[wasm] Fix memory leak in wasm-module-runner.cc

test/common/wasm/wasm-module-runner.cc

Index: test/common/wasm/wasm-module-runner.cc
diff --git a/test/common/wasm/wasm-module-runner.cc b/test/common/wasm/wasm-module-runner.cc
index 7629233ed94bb3eedc0f510e0c185c25c2a71c7f..55ccffd977cdd8ecae33d27708c21653fcba886b 100644
--- a/test/common/wasm/wasm-module-runner.cc
+++ b/test/common/wasm/wasm-module-runner.cc
@@ -81,14 +81,14 @@ const Handle<JSObject> InstantiateModuleForTesting(Isolate* isolate,
 const Handle<JSObject> CompileInstantiateWasmModuleForTesting(
     Isolate* isolate, ErrorThrower* thrower, const byte* module_start,
     const byte* module_end, ModuleOrigin origin) {
-  const WasmModule* module = DecodeWasmModuleForTesting(
-      isolate, thrower, module_start, module_end, origin);
+  std::unique_ptr<const WasmModule> module(DecodeWasmModuleForTesting(

[titzer, 2016/10/24 13:34:40]

This isn't quite right.

This C++ object should be cleaned up by the garbage collector, since the
instance now holds a special Managed<WasmModule> reference to it. Adding this
unique pointer reclaims the C++ object after reaching the end of the method, but
the instance still holds a pointer to it.

If this is not getting cleaned up because the GC is not running finalizers, then
we should find a way to clean it up by explicitly, perhaps by manually deleting
the Managed<WasmModule> in InstantiateModuleForTesting.

[ahaas, 2016/10/24 14:04:29]

This is not the WasmModule that is given to the instance in
InstantiateModuleForTesting, so the garbage collector does not deallocate this
WasmModule. I added a TODO in InstantiateModuleForTesting that this module
should be given to the instance instead of decoding the module bytes again to
make a new WasmModule.

+      isolate, thrower, module_start, module_end, origin));
 
   if (module == nullptr) {
     thrower->CompileError("Wasm module decoding failed");
     return Handle<JSObject>::null();
   }
-  return InstantiateModuleForTesting(isolate, thrower, module);
+  return InstantiateModuleForTesting(isolate, thrower, module.get());
 }
 
 int32_t RunWasmModuleForTesting(Isolate* isolate, Handle<JSObject> instance,