Joseph Ferano
c897526e47
(Ptr Enemy) already says Enemy, at compile time, in the walk. What the renderer lacked was any way to know whether the storage at the far end is still there — and an allocation registry is exactly a record of which addresses it is still true to read. So the inspector follows a live one and renders the pointee by the same walk as anything else, and names what died at a dead one. println does not, and the split is not squeamishness: spec-memory.md fixes what a printed Ptr prints, a printed line belongs to the program and has to read the same in a release build, and a release build has no registry to ask. The two callers already differ in an emitter record; they differ in one more. No address appears in the text. An address is not stable across two runs, so printing one would make a rendering depend on where the heap landed — the rule Render already follows for an allocator. What a reader wants from a dangling pointer is what died. registry.flan is one program read twice: a dev build answers for an address at the heap, arena and pool tiers, and a release build answers 0 to all of it. The arena row is the free-all Valgrind cannot see — this does not make memcheck report it, it makes the same read answerable.
1019 lines
45 KiB
OCaml
1019 lines
45 KiB
OCaml
(** A live program: the declarations a running process was built from, plus
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every change accepted since.
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This is what makes an editor possible. [Check.program] builds a fresh
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environment from a declaration list on every call, which is exactly the
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property a session needs and the reason there is no scratch-environment
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machinery here: a form that fails to check leaves nothing behind, because
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nothing was mutated. The list is only replaced once the check has
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succeeded. Re-checking the whole program each time costs the whole frontend,
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which is under 10ms — less than the [llc] that follows it.
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Two things the session knows that no single evaluation could:
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- **which names the running process was built with.** A name it has is a
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symbol the loaded module binds to; a name it lacks goes through the
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by-name registry in runtime/flan_dev.c. Getting this wrong is silent:
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treating [rand-seed] as new gives it a registry cell nobody publishes,
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and the first call jumps to null. It has to come from the *checked*
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program, because [Check.program] prepends the prelude and no accumulated
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AST contains it.
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- **what the memory of that process looks like.** A cell is a bare pointer
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and carries no signature, so a redefined function whose parameters
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changed is called by every existing call site with the old ones — no link
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error, no trap, a wrong number. Struct fields and global types are the
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same class. Those are refused here, with the reason, rather than loaded.
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Not here, and deliberately: evaluating an expression. That is a separate
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primitive — synthesize a function around the form, call it, render the
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value — and it is not what redefining a name is. *)
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type t = {
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file : string; (* resolves an import's relative path *)
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mutable decls : Ast.decl list; (* post-Load: flat, one namespace *)
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mutable program : Tast.program; (* the last thing that checked *)
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mutable env : Check.env; (* the same, as the checker sees it *)
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host : Tast.program; (* what the process was built from *)
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pkgs : Load.pkg list; (* alias, directory, names owned *)
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mutable thunks : int; (* expression evaluations so far *)
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(* Whether the modules this session emits carry DWARF. It belongs to the
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session rather than to each call because it has to match the process the
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modules are loaded into: a redefinition with debug info, dlopened into a
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host built without it, gives a debugger a second module to resolve names
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against and nothing to line up the host's own frames with. Both ends are
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set from one flag — see [Dev.start]. *)
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debug : bool;
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}
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let fail = Loc.fail
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(* Structural, and conservative: anything this does not recognise counts as
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changed. Comparing emitted text instead would be wrong — [Emit.const] on a
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string allocates a name off a per-module counter, so two different strings
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in two throwaway modules both come out as [@".str.0"] and compare equal. *)
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let rec same_const (a : Tast.expr) (b : Tast.expr) =
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match (a.Tast.e, b.Tast.e) with
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| Tast.Int (x, k), Tast.Int (y, l) -> Int64.equal x y && k = l
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| Tast.Float (x, k), Tast.Float (y, l) -> Float.equal x y && k = l
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| Tast.Bool x, Tast.Bool y -> x = y
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| Tast.Str x, Tast.Str y -> String.equal x y
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| Tast.Unit, Tast.Unit -> true
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| Tast.Zero x, Tast.Zero y -> Types.equal x y
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| Tast.Arr xs, Tast.Arr ys ->
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List.length xs = List.length ys && List.for_all2 same_const xs ys
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| Tast.Make (x, xs), Tast.Make (y, ys) ->
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String.equal x y && List.length xs = List.length ys
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&& List.for_all2 same_const xs ys
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| _ -> false
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let create ?(debug = false) ~file () =
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let l = Load.program ~file (Parse.program (Reader.read_file file)) in
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let p, env = Check.program_with_env l.Load.decls in
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({ file; decls = l.Load.decls; program = p; env; host = p; pkgs = l.Load.pkgs;
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thunks = 0; debug }, l)
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(* Which package a file being edited belongs to, if any.
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A form typed into vendor/agent/agent.flan declares [poll], but the running
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program only ever knew it as [agent/poll]: the alias is chosen by whatever
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imported the directory, and is written nowhere in the file itself. Without
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this the form splices as a brand-new unrelated name, the evaluation reports
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success, and nothing changes — the exact failure this whole design is meant
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to make impossible.
