[wasm] Use handles in wasm::GetDebugInfo.

Handles are necessary in wasm::GetDebugInfo because a GC can be
triggered in this function.

R=titzer@chromium.org, mstarzinger@chromium.org

Review-Url: https://codereview.chromium.org/2132553002
Cr-Commit-Position: refs/heads/master@{#37601}

src/frames.cc

@@ -1434,8 +1434,8 @@ uint32_t WasmFrame::function_index() const {
 }
 
 Script* WasmFrame::script() const {
-  JSObject* wasm = JSObject::cast(wasm_obj());
-  Handle<wasm::WasmDebugInfo> debug_info(wasm::GetDebugInfo(wasm), isolate());
+  Handle<JSObject> wasm(JSObject::cast(wasm_obj()), isolate());
+  Handle<wasm::WasmDebugInfo> debug_info = wasm::GetDebugInfo(wasm);
   return wasm::WasmDebugInfo::GetFunctionScript(debug_info, function_index());
 }
 

src/runtime/runtime-debug.cc

@@ -1803,8 +1803,8 @@ RUNTIME_FUNCTION(Runtime_GetWasmFunctionOffsetTable) {
   CHECK(script_val->value()->IsScript());
   Handle<Script> script = Handle<Script>(Script::cast(script_val->value()));
 
-  Handle<wasm::WasmDebugInfo> debug_info(
-      wasm::GetDebugInfo(script->wasm_object()), isolate);
+  Handle<wasm::WasmDebugInfo> debug_info =
+      wasm::GetDebugInfo(handle(script->wasm_object(), isolate));
   Handle<FixedArray> elements = wasm::WasmDebugInfo::GetFunctionOffsetTable(
       debug_info, script->wasm_function_index());
   return *isolate->factory()->NewJSArrayWithElements(elements);
@@ -1818,8 +1818,8 @@ RUNTIME_FUNCTION(Runtime_DisassembleWasmFunction) {
   CHECK(script_val->value()->IsScript());
   Handle<Script> script = Handle<Script>(Script::cast(script_val->value()));
 
-  Handle<wasm::WasmDebugInfo> debug_info(
-      wasm::GetDebugInfo(script->wasm_object()), isolate);
+  Handle<wasm::WasmDebugInfo> debug_info =
+      wasm::GetDebugInfo(handle(script->wasm_object(), isolate));
   return *wasm::WasmDebugInfo::DisassembleFunction(
       debug_info, script->wasm_function_index());
 }

src/wasm/wasm-module.cc

@@ -1278,12 +1278,14 @@ SeqOneByteString* GetWasmBytes(JSObject* wasm) {
   return SeqOneByteString::cast(wasm->GetInternalField(kWasmModuleBytesString));
 }
 
-WasmDebugInfo* GetDebugInfo(JSObject* wasm) {
-  Object* info = wasm->GetInternalField(kWasmDebugInfo);
-  if (!info->IsUndefined(wasm->GetIsolate())) return WasmDebugInfo::cast(info);
-  Handle<WasmDebugInfo> new_info = WasmDebugInfo::New(handle(wasm));
+Handle<WasmDebugInfo> GetDebugInfo(Handle<JSObject> wasm) {
+  Handle<Object> info(wasm->GetInternalField(kWasmDebugInfo),
+                      wasm->GetIsolate());
+  if (!info->IsUndefined(wasm->GetIsolate()))
+    return Handle<WasmDebugInfo>::cast(info);
+  Handle<WasmDebugInfo> new_info = WasmDebugInfo::New(wasm);
   wasm->SetInternalField(kWasmDebugInfo, *new_info);
-  return *new_info;
+  return new_info;
 }
 
 bool UpdateWasmModuleMemory(Handle<JSObject> object, Address old_start,

src/wasm/wasm-module.h

@@ -354,7 +354,7 @@ SeqOneByteString* GetWasmBytes(JSObject* wasm);
 
 // Get the debug info associated with the given wasm object.
 // If no debug info exists yet, it is created automatically.
-WasmDebugInfo* GetDebugInfo(JSObject* wasm);
+Handle<WasmDebugInfo> GetDebugInfo(Handle<JSObject> wasm);
 
 // Return the number of functions in the given wasm object.
 int GetNumberOfFunctions(JSObject* wasm);