Joseph Ferano
d272a5b1e5
Item 12 asks five questions and says to answer them with a spike rather than a rewrite. spike/embed/ is that spike: one script, six binaries, each one built to fail loudly at the thing it is asking about. It is deliberately not a dune target -- the root dune only excludes old-ocaml/, so a dune file here would land in @default and make the spike part of the build. It drives ocamlfind and clang by hand against the flan.cmxa dune already produces. The probes, in the order they would kill the idea: the smallest possible link, a C main() reaching one OCaml function; the whole compiler linked in and doing real work; the same again with lib/dynload_stubs.c from the unmerged dlopen branch, because that is the only C the compiler itself is built from; the game keeping the main thread while caml_startup happens on a pthread beside it; the SIGSEGV disposition read on both sides of caml_startup; and an 8 MiB arena checked byte for byte across a compaction. No result is written down yet. This is the apparatus.
33 lines
1.5 KiB
OCaml
33 lines
1.5 KiB
OCaml
(* Step 4: the macOS shape. The game owns the main thread; the compiler and the
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listener run beside it.
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The question is NOT "can OCaml use threads" -- it is whether caml_startup can
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be called from a pthread that C spawned, while main() goes on to run a
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window loop it never returns from. That is the inversion item 11 settles on,
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and it is the one that has to be measured rather than assumed. *)
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let compile file =
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let l = Flan.Load.program ~file (Flan.Parse.program (Flan.Reader.read_file file)) in
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let p = Flan.Check.program l.Flan.Load.decls in
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String.length (Flan.Emit.program ~dev:true p)
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let () =
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Callback.register "spike_thread_compile" (fun (file : string) ->
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let tid = Thread.id (Thread.self ()) in
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match compile file with
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| n ->
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Printf.sprintf "compiled on OCaml thread %d: %d bytes of LLVM IR" tid n
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| exception e -> Printf.sprintf "FAILED: %s" (Printexc.to_string e));
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Callback.register "spike_domains" (fun () ->
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(* A second domain doing real work while the main thread is elsewhere --
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5.2's multicore runtime, which is the objection item 12 says has gone
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away. Confirmed rather than assumed. *)
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let d = Domain.spawn (fun () ->
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let s = ref 0 in
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for i = 1 to 5_000_000 do s := !s + i done;
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(Domain.self () :> int), !s)
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in
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let id, s = Domain.join d in
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Printf.sprintf "domain %d summed to %d; recommended_domain_count = %d"
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id s (Domain.recommended_domain_count ()))
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