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Derived from the path rather than sent by the editor for that same reason:
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the editor cannot know an alias the file does not mention. *)
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let package_of t origin =
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match origin with
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| "" -> None
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| origin ->
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let here =
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try Unix.realpath origin with Unix.Unix_error _ -> origin
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in
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let dir = Filename.dirname here in
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(* A package is a directory, or a single .flan file named outright — so the
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file being edited belongs to it if the package *is* that file, or if it
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sits in the package's directory. Comparing only the directory would miss
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the file case entirely and answer [None], which is the silent failure
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above rather than a loud one: the form splices unqualified and the
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running program keeps calling the name it already had. *)
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let same p =
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let d =
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try Unix.realpath p.Load.dir with Unix.Unix_error _ -> p.Load.dir
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in
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String.equal d here || String.equal d dir
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in
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(match List.filter same t.pkgs with
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| [] -> None
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| [ p ] -> Some p
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(* One directory under two aliases: both are live in the program and a
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form cannot mean both. Say so rather than picking one. *)
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| ps ->
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Loc.fail Loc.unknown
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"%s is imported under more than one alias (%s); a form here would \
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have to mean all of them"
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dir
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(String.concat ", " (List.map (fun p -> p.Load.alias) ps)))
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(* A name the running process exports. Everything else is looked up by name at
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install time — see [Emit.redefinition]'s [known]. *)
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let known t n =
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List.exists (fun (f : Tast.fn) -> String.equal f.Tast.name n) t.host.Tast.fns
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|| List.exists
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(fun (g : Tast.global) -> String.equal g.Tast.gname n)
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t.host.Tast.globals
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(* ── What a running process cannot be told ─────────────────────────── *)
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(* Everything here is a change that would load cleanly and then be wrong. The
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house rule (NEXT.md, Watch for) says recognise it and refuse with the
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reason, so each one names what it would have broken. *)
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let compatible ~loc (old_ : Tast.program) (new_ : Tast.program) =
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let find_fn p n =
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List.find_opt (fun (f : Tast.fn) -> String.equal f.Tast.name n) p.Tast.fns
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in
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List.iter
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(fun (f : Tast.fn) ->
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match find_fn old_ f.Tast.name with
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| None -> ()
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| Some g ->
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let same =
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List.length f.Tast.params = List.length g.Tast.params
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&& List.for_all2 Types.equal f.Tast.params g.Tast.params
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&& Types.equal f.Tast.ret g.Tast.ret
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in
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(* A cell holds a bare pointer. Every call site compiled before this
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change still passes the old arguments through it.
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This refusal is correct for what is built and is *not* the design
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plan.org now describes: a signature change should make a new
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internal function version with its own trampoline, leave existing
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callers and stored [Fn] values safely on the old one, and warn at
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each tracked stale caller site. That needs versions, trampolines
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and caller tracking, none of which exist — so this stays a refusal
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until they do, rather than becoming a silent mismatch. See
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plan.org, Hot reload, and open decision #6. *)
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if not same then
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fail loc
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"%s changes signature, from (Fn [%s] %s) to (Fn [%s] %s); \
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the calls already compiled into the running program pass the old \
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one. Restart to change it."
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f.Tast.name
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(String.concat " " (List.map Types.to_string g.Tast.params))
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(Types.to_string g.Tast.ret)
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(String.concat " " (List.map Types.to_string f.Tast.params))
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(Types.to_string f.Tast.ret))
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new_.Tast.fns;
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List.iter
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(fun (g : Tast.global) ->
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match
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List.find_opt
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(fun (h : Tast.global) -> String.equal h.Tast.gname g.Tast.gname)
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old_.Tast.globals
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with
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(* A [defconst] is folded into its call sites — into an array length, at
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worst, which is decided before any type resolves — so its value is in
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the running program's code and not only in its storage. A [defvar]'s
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initial value is the opposite case and must *not* be refused: the
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storage holds live state the program has long since moved past, which
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is the whole of "edit the code, keep the sand". Same record, opposite
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answers, told apart by [gconst]. *)
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(* Only a constant the *checker* consumed. Its value is in the shape of
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the running program — [(defconst rows (/ h c))] decides the type of
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[grid] before anything else resolves — so no store can reach it. A
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constant that is only ever read at run time is just bytes in memory:
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a dev build emits it as a mutable global and a redefinition stores
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the new value, which is how a colour table is tuned live. *)
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| Some h
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when h.Tast.gconst && g.Tast.gconst && h.Tast.gfolded
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&& Types.equal g.Tast.gty h.Tast.gty
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&& not (same_const g.Tast.ginit h.Tast.ginit) ->
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fail loc
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"%s is used at compile time — an array length or a type — so the \
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running program has its old value in its shape, where a reload \
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cannot reach it. Restart to change it."
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g.Tast.gname
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| Some h when not (Types.equal g.Tast.gty h.Tast.gty) ->
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(* The storage exists and has a shape. Reusing it for another one
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reads fields at the wrong offsets; allocating fresh storage would
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silently discard the state the reload exists to preserve. *)
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fail loc
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"%s changes type, from %s to %s; the running program already laid \
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that storage out. Restart to change it."
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g.Tast.gname (Types.to_string h.Tast.gty) (Types.to_string g.Tast.gty)
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| _ -> ())
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new_.Tast.globals;
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List.iter
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(fun (s : Tast.structure) ->
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match
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List.find_opt
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(fun (r : Tast.structure) -> String.equal r.Tast.sname s.Tast.sname)
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old_.Tast.structs
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with
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| Some r ->
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let fields (x : Tast.structure) =
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List.map (fun (f : Tast.field) -> (f.Tast.fname, f.Tast.fty))
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x.Tast.fields
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in
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let same =
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List.length s.Tast.fields = List.length r.Tast.fields
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&& List.for_all2
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(fun (an, at) (bn, bt) -> String.equal an bn && Types.equal at bt)
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(fields s) (fields r)
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in
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(* Every value of this type in the running program has the old layout,
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including ones held in globals that the reload is preserving. *)
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if not same then
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fail loc
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"%s changes layout; the values the running program is holding have \
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the old one. Restart to change it."
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s.Tast.sname
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| None -> ())
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new_.Tast.structs
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(* An enum member is erased to an [i32] literal in the caller — [:space] at a
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call site resolves to a number and is folded there — so changing one cannot
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reach code that is already compiled, exactly like a [defconst]. It has to be
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compared over declarations rather than over [Tast.program], which carries no
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enums at all for that same reason. *)
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let compatible_enums ~loc old_ new_ =
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let members (ds : Ast.decl list) =
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List.filter_map
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(fun (d : Ast.decl) ->
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match d.Ast.d with Ast.Defenum (n, ms) -> Some (n, ms) | _ -> None)
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ds
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in
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let before = members old_ in
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List.iter
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(fun (n, ms) ->
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match List.assoc_opt n before with
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| Some old_ms when old_ms <> ms ->
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fail loc
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"%s changes its members; the running program folded the old values \
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into every call site that names one. Restart to change it."
