[wasm] Memory is exported on the module.exports object.

R=ahaas@chromium.org,bradnelson@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1775353003

Cr-Commit-Position: refs/heads/master@{#34621}

src/wasm/wasm-module.cc

@@ -378,13 +378,6 @@ MaybeHandle<JSObject> WasmModule::Instantiate(Isolate* isolate,
                                        *instance.mem_buffer);
   LoadDataSegments(this, instance.mem_start, instance.mem_size);
 
-  if (mem_export) {
-    // Export the memory as a named property.
-    Handle<String> name = factory->InternalizeUtf8String("memory");
-    JSObject::AddProperty(instance.js_object, name, instance.mem_buffer,
-                          READ_ONLY);
-  }
-
   //-------------------------------------------------------------------------
   // Allocate the globals area if necessary.
   //-------------------------------------------------------------------------
@@ -478,7 +471,7 @@ MaybeHandle<JSObject> WasmModule::Instantiate(Isolate* isolate,
   //-------------------------------------------------------------------------
   // Create and populate the exports object.
   //-------------------------------------------------------------------------
-  if (export_table.size() > 0) {
+  if (export_table.size() > 0 || mem_export) {
     index = 0;
     // Create the "exports" object.
     Handle<JSFunction> object_function = Handle<JSFunction>(
@@ -499,6 +492,13 @@ MaybeHandle<JSObject> WasmModule::Instantiate(Isolate* isolate,
           isolate, &module_env, name, code, instance.js_object, exp.func_index);
       JSObject::AddProperty(exports_object, name, function, READ_ONLY);
     }
+
+    if (mem_export) {
+      // Export the memory as a named property.
+      Handle<String> name = factory->InternalizeUtf8String("memory");
+      JSObject::AddProperty(exports_object, name, instance.mem_buffer,
+                            READ_ONLY);
+    }
   }
 
   // Run the start function if one was specified.

test/mjsunit/wasm/calls.js

@@ -15,18 +15,18 @@ function assertModule(module, memsize) {
   assertEquals("object", typeof module);
 
   // Check the memory is an ArrayBuffer.
-  var mem = module.memory;
+  var mem = module.exports.memory;
   assertFalse(mem === undefined);
   assertFalse(mem === null);
   assertFalse(mem === 0);
   assertEquals("object", typeof mem);
   assertTrue(mem instanceof ArrayBuffer);
   for (var i = 0; i < 4; i++) {
-    module.memory = 0;  // should be ignored
-    assertEquals(mem, module.memory);
+    module.exports.memory = 0;  // should be ignored
+    assertEquals(mem, module.exports.memory);
   }
 
-  assertEquals(memsize, module.memory.byteLength);
+  assertEquals(memsize, module.exports.memory.byteLength);
 }
 
 function assertFunction(module, func) {

test/mjsunit/wasm/instantiate-module-basic.js

@@ -27,18 +27,18 @@ assertFalse(module === 0);
 assertEquals("object", typeof module);
 
 // Check the memory is an ArrayBuffer.
-var mem = module.memory;
+var mem = module.exports.memory;
 assertFalse(mem === undefined);
 assertFalse(mem === null);
 assertFalse(mem === 0);
 assertEquals("object", typeof mem);
 assertTrue(mem instanceof ArrayBuffer);
 for (var i = 0; i < 4; i++) {
-  module.memory = 0;  // should be ignored
-  assertEquals(mem, module.memory);
+  module.exports.memory = 0;  // should be ignored
+  assertEquals(mem, module.exports.memory);
 }
 
-assertEquals(65536, module.memory.byteLength);
+assertEquals(65536, module.exports.memory.byteLength);
 
 // Check the properties of the main function.
 var main = module.exports.main;

test/mjsunit/wasm/module-memory.js

@@ -33,7 +33,7 @@ function genModule(memory) {
 
 function testPokeMemory() {
   var module = genModule(null);
-  var buffer = module.memory;
+  var buffer = module.exports.memory;
   var main = module.exports.main;
   assertEquals(kMemSize, buffer.byteLength);
 

test/mjsunit/wasm/start-function.js

@@ -84,7 +84,7 @@ assertFails([kAstI32, kAstI32, kAstF32, kAstF64], [kExprGetLocal, 0]);
   builder.addStart(func.index);
 
   var module = builder.instantiate();
-  var memory = module.memory;
+  var memory = module.exports.memory;
   var view = new Int8Array(memory);
   assertEquals(77, view[0]);
 })();