[wasm] Move ScheduledErrorThrower to wasm-api.h

The ScheduledErrorThrower is also needed in the wasm-async fuzzer so I
moved the implementation from wasm-js.cc to wasm-api.[h|cc].

R=clemensh@chromium.org

Bug: chromium:749838
Change-Id: I49d7438d1ec0281285ce0c64ba462c22001be08e
Reviewed-on: https://chromium-review.googlesource.com/591447
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47112}

BUILD.gn

@@ -1997,6 +1997,8 @@ v8_source_set("v8_base") {
     "src/wasm/signature-map.h",
     "src/wasm/streaming-decoder.cc",
     "src/wasm/streaming-decoder.h",
+    "src/wasm/wasm-api.cc",
+    "src/wasm/wasm-api.h",
     "src/wasm/wasm-code-specialization.cc",
     "src/wasm/wasm-code-specialization.h",
     "src/wasm/wasm-debug.cc",

src/v8.gyp

@@ -1440,6 +1440,8 @@
         'wasm/signature-map.h',
         'wasm/streaming-decoder.cc',
         'wasm/streaming-decoder.h',
+        'wasm/wasm-api.cc',
+        'wasm/wasm-api.h',
         'wasm/wasm-code-specialization.h',
         'wasm/wasm-code-specialization.cc',
         'wasm/wasm-debug.cc',

src/wasm/wasm-api.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/wasm/wasm-api.h"
+
+#include "src/isolate-inl.h"
+#include "src/isolate.h"
+
+namespace v8 {
+namespace internal {
+namespace wasm {
+
+ScheduledErrorThrower::~ScheduledErrorThrower() {
+  // There should never be both a pending and a scheduled exception.
+  DCHECK(!isolate()->has_scheduled_exception() ||
+         !isolate()->has_pending_exception());
+  // Don't throw another error if there is already a scheduled error.
+  if (isolate()->has_scheduled_exception()) {
+    Reset();
+  } else if (isolate()->has_pending_exception()) {
+    Reset();
+    isolate()->OptionalRescheduleException(false);
+  } else if (error()) {
+    isolate()->ScheduleThrow(*Reify());
+  }
+}
+
+}  // namespace wasm
+}  // namespace internal
+}  // namespace v8

src/wasm/wasm-api.h

+// 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.
+
+#ifndef V8_WASM_API_H_
+#define V8_WASM_API_H_
+
+#include "src/wasm/wasm-result.h"
+
+namespace v8 {
+namespace internal {
+namespace wasm {
+
+// Like an ErrorThrower, but turns all pending exceptions into scheduled
+// exceptions when going out of scope. Use this in API methods.
+// Note that pending exceptions are not necessarily created by the ErrorThrower,
+// but e.g. by the wasm start function. There might also be a scheduled
+// exception, created by another API call (e.g. v8::Object::Get). But there
+// should never be both pending and scheduled exceptions.
+class V8_EXPORT_PRIVATE ScheduledErrorThrower : public ErrorThrower {
+ public:
+  ScheduledErrorThrower(v8::Isolate* isolate, const char* context)
+      : ScheduledErrorThrower(reinterpret_cast<Isolate*>(isolate), context) {}
+
+  ScheduledErrorThrower(Isolate* isolate, const char* context)
+      : ErrorThrower(isolate, context) {}
+
+  ~ScheduledErrorThrower();
+};
+
+}  // namespace wasm
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_WASM_API_H_

test/fuzzer/wasm-async.cc

@@ -12,6 +12,7 @@
 #include "src/isolate.h"
 #include "src/objects-inl.h"
 #include "src/objects.h"
+#include "src/wasm/wasm-api.h"
 #include "src/wasm/wasm-module.h"
 #include "test/common/wasm/flag-utils.h"
 #include "test/common/wasm/wasm-module-runner.h"
@@ -59,7 +60,7 @@ void InstantiateCallback(const v8::FunctionCallbackInfo<v8::Value>& args) {
 
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
 
-  ErrorThrower thrower(i_isolate, "WebAssembly Instantiation");
+  ScheduledErrorThrower thrower(i_isolate, "WebAssembly Instantiation");
 
   i::Handle<i::WasmModuleObject> module_obj = ToWasmModuleObjectUnchecked(
       v8::Utils::OpenHandle(v8::Object::Cast(*module)));