[asm.js] Cleanup asm.js instantiation API.

This refactors the {AsmJs} methods used for instantiating an asm.js
module to only use one single entry point. It is in preparation to
validate the "memory" argument as well.

R=clemensh@chromium.org
BUG=chromium:715505

Change-Id: I5e26fcf46f98c053080c70b26c0f562afc7f794a
Reviewed-on: https://chromium-review.googlesource.com/488226
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44922}

src/asmjs/asm-js.cc

@@ -63,12 +63,8 @@ Handle<Object> StdlibMathMember(Isolate* isolate, Handle<JSReceiver> stdlib,
 }
 
 bool IsStdlibMemberValid(Isolate* isolate, Handle<JSReceiver> stdlib,
-                         Handle<Object> member_id) {
-  int32_t member_kind;
-  if (!member_id->ToInt32(&member_kind)) {
-    UNREACHABLE();
-  }
-  switch (static_cast<wasm::AsmTyper::StandardMember>(member_kind)) {
+                         wasm::AsmTyper::StandardMember member) {
+  switch (member) {
     case wasm::AsmTyper::StandardMember::kNone:
     case wasm::AsmTyper::StandardMember::kModule:
     case wasm::AsmTyper::StandardMember::kStdlib:
@@ -286,29 +282,30 @@ MaybeHandle<FixedArray> AsmJs::CompileAsmViaWasm(CompilationInfo* info) {
   return result;
 }
 
-bool AsmJs::IsStdlibValid(Isolate* isolate, Handle<FixedArray> wasm_data,
-                          Handle<JSReceiver> stdlib) {
-  Handle<FixedArray> uses(FixedArray::cast(wasm_data->get(kWasmDataUsesArray)));
-  for (int i = 0; i < uses->length(); ++i) {
-    if (!IsStdlibMemberValid(isolate, stdlib,
-                             uses->GetValueChecked<Object>(isolate, i))) {
-      return false;
-    }
-  }
-  return true;
-}
-
 MaybeHandle<Object> AsmJs::InstantiateAsmWasm(Isolate* isolate,
                                               Handle<FixedArray> wasm_data,
-                                              Handle<JSArrayBuffer> memory,
-                                              Handle<JSReceiver> foreign) {
+                                              Handle<JSReceiver> stdlib,
+                                              Handle<JSReceiver> foreign,
+                                              Handle<JSArrayBuffer> memory) {
   base::ElapsedTimer instantiate_timer;
   instantiate_timer.Start();
+  Handle<FixedArray> stdlib_uses(
+      FixedArray::cast(wasm_data->get(kWasmDataUsesArray)));
   Handle<WasmModuleObject> module(
       WasmModuleObject::cast(wasm_data->get(kWasmDataCompiledModule)));
   Handle<FixedArray> foreign_globals(
       FixedArray::cast(wasm_data->get(kWasmDataForeignGlobals)));
 
+  // Check that all used stdlib members are valid.
+  for (int i = 0; i < stdlib_uses->length(); ++i) {
+    int member_id = Smi::cast(stdlib_uses->get(i))->value();
+    wasm::AsmTyper::StandardMember member =
+        static_cast<wasm::AsmTyper::StandardMember>(member_id);
+    if (!IsStdlibMemberValid(isolate, stdlib, member)) {
+      return MaybeHandle<Object>();
+    }
+  }
+
   // Create the ffi object for foreign functions {"": foreign}.
   Handle<JSObject> ffi_object;
   if (!foreign.is_null()) {

src/asmjs/asm-js.h

@@ -13,18 +13,18 @@ namespace internal {
 class CompilationInfo;
 class JSArrayBuffer;
 
-// Interface to compile and instantiate for asmjs.
+// Interface to compile and instantiate for asm.js modules.
 class AsmJs {
  public:
   static MaybeHandle<FixedArray> CompileAsmViaWasm(CompilationInfo* info);
-  static bool IsStdlibValid(Isolate* isolate, Handle<FixedArray> wasm_data,
-                            Handle<JSReceiver> stdlib);
   static MaybeHandle<Object> InstantiateAsmWasm(Isolate* isolate,
                                                 Handle<FixedArray> wasm_data,
-                                                Handle<JSArrayBuffer> memory,
-                                                Handle<JSReceiver> foreign);
+                                                Handle<JSReceiver> stdlib,
+                                                Handle<JSReceiver> foreign,
+                                                Handle<JSArrayBuffer> memory);
 };
 
 }  // namespace internal
 }  // namespace v8
-#endif
+
+#endif  // V8_ASMJS_ASM_JS_H_

src/runtime/runtime-compiler.cc

@@ -85,12 +85,10 @@ RUNTIME_FUNCTION(Runtime_InstantiateAsmJs) {
   if (args[3]->IsJSArrayBuffer()) {
     memory = args.at<JSArrayBuffer>(3);
   }
-  if (function->shared()->HasAsmWasmData() &&
-      AsmJs::IsStdlibValid(isolate, handle(function->shared()->asm_wasm_data()),
-                           stdlib)) {
-    MaybeHandle<Object> result;
-    result = AsmJs::InstantiateAsmWasm(
-        isolate, handle(function->shared()->asm_wasm_data()), memory, foreign);
+  if (function->shared()->HasAsmWasmData()) {
+    Handle<FixedArray> data(function->shared()->asm_wasm_data());
+    MaybeHandle<Object> result =
+        AsmJs::InstantiateAsmWasm(isolate, data, stdlib, foreign, memory);
     if (!result.is_null()) {
       return *result.ToHandleChecked();
     }