[wasm] Introduce WasmStackGuard builtin

src/builtins/builtins-wasm.cc

+// Copyright 2017 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.
+
+#include "src/builtins/builtins-utils.h"
+#include "src/builtins/builtins.h"
+#include "src/code-stub-assembler.h"
+#include "src/wasm/wasm-module.h"

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

Do we need all these includes here?

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

Thanks for the hint. Removed three of them.

+#include "src/wasm/wasm-objects.h"
+
+namespace v8 {
+namespace internal {
+
+typedef compiler::Node Node;
+typedef CodeStubAssembler::ParameterMode ParameterMode;

[Michael Starzinger, 2017/02/14 14:43:22]

nit: The "ParameterMode" typedef seems to be unused.

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

Done, also CodeAssemblerState.

+typedef compiler::CodeAssemblerState CodeAssemblerState;
+
+TF_BUILTIN(WasmStackGuard, CodeStubAssembler) {
+  Node* context = SmiConstant(0);

[ahaas, 2017/02/14 14:45:39]

I wonder if SmiConstant(Smi::kZero) would be better here.

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

Done.

+  TailCallRuntime(Runtime::kWasmStackGuard, context);
+}
+
+}  // namespace internal
+}  // namespace v8