Joseph Ferano
a4c6b996ff
The trio the author decided on 2026-09-20 is now all built: def is CL's defparameter — its initialiser runs on every daemon re-run, unguarded, so an edited initialiser repaints the same storage on C-c C-c plus re-run — defonce (Clojure's name for CL's defvar, per the author) initialises once behind the .init~once. flag, and defconst stays the image. One parse arm reads both forms; the difference is Ast.reinit, carried to Tast.global's grerun. Emit.startup_plan gives a def no guard flag, and Check.check_global lifts every def initialiser — zero and literal included — into global/<n>, so the host's startup reaches it through the function cell and a re-evaluated def swaps it (Session's def_inits; Emit.redefinition declares the cell for a non-sibling target). The old defvar spelling is refused with the rename and both compiling spellings, and every program, test, doc and editor list is swept — except sand.flan, the author's live WIP, whose seven defvar lines are flagged in FIX.org and keep its three dependent tests red on this branch.
172 lines
6.6 KiB
OCaml
172 lines
6.6 KiB
OCaml
(* What redefining a generic function costs the dev loop, measured.
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The question the spike exists to answer: C-c C-c on a concrete function is
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about 35 ms today, and a generic function that is redefined has to rebuild
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*every* instantiation. So the sweep is one generic called at N concrete
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types, N = 1..8, against the handwritten N-copies program it replaces, and
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the three things a C-c C-c actually pays for are timed separately:
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check Check.program_with_env over the whole accumulated program —
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which is what Session.eval does on every evaluation, so this is
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paid whether the redefined function is generic or not.
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emit Emit.redefinition for the fns being installed.
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build llc + ld -shared, from Build.shared — the dominant term.
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Nothing here modifies the session or the dev loop; it drives the real ones. *)
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let tys = [| "i8"; "i16"; "i32"; "i64"; "u8"; "u16"; "u32"; "f32" |]
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let time f =
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let t0 = Unix.gettimeofday () in
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let x = f () in
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(x, (Unix.gettimeofday () -. t0) *. 1000.)
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(* Best of k, because llc and the linker are processes and the machine is
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noisy; a median would hide a systematic cost and a mean would report the
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scheduler. *)
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let best k f =
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let rec go i acc = if i = 0 then acc else
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let _, ms = time f in go (i - 1) (min acc ms) in
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go k infinity
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let generic_src n =
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let b = Buffer.create 1024 in
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Buffer.add_string b
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"(defn gswap [xs [$t] i i32 j i32] ()\n\
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\ (let [tmp (at xs i)]\n\
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\ (set (at xs i) (at xs j))\n\
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\ (set (at xs j) tmp)))\n\n\
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(defn gsort [s [$t] before? (Fn [$t $t] bool)] ()\n\
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\ (let [i 1]\n\
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\ (while (< i (len s))\n\
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\ (let [j i]\n\
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\ (while (and (> j 0) (before? (at s j) (at s (- j 1))))\n\
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\ (gswap s (- j 1) j)\n\
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\ (set j (- j 1))))\n\
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\ (set i (+ i 1)))))\n\n";
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for i = 0 to n - 1 do
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Buffer.add_string b (Printf.sprintf "(defonce xs-%s [8 %s])\n" tys.(i) tys.(i))
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done;
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Buffer.add_string b "\n(defn main [] ()\n";
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for i = 0 to n - 1 do
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Buffer.add_string b
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(Printf.sprintf " (gsort (slice xs-%s 0 8) (fn [a b] (< a b)))\n" tys.(i))
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done;
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Buffer.add_string b " )\n";
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Buffer.contents b
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(* The same program as it is written today: one copy of each function per
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element type, by hand. This is prelude.ml's shape. *)
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let mono_src n =
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let b = Buffer.create 1024 in
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for i = 0 to n - 1 do
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let t = tys.(i) in
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Buffer.add_string b
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(Printf.sprintf
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"(defn mswap-%s [xs [%s] i i32 j i32] ()\n\
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\ (let [tmp (at xs i)]\n\
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\ (set (at xs i) (at xs j))\n\
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\ (set (at xs j) tmp)))\n\n\
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(defn msort-%s [s [%s] before? (Fn [%s %s] bool)] ()\n\
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\ (let [i 1]\n\
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\ (while (< i (len s))\n\
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\ (let [j i]\n\
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\ (while (and (> j 0) (before? (at s j) (at s (- j 1))))\n\
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\ (mswap-%s s (- j 1) j)\n\
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\ (set j (- j 1))))\n\
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\ (set i (+ i 1)))))\n\n"
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t t t t t t t);
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Buffer.add_string b (Printf.sprintf "(defonce xs-%s [8 %s])\n\n" t t)
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done;
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Buffer.add_string b "(defn main [] ()\n";