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n
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| _ -> ())
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(members new_)
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(* ── Accepting a change ────────────────────────────────────────────── *)
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|
(* The redefinition unit is a list of top-level forms, so this is one path for
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both editor commands: C-c C-c sends one form, C-c C-k sends a file. *)
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type change = {
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ir : string; (* the module to build and send *)
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names : string list; (* everything the forms declared *)
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fns : string list; (* the subset that has a body to install *)
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(* False when the module would define nothing: no body to publish and no
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storage to allocate. Building and delivering one anyway reports success
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for a change that cannot have had an effect, and costs the program a
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frame's worth of reload it did not need. *)
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installs : bool;
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}
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let eval ?(origin = "<eval>") t src : change =
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let forms = Reader.read_all ~file:origin src in
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(* Through [Load] like any other source, so an evaluated (import ...) means
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what it means in a file. Its expansion is what gets spliced, which is also
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why the accumulated list is the post-Load one: re-evaluating a file that
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imports something would otherwise append a second copy of the import and
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the duplicate-name pass would reject it. *)
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let incoming =
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let ds = (Load.program ~file:t.file (Parse.program forms)).Load.decls in
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match package_of t origin with
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| None -> ds
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| Some p ->
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(* Qualified exactly as the import qualified them, so a redefined
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[settle] lands on [sim/settle] and its call to [move-grain] lands on
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[sim/move-grain]. A name the package does not own — the prelude's, or
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another package's — is left alone, which is the same rule [Load] uses
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at import time and the reason both go through [qualify_decl]. *)
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let owns =
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p.Load.owns
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@ List.filter_map Ast.declared_name ds
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in
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List.map (Load.qualify_decl owns p.Load.alias) ds
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in
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let loc =
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match incoming with d :: _ -> d.Ast.dloc | [] -> Loc.unknown
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in
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let names = List.filter_map Ast.declared_name incoming in
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let replacement n =
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List.find_opt
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(fun (d : Ast.decl) -> Ast.declared_name d = Some n)
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incoming
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in
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(* Replaced in place and appended only when genuinely new, so declaration
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order — which is emission order for globals — does not shuffle on every
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evaluation. *)
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let replaced = ref [] in
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let kept =
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List.map
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(fun (d : Ast.decl) ->
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match Ast.declared_name d with
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| Some n ->
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(match replacement n with
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| Some nd -> replaced := n :: !replaced; nd
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| None -> d)
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| None -> d)
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t.decls
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in
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let added =
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List.filter
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(fun (d : Ast.decl) ->
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match Ast.declared_name d with
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| Some n -> not (List.exists (String.equal n) !replaced)
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| None -> false)
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incoming
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in
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let decls = kept @ added in
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(* Nothing above this line has changed the session. A [Loc.Error] from here
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leaves it exactly as it was. *)
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|
let program, env = Check.program_with_env decls in
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compatible ~loc t.program program;
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compatible_enums ~loc t.decls decls;
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let fns =
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List.filter
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|
(fun n ->
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|
List.exists
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|
(fun (f : Tast.fn) -> String.equal f.Tast.name n)
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|
program.Tast.fns)
|
|
names
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|
in
|
|
(* A constant that changed and can be published: known to the host, not
|
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consumed by the checker. The module stores its new value at the frame
|
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boundary, exactly as it stores a new function body. *)
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|
let consts =
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|
List.filter
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|
(fun n ->
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|
known t n
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|
&& List.exists
|
|
(fun (g : Tast.global) ->
|
|
String.equal g.Tast.gname n && g.Tast.gconst
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|
&& not g.Tast.gfolded)
|
|
program.Tast.globals)
|
|
names
|
|
in
|
|
let ir =
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Emit.redefinition ~dev:true ~debug:t.debug ~known:(known t) ~consts program
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|
~fns
|
|
in
|
|
let allocates =
|
|
List.exists
|
|
(fun (g : Tast.global) -> not (known t g.Tast.gname))
|
|
program.Tast.globals
|
|
in
|
|
t.decls <- decls;
|
|
t.program <- program;
|
|
t.env <- env;
|
|
{ ir; names; fns; installs = fns <> [] || allocates || consts <> [] }
|
|
|
|
(* ── Evaluating an expression ──────────────────────────────────────── *)
|
|
|
|
(* [C-x C-e] is a different primitive from redefining a name, and this is where
|
|
the difference lives: there is no name to install a body into, so the
|
|
expression is wrapped in a function that has nowhere to be called from, and
|
|
the module says "run this once". The agent does, at a frame boundary.
|
|
|
|
Getting the value back does not marshal anything. A Flan value carries no
|
|
header, so nothing at run time could say what it is; the compiler knows the
|
|
type and renders it *there*, in the thunk. That is the layout decision's
|
|
bill, paid here — and it is why the renderer is a compile-time walk over the
|
|
type rather than a function in the runtime.
|
|
|
|
The rendering goes to [flan_dev_emit], a piece at a time, not to stdout.
|
|
Piecewise because a struct is its fields with punctuation between them and
|
|
concatenating that in generated IR would need an allocator the language does
|
|
not have; not stdout because stdout belongs to the program, is in the hot
|
|
path for anything that prints, and a dev-only feature must not put a branch
|
|
in it. *)
|
|
|
|
type emitter = { ename : string; ety : Types.t }
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|
|
|
let emit_bytes = { ename = "flan/dev-emit"; ety = Types.Slice (Types.Int Types.U8) }
|
|
let emit_str = { ename = "flan/dev-emit-str"; ety = Types.Slice (Types.Int Types.U8) }
|
|
let emit_i64 = { ename = "flan/dev-emit-i64"; ety = Types.Int Types.I64 }
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|
let emit_u64 = { ename = "flan/dev-emit-u64"; ety = Types.Int Types.U64 }
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|
let emit_f64 = { ename = "flan/dev-emit-f64"; ety = Types.Float Types.F64 }
|
|
|
|
let externs : Tast.extern list =
|
|
let one e sym = { Tast.ename = e.ename; esym = sym; eparams = [ e.ety ];
|
|
eret = Types.Unit } in
|
|
[ one emit_bytes "flan_dev_emit";
|
|
one emit_str "flan_dev_emit_str";
|
|
one emit_i64 "flan_dev_emit_i64";
|
|
one emit_u64 "flan_dev_emit_u64";
|
|
one emit_f64 "flan_dev_emit_f64";
|
|
(* The address of a slot in a *stopped* frame, resolved by the agent
|
|
against the snapshot that break took. It is the one piece a locals
|
|
thunk cannot work out for itself: the compiler knows every slot's type
|
|
and name, and nothing but the running program knows where the frame
|
|
is. See [render_locals]. *)
|
|
{ Tast.ename = "flan/dev-slot"; esym = "flan_agent_frame_slot";
|
|
eparams = [ Types.Int Types.I64; Types.Int Types.I64 ];
|
|
eret = Types.Ptr (Types.Int Types.U8) };
|
|
{ Tast.ename = "flan/dev-begin"; esym = "flan_dev_result_begin";
|
|
eparams = []; eret = Types.Unit };
|
|
{ Tast.ename = "flan/dev-end"; esym = "flan_dev_result_end";
|
|
eparams = []; eret = Types.Unit };
|
|
(* The allocation registry's two questions about an address. Both take a
|
|
[(Ptr u8)] and every pointer is cast to it: the registry is asked
|
|
whether a *byte* is inside a block it knows, and the type at the far
|
|
end is the renderer's business and already known there.
