flan/bin/main.ml
Joseph Ferano 1a1486a17b The compiler moves into the program, and the socket does not move at all
`flan dev` now builds one binary that is the compiled Flan program and holds
the whole OCaml compiler, and execs it. The program keeps main() — macOS needs
the window there — and caml_startup happens on a pthread beside it, next to the
listener flan_agent.c already starts. The editor's socket and the wire protocol
are untouched: Emacs cannot tell the difference.

Two rules are written into lib/dev.ml rather than discovered later. The game
thread must never call into OCaml, because a native thread has no safe points
and so can never be stopped by the collector — which is exactly why a frame is
never paused, and exactly what one convenient direct call would undo. And no
OCaml value may be stored in Flan memory without caml_register_global_root,
which is the way the spike's "the GC does not touch the arenas" measurement
stops being true.

The link is spelled in dev.ml out of Build's existing public pieces rather than
as a mode of Build.executable: lib/build.ml belongs to another lane this week.
It should collapse into Build once that lands.

A Flan main does not return — Emit ends it with flan_exit and an unreachable —
so in one process that call would take the compiler down with a program that
merely finished. flan_rt.c grows a hook, null in every other build, that the
merged entry point uses to flush, close stdout and park. The compiler then
learns the program is done the same way the daemon did: the pipe reads EOF.

--two-process keeps the old shape for a machine that cannot build the compiler
object, and nothing has been deleted.
2026-09-12 21:44:57 +07:00

407 lines
18 KiB
OCaml

(* flan — milestone 2 driver. *)
let with_errors path f =
try f () with
| Flan.Loc.Error (loc, msg) ->
Printf.eprintf "%s: %s\n" (Flan.Loc.to_string loc) msg;
ignore path;
exit 1
let summarise (d : Flan.Ast.decl) =
let open Flan.Ast in
match d.d with
| Package n -> Printf.sprintf "package %s" n
| Import (a, p) -> Printf.sprintf "import %s %S" a p
| Defalias (n, _) -> Printf.sprintf "defalias %s" n
| Defstruct (n, fs) -> Printf.sprintf "defstruct %s (%d fields)" n (List.length fs)
| Defunion (n, vs) -> Printf.sprintf "defunion %s (%d cases)" n (List.length vs)
| Defvar (n, _, _) -> Printf.sprintf "defvar %s" n
| Defconst (n, _, _) -> Printf.sprintf "defconst %s" n
| Declare (fn, csym) ->
Printf.sprintf "declare %s (%d params) = %s" fn.name (List.length fn.params)
csym
| DeclareC (fn, csym) ->
Printf.sprintf "declare-c %s (%d params) = %s" fn.name
(List.length fn.params) csym
| Defenum (n, ms) -> Printf.sprintf "defenum %s (%d members)" n (List.length ms)
| Defn fn ->
Printf.sprintf "defn %s (%d params, %s return, %d body forms)"
fn.name (List.length fn.params)
(match fn.ret with None -> "Unit" | Some _ -> "explicit")
(List.length fn.fbody)
(* Every path past [parse] goes through [Load]: an import is resolved into the
declarations it stands for, and the package's C shim and linker arguments
come back with them. *)
let load path : Flan.Load.t =
Flan.Load.program ~file:path (Flan.Parse.program (Flan.Reader.read_file path))
let checked path = Flan.Check.program (load path).decls
(* What the source called each parameter, per function. The typed IR refers to
locals by slot index and records no names — [Check] has them in its scope
list and drops them — so the debug info would otherwise print [p0] for
every argument. Slots 0..n-1 are the parameters in order ([Tast.fn]), which
is what makes this recoverable here, from declarations that are already in
hand, rather than needing a change to the typed IR. It stops at the
parameters: a let-bound local's name is genuinely not available without one.
Only gathered for a debug build. *)
let param_names (l : Flan.Load.t) =
List.filter_map
(fun (d : Flan.Ast.decl) ->
match d.Flan.Ast.d with
| Flan.Ast.Defn fn ->
Some (fn.Flan.Ast.name,
List.map (fun (p : Flan.Ast.field) -> p.Flan.Ast.fname)
fn.Flan.Ast.params)
| _ -> None)
l.Flan.Load.decls
(* Bounds checks are on unless a build asks for them off — the release
decision, not the optimisation level (NEXT.md, Bounds checks). *)
let no_checks_flag = "--no-bounds-checks"
(* A dev build is the one a REPL can attach to: every call goes through a cell
so a redefinition can be installed, and the cells and globals are exported
so a loaded module can reach them (NEXT.md, the dev loop). *)
let dev_flag = "--dev"
(* Source-level debugging: DWARF in the IR, -g on the C, and -O0 forced.
