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|
local
structure I =
struct
include "alphaInstr.sml"
end
in
functor AlphaPeephole
(structure Instr : ALPHAINSTR
structure Eval : MLTREE_EVAL
sharing Instr.T = Eval.T
) : PEEPHOLE =
struct
structure I = Instr
structure CB = CellsBasis
(* IMPORTANT: instructions are now given in forward order *)
fun peephole instrs =
let fun isZero(I.LABop le) = ((Eval.valueOf le = 0) handle _ => false)
| isZero(I.REGop r) = CB.registerNum r = 31
| isZero(I.IMMop i) = i = 0
| isZero _ = false
fun removable(I.INSTR(I.LDA{r, b, d})) =
isZero d andalso CB.sameColor(r,b)
| removable(I.INSTR(I.OPERATE{oper=(I.ADDQ | I.SUBQ), ra, rb, rc})) =
CB.sameColor(ra,rc) andalso isZero rb
| removable(I.ANNOTATION{i,a}) = removable i
| removable _ = false
fun symmetric(I.STQ, I.LDQ) = true
| symmetric(I.STL, I.LDL) = true
| symmetric(I.STW, I.LDW) = true
| symmetric(I.STB, I.LDB) = true
| symmetric _ = false
fun sameOperand (I.REGop r1, I.REGop r2) = CB.sameColor(r1,r2)
| sameOperand (I.IMMop i1, I.IMMop i2) = i1 = i2
| sameOperand (I.LABop l1, I.LABop l2) =
((Eval.valueOf l1 = Eval.valueOf l2) handle _ => false)
| sameOperand _ = false
fun loop(current, instrs) =
case current of
[] => instrs
| (st as I.INSTR(I.STORE{stOp, r=r1, b=b1, d=d1, ...}))::
(ld as I.INSTR(I.LOAD {ldOp, r=r2, b=b2, d=d2, ...}))::rest
where symmetric(stOp, ldOp) andalso
CB.sameColor(r1,r2) andalso
CB.sameColor(b1,b2) andalso
sameOperand(d1,d2) => loop(rest, st::instrs)
| i::rest where removable i => loop(rest, instrs)
| i::rest => loop(rest, i::instrs)
in loop(instrs, [])
end
end
end
|
