    noFreeRegs :: FreeRegs
    noFreeRegs = Word32 -> FreeRegs
    FreeRegs Word32
    0

    releaseReg :: RealReg -> FreeRegs -> FreeRegs
    releaseReg :: RealReg -> FreeRegs -> FreeRegs
    releaseReg (RealRegSingle RegNo
    n) (FreeRegs Word32
    f)
            = Word32 -> FreeRegs
    FreeRegs (Word32
    f forall a. Bits a => a -> a -> a
    .|. (Word32
    1 forall a. Bits a => a -> RegNo -> a
    `shiftL` RegNo
    n))

    releaseReg RealReg
    _ FreeRegs
    _
            = forall a. String -> a
    panic String
    "RegAlloc.Linear.X86.FreeRegs.releaseReg: no reg"

    initFreeRegs :: Platform -> FreeRegs
    initFreeRegs :: Platform -> FreeRegs
    initFreeRegs Platform
    platform
            = forall (t :: * -> *) b a.
    Foldable t =>
    (b -> a -> b) -> b -> t a -> b
    foldl' (forall a b c. (a -> b -> c) -> b -> a -> c
    flip RealReg -> FreeRegs -> FreeRegs
    releaseReg) FreeRegs
    noFreeRegs (Platform -> [RealReg]
    allocatableRegs Platform
    platform)

    getFreeRegs :: Platform -> RegClass -> FreeRegs -> [RealReg] -- lazily
    getFreeRegs :: Platform -> RegClass -> FreeRegs -> [RealReg]
    getFreeRegs Platform
    platform RegClass
    cls (FreeRegs Word32
    f) = Word32 -> RegNo -> [RealReg]
    go Word32
    f RegNo
    0

      where go :: Word32 -> RegNo -> [RealReg]
    go Word32
    0 RegNo
    _ = []
            go Word32
    n RegNo
    m
              | Word32
    n forall a. Bits a => a -> a -> a
    .&. Word32
    1 forall a. Eq a => a -> a -> Bool
    /= Word32
    0 Bool -> Bool -> Bool
    && Platform -> RealReg -> RegClass
    classOfRealReg Platform
    platform (RegNo -> RealReg
    RealRegSingle RegNo
    m) forall a. Eq a => a -> a -> Bool
    == RegClass
    cls
              = RegNo -> RealReg
    RealRegSingle RegNo
    m forall a. a -> [a] -> [a]
    : (Word32 -> RegNo -> [RealReg]
    go (Word32
    n forall a. Bits a => a -> RegNo -> a
    `shiftR` RegNo
    1) forall a b. (a -> b) -> a -> b
    $! (RegNo
    mforall a. Num a => a -> a -> a
    +RegNo
    1))

              | Bool
    otherwise
              = Word32 -> RegNo -> [RealReg]
    go (Word32
    n forall a. Bits a => a -> RegNo -> a
    `shiftR` RegNo
    1) forall a b. (a -> b) -> a -> b
    $! (RegNo
    mforall a. Num a => a -> a -> a
    +RegNo
    1)
            -- ToDo: there's no point looking through all the integer registers
            -- in order to find a floating-point one.

    allocateReg :: RealReg -> FreeRegs -> FreeRegs
    allocateReg :: RealReg -> FreeRegs -> FreeRegs
    allocateReg (RealRegSingle RegNo
    r) (FreeRegs Word32
    f)
            = Word32 -> FreeRegs
    FreeRegs (Word32
    f forall a. Bits a => a -> a -> a
    .&. forall a. Bits a => a -> a
    complement (Word32
    1 forall a. Bits a => a -> RegNo -> a
    `shiftL` RegNo
    r))

    allocateReg RealReg
    _ FreeRegs
    _
            = forall a. String -> a
    panic String
    "RegAlloc.Linear.X86.FreeRegs.allocateReg: no reg"