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module X64Optimiser(x64Optimise) where
import Defs
import X64
x64Optimise :: Asm -> Error Asm
x64Optimise asm =
return $
optUnnecessaryJumps $
funcopt optSimpleInstructions $
asm
funcopt :: (Func -> Func) -> Asm -> Asm
funcopt f (Asm funcs) = Asm (map f funcs)
optUnnecessaryJumps :: Asm -> Asm
optUnnecessaryJumps (Asm funcs) = Asm $ map goF (zip funcs (tail funcs)) ++ [last funcs]
where
goF :: (Func, Func) -> Func
goF (f1@(_, f1i), (f2n, _)) = case last f1i of
JMP n | n == f2n -> fmap init f1
_ -> f1
optSimpleInstructions :: Func -> Func
optSimpleInstructions (name, inss) = (name, concat $ map goI inss)
where
goI :: Ins -> [Ins]
goI (MOV (RegMem a) (RegMem b)) | a == b = []
goI (MOVi (RegMem (XReg 8 r)) (Imm (XImm 0))) = [XOR (RegMem (XReg 4 r)) (RegMemImm (XReg 4 r))]
goI (MOVi (RegMem a@(XReg _ _)) (Imm (XImm 0))) = [XOR (RegMem a) (RegMemImm a)]
goI (MOVi64 (Reg (XReg 8 r)) (Imm (XImm 0))) = [XOR (RegMem (XReg 4 r)) (RegMemImm (XReg 4 r))]
goI (MOVi64 (Reg a) (Imm (XImm 0))) = [XOR (RegMem a) (RegMemImm a)]
goI (MOVSX (Reg a) (RegMem b)) | a == b = []
goI ins = [ins]
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