[wasm] Add support for a start function.

test/mjsunit/wasm/start-function.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --expose-wasm
+
+load("test/mjsunit/wasm/wasm-constants.js");
+

[bradnelson, 2016/02/12 17:29:55]

Maybe add a test that two start sections fail?

+function instantiate(sig, body) {
+  var module = new Array();
+  module = module.concat([
+    // -- signatures
+    kDeclSignatures, 1,
+  ]);
+  module = module.concat(sig);
+  module = module.concat([
+    // -- functions
+    kDeclFunctions, 1,
+    0,                 // decl flags
+    0, 0,              // signature
+    body.length, 0,    // body size
+  ]);
+  module = module.concat(body);
+  module = module.concat([
+    // -- declare start function
+    kDeclStartFunction,
+    0
+  ]);
+
+  var data = bytes.apply(this, module);
+  print(module);
+  print(data instanceof ArrayBuffer);
+  print(data.byteLength);
+  return _WASMEXP_.instantiateModule(data);
+}
+
+function assertFails(sig, body) {
+  try {
+    var module = instantiate(sig, body);
+    print("expected failure, but passes");
+    assertFalse(true);
+  } catch (expected) {
+    print("ok: " + expected);
+  }
+}
+
+function assertVerifies(sig, body) {
+  var module = instantiate(sig, body);
+  assertFalse(module === undefined);
+  assertFalse(module === null);
+  assertFalse(module === 0);
+  assertEquals("object", typeof module);
+  return module;
+}
+
+assertVerifies([0, kAstStmt], [kExprNop]);
+assertVerifies([0, kAstI32], [kExprI8Const, 0]);
+assertFails([1, kAstI32, kAstI32], [kExprGetLocal, 0]);

[bradnelson, 2016/02/12 17:29:55]

Maybe either comment the goal is to confirm functions >0 args are forbidden, or
maybe assert the particular exception string?

+assertFails([2, kAstI32, kAstI32, kAstF32], [kExprGetLocal, 0]);
+assertFails([3, kAstI32, kAstI32, kAstF32, kAstF64], [kExprGetLocal, 0]);
+
+(function testInvalidIndex() {
+  var kBodySize = 1;
+  var data = bytes(
+    // -- signatures
+    kDeclSignatures, 1,
+    0, kAstStmt,
+    // -- functions
+    kDeclFunctions, 1,
+    0,                 // decl flags
+    0, 0,              // signature
+    kBodySize, 0,      // body size
+    kExprNop,          // body
+    // -- declare start function
+    kDeclStartFunction,
+    1
+  );
+
+  assertThrows(function() { _WASMEXP_.instantiateModule(data); });
+})();
+
+
+(function testRun() {
+  var kBodySize = 6;
+
+  var data = bytes(
+    kDeclMemory,
+    12, 12, 1,                  // memory
+    // -- signatures
+    kDeclSignatures, 1,
+    0, kAstStmt,
+    // -- start function
+    kDeclFunctions, 1,
+    0,                          // decl flags
+    0, 0,                       // signature
+    kBodySize, 0,               // code size
+    // -- start body
+    kExprI32StoreMem, 0, kExprI8Const, 0, kExprI8Const, 77,
+    // -- declare start function
+    kDeclStartFunction,
+    0
+  );
+
+  var module = _WASMEXP_.instantiateModule(data);
+  var memory = module.memory;
+  var view = new Int8Array(memory);
+  assertEquals(77, view[0]);
+})();
+
+(function testStartFFI() {
+  var kBodySize = 2;
+  var kNameOffset = 4 + 9 + 7 + 3;
+
+  var data = bytes(
+    // -- signatures
+    kDeclSignatures, 1,
+    0, kAstStmt,
+    // -- imported function
+    kDeclFunctions, 2,
+    kDeclFunctionImport | kDeclFunctionName,     // decl flags
+    0, 0,                       // signature
+    kNameOffset, 0, 0, 0,
+    // -- start function
+    0,                          // decl flags
+    0, 0,                       // signature
+    kBodySize, 0,               // code size
+    // -- start body
+    kExprCallFunction, 0,
+    // -- declare start function
+    kDeclStartFunction,
+    1,
+    kDeclEnd,
+    'f', 'o', 'o', 0
+  );
+
+  var ranned = false;
+  var ffi = new Object();
+  ffi.foo = function() {
+    print("we ranned at stert!");

[bradnelson, 2016/02/12 17:29:55]

This was totally done at 1am yeah? :-)

+    ranned = true;
+  }
+  var module = _WASMEXP_.instantiateModule(data, ffi);
+  var memory = module.memory;
+  var view = new Int8Array(memory);
+  assertTrue(ranned);
+})();