Revision c287ba28 src/optimize_machine.ml
src/optimize_machine.ml  

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and eliminate_expr elim expr = 
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match expr with 
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 StateVar v 

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 LocalVar v > (try IMap.find v.var_id elim with Not_found > expr) 
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 Fun (id, vl) > Fun (id, List.map (eliminate_expr elim) vl) 
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 Array(vl) > Array(List.map (eliminate_expr elim) vl) 
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 Access(v1, v2) > Access(eliminate_expr elim v1, eliminate_expr elim v2) 
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 Power(v1, v2) > Power(eliminate_expr elim v1, eliminate_expr elim v2) 
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 Cst _  StateVar _ > expr


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 Cst _ > expr 

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let eliminate_dim elim dim = 
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Dimension.expr_replace_expr (fun v > try dimension_of_value (IMap.find v elim) with Not_found > mkdim_ident dim.dim_loc v) dim 
...  ...  
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 Const_tag _ > true 
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 _ > false 
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let basic_unfoldable_expr expr = 

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match expr with 

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 Cst c when is_scalar_const c > true 

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 LocalVar _ 

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 StateVar _ > true 

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 _ > false 

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let unfoldable_assign fanin v expr = 
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try 
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let d = Hashtbl.find fanin v.var_id 
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in match expr with 

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 Cst c when is_scalar_const c > true 

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 Cst c when d < 2 > true 

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 LocalVar _ 

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 StateVar _ > true 

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in basic_unfoldable_expr expr  

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match expr with 

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 Cst c when d < 2 > true 

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 Fun (id, _) when d < 2 && Basic_library.is_internal_fun id > true 
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 _ > false 
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with Not_found > false 
...  ...  
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in machine_unfold fanin elim_consts m) 
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machines 
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let get_assign_lhs instr = 

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match instr with 

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 MLocalAssign(v, _) > LocalVar v 

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 MStateAssign(v, _) > StateVar v 

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 _ > assert false 

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let get_assign_rhs instr = 

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match instr with 

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 MLocalAssign(_, e) 

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 MStateAssign(_, e) > e 

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 _ > assert false 

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let is_assign instr = 

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match instr with 

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 MLocalAssign _ 

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 MStateAssign _ > true 

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 _ > false 

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let mk_assign v e = 

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match v with 

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 LocalVar v > MLocalAssign(v, e) 

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 StateVar v > MStateAssign(v, e) 

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 _ > assert false 

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let rec assigns_instr instr assign = 

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match instr with 

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 MLocalAssign (i,_) 

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 MStateAssign (i,_) > ISet.add i assign 

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 MStep (ol, _, _) > List.fold_right ISet.add ol assign 

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 MBranch (_,hl) > List.fold_right (fun (_, il) > assigns_instrs il) hl assign 

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 _ > assign 

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and assigns_instrs instrs assign = 

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List.fold_left (fun assign instr > assigns_instr instr assign) assign instrs 

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(* 

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and substitute_expr subst expr = 

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match expr with 

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 StateVar v 

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 LocalVar v > (try IMap.find expr subst with Not_found > expr) 

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 Fun (id, vl) > Fun (id, List.map (substitute_expr subst) vl) 

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 Array(vl) > Array(List.map (substitute_expr subst) vl) 

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 Access(v1, v2) > Access(substitute_expr subst v1, substitute_expr subst v2) 

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 Power(v1, v2) > Power(substitute_expr subst v1, substitute_expr subst v2) 

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 Cst _ > expr 

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*) 

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(** Finds a substitute for [instr] in [instrs], 

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i.e. another instr' with the same rhs expression. 

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Then substitute this expression with the first assigned var 

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*) 

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let subst_instr subst instrs instr = 

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(*Format.eprintf "subst instr: %a@." Machine_code.pp_instr instr;*) 

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let instr = eliminate subst instr in 

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let v = get_assign_lhs instr in 

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let e = get_assign_rhs instr in 

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try 

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let instr' = List.find (fun instr' > is_assign instr' && get_assign_rhs instr' = e) instrs in 

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match v with 

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 LocalVar v > 

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IMap.add v.var_id (get_assign_lhs instr') subst, instrs 

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 StateVar v > 

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(match get_assign_lhs instr' with 

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 LocalVar v' > 

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let instr = eliminate subst (mk_assign (StateVar v) (LocalVar v')) in 

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subst, instr :: instrs 

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 StateVar v' > 

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let subst_v' = IMap.add v'.var_id (StateVar v) IMap.empty in 

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let instrs' = snd (List.fold_right (fun instr (ok, instrs) > (ok  instr = instr', if ok then instr :: instrs else if instr = instr' then instrs else eliminate subst_v' instr :: instrs)) instrs (false, [])) in 

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IMap.add v'.var_id (StateVar v) subst, instr :: instrs' 

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 _ > assert false) 

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 _ > assert false 

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with Not_found > subst, instr :: instrs 

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(** Common subexpression elimination for machine instructions *) 

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(*  [subst] : hashtable from ident to (simple) definition 

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it is an equivalence table 

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 [elim] : set of eliminated variables 

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 [instrs] : previous instructions, which [instr] is compared against 

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 [instr] : current instruction, normalized by [subst] 

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*) 

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let rec instr_cse (subst, instrs) instr = 

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match instr with 

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(* Simple cases*) 

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 MStep([v], id, vl) when Basic_library.is_internal_fun id 

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> instr_cse (subst, instrs) (MLocalAssign (v, Fun (id, vl))) 

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 MLocalAssign(v, expr) when basic_unfoldable_expr expr 

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> (IMap.add v.var_id expr subst, instr :: instrs) 

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 _ when is_assign instr 

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> subst_instr subst instrs instr 

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 _ > (subst, instr :: instrs) 

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(** Apply common subexpression elimination to a sequence of instrs 

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*) 

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let rec instrs_cse subst instrs = 

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let subst, rev_instrs = 

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List.fold_left instr_cse (subst, []) instrs 

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in subst, List.rev rev_instrs 

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(** Apply common subexpression elimination to a machine 

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 iterate through step instructions and remove simple local assigns 

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*) 

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let machine_cse subst machine = 

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(*Log.report ~level:1 (fun fmt > Format.fprintf fmt "machine_cse %a@." pp_elim subst);*) 

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let subst, instrs = instrs_cse subst machine.mstep.step_instrs in 

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let assigned = assigns_instrs instrs ISet.empty 

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in 

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{ 

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machine with 

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mmemory = List.filter (fun vdecl > ISet.mem vdecl assigned) machine.mmemory; 

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mstep = { 

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machine.mstep with 

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step_locals = List.filter (fun vdecl > ISet.mem vdecl assigned) machine.mstep.step_locals; 

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step_instrs = instrs 

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} 

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} 

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let machines_cse machines = 

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List.map 

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(machine_cse IMap.empty) 

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machines 

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(* variable substitution for optimizing purposes *) 
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(* checks whether an [instr] is skip and can be removed from program *) 
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