Track async causal stack traces

runtime/vm/intrinsifier_ia32.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.
 //
 // The intrinsic code below is executed before a method has built its frame.
 // The return address is on the stack and the arguments below it.
 // Registers EDX (arguments descriptor) and ECX (function) must be preserved.
 // Each intrinsification method returns true if the corresponding
 // Dart method was intrinsified.
 
@@ skipping 2298 matching lines @@
   __ j(NOT_ZERO, &true_label, Assembler::kNearJump);
   // Not enabled.
   __ LoadObject(EAX, Bool::False());
   __ ret();
   // Enabled.
   __ Bind(&true_label);
   __ LoadObject(EAX, Bool::True());
   __ ret();
 }
 
+
+void Intrinsifier::ClearAsyncThreadStackTrace(Assembler* assembler) {
+  __ LoadObject(EAX, Object::null_object());
+  __ movl(Address(THR, Thread::async_stack_trace_offset()), EAX);
+  __ ret();
+}
+
+
+void Intrinsifier::SetAsyncThreadStackTrace(Assembler* assembler) {
+  __ movl(Address(THR, Thread::async_stack_trace_offset()), EAX);
+  __ LoadObject(EAX, Object::null_object());
+  __ ret();
+}
+
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32