445 lines
16 KiB
OCaml
445 lines
16 KiB
OCaml
(* codegen.ml : translation of lambda terms to lists of instructions. *)
|
|
|
|
open Misc
|
|
open Asttypes
|
|
open Lambda
|
|
open Instruct
|
|
|
|
(**** Label generation ****)
|
|
|
|
let label_counter = ref 0
|
|
|
|
let new_label () =
|
|
incr label_counter; !label_counter
|
|
|
|
(**** Structure of the compilation environment. ****)
|
|
|
|
type compilation_env =
|
|
{ ce_stack: int Ident.tbl; (* Positions of variables in the stack *)
|
|
ce_heap: int Ident.tbl } (* Structure of the heap-allocated env *)
|
|
|
|
(* The ce_stack component gives locations of variables residing
|
|
in the stack. The locations are offsets w.r.t. the origin of the
|
|
stack frame.
|
|
The ce_heap component gives the positions of variables residing in the
|
|
heap-allocated environment. *)
|
|
|
|
let empty_env =
|
|
{ ce_stack = Ident.empty; ce_heap = Ident.empty }
|
|
|
|
(* Add a stack-allocated variable *)
|
|
|
|
let add_var id pos env =
|
|
{ ce_stack = Ident.add id pos env.ce_stack;
|
|
ce_heap = env.ce_heap }
|
|
|
|
(**** Examination of the continuation ****)
|
|
|
|
(* Return a label to the beginning of the given continuation.
|
|
If the sequence starts with a branch, use the target of that branch
|
|
as the label, thus avoiding a jump to a jump. *)
|
|
|
|
let label_code = function
|
|
Kbranch lbl :: _ as cont -> (lbl, cont)
|
|
| Klabel lbl :: _ as cont -> (lbl, cont)
|
|
| cont -> let lbl = new_label() in (lbl, Klabel lbl :: cont)
|
|
|
|
(* Return a branch to the continuation. That is, an instruction that,
|
|
when executed, branches to the continuation or performs what the
|
|
continuation performs. We avoid generating branches to branches and
|
|
branches to returns. *)
|
|
|
|
let make_branch cont =
|
|
match cont with
|
|
(Kbranch _ as branch) :: _ -> (branch, cont)
|
|
| (Kreturn _ as return) :: _ -> (return, cont)
|
|
| Kraise :: _ -> (Kraise, cont)
|
|
| Klabel lbl :: _ -> (Kbranch lbl, cont)
|
|
| _ -> let lbl = new_label() in (Kbranch lbl, Klabel lbl :: cont)
|
|
|
|
(* Discard all instructions up to the next label.
|
|
This function is to be applied to the continuation before adding a
|
|
non-terminating instruction (branch, raise, return) in front of it. *)
|
|
|
|
let rec discard_dead_code = function
|
|
[] -> []
|
|
| (Klabel _ | Krestart) :: _ as cont -> cont
|
|
| _ :: cont -> discard_dead_code cont
|
|
|
|
(* Check if we're in tailcall position *)
|
|
|
|
let rec is_tailcall = function
|
|
Kreturn _ :: _ -> true
|
|
| Klabel _ :: c -> is_tailcall c
|
|
| _ -> false
|
|
|
|
(* Add a Kpop N instruction in front of a continuation *)
|
|
|
|
let rec add_pop n cont =
|
|
if n = 0 then cont else
|
|
match cont with
|
|
Kpop m :: cont -> add_pop (n + m) cont
|
|
| Kreturn m :: cont -> Kreturn(n + m) :: cont
|
|
| Kraise :: _ -> cont
|
|
| _ -> Kpop n :: cont
|
|
|
|
(* Add the constant "unit" in front of a continuation *)
|
|
|
|
let add_const_unit = function
|
|
(Kacc _ | Kconst _ | Kgetglobal _ | Kpush_retaddr _) :: _ as cont -> cont
|
|
| cont -> Kconst const_unit :: cont
|
|
|
|
(**** Compilation of a lambda expression ****)
|
|
|
|
(* The label to which Lstaticfail branches, and the stack size at that point.*)
|
|
|
|
let lbl_staticfail = ref 0
|
|
and sz_staticfail = ref 0
|
|
|
|
(* Function bodies that remain to be compiled *)
|
|
|
|
let functions_to_compile =
|
|
(Stack.new () : (Ident.t * lambda * label * Ident.t list) Stack.t)
|
|
|
|
(* Compile an expression.
