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[interpreter] Add event section #151

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[interpreter] Add event section #151

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b3b3ed2
[interpreter] Add event section
thibaudmichaud Apr 20, 2021
3fc8553
fixup! [interpreter] Add event section
thibaudmichaud Apr 23, 2021
34925f9
fixup! [interpreter] Add event section
thibaudmichaud May 5, 2021
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25 changes: 21 additions & 4 deletions interpreter/binary/decode.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -135,6 +135,9 @@ let sized f s =

open Types

let zero s = expect 0x00 s "zero byte expected"
let var s = vu32 s

let num_type s =
match vs7 s with
| -0x01 -> I32Type
Expand Down Expand Up @@ -189,17 +192,17 @@ let global_type s =
let mut = mutability s in
GlobalType (t, mut)

let event_type s =
zero s; at var s


(* Decode instructions *)

open Ast
open Operators

let var s = vu32 s

let op s = u8 s
let end_ s = expect 0x0b s "END opcode expected"
let zero s = expect 0x00 s "zero byte expected"

let memop s =
let align = vu32 s in
Expand Down Expand Up @@ -527,6 +530,7 @@ let id s =
| 10 -> `CodeSection
| 11 -> `DataSection
| 12 -> `DataCountSection
| 13 -> `EventSection
| _ -> error s (pos s) "malformed section id"
) bo

Expand Down Expand Up @@ -555,6 +559,7 @@ let import_desc s =
| 0x01 -> TableImport (table_type s)
| 0x02 -> MemoryImport (memory_type s)
| 0x03 -> GlobalImport (global_type s)
| 0x04 -> EventImport (event_type s)
| _ -> error s (pos s - 1) "malformed import kind"

let import s =
Expand Down Expand Up @@ -592,6 +597,14 @@ let memory s =
let memory_section s =
section `MemorySection (vec (at memory)) [] s

(* Event section *)

let event s =
let etype = event_type s in
{etype}

let event_section s =
section `EventSection (vec (at event)) [] s

(* Global section *)

Expand All @@ -612,6 +625,7 @@ let export_desc s =
| 0x01 -> TableExport (at var s)
| 0x02 -> MemoryExport (at var s)
| 0x03 -> GlobalExport (at var s)
| 0x04 -> EventExport (at var s)
| _ -> error s (pos s - 1) "malformed export kind"

let export s =
Expand Down Expand Up @@ -787,6 +801,8 @@ let module_ s =
iterate custom_section s;
let memories = memory_section s in
iterate custom_section s;
let events = event_section s in
iterate custom_section s;
let globals = global_section s in
iterate custom_section s;
let exports = export_section s in
Expand All @@ -812,7 +828,8 @@ let module_ s =
let funcs =
List.map2 Source.(fun t f -> {f.it with ftype = t} @@ f.at)
func_types func_bodies
in {types; tables; memories; globals; funcs; imports; exports; elems; datas; start}
in {types; tables; memories; events; globals; funcs; imports; exports; elems;
datas; start}


let decode name bs = at module_ (stream name bs)
17 changes: 14 additions & 3 deletions interpreter/binary/encode.ml
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Expand Up @@ -90,6 +90,9 @@ let encode m =
(* Types *)

open Types
open Source

let var x = vu32 x.it

let num_type = function
| I32Type -> vs7 (-0x01)
Expand Down Expand Up @@ -118,6 +121,8 @@ let encode m =
let memory_type = function
| MemoryType lim -> limits vu32 lim

let event_type x = vu32 0x00l; var x
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Suggested change
let event_type x = vu32 0x00l; var x
let event_type x = u8 0x00; var x

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Done


let mutability = function
| Immutable -> u8 0
| Mutable -> u8 1
Expand All @@ -127,7 +132,6 @@ let encode m =

