[wasm] Provide better stack traces for asm.js code

src/wasm/wasm-module.cc

Index: src/wasm/wasm-module.cc
diff --git a/src/wasm/wasm-module.cc b/src/wasm/wasm-module.cc
index 3a4ac2dbef552e48cb2562ed785b3c3120a403b5..97b8295b8f2d49b69d401665a7cf94e0256f3cc8 100644
--- a/src/wasm/wasm-module.cc
+++ b/src/wasm/wasm-module.cc
@@ -785,6 +785,8 @@ const char* SectionName(WasmSectionCode code) {
       return "Data";
     case kNameSectionCode:
       return "Name";
+    case kAsmOffsetsSectionCode:
+      return "AsmOffsets";
     default:
       return "<unknown>";
   }
@@ -2002,6 +2004,27 @@ bool IsWasmObject(Object* object) {
   return true;
 }
 
+bool WasmIsAsm(Object* wasm, Isolate* isolate) {
+  if (wasm->IsUndefined(isolate)) return false;
+  DCHECK(IsWasmObject(wasm));
+  Object* compiled_module =
+      JSObject::cast(wasm)->GetInternalField(kWasmCompiledModule);
+  return WasmCompiledModule::cast(compiled_module)->has_asm_js_script();
+}
+
+Handle<Script> GetAsmWasmScript(Handle<JSObject> wasm) {
+  DCHECK(IsWasmObject(*wasm));
+  Object* compiled_module =
+      JSObject::cast(*wasm)->GetInternalField(kWasmCompiledModule);
+  return WasmCompiledModule::cast(compiled_module)->asm_js_script();
+}
+
+int GetAsmWasmSourcePosition(Handle<JSObject> wasm, int func_index,
+                             int byte_offset) {
+  return WasmDebugInfo::GetAsmJsSourcePosition(GetDebugInfo(wasm), func_index,
+                                               byte_offset);
+}
+
 Handle<SeqOneByteString> GetWasmBytes(Handle<JSObject> wasm) {
   DCHECK(IsWasmObject(*wasm));
   Object* compiled_module = wasm->GetInternalField(kWasmCompiledModule);
@@ -2119,11 +2142,10 @@ Handle<JSObject> CreateCompiledModuleObject(
   return module_obj;
 }
 
-MaybeHandle<JSObject> CreateModuleObjectFromBytes(Isolate* isolate,
-                                                  const byte* start,
-                                                  const byte* end,
-                                                  ErrorThrower* thrower,
-                                                  ModuleOrigin origin) {
+// TODO(clemensh): origin can be inferred from asm_js_script; remove it.
+MaybeHandle<JSObject> CreateModuleObjectFromBytes(
+    Isolate* isolate, const byte* start, const byte* end, ErrorThrower* thrower,
+    ModuleOrigin origin, Handle<Script> asm_js_script) {
   MaybeHandle<JSObject> nothing;
   Zone zone(isolate->allocator());
   ModuleResult result =
@@ -2133,12 +2155,19 @@ MaybeHandle<JSObject> CreateModuleObjectFromBytes(Isolate* isolate,
     thrower->Failed("Wasm decoding failed", result);
     return nothing;
   }
-  MaybeHandle<WasmCompiledModule> compiled_module =
+  MaybeHandle<WasmCompiledModule> maybe_compiled_module =
       decoded_module->CompileFunctions(isolate, thrower);
-  if (compiled_module.is_null()) return nothing;
+  if (maybe_compiled_module.is_null()) return nothing;
+  Handle<WasmCompiledModule> compiled_module =
+      maybe_compiled_module.ToHandleChecked();
+
+  DCHECK_EQ(origin == kAsmJsOrigin, !asm_js_script.is_null());
+  DCHECK(!compiled_module->has_asm_js_script());
+  if (origin == kAsmJsOrigin) {
+    compiled_module->set_asm_js_script(asm_js_script);
+  }
 
-  return CreateCompiledModuleObject(isolate, compiled_module.ToHandleChecked(),
-                                    origin);
+  return CreateCompiledModuleObject(isolate, compiled_module, origin);
 }
 
 bool ValidateModuleBytes(Isolate* isolate, const byte* start, const byte* end,