|
|
The value of the expression is left in the accumulator.
|
|
env = compilation environment
|
|
exp = the lambda expression to compile
|
|
sz = current size of the stack frame
|
|
cont = list of instructions to execute afterwards
|
|
Result = list of instructions that evaluate exp, then perform cont. *)
|
|
|
|
open Format
|
|
|
|
let rec comp_expr env exp sz cont =
|
|
match exp with
|
|
Lvar id ->
|
|
begin try
|
|
let pos = Ident.find_same id env.ce_stack in
|
|
Kacc(sz - pos) :: cont
|
|
with Not_found ->
|
|
try
|
|
let pos = Ident.find_same id env.ce_heap in
|
|
Kenvacc(pos) :: cont
|
|
with Not_found ->
|
|
Ident.print id; print_newline();
|
|
fatal_error "Codegen.comp_expr: var"
|
|
end
|
|
| Lconst cst ->
|
|
Kconst cst :: cont
|
|
| Lapply(func, args) ->
|
|
let nargs = List.length args in
|
|
if is_tailcall cont then
|
|
comp_args env args sz
|
|
(Kpush :: comp_expr env func (sz + nargs)
|
|
(Kappterm(nargs, sz + nargs) :: discard_dead_code cont))
|
|
else
|
|
if nargs < 4 then
|
|
comp_args env args sz
|
|
(Kpush :: comp_expr env func (sz + nargs) (Kapply nargs :: cont))
|
|
else begin
|
|
let (lbl, cont1) = label_code cont in
|
|
Kpush_retaddr lbl ::
|
|
comp_args env args (sz + 3)
|
|
(Kpush :: comp_expr env func (sz + 3 + nargs)
|
|
(Kapply nargs :: cont1))
|
|
end
|
|
| Lfunction(param, body) ->
|
|
let lbl = new_label() in
|
|
let fv = free_variables exp in
|
|
Stack.push (param, body, lbl, fv) functions_to_compile;
|
|
comp_args env (List.map (fun n -> Lvar n) fv) sz
|
|
(Kclosure(lbl, List.length fv) :: cont)
|
|
| Llet(id, arg, body) ->
|
|
comp_expr env arg sz
|
|
(Kpush :: comp_expr (add_var id (sz+1) env) body (sz+1)
|
|
(add_pop 1 cont))
|
|
| Lletrec(([id, Lfunction(param, funct_body), _] as decl), let_body) ->
|
|
let lbl = new_label() in
|
|
let fv = free_variables (Lletrec(decl, lambda_unit)) in
|
|
Stack.push (param, funct_body, lbl, id :: fv) functions_to_compile;
|
|
comp_args env (List.map (fun n -> Lvar n) fv) sz
|
|
(Kclosurerec(lbl, List.length fv) :: Kpush ::
|
|
(comp_expr (add_var id (sz+1) env) let_body (sz+1)
|
|
(add_pop 1 cont)))
|
|
| Lletrec(decl, body) ->
|
|
let ndecl = List.length decl in
|
|
let rec comp_decl new_env sz i = function
|
|
[] ->
|
|
comp_expr new_env body sz (add_pop ndecl cont)
|
|
| (id, exp, blocksize) :: rem ->
|
|
comp_expr new_env exp sz
|
|
(Kpush :: Kacc i :: Kupdate blocksize ::
|
|
comp_decl new_env sz (i-1) rem) in
|
|
let rec comp_init new_env sz = function
|
|
[] ->
|
|
comp_decl new_env sz ndecl decl
|
|
| (id, exp, blocksize) :: rem ->
|
|
Kdummy blocksize :: Kpush ::
|
|
comp_init (add_var id (sz+1) new_env) (sz+1) rem in
|
|
comp_init env sz decl
|
|
| Lprim(Pidentity, [arg]) ->
|
|
comp_expr env arg sz cont
|
|
| Lprim(Pnot, [arg]) ->
|
|
let newcont =
|
|
match cont with
|
|
Kbranchif lbl :: cont1 -> Kbranchifnot lbl :: cont1
|
|
| Kbranchifnot lbl :: cont1 -> Kbranchif lbl :: cont1
|
|
| _ -> Kboolnot :: cont in
|
|
comp_expr env arg sz newcont
|
|
| Lprim(Psequand, [exp1; exp2]) ->
|
|
begin match cont with
|
|
Kbranchifnot lbl :: _ ->