|
|
|
|
[reg-live] returns i32 rather than bool because that is what the C
|
|
returns, and a Flan bool is one bit wide; the comparison to zero is
|
|
made below, where the type is spelled once.
|
|
|
|
[reg-emit] writes into the same result buffer every other piece of a
|
|
rendering goes to. It answers whether it wrote anything, which this
|
|
side ignores — the renderer needs the *emission*, and "nothing was
|
|
written" is already the right rendering for an address the registry
|
|
never saw. *)
|
|
{ Tast.ename = "flan/reg-live"; esym = "flan_dev_reg_live";
|
|
eparams = [ Types.Ptr (Types.Int Types.U8) ];
|
|
eret = Types.Int Types.I32 };
|
|
{ Tast.ename = "flan/reg-emit"; esym = "flan_dev_reg_emit";
|
|
eparams = [ Types.Ptr (Types.Int Types.U8) ];
|
|
eret = Types.Int Types.I32 } ]
|
|
|
|
(* The REPL's emitter. Each piece is one extern call: the dev runtime already
|
|
has a renderer per scalar, and [flan_dev_emit_str] already quotes and
|
|
escapes. See render.ml for what the five are and why they are functions. *)
|
|
let dev_emitter : Render.emitter =
|
|
let call em (x : Tast.expr) : Tast.expr =
|
|
{ Tast.e = Tast.Call (em.ename, [ x ]); ty = Types.Unit; loc = x.Tast.loc }
|
|
in
|
|
{ Render.ebytes = call emit_bytes;
|
|
estr = call emit_str;
|
|
ei64 = call emit_i64;
|
|
eu64 = call emit_u64;
|
|
ef64 = call emit_f64 }
|
|
|
|
(* And what the REPL may do with a pointer, which [println] may not. See
|
|
render.ml's [pointers] for why the two sides differ. *)
|
|
let dev_pointers : Render.pointers =
|
|
let i32 = Types.Int Types.I32 in
|
|
let ask name (p : Tast.expr) : Tast.expr =
|
|
let loc = p.Tast.loc in
|
|
let byte =
|
|
{ Tast.e = Tast.Prim (Tast.Cast (Types.Ptr (Types.Int Types.U8)), [ p ]);
|
|
ty = Types.Ptr (Types.Int Types.U8); loc }
|
|
in
|
|
{ Tast.e = Tast.Call (name, [ byte ]); ty = i32; loc }
|
|
in
|
|
{ Render.live =
|
|
(fun p ->
|
|
let loc = p.Tast.loc in
|
|
let zero = { Tast.e = Tast.Int (0L, Types.I32); ty = i32; loc } in
|
|
{ Tast.e = Tast.Prim (Tast.Ne, [ ask "flan/reg-live" p; zero ]);
|
|
ty = Types.Bool; loc });
|
|
(* Called for the emission and not for the answer, so the i32 is discarded
|
|
here rather than in render.ml: a [Do] whose last element is the unit is
|
|
the honest way to say "run this and forget what it said", and it keeps
|
|
the walk's node types true. *)
|
|
epitaph =
|
|
(fun p ->
|
|
let loc = p.Tast.loc in
|
|
{ Tast.e =
|
|
Tast.Do [ ask "flan/reg-emit" p;
|
|
{ Tast.e = Tast.Unit; ty = Types.Unit; loc } ];
|
|
ty = Types.Unit; loc }) }
|
|
|
|
(* ── The locals of a stopped frame ─────────────────────────────────── *)
|
|
|
|
(* The second half of what a break loop can show, and it is the same primitive
|
|
as [C-x C-e] pointed somewhere else.
|
|
|
|
Nothing marshals and nothing is read across the process boundary. A Flan
|
|
value carries no header, so the daemon could not make sense of bytes it
|
|
copied out even if it had them; what it has instead is the *type*, from
|
|
[Tast.fn.slots], and a name for it, from [snames] beside it. So it compiles
|
|
a thunk that renders those types at those addresses, in the program, and
|
|
reads back the text — exactly what an evaluated expression does, except
|
|
that the root is an address rather than an expression. That address is the
|
|
only thing that comes from the running program.
|
|
|
|
[bound] is which slots the program says have been reached. It is not an
|
|
optimisation: an unbound slot's entry is null, and a thunk that rendered
|
|
one would dereference null on the game thread of a program that is already
|
|
stopped. So the refusal happens here, before any code is emitted for it.
|
|
|
|
What comes back is one line per slot — name, type, value, tab separated.
|
|
Tab and newline are safe separators because every string the renderer emits
|
|
goes through [flan_dev_emit_str], which escapes both.
