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-- | Free regs map for i386 and x86_64
module RegAlloc.Linear.X86.FreeRegs
where
import X86.Regs
import RegClass
import Reg
import Panic
import Data.Word
import Data.Bits
import Data.List
type FreeRegs
= Word32
noFreeRegs :: FreeRegs
noFreeRegs = 0
releaseReg :: RealReg -> FreeRegs -> FreeRegs
releaseReg (RealRegSingle n) f
= f .|. (1 `shiftL` n)
releaseReg _ _
= panic "RegAlloc.Linear.X86.FreeRegs.realeaseReg: no reg"
initFreeRegs :: FreeRegs
initFreeRegs
= foldr releaseReg noFreeRegs allocatableRegs
getFreeRegs :: RegClass -> FreeRegs -> [RealReg] -- lazilly
getFreeRegs cls f = go f 0
where go 0 _ = []
go n m
| n .&. 1 /= 0 && classOfRealReg (RealRegSingle m) == cls
= RealRegSingle m : (go (n `shiftR` 1) $! (m+1))
| otherwise
= go (n `shiftR` 1) $! (m+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 (RealRegSingle r) f
= f .&. complement (1 `shiftL` fromIntegral r)
allocateReg _ _
= panic "RegAlloc.Linear.X86.FreeRegs.allocateReg: no reg"
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