|
|
comp_expr env exp1 sz (Kbranchifnot lbl ::
|
|
comp_expr env exp2 sz cont)
|
|
| Kbranchif lbl :: cont1 ->
|
|
let (lbl2, cont2) = label_code cont1 in
|
|
comp_expr env exp1 sz (Kbranchifnot lbl2 ::
|
|
comp_expr env exp2 sz (Kbranchif lbl :: cont2))
|
|
| _ ->
|
|
let (lbl, cont1) = label_code cont in
|
|
comp_expr env exp1 sz (Kstrictbranchifnot lbl ::
|
|
comp_expr env exp2 sz cont1)
|
|
end
|
|
| Lprim(Psequor, [exp1; exp2]) ->
|
|
begin match cont with
|
|
Kbranchif lbl :: _ ->
|
|
comp_expr env exp1 sz (Kbranchif lbl ::
|
|
comp_expr env exp2 sz cont)
|
|
| Kbranchifnot lbl :: cont1 ->
|
|
let (lbl2, cont2) = label_code cont1 in
|
|
comp_expr env exp1 sz (Kbranchif lbl2 ::
|
|
comp_expr env exp2 sz (Kbranchifnot lbl :: cont2))
|
|
| _ ->
|
|
let (lbl, cont1) = label_code cont in
|
|
comp_expr env exp1 sz (Kstrictbranchif lbl ::
|
|
comp_expr env exp2 sz cont1)
|
|
end
|
|
| Lprim(Praise, [arg]) ->
|
|
comp_expr env arg sz (Kraise :: discard_dead_code cont)
|
|
| Lprim((Paddint | Psubint as prim), [arg; Lconst(Const_base(Const_int n))])
|
|
when n >= immed_min & n <= immed_max ->
|
|
let ofs = if prim == Paddint then n else -n in
|
|
comp_expr env arg sz (Koffsetint ofs :: cont)
|
|
| Lprim(p, args) ->
|
|
let instr =
|
|
match p with
|
|
Pgetglobal id -> Kgetglobal id
|
|
| Psetglobal id -> Ksetglobal id
|
|
| Pintcomp cmp -> Kintcomp cmp
|
|
| Pmakeblock tag -> Kmakeblock(List.length args, tag)
|
|
| Pfield n -> Kgetfield n
|
|
| Psetfield n -> Ksetfield n
|
|
| Pccall(name, n) -> Kccall(name, n)
|
|
| Pnegint -> Knegint
|
|
| Paddint -> Kaddint
|
|
| Psubint -> Ksubint
|
|
| Pmulint -> Kmulint
|
|
| Pdivint -> Kdivint
|
|
| Pmodint -> Kmodint
|
|
| Pandint -> Kandint
|
|
| Porint -> Korint
|
|
| Pxorint -> Kxorint
|
|
| Plslint -> Klslint
|
|
| Plsrint -> Klsrint
|
|
| Pasrint -> Kasrint
|
|
| Poffsetint n -> Koffsetint n
|
|
| Poffsetref n -> Koffsetref n
|
|
| Pnegfloat -> Kccall("neg_float", 1)
|
|
| Paddfloat -> Kccall("add_float", 2)
|
|
| Psubfloat -> Kccall("sub_float", 2)
|
|
| Pmulfloat -> Kccall("mul_float", 2)
|
|
| Pdivfloat -> Kccall("div_float", 2)
|
|
| Pfloatcomp Ceq -> Kccall("eq_float", 2)
|
|
| Pfloatcomp Cneq -> Kccall("neq_float", 2)
|
|
| Pfloatcomp Clt -> Kccall("lt_float", 2)
|
|
| Pfloatcomp Cgt -> Kccall("gt_float", 2)
|
|
| Pfloatcomp Cle -> Kccall("le_float", 2)
|
|
| Pfloatcomp Cge -> Kccall("ge_float", 2)
|
|
| Pgetstringchar -> Kgetstringchar
|
|
| Psetstringchar -> Ksetstringchar
|
|
| Pvectlength -> Kvectlength
|
|
| Pgetvectitem -> Kgetvectitem
|
|
| Psetvectitem -> Ksetvectitem
|
|
| Ptranslate tbl -> Ktranslate tbl
|
|
| _ -> fatal_error "Codegen.comp_expr: prim" in
|
|
comp_args env args sz (instr :: cont)
|
|
| Lcatch(body, Lstaticfail) ->
|
|
comp_expr env body sz cont
|
|
| Lcatch(body, handler) ->
|
|
let (branch1, cont1) = make_branch cont in
|
|
let (lbl_handler, cont2) = label_code (comp_expr env handler sz cont1) in
|
|
let saved_lbl_staticfail = !lbl_staticfail
|
|
and saved_sz_staticfail = !sz_staticfail in
|
|
lbl_staticfail := lbl_handler;
