Revert "Revert "JumpToFrame refactor"" + Fix

runtime/vm/simulator_dbc.cc

Index: runtime/vm/simulator_dbc.cc
diff --git a/runtime/vm/simulator_dbc.cc b/runtime/vm/simulator_dbc.cc
index ae9eaf87a2d19119aa6a52e5f128fcbaed6b0412..8febf13468918bb2fb8946a1becdc1b78815e38e 100644
--- a/runtime/vm/simulator_dbc.cc
+++ b/runtime/vm/simulator_dbc.cc
@@ -3691,12 +3691,7 @@ RawObject* Simulator::Call(const Code& code,
 }
 
 
-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();
@@ -3716,12 +3711,22 @@ void Simulator::Longjmp(uword pc,
   // 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();
 }