(* Expressions *)

open Source
open Ast
open Values

Expand All @@ -136,8 +140,6 @@ let encode m =

let memop {align; offset; _} = vu32 (Int32.of_int align); vu32 offset

let var x = vu32 x.it

let block_type = function
| VarBlockType x -> vs33 x.it
| ValBlockType None -> vs7 (-0x40)
Expand Down Expand Up @@ -426,6 +428,7 @@ let encode m =
| TableImport t -> u8 0x01; table_type t
| MemoryImport t -> u8 0x02; memory_type t
| GlobalImport t -> u8 0x03; global_type t
| EventImport t -> u8 0x04; event_type t

let import im =
let {module_name; item_name; idesc} = im.it in
Expand Down Expand Up @@ -456,6 +459,12 @@ let encode m =
let memory_section mems =
section 5 (vec memory) mems (mems <> [])

(* Event section *)
let event (e : event) = u8 0x00; var e.it.etype

let event_section es =
section 13 (vec event) es (es <> [])

(* Global section *)
let global g =
let {gtype; ginit} = g.it in
Expand All @@ -471,6 +480,7 @@ let encode m =
| TableExport x -> u8 1; var x
| MemoryExport x -> u8 2; var x
| GlobalExport x -> u8 3; var x
| EventExport x -> u8 4; var x

let export ex =
let {name = n; edesc} = ex.it in
Expand Down Expand Up @@ -579,6 +589,7 @@ let encode m =
func_section m.it.funcs;
table_section m.it.tables;
memory_section m.it.memories;
event_section m.it.events;
global_section m.it.globals;
export_section m.it.exports;
start_section m.it.start;
Expand Down
9 changes: 8 additions & 1 deletion interpreter/exec/eval.ml
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Expand Up @@ -85,6 +85,7 @@ let type_ (inst : module_inst) x = lookup "type" inst.types x
let func (inst : module_inst) x = lookup "function" inst.funcs x
let table (inst : module_inst) x = lookup "table" inst.tables x
let memory (inst : module_inst) x = lookup "memory" inst.memories x
let event (inst : module_inst) x = lookup "event" inst.events x
let global (inst : module_inst) x = lookup "global" inst.globals x
let elem (inst : module_inst) x = lookup "element segment" inst.elems x
let data (inst : module_inst) x = lookup "data segment" inst.datas x
Expand Down Expand Up @@ -580,6 +581,9 @@ let create_memory (inst : module_inst) (mem : memory) : memory_inst =
let {mtype} = mem.it in
Memory.alloc mtype

let create_event (inst : module_inst) (e : event) : event_inst =
Event.alloc (type_ inst e.it.etype)

let create_global (inst : module_inst) (glob : global) : global_inst =
let {gtype; ginit} = glob.it in
let v = eval_const inst ginit in
Expand All @@ -593,6 +597,7 @@ let create_export (inst : module_inst) (ex : export) : export_inst =
| TableExport x -> ExternTable (table inst x)
| MemoryExport x -> ExternMemory (memory inst x)
| GlobalExport x -> ExternGlobal (global inst x)
| EventExport x -> ExternEvent (event inst x)
in (name, ext)

let create_elem (inst : module_inst) (seg : elem_segment) : elem_inst =
Expand All @@ -612,6 +617,7 @@ let add_import (m : module_) (ext : extern) (im : import) (inst : module_inst)
| ExternFunc func -> {inst with funcs = func :: inst.funcs}
| ExternTable tab -> {inst with tables = tab :: inst.tables}
| ExternMemory mem -> {inst with memories = mem :: inst.memories}
| ExternEvent event -> {inst with events = event :: inst.events}
| ExternGlobal glob -> {inst with globals = glob :: inst.globals}

let init_func (inst : module_inst) (func : func_inst) =
Expand Down Expand Up @@ -654,7 +660,7 @@ let run_start start =

let init (m : module_) (exts : extern list) : module_inst =
let
{ imports; tables; memories; globals; funcs; types;
{ imports; tables; memories; events; globals; funcs; types;
exports; elems; datas; start
} = m.it
in
Expand All @@ -670,6 +676,7 @@ let init (m : module_) (exts : extern list) : module_inst =
{ inst1 with
tables = inst1.tables @ List.map (create_table inst1) tables;
memories = inst1.memories @ List.map (create_memory inst1) memories;
events = inst1.events @ List.map (create_event inst1) events;
globals = inst1.globals @ List.map (create_global inst1) globals;
}
in
Expand Down
10 changes: 10 additions & 0 deletions interpreter/runtime/event.ml
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@@ -0,0 +1,10 @@
open Types
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Even if its kind of trivial, can you also add an .mli file for this module?