|
|
sz_staticfail := sz;
|
|
let cont3 = comp_expr env body sz (branch1 :: cont2) in
|
|
lbl_staticfail := saved_lbl_staticfail;
|
|
sz_staticfail := saved_sz_staticfail;
|
|
cont3
|
|
| Lstaticfail ->
|
|
add_pop (sz - !sz_staticfail)
|
|
(Kbranch !lbl_staticfail :: discard_dead_code cont)
|
|
| Ltrywith(body, id, handler) ->
|
|
let (branch1, cont1) = make_branch cont in
|
|
let lbl_handler = new_label() in
|
|
Kpushtrap lbl_handler ::
|
|
comp_expr env body (sz+4) (Kpoptrap :: branch1 ::
|
|
Klabel lbl_handler :: Kpush ::
|
|
comp_expr (add_var id (sz+1) env) handler (sz+1) (add_pop 1 cont1))
|
|
| Lifthenelse(cond, ifso, ifnot) ->
|
|
comp_binary_test env cond ifso ifnot sz cont
|
|
| Lsequence(exp1, exp2) ->
|
|
comp_expr env exp1 sz (comp_expr env exp2 sz cont)
|
|
| Lwhile(cond, body) ->
|
|
let lbl_loop = new_label() in
|
|
let lbl_test = new_label() in
|
|
Kbranch lbl_test :: Klabel lbl_loop :: Kcheck_signals ::
|
|
comp_expr env body sz
|
|
(Klabel lbl_test ::
|
|
comp_expr env cond sz (Kbranchif lbl_loop :: add_const_unit cont))
|
|
| Lfor(param, start, stop, dir, body) ->
|
|
let lbl_loop = new_label() in
|
|
let lbl_test = new_label() in
|
|
let offset = match dir with Upto -> 1 | Downto -> -1 in
|
|
let comp = match dir with Upto -> Cle | Downto -> Cge in
|
|
comp_expr env start sz
|
|
(Kpush :: comp_expr env stop (sz+1)
|
|
(Kpush :: Kbranch lbl_test ::
|
|
Klabel lbl_loop :: Kcheck_signals ::
|
|
comp_expr (add_var param (sz+1) env) body (sz+2)
|
|
(Kacc 1 :: Koffsetint offset :: Kassign 1 ::
|
|
Klabel lbl_test ::
|
|
Kacc 0 :: Kpush :: Kacc 2 :: Kintcomp comp ::
|
|
Kbranchif lbl_loop ::
|
|
add_const_unit (add_pop 2 cont))))
|
|
| Lswitch(arg, num_consts, consts, num_blocks, blocks) ->
|
|
(* To ensure stack balancing, we must have either sz = !sz_staticfail
|
|
or none of the actv.(i) contains an unguarded Lstaticfail. *)
|
|
let (branch, cont1) = make_branch cont in
|
|
let c = ref (discard_dead_code cont1) in
|
|
let act_consts = Array.new num_consts Lstaticfail in
|
|
List.iter (fun (n, act) -> act_consts.(n) <- act) consts;
|
|
let act_blocks = Array.new num_blocks Lstaticfail in
|
|
List.iter (fun (n, act) -> act_blocks.(n) <- act) blocks;
|
|
let lbl_consts = Array.new num_consts 0 in
|
|
let lbl_blocks = Array.new num_blocks 0 in
|
|
for i = num_blocks - 1 downto 0 do
|
|
let (lbl, c1) =
|
|
label_code(comp_expr env act_blocks.(i) sz (branch :: !c)) in
|
|
lbl_blocks.(i) <- lbl;
|
|
c := discard_dead_code c1
|
|
done;
|
|
for i = num_consts - 1 downto 0 do
|
|
let (lbl, c1) =
|
|
label_code(comp_expr env act_consts.(i) sz (branch :: !c)) in
|
|
lbl_consts.(i) <- lbl;
|
|
c := discard_dead_code c1
|
|
done;
|
|
comp_expr env arg sz (Kswitch(lbl_consts, lbl_blocks) :: !c)
|
|
| Lshared(expr, lblref) ->
|
|
begin match !lblref with
|
|
None ->
|
|
let (lbl, cont1) = label_code(comp_expr env expr sz cont) in
|
|
lblref := Some lbl;
|
|
cont1
|
|
| Some lbl ->
|
|
Kbranch lbl :: discard_dead_code cont
|
|
end
|
|
|
|
(* Compile a list of arguments [e1; ...; eN] to a primitive operation.
