Joshua Wise's Git repositories - snipe.git/blame_incremental

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Commit	Line	Data
	1	(* L3 compiler
	2	* peephole optimizer
	3	* optimizes away redundant insns such as:
	4	mov a, b
	5	mov a, b
	6
	7	mov a, b
	8	mov b, a
	9
	10	mov a, a
	11
	12	neg a
	13	neg a
	14	* Author: Chris Lu <czl@andrew.cmu.edu>
	15	*)
	16
	17	signature PEEPHOLE =
	18	sig
	19	val peephole : x86.insn list -> x86.insn list
	20	end
	21
	22	structure Peephole :> PEEPHOLE =
	23	struct
	24	structure X = x86
	25
	26	(* val peephole : x86.insn list -> x86.insn list *)
	27
	28	fun peephole ((insn1 as X.MOV(a1,b1))::(insn2 as X.MOV(a2,b2))::l) =
	29	if(x86.opereq(a1, b1) orelse (x86.opereq(a1, a2) andalso x86.opereq(b1, b2))) then
	30	peephole (insn2::l)
	31	else if(x86.opereq(a2, b2) orelse (x86.opereq(a1, b2) andalso x86.opereq(b1, a2))) then
	32	peephole (insn1::l)
	33	else
	34	insn1::(peephole (insn2::l))
	35	\| peephole (X.MOV (X.REG r, X.CONST 0w0)::l) = (X.XOR (X.REG r, X.REG r))::(peephole l)
	36	\| peephole ((insn as X.MOV(a,b))::l) = if x86.opereq(a, b) then peephole l else insn::(peephole l)
	37	\| peephole ((insn1 as X.NEG(a))::(insn2 as X.NEG(b))::l) = if x86.opereq(a, b) then peephole l else insn1::(peephole (insn2::l))
	38	\| peephole (X.ADD (_, X.CONST 0w0)::l) = peephole l
	39	\| peephole (X.SUB (_, X.CONST 0w0)::l) = peephole l
	40	\| peephole (X.CMP (X.REG r, X.CONST 0w0)::l) = (X.TEST (X.REG r, X.REG r))::(peephole l)
	41	\| peephole ((X.JMP a)::(X.JMP b)::l) = peephole ((X.JMP a)::l) (* What the cock? Yes, we actually generate this. *)
	42	\| peephole ((X.JMP l1)::(X.LABEL l2)::l) = if (Label.compare (l1,l2) = EQUAL) then (X.LABEL l2)::(peephole l) else (X.JMP l1)::(X.LABEL l2)::(peephole l)
	43	\| peephole (X.SIZE (s, i)::l) = map (fn i => X.SIZE (s, i)) (peephole [i]) @ (peephole l) (* :/ that kind of sucks, but oh well *)
	44	\| peephole (a::l) = a::(peephole l)
	45	\| peephole nil = nil
	46
	47	end