Add support for interrupting an isolate in the vm. Interrupts are

runtime/vm/code_generator.cc

 // Copyright (c) 2011, 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 "vm/code_generator.h"
 
 #include "vm/code_index_table.h"
 #include "vm/code_patcher.h"
 #include "vm/compiler.h"
 #include "vm/dart_api_impl.h"
@@ skipping 854 matching lines @@
   ASSERT(arguments.Count() ==
          kClosureArgumentMismatchRuntimeEntry.argument_count());
   GrowableArray<const Object*> args;
   Exceptions::ThrowByType(Exceptions::kClosureArgumentMismatch, args);
 }
 
 
 DEFINE_RUNTIME_ENTRY(StackOverflow, 0) {
   ASSERT(arguments.Count() ==
          kStackOverflowRuntimeEntry.argument_count());
-  // Use a preallocated stack overflow exception to avoid calling into
-  // dart code.
-  const Instance& exception =
-      Instance::Handle(isolate->object_store()->stack_overflow());
-  Exceptions::Throw(exception);
-  UNREACHABLE();
+  uword stack_pos = reinterpret_cast<uword>(&arguments);
+
+  // If an interrupt happens at the same time as a stack overflow, we
+  // process the stack overflow first.
+  if (stack_pos < isolate->saved_stack_limit()) {
+    // Use the preallocated stack overflow exception to avoid calling
+    // into dart code.
+    const Instance& exception =
+        Instance::Handle(isolate->object_store()->stack_overflow());
+    Exceptions::Throw(exception);
+    UNREACHABLE();
+  }
+
+  uword interrupt_bits = isolate->GetAndClearInterrupts();
+  if (interrupt_bits & Isolate::kApiInterrupt) {
+    Dart_IsolateInterruptCallback callback = isolate->InterruptCallback();
+    if (callback) {
+      if ((*callback)()) {
+        return;
+      } else {
+        // TODO(turnidge): Unwind the stack.
+        UNIMPLEMENTED();
+      }
+    }
+  }
 }
 
 
 // Only unoptimized code has invocation counter threshold checking.
 // Once the invocation counter threshold is reached any entry into the
 // unoptimized code is redirected to this function.
 DEFINE_RUNTIME_ENTRY(OptimizeInvokedFunction, 1) {
   ASSERT(arguments.Count() ==
          kOptimizeInvokedFunctionRuntimeEntry.argument_count());
   const Function& function = Function::CheckedHandle(arguments.At(0));
@@ skipping 198 matching lines @@
       }
     }
   }
   // The cache is null terminated, therefore the loop above should never
   // terminate by itself.
   UNREACHABLE();
   return Code::null();
 }
 
 }  // namespace dart