Its own flag and not a mode of --dev, because the two answer different
questions — --dev is "can I redefine this while it runs", --debug is "can I
stop it and read it". See [Build.opts]. *)
let debug_flag = "--debug"
(* ASan and UBSan over the whole program, the runtime's C and the Flan alike.
Its own flag for the same reason --debug is: it answers "is this program
touching memory it does not own", which is neither of the other two
questions. It does not imply -O0 — see [Build.opts], which also records
what each of the two sanitizers actually reaches. *)
let sanitize_flag = "--sanitize"
(* [flan dev] builds one binary that is the program and holds the compiler,
and serves the editor from a thread inside it. This asks for the old shape
instead — a compiler process that launches the program and talks to it over
a socket. It is the escape hatch for a machine that cannot build the
compiler object (no ocamlfind, no flan.cmxa beside this binary), not a
preference, and it goes away with the transport it drives. *)
let two_process_flag = "--two-process"
let flags =
[ no_checks_flag; dev_flag; debug_flag; sanitize_flag; two_process_flag ]
(* [--target=wasm32-wasi] and [--target=web], the two cross targets. Unlike
the flags above, a target
carries a value, so it is matched by prefix and stripped from the residual
arguments by the same test — otherwise [-o out --target=X] falls into the
usage error. *)
let target_prefix = "--target="
let is_flag a =
List.mem a flags || String.starts_with ~prefix:target_prefix a
let target_of args =
List.find_map
(fun a ->
if String.starts_with ~prefix:target_prefix a then
Some (String.sub a (String.length target_prefix)
(String.length a - String.length target_prefix))
else None)
args
let () =
match Array.to_list Sys.argv with
| _ :: "read" :: files when files <> [] ->
List.iter
(fun path ->
with_errors path (fun () ->
Flan.Reader.read_file path
|> List.iter (fun f -> print_endline (Flan.Form.to_string f))))
files
| _ :: "parse" :: files when files <> [] ->
List.iter
(fun path ->
with_errors path (fun () ->
Flan.Reader.read_file path
|> Flan.Parse.program
|> List.iter (fun d -> print_endline (summarise d))))
files
| _ :: "check" :: files when files <> [] ->
List.iter
(fun path ->
with_errors path (fun () ->
let p = checked path in
List.iter
(fun (g : Flan.Tast.global) ->
Printf.printf "%s %s %s\n"
(if g.gconst then "defconst" else "defvar")
g.gname (Flan.Types.to_string g.gty))
p.globals;
List.iter
(fun (f : Flan.Tast.fn) ->
Printf.printf "defn %s : (Fn [%s] %s) %d slots\n" f.name
(String.concat " "
(List.map Flan.Types.to_string f.params))
(Flan.Types.to_string f.ret) (Array.length f.slots))
p.fns))
files
(* The generated C, for looking at. A wrong FFI binding is wrong in the
wrapper, and the wrapper is not on disk anywhere — [Build] hands the text
straight to clang — so without this the only way to read one is to catch
it in the object cache. *)
| _ :: "shim" :: files when files <> [] ->
List.iter
(fun path ->
with_errors path (fun () ->
match (checked path).Flan.Tast.cshim with
| [] -> Printf.printf "%s: no declare-c, so no generated C\n" path
| parts -> List.iter (fun (_, src) -> print_string src) parts))
files
(* A header, read. The importer is a pure function of the header and the
package beside it, so it can be looked at without building anything —
which is what makes the diff against a hand-written binding possible, and
what makes "generate once and commit the result" a usable option rather
than a description of one. Prints the declarations it would produce, then
what it refused and why, then how the package's defstructs compare with
the header's records. *)
| _ :: "import-c" :: header :: rest ->
with_errors header (fun () ->
let pkg = List.filter (fun a -> Filename.check_suffix a ".flan") rest in
let flags =
List.filter (fun a -> not (Filename.check_suffix a ".flan")) rest
in
let ds =
List.concat_map
(fun f -> Flan.Parse.program (Flan.Reader.read_file f)) pkg
in
let structs =
List.filter_map
(fun (d : Flan.Ast.decl) ->
match d.Flan.Ast.d with
| Flan.Ast.Defstruct (n, fs) -> Some (n, fs)
| _ -> None)
ds
in
let known_enums =
List.filter_map
(fun (d : Flan.Ast.decl) ->
match d.Flan.Ast.d with
