| | 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 | structure Peephole :> OPTIMIZATION = |
| | 18 | struct |
| | 19 | structure X = x86 |
| | 20 | |
| | 21 | (* val peephole : x86.insn list -> x86.insn list *) |
| | 22 | fun peephole ((insn1 as X.MOV(d1, s1 as (X.REL a,_)))::(insn2 as X.MOV(d2, s2 as (X.REL(a2,b2,m),_)))::l) = |
| | 23 | if(X.opereq(a2,d1) orelse X.opereq(b2,d1)) then |
| | 24 | insn1::(peephole (insn2::l)) |
| | 25 | else if(X.opereq(s1,s2) andalso X.opereq (d1,d2)) then |
| | 26 | peephole (insn2::l) |
| | 27 | else |
| | 28 | insn1::(peephole (insn2::l)) |
| | 29 | | peephole ((insn1 as X.MOV(a1,b1))::(insn2 as X.MOV(a2,b2))::l) = |
| | 30 | if(X.opereq(a1, b1) orelse (X.opereq(a1, a2) andalso X.opereq(b1, b2))) then |
| | 31 | peephole (insn2::l) |
| | 32 | else if(X.opereq(a2, b2) orelse (X.opereq(a1, b2) andalso X.opereq(b1, a2))) then |
| | 33 | peephole (insn1::l) |
| | 34 | else |
| | 35 | insn1::(peephole (insn2::l)) |
| | 36 | | peephole (X.MOV (a as (X.REG r,s), (X.CONST 0w0,_))::l) = (X.XOR (a, a))::(peephole l) |
| | 37 | | peephole ((insn as X.MOV(a,b))::l) = if X.opereq(a, b) then peephole l else insn::(peephole l) |
| | 38 | | peephole ((insn1 as X.NEG(a))::(insn2 as X.NEG(b))::l) = if X.opereq(a, b) then peephole l else insn1::(peephole (insn2::l)) |
| | 39 | | peephole (X.ADD (_, (X.CONST 0w0,_))::l) = peephole l |
| | 40 | | peephole (X.SUB (_, (X.CONST 0w0,_))::l) = peephole l |
| | 41 | (* | peephole (X.CMP ((X.REG r,s), (X.CONST 0w0,_))::l) = (X.TEST ((X.REG r,s), (X.REG r,s)))::(peephole l) *) |
| | 42 | | peephole ((X.JMP a)::(X.JMP b)::l) = peephole ((X.JMP a)::l) (* What the cock? Yes, we actually generate this. *) |
| | 43 | | 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) |
| | 44 | | peephole (a::l) = a::(peephole l) |
| | 45 | | peephole nil = nil |
| | 46 | |
| | 47 | val optimizer = { shortname = "peephole", description = "Peephole analysis", func = Optimizer.FINAL peephole } |
| | 48 | end |
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