|
|
|
|
Each slot is rendered from its address rather than copied into the thunk
|
|
first. A copy would be one [alloca] the size of the slot — 40KB for sand's
|
|
grid — and the walk only ever shows eight elements of it. The cost is one
|
|
call to [flan/dev-slot] per leaf the walk reaches instead of one per slot,
|
|
which the depth and span caps already bound. *)
|
|
let render_locals ?(origin = "<locals>") t ~frame ~(fn : Tast.fn) ~bound
|
|
: change * (string * string) list =
|
|
let loc = fn.Tast.floc in
|
|
let extra = ref [] and nslots = ref 0 in
|
|
let c =
|
|
{ Render.structs = t.program.Tast.structs;
|
|
unions = t.program.Tast.unions;
|
|
enums = Hashtbl.fold (fun k v acc -> (k, v) :: acc) t.env.Check.enums [];
|
|
emit = dev_emitter;
|
|
ptrs = Some dev_pointers;
|
|
alloc = (fun ty ->
|
|
let i = !nslots in
|
|
incr nslots;
|
|
extra := ty :: !extra;
|
|
i) }
|
|
in
|
|
let nullary n = { Tast.e = Tast.Call (n, []); ty = Types.Unit; loc } in
|
|
let bytes_of str =
|
|
{ Tast.e =
|
|
Tast.Prim (Tast.Bytes, [ { Tast.e = Tast.Str str; ty = Types.String; loc } ]);
|
|
ty = Types.Slice (Types.Int Types.U8); loc }
|
|
in
|
|
let lit str = c.Render.emit.Render.ebytes (bytes_of str) in
|
|
let refused = ref [] in
|
|
let refuse name why = refused := (name, why) :: !refused in
|
|
let one i ty name =
|
|
let idx n =
|
|
{ Tast.e = Tast.Int (Int64.of_int n, Types.I64); ty = Types.Int Types.I64; loc }
|
|
in
|
|
let address =
|
|
{ Tast.e = Tast.Call ("flan/dev-slot", [ idx frame; idx i ]);
|
|
ty = Types.Ptr (Types.Int Types.U8); loc }
|
|
in
|
|
let typed =
|
|
{ Tast.e = Tast.Prim (Tast.Cast (Types.Ptr ty), [ address ]);
|
|
ty = Types.Ptr ty; loc }
|
|
in
|
|
let v = { Tast.e = Tast.Deref typed; ty; loc } in
|
|
match Render.render c 0 v with
|
|
| parts ->
|
|
(* The slot *index* travels with the line, last, and it is what makes
|
|
[i] in the break buffer able to name this exact slot back to the
|
|
daemon. The name cannot: [check.ml]'s [fresh_slot] only ever
|
|
allocates, so (let [v 22] …) inside (let [v 11] …) is two slots both
|
|
called [v] and both listed here. Nor can the position in the list,
|
|
because a refused slot is not in it. See [render_slot]. *)
|
|
Some
|
|
((lit (name ^ "\t" ^ Types.to_string ty ^ "\t") :: parts)
|
|
@ [ lit ("\t" ^ string_of_int i ^ "\n") ])
|
|
| exception Loc.Error { Loc.dmsg = why; _ } ->
|
|
(* A type the structural printer has no arm for — a map, a function
|
|
value, a type variable. Named, with the reason, rather than left out
|
|
of the list: a local that is missing and a local that could not be
|
|
printed are different facts. *)
|
|
refuse name why;
|
|
None
|
|
in
|
|
let body =
|
|
List.concat
|
|
((List.filter_map
|
|
(fun i ->
|
|
let ty = fn.Tast.slots.(i) in
|
|
let name =
|
|
if i < Array.length fn.Tast.snames then fn.Tast.snames.(i)
|
|
else None
|
|
in
|
|
match name with
|
|
| None ->
|
|
(* A slot the compiler made up: [dotimes]'s hidden bound, the
|
|
temporary a (min) evaluates an operand into. There is no
|
|
name to show and inventing one would put a variable in the
|
|
list that nobody can find in the file. *)
|
|
refuse (Printf.sprintf "s%d" i)
|
|
"a slot the compiler made up; no name was written for it";
|
|
None
|
|
| Some name when not (List.mem i bound) ->
|
|
refuse name
|
|
"not bound yet at the point the program stopped";
|
|
None
|
|
| Some name -> one i ty name)
|
|
(List.init (Array.length fn.Tast.slots) (fun i -> i))))
|
|
in
|
|
t.thunks <- t.thunks + 1;
|
|
let name = Printf.sprintf "locals/%d" t.thunks in
|
|
let thunk : Tast.fn =
|
|
{ Tast.name; params = []; ret = Types.Unit;
|
|
body = (nullary "flan/dev-begin" :: body) @ [ nullary "flan/dev-end" ];
|
|
fdefers = []; fparent = None; floc = loc;
|
|
slots = Array.of_list (List.rev !extra);
|
|
(* Every slot in here is the walk's own scratch: the locals being shown
|
|
are the *other* frame's, and this thunk reaches them by address. *)
|
|
snames = Array.make (List.length !extra) None }
|
|
in
|
|
let program =
|
|
{ t.program with
|
|
Tast.fns = t.program.Tast.fns @ [ thunk ];
|
|
externs = t.program.Tast.externs @ externs }
|
|
in
|
|
let ir =
|
|
Emit.redefinition ~dev:true ~debug:t.debug ~known:(known t) ~call:name
|
|
program ~fns:[ name ]
|
|
in
|
|
ignore origin;
|
|
({ ir; names = []; fns = []; installs = true }, List.rev !refused)
|
|
|
|
(* ── One slot of a stopped frame, walked ───────────────────────────── *)
|
|
|
|
(* The inspector's second rooting mode, and the whole of what it needed.
|
|
|
|
The inspector navigates by rewriting *expressions* — `(.pos b)' where the
|
|
last one was `b' — because a Flan value has no header and the thunk that
|
|
rendered it is [dlclose]d as soon as it returns, so nothing can be held on
|
|
this side the way CIDER holds a JVM object. The cost of that is the bug it
|
|
had: a name sent back to be evaluated is evaluated wherever the evaluator
|
|
stands, which on any frame but the innermost may resolve to a global, to a
|
|
different binding, or to nothing, with the listing above it still showing
|
|
the frame's own storage.
|
|
|
|
Rooting at the slot's address alone does not fix it — an address is not an
|
|
expression, so the first step has nothing to build from. What makes this
|
|
work is that the step does not have to be an expression either. A frame's
|
|
address comes from the shadow stack and every slot's type comes from
|
|
[Tast.fn.slots], so a step into a field is an address plus an offset with
|
|
that field's type, which is *exactly* the arithmetic [Render.render] does
|
|
for the locals listing. So this is [render_locals] with a path applied to
|
|
the root before the walk, and not a second walk.
