[wasm] Honor the names section for modules coming from asm.js.

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

Review-Url: https://codereview.chromium.org/2553123002
Cr-Commit-Position: refs/heads/master@{#41528}

src/wasm/wasm-module.cc

@@ -1760,8 +1760,16 @@ class WasmInstanceBuilder {
             // Wrap the exported code as a JSFunction.
             Handle<Code> export_code =
                 code_table->GetValueChecked<Code>(isolate_, func_index);
+            Handle<String> func_name = name;
+            if (module_->origin == kAsmJsOrigin) {
+              // For modules arising from asm.js, honor the names section.
+              func_name = ExtractStringFromModuleBytes(
+                              isolate_, compiled_module_, function.name_offset,
+                              function.name_length)
+                              .ToHandleChecked();
+            }
             js_function = WasmExportedFunction::New(
-                isolate_, instance, name, export_code,
+                isolate_, instance, func_name, export_code,
                 static_cast<int>(function.sig->parameter_count()),
                 function.func_index);
             js_wrappers_[exp.index] = js_function;
@@ -1913,10 +1921,17 @@ class WasmInstanceBuilder {
 
               Handle<Code> wrapper_code = compiler::CompileJSToWasmWrapper(
                   isolate_, module_, wasm_code, func_index);
+              Handle<String> func_name = isolate_->factory()->empty_string();
+              if (module_->origin == kAsmJsOrigin) {
+                // For modules arising from asm.js, honor the names section.
+                func_name = ExtractStringFromModuleBytes(
+                                isolate_, compiled_module_,
+                                function->name_offset, function->name_length)
+                                .ToHandleChecked();
+              }
               Handle<WasmExportedFunction> js_function =
                   WasmExportedFunction::New(
-                      isolate_, instance, isolate_->factory()->empty_string(),
-                      wrapper_code,
+                      isolate_, instance, func_name, wrapper_code,
                       static_cast<int>(function->sig->parameter_count()),
                       func_index);
               js_wrappers_[func_index] = js_function;

test/mjsunit/wasm/asm-wasm-names.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: --validate-asm
+
+function Module(stdlib, foreign, buffer) {
+  "use asm";
+  function foo() {}
+  return {bar: foo};
+}
+
+var func = Module({}, {}, new ArrayBuffer(65536)).bar;
+assertEquals("Module", Module.name);
+assertEquals("foo", func.name);