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Done


type event = {ty : func_type}
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Hm, it's a bit odd that this is func_type not event_type. I can see why, but it would break down once an event type has additional attributes.

The underlying problem is that there are two notions of event_type: the syntactic one (with a typeidx) and the semantic one (with the function type inline). Depending on context, we want one or the other. This is not a situation we've had before, so I don't have any great suggestion right now. We can resolve this later.

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Ack. Regarding the syntactic vs semantic event_type: I don't see how this is too different from functions, where the type can also be represented directly or through the type ID? It makes sense to me that if one uses the "semantic" encoding, the other does too.

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The difference is the extra indirection. For function types, the type section is just mapping a typeidx to a func type, and the functype itself is a closed type description. Once looked up, we can use that directly. But for event types, the definition itself refers to another typeidx, so isn't self-contained. This becomes clearer if we assume that an event type has additional ingredients, say, a hypothetical event_mode (as per the reserved zero byte). Then for the syntax, we'd need
event_type = EventType of typeidx * event_mode
But but when e.g. defining extern_type, that index is meaningless (because it's used outside any module) and you want ExternEventType of event_type' where
event_type' = EventType' of func_type * event_mode
FWIW, a similar problem also arises with typed reference types, so the syntactic vs semantic distinction becomes rather ubiquitous.

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I agree, and for this reason I think types.ml should contain the resolved type.
We already have the typeidx in the AST:

type event = event' Source.phrase
and event' =
{
  etype : var;
}

which makes sense for encoding, decoding and pretty-printing. For type checking, imports/exports and everything else, the resolved type is easier to work with. WDYT about simply reverting back to type event_type = EventType of func_type?

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Actually, both etype and EventImport ought to carry an event_type, not a var. Otherwise, they in turn don't factorise correctly, e.g., when event types were to consist of more than just a var.

I'm afraid we can't hack around the two facets, they're inherent. It's relatively localised here, but becomes ubiquitous with concrete reference types. In the function references proposal I currently resolve it by actually distinguishing syntactic and semantic types. They differ by how variables are represented: for syntactic types it's just an index, with semantic types they become a pointer to the actual definition.

But I suggest to not worry about it for now. I want to play with streamlining this a bit and can fix it later. This needs a representation that cleanly carries over to the paper spec.

type t = event

let alloc ty =
{ty}

let type_of evt =
evt.ty
7 changes: 7 additions & 0 deletions interpreter/runtime/event.mli
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@@ -0,0 +1,7 @@
open Types

type event = {ty : func_type}
type t = event

val alloc : func_type -> event
val type_of : event -> func_type
8 changes: 6 additions & 2 deletions interpreter/runtime/instance.ml
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Expand Up @@ -6,6 +6,7 @@ type module_inst =
funcs : func_inst list;
tables : table_inst list;
memories : memory_inst list;
events : event_inst list;
globals : global_inst list;
exports : export_inst list;
elems : elem_inst list;
Expand All @@ -15,6 +16,7 @@ type module_inst =
and func_inst = module_inst ref Func.t
and table_inst = Table.t
and memory_inst = Memory.t
and event_inst = Event.t
and global_inst = Global.t
and export_inst = Ast.name * extern
and elem_inst = Values.ref_ list ref
Expand All @@ -24,6 +26,7 @@ and extern =
| ExternFunc of func_inst
| ExternTable of table_inst
| ExternMemory of memory_inst
| ExternEvent of event_inst
| ExternGlobal of global_inst