|
|
|
|
What the path cannot do is the honest half. Every step is refused by name
|
|
with its reason rather than guessed at: a field the type does not have, an
|
|
index past the end of a fixed array, an option's payload on something that
|
|
is not an option. A pointer is still never followed — that is the
|
|
renderer's rule and not this mode's. *)
|
|
|
|
(* A step, as the editor sends it. [Sfield] on a union carries the case as
|
|
well, because a union's payload is at an offset that depends on which case
|
|
it is, and the renderer is what told the editor which case this value
|
|
currently holds. Guessing the case from a field name that two cases share
|
|
would read one case's layout over another's payload. *)
|
|
type step = Sfield of string | Sindex of int | Ssome
|
|
|
|
let step_text = function
|
|
| Sfield f -> "." ^ f
|
|
| Sindex i -> Printf.sprintf "[%d]" i
|
|
| Ssome -> ".some"
|
|
|
|
let path_text path = String.concat "" (List.map step_text path)
|
|
|
|
let step_into t (v : Tast.expr) (s : step) : (Tast.expr, string) result =
|
|
let loc = v.Tast.loc in
|
|
let ty = v.Tast.ty in
|
|
let no why = Error why in
|
|
match s with
|
|
| Ssome ->
|
|
(match ty with
|
|
| Types.Option pay -> Ok { Tast.e = Tast.Field (v, 1); ty = pay; loc }
|
|
| _ ->
|
|
no
|
|
(Printf.sprintf "%s is not an option, so it has no payload to go into"
|
|
(Types.to_string ty)))
|
|
| Sindex i ->
|
|
(match ty with
|
|
| Types.Array (n, el) ->
|
|
if i < 0 || Int64.compare (Int64.of_int i) n >= 0 then
|
|
no
|
|
(Printf.sprintf "%d is past the end of %s, which has %Ld elements" i
|
|
(Types.to_string ty) n)
|
|
else
|
|
Ok
|
|
{ Tast.e =
|
|
Tast.Prim
|
|
(Tast.At,
|
|
[ v;
|
|
{ Tast.e = Tast.Int (Int64.of_int i, Types.I32);
|
|
ty = Types.Int Types.I32; loc } ]);
|
|
ty = el; loc }
|
|
| Types.Slice el ->
|
|
(* A slice's length is not in its type, so this is the one step whose
|
|
range cannot be settled here. It is checked in the program, like
|
|
every other index in a dev build. *)
|
|
if i < 0 then no (Printf.sprintf "%d is not an index" i)
|
|
else
|
|
Ok
|
|
{ Tast.e =
|
|
Tast.Prim
|
|
(Tast.At,
|
|
[ v;
|
|
{ Tast.e = Tast.Int (Int64.of_int i, Types.I32);
|
|
ty = Types.Int Types.I32; loc } ]);
|
|
ty = el; loc }
|
|
| _ ->
|
|
no
|
|
(Printf.sprintf "%s is not an array or a slice, so it has no element %d"
|
|
(Types.to_string ty) i))
|
|
| Sfield spec ->
|
|
(match ty with
|
|
| Types.Named n
|
|
when List.exists (fun (u : Tast.union) -> String.equal u.Tast.uname n)
|
|
t.program.Tast.unions ->
|
|
let u =
|
|
List.find (fun (u : Tast.union) -> String.equal u.Tast.uname n)
|
|
t.program.Tast.unions
|
|
in
|
|
(* The editor spells this `Union.case.field', which is the head the
|
|
renderer wrote — `(Union.case {.field …})' — with the field appended.
|
|
A bare `case.field' is taken too, since that is the same fact said
|
|
shorter. *)
|
|
(match String.rindex_opt spec '.' with
|
|
| None ->
|
|
no
|
|
(Printf.sprintf
|
|
"%s is a union: a field of it has to name the case that holds \
|
|
it, because the payload's offset depends on which case the \
|
|
value is in"
|
|
n)
|
|
| Some k ->
|
|
let case = String.sub spec 0 k
|
|
and fname = String.sub spec (k + 1) (String.length spec - k - 1) in
|
|
let case =
|
|
let pre = n ^ "." in
|
|
let lp = String.length pre in
|
|
if String.length case > lp && String.equal (String.sub case 0 lp) pre
|
|
then String.sub case lp (String.length case - lp)
|
|
else case
|
|
in
|
|
(match
|
|
List.find_opt
|
|
(fun (vr : Tast.variant) -> String.equal vr.Tast.vname case)
|
|
u.Tast.cases
|
|
with
|
|
| None ->
|
|
no (Printf.sprintf "%s has no case called %s" n case)
|
|
| Some vr ->
|
|
let rec idx i = function
|
|
| [] -> None
|
|
| (f : Tast.field) :: rest ->
|
|
if String.equal f.Tast.fname fname then Some (i, f.Tast.fty)
|
|
else idx (i + 1) rest
|
|
in
|
|
(match idx 0 vr.Tast.vfields with
|
|
| None ->
|
|
no
|
|
(Printf.sprintf "%s.%s has no field called %s" n case fname)
|
|
| Some (i, fty) ->
|
|
Ok
|
|
{ Tast.e = Tast.CaseField (v, vr.Tast.vname, i); ty = fty; loc })))
|
|
| Types.Named n ->
|
|
(match
|
|
List.find_opt
|
|
(fun (s : Tast.structure) -> String.equal s.Tast.sname n)
|
|
t.program.Tast.structs
|
|
with
|
|
| None ->
|
|
no
|
|
(Printf.sprintf
|
|
"%s is a type this session has no layout for, so there is no \
|
|
field to step to"
|
|
n)
|
|
| Some st ->
|
|
let rec idx i = function
|
|
| [] -> None
|
|
| (f : Tast.field) :: rest ->
|
|
if String.equal f.Tast.fname spec then Some (i, f.Tast.fty)
|
|
else idx (i + 1) rest
|
|
in
|
|
(match idx 0 st.Tast.fields with
|
|
| None ->
|
|
no (Printf.sprintf "%s has no field called %s" n spec)
|
|
| Some (i, fty) -> Ok { Tast.e = Tast.Field (v, i); ty = fty; loc }))
|
|
| _ ->
|
|
no
|
|
(Printf.sprintf "%s has no fields, so there is no .%s in it"
|
|
(Types.to_string ty) spec))
|
|
|
|
(* Renders slot [slot] of frame [frame], after walking [path] into it. The
|
|
thunk is [render_locals]'s, minus the loop over every slot: one root, one
|
|
line, and the reply carries the type the path ended at so the editor can
|
|
say what it is looking at.
