[wasm] Introduce WasmStackGuard builtin

src/runtime/runtime-wasm.cc

Index: src/runtime/runtime-wasm.cc
diff --git a/src/runtime/runtime-wasm.cc b/src/runtime/runtime-wasm.cc
index 3ed63879add0dd24a128c273ff0075f92070f276..2e579753363e5aedb322ebc9b0d5e23a8caafafb 100644
--- a/src/runtime/runtime-wasm.cc
+++ b/src/runtime/runtime-wasm.cc
@@ -12,6 +12,7 @@
 #include "src/factory.h"
 #include "src/frames-inl.h"
 #include "src/objects-inl.h"
+#include "src/runtime/runtime.h"
 #include "src/v8memory.h"
 #include "src/wasm/wasm-module.h"
 #include "src/wasm/wasm-objects.h"
@@ -21,7 +22,7 @@ namespace v8 {
 namespace internal {
 
 namespace {
-Handle<WasmInstanceObject> GetWasmInstanceOnStackTop(Isolate* isolate) {
+WasmInstanceObject* GetWasmInstanceOnStackTop(Isolate* isolate) {
   DisallowHeapAllocation no_allocation;
   const Address entry = Isolate::c_entry_fp(isolate->thread_local_top());
   Address pc =
@@ -30,7 +31,7 @@ Handle<WasmInstanceObject> GetWasmInstanceOnStackTop(Isolate* isolate) {
   DCHECK_EQ(Code::WASM_FUNCTION, code->kind());
   WasmInstanceObject* owning_instance = wasm::GetOwningWasmInstance(code);
   CHECK_NOT_NULL(owning_instance);
-  return handle(owning_instance, isolate);
+  return owning_instance;
 }
 }  // namespace
 
@@ -38,7 +39,8 @@ RUNTIME_FUNCTION(Runtime_WasmMemorySize) {
   HandleScope scope(isolate);
   DCHECK_EQ(0, args.length());
 
-  Handle<WasmInstanceObject> instance = GetWasmInstanceOnStackTop(isolate);
+  Handle<WasmInstanceObject> instance(GetWasmInstanceOnStackTop(isolate),
+                                      isolate);
   return *isolate->factory()->NewNumberFromInt(
       wasm::GetInstanceMemorySize(isolate, instance));
 }
@@ -47,7 +49,8 @@ RUNTIME_FUNCTION(Runtime_WasmGrowMemory) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   CONVERT_UINT32_ARG_CHECKED(delta_pages, 0);
-  Handle<WasmInstanceObject> instance = GetWasmInstanceOnStackTop(isolate);
+  Handle<WasmInstanceObject> instance(GetWasmInstanceOnStackTop(isolate),
+                                      isolate);
   return *isolate->factory()->NewNumberFromInt(
       wasm::GrowMemory(isolate, instance, delta_pages));
 }
@@ -161,7 +164,7 @@ RUNTIME_FUNCTION(Runtime_WasmGetCaughtExceptionValue) {
 }
 
 RUNTIME_FUNCTION(Runtime_WasmRunInterpreter) {
-  DCHECK(args.length() == 3);
+  DCHECK_EQ(3, args.length());
   HandleScope scope(isolate);
   CONVERT_ARG_HANDLE_CHECKED(JSObject, instance_obj, 0);
   CONVERT_NUMBER_CHECKED(int32_t, func_index, Int32, args[1]);
@@ -177,13 +180,27 @@ RUNTIME_FUNCTION(Runtime_WasmRunInterpreter) {
   CHECK(arg_buffer_obj->IsSmi());
   uint8_t* arg_buffer = reinterpret_cast<uint8_t*>(*arg_buffer_obj);
 
-  // Set the current isolate's context, saving the previous one.
-  SaveContext save(isolate);
+  // Set the current isolate's context.
   isolate->set_context(*instance->compiled_module()->native_context());

[ahaas, 2017/02/14 14:45:38]

nit: Can you add a DCHECK_NULL(isolate->context()); here?

[Clemens Hammacher, 2017/02/14 17:23:14]

Done.

 
   instance->debug_info()->RunInterpreter(func_index, arg_buffer);
   return isolate->heap()->undefined_value();
 }
 
+RUNTIME_FUNCTION(Runtime_WasmStackGuard) {
+  SealHandleScope shs(isolate);
+  DCHECK_EQ(0, args.length());
+
+  // Set the current isolate's context.
+  WasmInstanceObject* instance = GetWasmInstanceOnStackTop(isolate);
+  isolate->set_context(instance->compiled_module()->ptr_to_native_context());

[ahaas, 2017/02/14 14:45:38]

nit: Can you add a DCHECK_NULL(isolate->context()); here?

[Clemens Hammacher, 2017/02/14 17:23:14]

Done.

+
+  // Check if this is a real stack overflow.
+  StackLimitCheck check(isolate);
+  if (check.JsHasOverflowed()) return isolate->StackOverflow();
+
+  return isolate->stack_guard()->HandleInterrupts();
+}
+
 }  // namespace internal
 }  // namespace v8