| Flan.Ast.Defenum (n, _) -> Some n
| _ -> None)
ds
in
let taken = Hashtbl.create 64 in
List.iter
(fun d ->
match Flan.Ast.declared_name d with
| Some n -> Hashtbl.replace taken n ()
| None -> ())
ds;
let bound_syms =
List.filter_map
(fun (d : Flan.Ast.decl) ->
match d.Flan.Ast.d with
| Flan.Ast.Declare (_, s) | Flan.Ast.DeclareC (_, s) -> Some s
| _ -> None)
ds
in
let imported, dump, env =
Flan.Cimport.header ~loc:(Flan.Loc.make header 0 0) ~header ~flags
~known_structs:(List.map fst structs) ~known_enums ~taken ~bound_syms
in
List.iter
(fun d -> print_endline (Flan.Cimport.decl_source d))
imported.Flan.Cimport.decls;
Printf.printf "\n;; %d imported, %d refused, of %d functions in %s\n"
(List.length imported.Flan.Cimport.decls)
(List.length imported.Flan.Cimport.hidden)
(List.length dump.Flan.Cimport.fns) header;
List.iter
(fun (n, why) -> Printf.printf ";; refused %s: %s\n" n why)
imported.Flan.Cimport.hidden;
(match Flan.Cimport.check_structs ~env ~structs dump with
| [] ->
if structs <> [] then
Printf.printf ";; every defstruct agrees with the header\n"
| bad ->
List.iter
(fun (n, why) -> Printf.printf ";; DISAGREES %s: %s\n" n why)
bad);
(* And the bindings the package already wrote by hand, against the
header's own signatures. Nothing else in the build can do this: a
wrong declare-c is wrong in the generated prototype too, so the two
agree with each other and only the library disagrees. *)
let bound =
List.filter_map
(fun (d : Flan.Ast.decl) ->
match d.Flan.Ast.d with
| Flan.Ast.DeclareC (fn, sym) -> Some (fn, sym)
| _ -> None)
ds
in
if bound <> [] then
match Flan.Cimport.diff_bound ~env ~bound dump with
| [] ->
Printf.printf
";; all %d hand-written declare-c agree with the header\n"
(List.length bound)
| ds ->
Printf.printf ";; %d of %d hand-written declare-c disagree\n"
(List.length ds) (List.length bound);
List.iter
(fun (x : Flan.Cimport.sig_diff) ->
Printf.printf ";; DIFFERS %s (%s): %s\n"
x.Flan.Cimport.dflan x.Flan.Cimport.dsym x.Flan.Cimport.dwhy)
ds)
(* The IR is target-independent — [Emit] writes no triple and no datalayout,
which is what lets one .ll serve both targets — so there is nothing for a
target to change here. Refused rather than accepted and ignored: silently
swallowing a flag is the shape the house rule exists to prevent. *)
| _ :: "emit" :: args when target_of args <> None ->
prerr_endline
"flan emit: --target is refused — the emitted IR carries no triple and \
no datalayout, and the target is chosen at build.";
exit 2
| _ :: "emit" :: args when List.exists (fun a -> not (is_flag a)) args ->
let checks = not (List.mem no_checks_flag args) in
let dev = List.mem dev_flag args in
let debug = List.mem debug_flag args in
(* --sanitize changes the IR — every [define] names the attribute group
ASan's pass selects on — so [emit] has to honour it or what this prints
is not what a sanitized build compiles. *)
let sanitize = List.mem sanitize_flag args in
let files = List.filter (fun a -> not (is_flag a)) args in
List.iter
(fun path ->
with_errors path (fun () ->
let l = load path in
let pnames = if debug then param_names l else [] in
Flan.Check.program l.decls
|> Flan.Emit.program ~checks ~dev ~debug ~pnames ~sanitize
|> print_string))
files
| _ :: "build" :: path :: rest ->
let checks = not (List.mem no_checks_flag rest) in
let dev = List.mem dev_flag rest in
let debug = List.mem debug_flag rest in
let sanitize = List.mem sanitize_flag rest in
let target = target_of rest in
let out =
match List.filter (fun a -> not (is_flag a)) rest with
| [ "-o"; o ] -> o
| [] ->
let base = Filename.remove_extension (Filename.basename path) in
(* A wasm module is not an executable and must not be named like one:
the extension is what tells a runtime, and a reader, what it is. *)
(* A web build is three files — the page, its JS and the module — and
the page is the one named here: emcc derives the other two from it,
and it is the one a browser opens. *)
(match target with
| Some t when Flan.Build.is_web t -> base ^ ".html"
| Some t when String.starts_with ~prefix:"wasm32" t -> base ^ ".wasm"
| _ -> base)
| _ ->
prerr_endline
"usage: flan build <file.flan> [-o out] [--no-bounds-checks] \
[--dev] [--debug] [--sanitize] [--target=wasm32-wasi|web]";