|
|
|
|
The caller has already established that the frame is the body this session
|
|
holds — the slot fingerprint — and that the slot is bound. This function
|
|
does not re-derive either; it is handed the [fn] that check passed. *)
|
|
let render_slot ?(origin = "<inspect>") t ~frame ~(fn : Tast.fn) ~slot ~path
|
|
: (change * string * string, string) result =
|
|
let loc = fn.Tast.floc in
|
|
let nslots_of_fn = Array.length fn.Tast.slots in
|
|
if slot < 0 || slot >= nslots_of_fn then
|
|
Error
|
|
(Printf.sprintf "there is no slot %d in %s; it has %d" slot fn.Tast.name
|
|
nslots_of_fn)
|
|
else
|
|
let sname =
|
|
if slot < Array.length fn.Tast.snames then fn.Tast.snames.(slot) else None
|
|
in
|
|
match sname with
|
|
| None ->
|
|
Error
|
|
(Printf.sprintf
|
|
"slot %d of %s is one the compiler made up; no name was written for \
|
|
it, and it is not something the listing offers"
|
|
slot fn.Tast.name)
|
|
| Some name ->
|
|
let extra = ref [] and nslots = ref 0 in
|
|
let c =
|
|
{ Render.structs = t.program.Tast.structs;
|
|
unions = t.program.Tast.unions;
|
|
enums = Hashtbl.fold (fun k v acc -> (k, v) :: acc) t.env.Check.enums [];
|
|
emit = dev_emitter;
|
|
ptrs = Some dev_pointers;
|
|
alloc = (fun ty ->
|
|
let i = !nslots in
|
|
incr nslots;
|
|
extra := ty :: !extra;
|
|
i) }
|
|
in
|
|
let idx n =
|
|
{ Tast.e = Tast.Int (Int64.of_int n, Types.I64); ty = Types.Int Types.I64;
|
|
loc }
|
|
in
|
|
let ty = fn.Tast.slots.(slot) in
|
|
let address =
|
|
{ Tast.e = Tast.Call ("flan/dev-slot", [ idx frame; idx slot ]);
|
|
ty = Types.Ptr (Types.Int Types.U8); loc }
|
|
in
|
|
let typed =
|
|
{ Tast.e = Tast.Prim (Tast.Cast (Types.Ptr ty), [ address ]);
|
|
ty = Types.Ptr ty; loc }
|
|
in
|
|
let root = { Tast.e = Tast.Deref typed; ty; loc } in
|
|
let rec walk v = function
|
|
| [] -> Ok v
|
|
| s :: rest ->
|
|
(match step_into t v s with
|
|
| Error why -> Error why
|
|
| Ok v' -> walk v' rest)
|
|
in
|
|
(match walk root path with
|
|
| Error why -> Error (name ^ path_text path ^ ": " ^ why)
|
|
| Ok v ->
|
|
(match Render.render c 0 v with
|
|
| exception Loc.Error { Loc.dmsg = why; _ } -> Error (name ^ path_text path ^ ": " ^ why)
|
|
| parts ->
|
|
let nullary n = { Tast.e = Tast.Call (n, []); ty = Types.Unit; loc } in
|
|
t.thunks <- t.thunks + 1;
|
|
let tname = Printf.sprintf "inspect/%d" t.thunks in
|
|
let thunk : Tast.fn =
|
|
{ Tast.name = tname; params = []; ret = Types.Unit;
|
|
body =
|
|
(nullary "flan/dev-begin" :: parts) @ [ nullary "flan/dev-end" ];
|
|
fdefers = []; fparent = None; floc = loc;
|
|
slots = Array.of_list (List.rev !extra);
|
|
snames = Array.make (List.length !extra) None }
|
|
in
|
|
let program =
|
|
{ t.program with
|
|
Tast.fns = t.program.Tast.fns @ [ thunk ];
|
|
externs = t.program.Tast.externs @ externs }
|
|
in
|
|
let ir =
|
|
Emit.redefinition ~dev:true ~debug:t.debug ~known:(known t)
|
|
~call:tname program ~fns:[ tname ]
|
|
in
|
|
ignore origin;
|
|
Ok
|
|
({ ir; names = []; fns = []; installs = true },
|
|
name ^ path_text path,
|
|
Types.to_string v.Tast.ty)))
|
|
|
|
(* ── The globals a stopped stack reaches ───────────────────────────── *)
|
|
|
|
(* The other half of what a break loop can show, and in this language arguably
|
|
the more useful one: a game keeps most of its state in top-level [defvar]s,
|
|
and sand.flan holds its entire grid that way.
|
|
|
|
Almost the same thunk as [render_locals] with a different root, and the
|
|
difference is the whole reason this is a second function rather than a
|
|
parameter. A local is reached by *address* — [flan/dev-slot] hands back
|
|
where the frame is, and only the stopped program knows that. A global is
|
|
reached by *name*: [Emit.redefinition] writes a global the host already has
|
|
as [external], so the loaded module binds to the program's own storage and
|
|
the dynamic linker does the work. Nothing has to be asked of the stopped
|
|
thread at all, which is also why there is no [bound] list here — a global's
|
|
storage exists from the moment the process started, so there is no
|
|
not-yet-bound case to refuse.
|
|
|
|
[globals] is chosen by the caller and not here, because the choice is about
|
|
the *stack* and this function is about rendering. See [Dev.globals_op].
