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

R=bradnelson@chromium.org,rossberg@chromium.org
BUG=v8:5705

Review-Url: https://codereview.chromium.org/2551323003
Cr-Commit-Position: refs/heads/master@{#41530}

src/wasm/wasm-module.cc

@@ -1338,8 +1338,8 @@ class WasmInstanceBuilder {
       Handle<Code> wrapper_code = compiler::CompileJSToWasmWrapper(
           isolate_, module_, startup_code, start_index);
       Handle<WasmExportedFunction> startup_fct = WasmExportedFunction::New(
-          isolate_, instance, factory->InternalizeUtf8String("start"),
-          wrapper_code, static_cast<int>(sig->parameter_count()), start_index);
+          isolate_, instance, MaybeHandle<String>(), start_index,
+          static_cast<int>(sig->parameter_count()), wrapper_code);
       RecordStats(isolate_, *startup_code);
       // Call the JS function.
       Handle<Object> undefined = factory->undefined_value();
@@ -1760,7 +1760,7 @@ 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;
+            MaybeHandle<String> func_name;
             if (module_->origin == kAsmJsOrigin) {
               // For modules arising from asm.js, honor the names section.
               func_name = ExtractStringFromModuleBytes(
@@ -1769,9 +1769,8 @@ class WasmInstanceBuilder {
                               .ToHandleChecked();
             }
             js_function = WasmExportedFunction::New(
-                isolate_, instance, func_name, export_code,
-                static_cast<int>(function.sig->parameter_count()),
-                function.func_index);
+                isolate_, instance, func_name, function.func_index,
+                static_cast<int>(function.sig->parameter_count()), export_code);
             js_wrappers_[exp.index] = js_function;
           }
           desc.set_value(js_function);
@@ -1921,7 +1920,7 @@ class WasmInstanceBuilder {
 
               Handle<Code> wrapper_code = compiler::CompileJSToWasmWrapper(
                   isolate_, module_, wasm_code, func_index);
-              Handle<String> func_name = isolate_->factory()->empty_string();
+              MaybeHandle<String> func_name;
               if (module_->origin == kAsmJsOrigin) {
                 // For modules arising from asm.js, honor the names section.
                 func_name = ExtractStringFromModuleBytes(
@@ -1931,9 +1930,9 @@ class WasmInstanceBuilder {
               }
               Handle<WasmExportedFunction> js_function =
                   WasmExportedFunction::New(
-                      isolate_, instance, func_name, wrapper_code,
+                      isolate_, instance, func_name, func_index,
                       static_cast<int>(function->sig->parameter_count()),
-                      func_index);
+                      wrapper_code);
               js_wrappers_[func_index] = js_function;
             }
             table_instance.js_wrappers->set(table_index,

src/wasm/wasm-objects.cc

@@ -3,6 +3,7 @@
 // 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"
@@ -307,8 +308,20 @@ WasmExportedFunction* WasmExportedFunction::cast(Object* 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);
+  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);

src/wasm/wasm-objects.h

@@ -142,9 +142,9 @@ class WasmExportedFunction : public JSFunction {
 
   static Handle<WasmExportedFunction> New(Isolate* isolate,
                                           Handle<WasmInstanceObject> instance,
-                                          Handle<String> name,
-                                          Handle<Code> export_wrapper,
-                                          int arity, int func_index);
+                                          MaybeHandle<String> maybe_name,
+                                          int func_index, int arity,
+                                          Handle<Code> export_wrapper);
 };
 
 class WasmCompiledModule : public FixedArray {

test/cctest/wasm/wasm-run-utils.h

@@ -208,16 +208,15 @@ class TestingModule : public ModuleEnv {
 
   Handle<JSFunction> WrapCode(uint32_t index) {
     // Wrap the code so it can be called as a JS function.
-    Handle<String> name = isolate_->factory()->NewStringFromStaticChars("main");
     Handle<WasmInstanceObject> instance_obj(0, isolate_);
     Handle<Code> code = instance->function_code[index];
     WasmJs::InstallWasmMapsIfNeeded(isolate_, isolate_->native_context());
     Handle<Code> ret_code =
         compiler::CompileJSToWasmWrapper(isolate_, &module_, code, index);
     Handle<JSFunction> ret = WasmExportedFunction::New(
-        isolate_, instance_obj, name, ret_code,
+        isolate_, instance_obj, MaybeHandle<String>(), static_cast<int>(index),
         static_cast<int>(this->module->functions[index].sig->parameter_count()),
-        static_cast<int>(index));
+        ret_code);
     return ret;
   }
 

test/mjsunit/wasm/export-table.js

@@ -98,7 +98,7 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   print("TestExportMultipleIdentity...");
   var builder = new WasmModuleBuilder();
 
-  builder.addFunction("one", kSig_v_v).addBody([kExprNop])
+  var f = builder.addFunction("one", kSig_v_v).addBody([kExprNop])
     .exportAs("a")
     .exportAs("b")
     .exportAs("c");
@@ -110,5 +110,5 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   assertEquals("function", typeof e.c);
   assertSame(e.a, e.b);
   assertSame(e.a, e.c);
-  assertEquals("a", e.a.name);
+  assertEquals(String(f.index), e.a.name);
 })();

test/mjsunit/wasm/function-prototype.js

@@ -10,7 +10,7 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
 (function TestFunctionPrototype() {
   var builder = new WasmModuleBuilder();
 
-  builder.addFunction("nine", kSig_i_v)
+  var f = builder.addFunction("nine", kSig_i_v)
     .addBody([kExprI8Const, 9])
     .exportFunc();
 
@@ -19,7 +19,7 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   // Check type and existence of prototype
   assertEquals("function", typeof func.apply);
   assertTrue(func.prototype != undefined);
-  assertEquals("nine", func.name);
+  assertEquals(String(f.index), func.name);
   assertEquals(undefined, func.displayName);
 
   // Check that .apply() works.

test/mjsunit/wasm/indirect-tables.js

@@ -81,7 +81,7 @@ function js_div(a, b) { return (a / b) | 0; }
     assertEquals(2, mul.length);
     assertEquals(2, add.length);
     assertEquals(2, sub.length);
-    assertEquals("blarg", add.name);
+    assertEquals(String(f.add.index), add.name);
 
     let exp_div = table.get(i+3);
     assertEquals("function", typeof exp_div);