PR#5287: Optimized handling of partially-applied functions

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@11086 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

Changes

@@ -7,6 +7,9 @@ OCaml 3.13.0:
 Compilers:
 - Revised simplification of let-alias (PR#5205, PR#5288)
 
+Native-code compiler:
+- Optimized handling of partially-applied functions (PR#5287)
+
 Standard library:
 - Added float functions "hypot" and "copysign" (PR#3806, PR#4752, PR#5246)
 - Hashtbl:

asmcomp/closure.ml

@@ -495,6 +495,9 @@ let rec close fenv cenv = function
       end
   | Lfunction(kind, params, body) as funct ->
       close_one_function fenv cenv (Ident.create "fun") funct
+
+    (* We convert [f a] to [let a' = a in fun b c -> f a' b c] 
+       when fun_arity > nargs *)
   | Lapply(funct, args, loc) ->
       let nargs = List.length args in
       begin match (close fenv cenv funct, close_list fenv cenv args) with
@@ -507,6 +510,31 @@ let rec close fenv cenv = function
         when nargs = fundesc.fun_arity ->
           let app = direct_apply fundesc funct ufunct uargs in
           (app, strengthen_approx app approx_res)
+
+      | ((ufunct, Value_closure(fundesc, approx_res)), uargs)
+          when nargs < fundesc.fun_arity ->
+	let first_args = List.map (fun arg ->
+	  (Ident.create "arg", arg) ) uargs in
+	let final_args = Array.to_list (Array.init (fundesc.fun_arity - nargs) (fun _ ->
+	  Ident.create "arg")) in
+	let rec iter args body =
+	  match args with
+	      [] -> body
+	    | (arg1, arg2) :: args ->
+	      iter args
+		(Ulet ( arg1, arg2, body))
+	in
+	let internal_args =
+	  (List.map (fun (arg1, arg2) -> Lvar arg1) first_args)
+	  @ (List.map (fun arg -> Lvar arg ) final_args)
+	in
+	let (new_fun, approx) = close fenv cenv
+	  (Lfunction(
+	    Curried, final_args, Lapply(funct, internal_args, loc)))
+	in
+	let new_fun = iter first_args new_fun in
+	(new_fun, approx)
+
       | ((ufunct, Value_closure(fundesc, approx_res)), uargs)
         when fundesc.fun_arity > 0 && nargs > fundesc.fun_arity ->
           let (first_args, rem_args) = split_list fundesc.fun_arity uargs in

asmcomp/cmmgen.ml

@@ -1896,18 +1896,25 @@ let tuplify_function arity =
 
 (* Generate currying functions:
       (defun caml_curryN (arg clos)
-         (alloc HDR caml_curryN_1 arg clos))
+         (alloc HDR caml_curryN_1 <arity (N-1)> caml_curry_N_1_app arg clos))
       (defun caml_curryN_1 (arg clos)
-         (alloc HDR caml_curryN_2 arg clos))
+         (alloc HDR caml_curryN_2 <arity (N-2)> caml_curry_N_2_app arg clos))
       ...
       (defun caml_curryN_N-1 (arg clos)
-         (let (closN-2 clos.cdr
-               closN-3 closN-2.cdr
+         (let (closN-2 clos.vars[1]
+               closN-3 closN-2.vars[1]
                ...
-               clos1 clos2.cdr
-               clos clos1.cdr)
+               clos1 clos2.vars[1]
+               clos clos1.vars[1])
            (app clos.direct
-                clos1.car clos2.car ... closN-2.car clos.car arg clos))) *)
+                clos1.vars[0] ... closN-2.vars[0] clos.vars[0] arg clos)))
+    Special "shortcut" functions are also generated to handle the
+    case where a partially applied function is applied to all remaining
+    arguments in one go.  For instance:
+      (defun caml_curry_N_1_app (arg2 ... argN clos)
+        (let clos' clos.vars[1]
+           (app clos'.direct clos.vars[0] arg2 ... argN clos')))
+*)
 
 let final_curry_function arity =
   let last_arg = Ident.create "arg" in
@@ -1917,11 +1924,19 @@ let final_curry_function arity =
       Cop(Capply(typ_addr, Debuginfo.none),
           get_field (Cvar clos) 2 ::
           args @ [Cvar last_arg; Cvar clos])
-    else begin
+    else
+      if n = arity - 1 then
+	begin
       let newclos = Ident.create "clos" in
       Clet(newclos,
            get_field (Cvar clos) 3,
            curry_fun (get_field (Cvar clos) 2 :: args) newclos (n-1))
+	end else
+	begin
+	  let newclos = Ident.create "clos" in
+	  Clet(newclos,
+               get_field (Cvar clos) 4,
+               curry_fun (get_field (Cvar clos) 3 :: args) newclos (n-1))
     end in
   Cfunction
    {fun_name = "caml_curry" ^ string_of_int arity ^
@@ -1940,12 +1955,50 @@ let rec intermediate_curry_functions arity num =
     Cfunction
      {fun_name = name2;
       fun_args = [arg, typ_addr; clos, typ_addr];
-      fun_body = Cop(Calloc,
+      fun_body =
+	 if arity - num > 2 then
+	   Cop(Calloc,
+               [alloc_closure_header 5;
+                Cconst_symbol(name1 ^ "_" ^ string_of_int (num+1));
+                int_const (arity - num - 1);
+                Cconst_symbol(name1 ^ "_" ^ string_of_int (num+1) ^ "_app");
+		Cvar arg; Cvar clos])
+	 else
+	   Cop(Calloc,
                      [alloc_closure_header 4;
                       Cconst_symbol(name1 ^ "_" ^ string_of_int (num+1));
                       int_const 1; Cvar arg; Cvar clos]);
       fun_fast = true}
-    :: intermediate_curry_functions arity (num+1)
+    ::
+      (if arity - num > 2 then
+	  let rec iter i =
+	    if i <= arity then
+	      let arg = Ident.create (Printf.sprintf "arg%d" i) in
+	      (arg, typ_addr) :: iter (i+1)
+	    else []
+	  in
+	  let direct_args = iter (num+2) in
+	  let rec iter i args clos =
+	    if i = 0 then
+	      Cop(Capply(typ_addr, Debuginfo.none),
+		  (get_field (Cvar clos) 2) :: args @ [Cvar clos])
+	    else
+	      let newclos = Ident.create "clos" in
+	      Clet(newclos,
+		   get_field (Cvar clos) 4,
+		   iter (i-1) (get_field (Cvar clos) 3 :: args) newclos)
+	  in
+	  let cf =
+	    Cfunction
+	      {fun_name = name1 ^ "_" ^ string_of_int (num+1) ^ "_app";
+	       fun_args = direct_args @ [clos, typ_addr];
+	       fun_body = iter (num+1)
+		  (List.map (fun (arg,_) -> Cvar arg) direct_args) clos;
+	       fun_fast = true}
+	  in
+	  cf :: intermediate_curry_functions arity (num+1)
+       else
+	  intermediate_curry_functions arity (num+1))
   end
 
 let curry_function arity =