|
|
The values of eN ... e2 are pushed on the stack, e2 at top of stack,
|
|
then e3, then ... The value of e1 is left in the accumulator. *)
|
|
|
|
and comp_args env argl sz cont =
|
|
comp_expr_list env (List.rev argl) sz cont
|
|
|
|
and comp_expr_list env exprl sz cont =
|
|
match exprl with
|
|
[] -> cont
|
|
| [exp] -> comp_expr env exp sz cont
|
|
| exp :: rem ->
|
|
comp_expr env exp sz (Kpush :: comp_expr_list env rem (sz+1) cont)
|
|
|
|
(* Compile an if-then-else test. *)
|
|
|
|
and comp_binary_test env cond ifso ifnot sz cont =
|
|
let cont_cond =
|
|
if ifnot = Lconst const_unit then begin
|
|
let (lbl_end, cont1) = label_code cont in
|
|
Kbranchifnot lbl_end :: comp_expr env ifso sz cont1
|
|
end else
|
|
if ifso = Lstaticfail & sz = !sz_staticfail then
|
|
Kbranchif !lbl_staticfail :: comp_expr env ifnot sz cont
|
|
else
|
|
if ifnot = Lstaticfail & sz = !sz_staticfail then
|
|
Kbranchifnot !lbl_staticfail :: comp_expr env ifso sz cont
|
|
else begin
|
|
let (branch_end, cont1) = make_branch cont in
|
|
let (lbl_not, cont2) = label_code(comp_expr env ifnot sz cont1) in
|
|
Kbranchifnot lbl_not :: comp_expr env ifso sz (branch_end :: cont2)
|
|
end in
|
|
comp_expr env cond sz cont_cond
|
|
|
|
(**** Compilation of functions ****)
|
|
|
|
let comp_function (param, body, entry_lbl, free_vars) cont =
|
|
(* Uncurry the function body *)
|
|
let rec uncurry = function
|
|
Lfunction(param, body) ->
|
|
let (params, final) = uncurry body in (param :: params, final)
|
|
| Lshared(exp, lblref) ->
|
|
uncurry exp
|
|
| exp ->
|
|
([], exp) in
|
|
let (params, fun_body) =
|
|
uncurry (Lfunction(param, body)) in
|
|
let arity = List.length params in
|
|
let rec pos_args pos delta = function
|
|
[] -> Ident.empty
|
|
| id :: rem -> Ident.add id pos (pos_args (pos+delta) delta rem) in
|
|
let env =
|
|
{ ce_stack = pos_args arity (-1) params;
|
|
ce_heap = pos_args 0 1 free_vars } in
|
|
let cont1 =
|
|
comp_expr env fun_body arity (Kreturn arity :: cont) in
|
|
if arity > 1 then
|
|
Krestart :: Klabel entry_lbl :: Kgrab(arity - 1) :: cont1
|
|
else
|
|
Klabel entry_lbl :: cont1
|
|
|
|
let comp_remainder cont =
|
|
let c = ref cont in
|
|
begin try
|
|
while true do
|
|
c := comp_function (Stack.pop functions_to_compile) !c
|
|
done
|
|
with Stack.Empty ->
|
|
()
|
|
end;
|
|
!c
|
|
|
|
(**** Compilation of a lambda phrase ****)
|
|
|
|
let compile_implementation expr =
|
|
Stack.clear functions_to_compile;
|
|
label_counter := 0;
|
|
lbl_staticfail := 0;
|
|
sz_staticfail := 0;
|
|
let init_code = comp_expr empty_env expr 0 [] in
|
|
if Stack.length functions_to_compile > 0 then begin
|
|
let lbl_init = new_label() in
|
|
Kbranch lbl_init :: comp_remainder (Klabel lbl_init :: init_code)
|
|
end else
|
|
init_code
|
|
|
|
let compile_phrase expr =
|
|
Stack.clear functions_to_compile;
|
|
label_counter := 0;
|
|
lbl_staticfail := 0;
|
|
sz_staticfail := 0;
|
|
let init_code = comp_expr empty_env expr 0 [Kstop] in
|
|
let fun_code = comp_remainder [] in
|
|
(init_code, fun_code)
|
|
|