Revert "Revert "JumpToFrame refactor"" + Fix

runtime/vm/simulator_dbc.cc

 // Copyright (c) 2016, 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 <setjmp.h>  // NOLINT
 #include <stdlib.h>
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_DBC)
 
@@ skipping 3673 matching lines @@
   {
   DispatchAfterException:
     DISPATCH();
   }
 
   UNREACHABLE();
   return 0;
 }
 
 
-void Simulator::Longjmp(uword pc,
-                        uword sp,
-                        uword fp,
-                        RawObject* raw_exception,
-                        RawObject* raw_stacktrace,
-                        Thread* thread) {
+void Simulator::JumpToFrame(uword pc, uword sp, uword fp, Thread* thread) {
   // Walk over all setjmp buffers (simulated --> C++ transitions)
   // and try to find the setjmp associated with the simulated stack pointer.
   SimulatorSetjmpBuffer* buf = last_setjmp_buffer();
   while ((buf->link() != NULL) && (buf->link()->fp() > fp)) {
     buf = buf->link();
   }
   ASSERT(buf != NULL);
   ASSERT(last_setjmp_buffer() == buf);
 
   // The C++ caller has not cleaned up the stack memory of C++ frames.
   // Prepare for unwinding frames by destroying all the stack resources
   // in the previous C++ frames.
   StackResource::Unwind(thread);
 
   // Set the tag.
   thread->set_vm_tag(VMTag::kDartTagId);
   // Clear top exit frame.
   thread->set_top_exit_frame_info(0);
 
-  ASSERT(raw_exception != Object::null());
   sp_ = reinterpret_cast<RawObject**>(sp);
   fp_ = reinterpret_cast<RawObject**>(fp);
-  pc_ = pc;
-  special_[kExceptionSpecialIndex] = raw_exception;
-  special_[kStacktraceSpecialIndex] = raw_stacktrace;
+
+  if (pc == StubCode::RunExceptionHandler_entry()->EntryPoint()) {
+    // Instead of executing the RunException stub, we implement its
+    // behavior here.
+    RawObject* raw_exception = thread->active_exception();
+    RawObject* raw_stacktrace = thread->active_stacktrace();
+    ASSERT(raw_exception != Object::null());
+    special_[kExceptionSpecialIndex] = raw_exception;
+    special_[kStacktraceSpecialIndex] = raw_stacktrace;
+    pc_ = thread->resume_pc();
+  } else {
+    pc_ = pc;
+  }
+
   buf->Longjmp();
   UNREACHABLE();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_DBC