[kernel] Free memory for kernel data.

runtime/vm/dart_api_impl.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 
 #include "lib/stacktrace.h"
 #include "platform/assert.h"
@@ skipping 5036 matching lines @@
     // Compilation errors are not Dart instances, so just mark the library
     // as having failed to load without providing an error instance.
     lib.SetLoadError(Object::null_instance());
   }
 }
 
 #if !defined(DART_PRECOMPILED_RUNTIME)
 static Dart_Handle LoadKernelProgram(Thread* T,
                                      const String& url,
                                      void* kernel) {
-  // NOTE: Now the VM owns the [kernel_program] memory!  Currently we do not
-  // free it because (similar to the token stream) it will be used to repeatedly
-  // run the `kernel::FlowGraphBuilder()`.
-  kernel::KernelReader reader(reinterpret_cast<kernel::Program*>(kernel));
+  // NOTE: Now the VM owns the [kernel_program] memory!
+  // We will promptly delete it when done.
+  kernel::Program* program = reinterpret_cast<kernel::Program*>(kernel);
+  kernel::KernelReader reader(program);
   const Object& tmp = reader.ReadProgram();
+  delete program;
+  program = NULL;

[Kevin Millikin (Google), 2017/08/14 06:20:50]

program = NULL and kernel = NULL don't seem necessary.

If you were worried that this function might grow a lot more code that used
program after it was deleted, you could put it in its own scope.  (But I
wouldn't worry too much about that.)

[jensj, 2017/08/14 08:38:12]

Done.

+  kernel = NULL;
+
   if (tmp.IsError()) {
     return Api::NewHandle(T, tmp.raw());
   }
   return Dart_Null();
 }
 #endif
 
 DART_EXPORT Dart_Handle Dart_LoadScript(Dart_Handle url,
                                         Dart_Handle resolved_url,
                                         Dart_Handle source,
@@ skipping 157 matching lines @@
 
   Library& library = Library::Handle(Z, I->object_store()->root_library());
   if (!library.IsNull()) {
     const String& library_url = String::Handle(Z, library.url());
     return Api::NewError("%s: A script has already been loaded from '%s'.",
                          CURRENT_FUNC, library_url.ToCString());
   }
   CHECK_CALLBACK_STATE(T);
   CHECK_COMPILATION_ALLOWED(I);
 
-  // NOTE: Now the VM owns the [kernel_program] memory!  Currently we do not
-  // free it because (similar to the token stream) it will be used to repeatedly
-  // run the `kernel::FlowGraphBuilder()`.
-  kernel::KernelReader reader(
-      reinterpret_cast<kernel::Program*>(kernel_program));
+  // NOTE: Now the VM owns the [kernel_program] memory!
+  // We will promptly delete it when done.
+  kernel::Program* program = reinterpret_cast<kernel::Program*>(kernel_program);
+  kernel::KernelReader reader(program);
   const Object& tmp = reader.ReadProgram();
+  delete program;
+  program = NULL;

[Kevin Millikin (Google), 2017/08/14 06:20:50]

Likewise, here I don't think setting them to NULL is really needed.

[jensj, 2017/08/14 08:38:12]

Done.

+  kernel_program = NULL;
+
   if (tmp.IsError()) {
     return Api::NewHandle(T, tmp.raw());
   }
   // TODO(kernel): Setting root library based on whether it has 'main' or not
   // is not correct because main can be in the exported namespace of a library
   // or it could be a getter.
   if (tmp.IsNull()) {
     return Api::NewError("%s: The binary program does not contain 'main'.",
                          CURRENT_FUNC);
   }
@@ skipping 1484 matching lines @@
 #endif
 }
 
 DART_EXPORT void Dart_DumpNativeStackTrace(void* context) {
 #ifndef PRODUCT
   Profiler::DumpStackTrace(context);
 #endif
 }
 
 }  // namespace dart