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for i = 0 to n - 1 do
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Buffer.add_string b
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(Printf.sprintf " (msort-%s (slice xs-%s 0 8) (fn [a b] (< a b)))\n"
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tys.(i) tys.(i))
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done;
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Buffer.add_string b " )\n";
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Buffer.contents b
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let write path s =
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let oc = open_out path in output_string oc s; close_out oc
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let dir =
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let d = Filename.concat (Filename.get_temp_dir_name ()) "flan-generics-spike" in
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(try Unix.mkdir d 0o700 with Unix.Unix_error (Unix.EEXIST, _, _) -> ());
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d
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let decls_of path =
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(Flan.Load.program ~file:path
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(Flan.Parse.program (Flan.Reader.read_file path))).Flan.Load.decls
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(* Every function the program ended up with whose name starts with one of the
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generic names — the instantiations, which is exactly what a redefinition of
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the generic would have to rebuild. *)
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let instantiations (p : Flan.Tast.program) =
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List.filter_map
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(fun (f : Flan.Tast.fn) ->
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let n = f.Flan.Tast.name in
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if String.length n > 6 && String.sub n 0 6 = "gswap-" then Some n
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else if String.length n > 6 && String.sub n 0 6 = "gsort-" then Some n
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else None)
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p.Flan.Tast.fns
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let build_ms ir =
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let out = Filename.concat dir "redef.so" in
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best 3 (fun () ->
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ignore
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(Flan.Build.shared
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~opts:{ Flan.Build.default with dev = true } ~ir ~out ()))
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let () =
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Printf.printf
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"n check-gen check-mono emit-1 emit-N build-1 build-N fns\n";
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(try
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for n = 1 to 8 do
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let gpath = Filename.concat dir (Printf.sprintf "gen%d.flan" n) in
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let mpath = Filename.concat dir (Printf.sprintf "mono%d.flan" n) in
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write gpath (generic_src n);
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write mpath (mono_src n);
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let gd = decls_of gpath and md = decls_of mpath in
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let check_gen = best 3 (fun () -> ignore (Flan.Check.program_with_env gd)) in
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let check_mono = best 3 (fun () -> ignore (Flan.Check.program_with_env md)) in
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let p, _ = Flan.Check.program_with_env gd in
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let insts = instantiations p in
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let one = [ List.hd insts ] in
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let ir_one =
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Flan.Emit.redefinition ~dev:true ~known:(fun _ -> true) p ~fns:one
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in
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let ir_all =
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Flan.Emit.redefinition ~dev:true ~known:(fun _ -> true) p ~fns:insts
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in
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let emit1 =
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best 3 (fun () ->
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ignore (Flan.Emit.redefinition ~dev:true ~known:(fun _ -> true) p ~fns:one))
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and emitn =
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best 3 (fun () ->
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ignore (Flan.Emit.redefinition ~dev:true ~known:(fun _ -> true) p ~fns:insts))
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in
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let b1 = build_ms ir_one and bn = build_ms ir_all in
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Printf.printf "%d %8.1f %10.1f %7.1f %7.1f %8.1f %8.1f %d\n%!"
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n check_gen check_mono emit1 emitn b1 bn (List.length insts)
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done
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with Flan.Loc.Error d -> prerr_endline (Flan.Loc.report d); exit 1);
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(* And what the session actually does when the generic itself is redefined.
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This is the real C-c C-c path — Session.eval on the form the editor sent
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— and what it reports is the finding, not the timing. *)
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let gpath = Filename.concat dir "gen4.flan" in
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let t, _ = Flan.Session.create ~file:gpath () in
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let form =
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"(defn gswap [xs [$t] i i32 j i32] ()\n\
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\ (let [tmp (at xs i)]\n\
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\ (set (at xs i) (at xs j))\n\
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\ (set (at xs j) tmp)))\n"
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in
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let c, ms = time (fun () -> Flan.Session.eval ~origin:gpath t form) in
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Printf.printf
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"\nSession.eval on the generic gswap itself: %.1f ms, installs=%b, \
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fns=[%s], names=[%s]\n"
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ms c.Flan.Session.installs
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(String.concat " " c.Flan.Session.fns)
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(String.concat " " c.Flan.Session.names)
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