[wasm] Names of exported functions should be the stringified function index.

src/wasm/wasm-objects.cc

 // Copyright 2015 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.
 
 #include "src/wasm/wasm-objects.h"
+#include "src/utils.h"
 
 #include "src/wasm/module-decoder.h"
 #include "src/wasm/wasm-module.h"
 #include "src/wasm/wasm-text.h"
 
 #define TRACE(...)                                      \
   do {                                                  \
     if (FLAG_trace_wasm_instances) PrintF(__VA_ARGS__); \
   } while (false)
 
@@ skipping 284 matching lines @@
 
 WasmExportedFunction* WasmExportedFunction::cast(Object* object) {
   DCHECK(object && object->IsJSFunction());
   DCHECK_EQ(Code::JS_TO_WASM_FUNCTION,
             JSFunction::cast(object)->code()->kind());
   // TODO(titzer): brand check for WasmExportedFunction.
   return reinterpret_cast<WasmExportedFunction*>(object);
 }
 
 Handle<WasmExportedFunction> WasmExportedFunction::New(
-    Isolate* isolate, Handle<WasmInstanceObject> instance, Handle<String> name,
-    Handle<Code> export_wrapper, int arity, int func_index) {
+    Isolate* isolate, Handle<WasmInstanceObject> instance,
+    MaybeHandle<String> maybe_name, int func_index, int arity,
+    Handle<Code> export_wrapper) {
+  ScopedVector<char> buffer(16);

[bradnelson, 2016/12/06 15:28:31]

But you can have up to 19 digits in 63-bit signed int :-)

+  int length = SNPrintF(buffer, "%d", func_index);
+  Handle<String> name;
+  if (maybe_name.is_null()) {
+    name = isolate->factory()
+               ->NewStringFromAscii(
+                   Vector<const char>::cast(buffer.SubVector(0, length)))
+               .ToHandleChecked();
+  } else {
+    name = maybe_name.ToHandleChecked();
+  }
   DCHECK_EQ(Code::JS_TO_WASM_FUNCTION, export_wrapper->kind());
   Handle<SharedFunctionInfo> shared =
       isolate->factory()->NewSharedFunctionInfo(name, export_wrapper, false);
   shared->set_length(arity);
   shared->set_internal_formal_parameter_count(arity);
   Handle<JSFunction> function = isolate->factory()->NewFunction(
       isolate->wasm_function_map(), name, export_wrapper);
   function->set_shared(*shared);
 
   function->SetInternalField(kInstance, *instance);
@@ skipping 262 matching lines @@
       !array->get(kPreviousInstanceWrapper)->IsFixedArray())
     return false;
   return true;
 }
 
 void WasmInstanceWrapper::set_instance_object(Handle<JSObject> instance,
                                               Isolate* isolate) {
   Handle<WeakCell> cell = isolate->factory()->NewWeakCell(instance);
   set(kWrapperInstanceObject, *cell);
 }