VM: Better handling of OOM errors in the background compiler

runtime/vm/exceptions.cc

Index: runtime/vm/exceptions.cc
diff --git a/runtime/vm/exceptions.cc b/runtime/vm/exceptions.cc
index 37a99f25dcae5330f9ae9ccad548e67247c7825b..10fb34b5851681260d3748eacd0231584e95ac76 100644
--- a/runtime/vm/exceptions.cc
+++ b/runtime/vm/exceptions.cc
@@ -11,6 +11,7 @@
 #include "vm/debugger.h"
 #include "vm/flags.h"
 #include "vm/log.h"
+#include "vm/longjump.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/stack_frame.h"
@@ -146,7 +147,7 @@ static bool FindExceptionHandler(Thread* thread,
                                  bool* needs_stacktrace) {
   StackFrameIterator frames(StackFrameIterator::kDontValidateFrames);
   StackFrame* frame = frames.NextFrame();
-  ASSERT(frame != NULL);  // We expect to find a dart invocation frame.
+  if (frame == NULL) return false;

[rmacnak, 2016/09/13 23:29:56]

// No Dart frame.

[Florian Schneider, 2016/09/14 00:13:21]

Done.

   bool handler_pc_set = false;
   *needs_stacktrace = false;
   bool is_catch_all = false;
@@ -327,6 +328,14 @@ static void ThrowExceptionHelper(Thread* thread,
                                           &handler_sp,
                                           &handler_fp,
                                           &handler_needs_stacktrace);
+    if (handler_pc == 0) {
+      // No Dart frame.
+      ASSERT(!thread->IsMutatorThread());

[rmacnak, 2016/09/13 23:29:56]

Maybe assert that incoming_exception is the preallocated OOM exceptions, since
preallocated_unhandled_exception is in fact
preallocated_unhandled_exception_for_oom_exception.

[Florian Schneider, 2016/09/14 00:13:21]

Done.

+      const UnhandledException& error = UnhandledException::Handle(
+          zone, isolate->object_store()->preallocated_unhandled_exception());
+      thread->long_jump_base()->Jump(1, error);
+      UNREACHABLE();
+    }
     if (handler_needs_stacktrace) {
       BuildStackTrace(&frame_builder);
     }