exit 2
in
with_errors path (fun () ->
let l = load path in
let p = Flan.Check.program l.decls in
(* The link follows the program, not the import list: a package nothing
reachable calls into contributes no C and no linker argument, and its
functions are not emitted either. That is what lets one file import
raylib and still be buildable for wasm32. *)
let p, csrcs, lflags = Flan.Reach.link ~dev l p in
ignore (Flan.Build.executable
~opts:{ Flan.Build.default with checks; dev; debug; sanitize;
target }
~csrcs ~lflags ~pnames:(if debug then param_names l else [])
p ~out))
(* The daemon an editor talks to: one session, the program it belongs to
running beside it, and a socket. Unlike [flan reload] the session persists,
so a defvar added by one evaluation is part of what the next one is checked
against — and it owns the build, which is what makes its layout rules
describe the process that is actually running. *)
| _ :: "dev" :: path :: rest ->
(* --debug builds the host *and* every module this daemon sends with DWARF,
which is one flag because it is one decision: a line breakpoint in a
.flan buffer needs a line table on the host to fire at all, and one in
each redefinition module to still be firing after C-c C-c. It implies
-O0 on both, so it is asked for rather than assumed. *)
let debug = List.mem debug_flag rest in
let merged = not (List.mem two_process_flag rest) in
let rest = List.filter (fun a -> not (is_flag a)) rest in
let sock =
match rest with
| [ "-s"; s ] -> s
| [] -> Filename.concat (Filename.dirname path) ".flan-dev.sock"
| _ ->
prerr_endline
"usage: flan dev <program.flan> [-s socket] [--debug] [--two-process]";
exit 2
in
with_errors path (fun () -> Flan.Dev.start ~debug ~merged ~file:path ~sock ())
(* One redefinition, built the way an editor will ask for it: a session over
the program the process was built from, and a file of the forms that
changed. The session works out which names are new and whether the change
is one a running process can be told at all — neither of which a command
given only a list of function names could. *)
| _ :: "reload" :: prog :: forms :: rest ->
let debug = List.mem debug_flag rest in
let rest = List.filter (fun a -> not (is_flag a)) rest in
let out =
match rest with
| [ "-o"; o ] -> o
| [] -> Filename.remove_extension (Filename.basename forms) ^ ".so"
| _ ->
prerr_endline
"usage: flan reload <program.flan> <forms.flan> [-o out.so] [--debug]";
exit 2
in
with_errors forms (fun () ->
let t, _ = Flan.Session.create ~debug ~file:prog () in
let src = In_channel.with_open_bin forms In_channel.input_all in
let c = Flan.Session.eval ~origin:forms t src in
let opts = { Flan.Build.default with dev = true; debug } in
let timing = Flan.Build.shared ~opts ~ir:c.Flan.Session.ir ~out () in
Printf.eprintf "%s %s llc %.1fms ld %.1fms\n" out
(String.concat " " c.Flan.Session.fns) timing.Flan.Build.llc_ms
timing.Flan.Build.link_ms)
(* [run] builds and execs. A .wasm is not executable, and picking a runtime
for it is a decision this command has no business making, so a cross
target is refused here by name rather than half-supported. *)
| _ :: "run" :: _ :: args when target_of args <> None ->
prerr_endline
"flan run: --target is refused — a cross-built module is not something \
this host can exec. Use flan build --target=... and a wasm runtime.";
exit 2
| _ :: "run" :: path :: args ->
with_errors path (fun () ->
let exe =
Filename.concat (Filename.get_temp_dir_name ())
(Printf.sprintf "flan-run-%d" (Unix.getpid ()))
in
let l = load path in
let p = Flan.Check.program l.decls in
let p, csrcs, lflags = Flan.Reach.link l p in
ignore (Flan.Build.executable ~csrcs ~lflags p ~out:exe);
let code =
Sys.command (String.concat " " (List.map Filename.quote (exe :: args)))
in
(try Sys.remove exe with Sys_error _ -> ());
exit code)
| _ ->
prerr_endline
"usage: flan (read|parse|check|emit|shim) <file.flan>...\n\
\ flan import-c <header.h> [package.flan...] [clang flags...]\n\
\ flan build <file.flan> [-o out] [--no-bounds-checks] [--dev] \
[--debug] [--sanitize] [--target=wasm32-wasi|web]\n\
\ flan run <file.flan> [args...]\n\
\ flan reload <program.flan> <forms.flan> [-o out.so]\n\
\ flan dev <program.flan> [-s socket]";
exit 2