|
|
|
|
One line per global — name, type, value, tab separated — the same framing
|
|
[render_locals] uses, and safe for the same reason: every string the
|
|
renderer emits goes through [flan_dev_emit_str], which escapes both. *)
|
|
let render_globals ?(origin = "<globals>") t ~(globals : Tast.global list)
|
|
: change * (string * string) list =
|
|
let loc = Loc.unknown in
|
|
let extra = ref [] and nslots = ref 0 in
|
|
let c =
|
|
{ Render.structs = t.program.Tast.structs;
|
|
unions = t.program.Tast.unions;
|
|
enums = Hashtbl.fold (fun k v acc -> (k, v) :: acc) t.env.Check.enums [];
|
|
emit = dev_emitter;
|
|
ptrs = Some dev_pointers;
|
|
alloc = (fun ty ->
|
|
let i = !nslots in
|
|
incr nslots;
|
|
extra := ty :: !extra;
|
|
i) }
|
|
in
|
|
let bytes_of str =
|
|
{ Tast.e =
|
|
Tast.Prim (Tast.Bytes, [ { Tast.e = Tast.Str str; ty = Types.String; loc } ]);
|
|
ty = Types.Slice (Types.Int Types.U8); loc }
|
|
in
|
|
let lit str = c.Render.emit.Render.ebytes (bytes_of str) in
|
|
let nullary n = { Tast.e = Tast.Call (n, []); ty = Types.Unit; loc } in
|
|
let refused = ref [] in
|
|
let one (g : Tast.global) =
|
|
let v = { Tast.e = Tast.Global g.Tast.gname; ty = g.Tast.gty; loc } in
|
|
match Render.render c 0 v with
|
|
| parts ->
|
|
Some
|
|
((lit (g.Tast.gname ^ "\t" ^ Types.to_string g.Tast.gty ^ "\t") :: parts)
|
|
@ [ lit "\n" ])
|
|
| exception Loc.Error { Loc.dmsg = why; _ } ->
|
|
(* A type the structural printer has no arm for. Named with its reason
|
|
rather than left out, for [render_locals]'s reason: a global that is
|
|
missing and a global that could not be printed are different facts,
|
|
and a list that showed neither would be the same lie twice. *)
|
|
refused := (g.Tast.gname, why) :: !refused;
|
|
None
|
|
in
|
|
let body = List.concat (List.filter_map one globals) in
|
|
t.thunks <- t.thunks + 1;
|
|
let name = Printf.sprintf "globals/%d" t.thunks in
|
|
let thunk : Tast.fn =
|
|
{ Tast.name; params = []; ret = Types.Unit;
|
|
body = (nullary "flan/dev-begin" :: body) @ [ nullary "flan/dev-end" ];
|
|
fdefers = []; fparent = None; floc = loc;
|
|
slots = Array.of_list (List.rev !extra);
|
|
(* Every slot in here is the walk's own scratch: what is being shown is
|
|
the program's storage, which this thunk reaches by name. *)
|
|
snames = Array.make (List.length !extra) None }
|
|
in
|
|
let program =
|
|
{ t.program with
|
|
Tast.fns = t.program.Tast.fns @ [ thunk ];
|
|
externs = t.program.Tast.externs @ externs }
|
|
in
|
|
let ir =
|
|
Emit.redefinition ~dev:true ~debug:t.debug ~known:(known t) ~call:name
|
|
program ~fns:[ name ]
|
|
in
|
|
ignore origin;
|
|
({ ir; names = []; fns = []; installs = true }, List.rev !refused)
|
|
|
|
let eval_expr ?(origin = "<eval>") t src : change =
|
|
let form =
|
|
match Reader.read_all ~file:origin src with
|
|
| [ f ] -> f
|
|
| [] -> fail Loc.unknown "nothing to evaluate"
|
|
| _ :: f :: _ -> fail f.Form.loc "one expression at a time"
|
|
in
|
|
let checked, base, bnames = Check.expression t.env (Parse.expr form) in
|
|
(* The thunk's frame starts at whatever [Check.expression] needed and grows
|
|
as the walk finds slices in it, so the slots the renderer asks for are
|
|
appended past [base] and collected here to size the frame below. *)
|
|
let extra = ref [] and nslots = ref (Array.length base) in
|
|
let c =
|
|
{ Render.structs = t.program.Tast.structs;
|
|
unions = t.program.Tast.unions;
|
|
enums = Hashtbl.fold (fun k v acc -> (k, v) :: acc) t.env.Check.enums [];
|
|
emit = dev_emitter;
|
|
ptrs = Some dev_pointers;
|
|
alloc = (fun ty ->
|
|
let i = !nslots in
|
|
incr nslots;
|
|
extra := ty :: !extra;
|
|
i) }
|
|
in
|
|
let loc = checked.Tast.loc in
|
|
let nullary n = { Tast.e = Tast.Call (n, []); ty = Types.Unit; loc } in
|
|
let body =
|
|
(nullary "flan/dev-begin" :: Render.render c 0 checked)
|
|
@ [ nullary "flan/dev-end" ]
|
|
in
|
|
t.thunks <- t.thunks + 1;
|
|
let name = Printf.sprintf "eval/%d" t.thunks in
|
|
let thunk : Tast.fn =
|
|
{ Tast.name; params = []; ret = Types.Unit; body; fdefers = []; fparent = None; floc = loc;
|
|
slots = Array.append base (Array.of_list (List.rev !extra));
|
|
(* The expression's own [let]s keep their names; the slots [render] added
|
|
behind them are the walk's own scratch and have none to keep. *)
|
|
snames = Array.append bnames (Array.make (List.length !extra) None) }
|
|
in
|
|
(* Built against the program but never spliced into it: an evaluation is not
|
|
a declaration, and adding one would leave the session carrying an eval/N
|
|
for every expression ever typed. *)
|
|
let program =
|
|
{ t.program with
|
|
Tast.fns = t.program.Tast.fns @ [ thunk ];
|
|
externs = t.program.Tast.externs @ externs }
|
|
in
|
|
let ir =
|
|
(* The thunk gets debug info on the same flag as everything else. It is a
|
|
function nobody sets a breakpoint on by name, but it is a frame on the
|
|
stack when the expression signals, and a frame the debugger cannot name
|
|
is the thing the conditions buffer is trying to stop showing. *)
|
|
Emit.redefinition ~dev:true ~debug:t.debug ~known:(known t) ~call:name
|
|
program ~fns:[ name ]
|
|
in
|
|
{ ir; names = []; fns = []; installs = true }
|