Expand All @@ -47,14 +50,15 @@ let () =
(* Auxiliary functions *)

let empty_module_inst =
{ types = []; funcs = []; tables = []; memories = []; globals = [];
exports = []; elems = []; datas = [] }
{ types = []; funcs = []; tables = []; memories = []; events = [];
globals = []; exports = []; elems = []; datas = [] }

let extern_type_of = function
| ExternFunc func -> ExternFuncType (Func.type_of func)
| ExternTable tab -> ExternTableType (Table.type_of tab)
| ExternMemory mem -> ExternMemoryType (Memory.type_of mem)
| ExternGlobal glob -> ExternGlobalType (Global.type_of glob)
| ExternEvent event -> ExternEventType (Event.type_of event)

let export inst name =
try Some (List.assoc name inst.exports) with Not_found -> None
2 changes: 2 additions & 0 deletions interpreter/script/run.ml
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Expand Up @@ -215,6 +215,7 @@ let print_import m im =
| ExternFuncType t -> "func", string_of_func_type t
| ExternTableType t -> "table", string_of_table_type t
| ExternMemoryType t -> "memory", string_of_memory_type t
| ExternEventType t -> "event", string_of_func_type t
| ExternGlobalType t -> "global", string_of_global_type t
in
Printf.printf " import %s \"%s\" \"%s\" : %s\n"
Expand All @@ -228,6 +229,7 @@ let print_export m ex =
| ExternFuncType t -> "func", string_of_func_type t
| ExternTableType t -> "table", string_of_table_type t
| ExternMemoryType t -> "memory", string_of_memory_type t
| ExternEventType t -> "event", string_of_func_type t
| ExternGlobalType t -> "global", string_of_global_type t
in
Printf.printf " export %s \"%s\" : %s\n"
Expand Down
16 changes: 16 additions & 0 deletions interpreter/syntax/ast.ml
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Expand Up @@ -150,6 +150,13 @@ and memory' =
mtype : memory_type;
}

type event = event' Source.phrase
and event' =
{
etype : var;
}


type segment_mode = segment_mode' Source.phrase
and segment_mode' =
| Passive
Expand Down Expand Up @@ -182,6 +189,7 @@ and export_desc' =
| TableExport of var
| MemoryExport of var
| GlobalExport of var
| EventExport of var

type export = export' Source.phrase
and export' =
Expand All @@ -196,6 +204,7 @@ and import_desc' =
| TableImport of table_type
| MemoryImport of memory_type
| GlobalImport of global_type
| EventImport of var

type import = import' Source.phrase
and import' =
Expand All @@ -212,6 +221,7 @@ and module_' =
globals : global list;
tables : table list;
memories : memory list;
events : event list;
funcs : func list;
start : var option;
elems : elem_segment list;
Expand All @@ -229,6 +239,7 @@ let empty_module =
globals = [];
tables = [];
memories = [];
events = [];
funcs = [];
start = None;
elems = [];
Expand All @@ -248,6 +259,7 @@ let import_type (m : module_) (im : import) : extern_type =
| FuncImport x -> ExternFuncType (func_type_for m x)
| TableImport t -> ExternTableType t
| MemoryImport t -> ExternMemoryType t
| EventImport x -> ExternEventType (func_type_for m x)
| GlobalImport t -> ExternGlobalType t

let export_type (m : module_) (ex : export) : extern_type =
Expand All @@ -268,6 +280,10 @@ let export_type (m : module_) (ex : export) : extern_type =
| GlobalExport x ->
let gts = globals its @ List.map (fun g -> g.it.gtype) m.it.globals in
ExternGlobalType (nth gts x.it)
| EventExport x ->
let ets =
events its @ List.map (fun (e : event) -> func_type_for m e.it.etype) m.it.events
in ExternEventType (nth ets x.it)

let string_of_name n =
let b = Buffer.create 16 in
Expand Down
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