Add an option to export the function table (#1001)

Author: dcodeIO

cli/asc.js

@@ -217,6 +217,7 @@ exports.main = function main(argv, options, callback) {
   assemblyscript.setImportMemory(compilerOptions, args.importMemory);
   assemblyscript.setSharedMemory(compilerOptions, args.sharedMemory);
   assemblyscript.setImportTable(compilerOptions, args.importTable);
+  assemblyscript.setExportTable(compilerOptions, args.exportTable);
   assemblyscript.setExplicitStart(compilerOptions, args.explicitStart);
   assemblyscript.setMemoryBase(compilerOptions, args.memoryBase >>> 0);
   assemblyscript.setSourceMap(compilerOptions, args.sourceMap != null);

cli/asc.json

@@ -123,7 +123,7 @@
     "default": false
   },
   "importMemory": {
-    "description": "Imports the memory instance provided by the embedder.",
+    "description": "Imports the memory provided as 'env.memory'.",
     "type": "b",
     "default": false
   },
@@ -138,7 +138,12 @@
     "default": 0
   },
   "importTable": {
-    "description": "Imports the function table instance provided by the embedder.",
+    "description": "Imports the function table provided as 'env.table'.",
+    "type": "b",
+    "default": false
+  },
+  "exportTable": {
+    "description": "Exports the function table as 'table'.",
     "type": "b",
     "default": false
   },

src/compiler.ts

@@ -198,6 +198,8 @@ export class Options {
   sharedMemory: i32 = 0;
   /** If true, imports the function table provided by the embedder. */
   importTable: bool = false;
+  /** If true, exports the function table. */
+  exportTable: bool = false;
   /** If true, generates information necessary for source maps. */
   sourceMap: bool = false;
   /** If true, generates an explicit start function. */
@@ -455,8 +457,9 @@ export class Compiler extends DiagnosticEmitter {
     module.setFunctionTable(functionTable.length, Module.UNLIMITED_TABLE, functionTable, module.i32(0));
     module.addFunction("null", NativeType.None, NativeType.None, null, module.unreachable());
 
-    // import table if requested (default table is named '0' by Binaryen)
+    // import and/or export table if requested (default table is named '0' by Binaryen)
     if (options.importTable) module.addTableImport("0", "env", "table");
+    if (options.exportTable) module.addTableExport("0", "table");
 
     // set up module exports
     for (let file of this.program.filesByName.values()) {

src/index.ts

@@ -43,6 +43,11 @@ export function setImportTable(options: Options, importTable: bool): void {
   options.importTable = importTable;
 }
 
+/** Sets the `exportTable` option. */
+export function setExportTable(options: Options, exportTable: bool): void {
+  options.exportTable = exportTable;
+}
+
 /** Sets the `sourceMap` option. */
 export function setSourceMap(options: Options, sourceMap: bool): void {
   options.sourceMap = sourceMap;

tests/compiler/exportimport-table.js

@@ -0,0 +1,5 @@
+exports.preInstantiate = function(imports, exports) {
+  imports.env = {
+    table: new WebAssembly.Table({ element: "anyfunc", initial: 2 })
+  };
+};

tests/compiler/exportimport-table.json

@@ -0,0 +1,7 @@
+{
+  "asc_flags": [
+    "--runtime none",
+    "--importTable",
+    "--exportTable"
+  ]
+}

tests/compiler/exportimport-table.optimized.wat

@@ -0,0 +1,14 @@
+(module
+ (type $none_=>_none (func))
+ (import "env" "table" (table $0 2 funcref))
+ (elem (i32.const 0) $null $start:exportimport-table~anonymous|0)
+ (memory $0 0)
+ (export "memory" (memory $0))
+ (export "table" (table $0))
+ (func $start:exportimport-table~anonymous|0 (; 0 ;)
+  nop
+ )
+ (func $null (; 1 ;)
+  unreachable
+ )
+)

tests/compiler/exportimport-table.ts

@@ -0,0 +1,2 @@
+var f = (): void => {};
+f;

tests/compiler/exportimport-table.untouched.wat

@@ -0,0 +1,23 @@
+(module
+ (type $none_=>_none (func))
+ (import "env" "table" (table $0 2 funcref))
+ (elem (i32.const 0) $null $start:exportimport-table~anonymous|0)
+ (memory $0 0)
+ (global $exportimport-table/f (mut i32) (i32.const 1))
+ (export "memory" (memory $0))
+ (export "table" (table $0))
+ (start $start)
+ (func $start:exportimport-table~anonymous|0 (; 0 ;)
+  nop
+ )
+ (func $start:exportimport-table (; 1 ;)
+  global.get $exportimport-table/f
+  drop
+ )
+ (func $start (; 2 ;)
+  call $start:exportimport-table
+ )
+ (func $null (; 3 ;)
+  unreachable
+ )
+)