Reapply "Lazy deopt without code patching."

runtime/vm/exceptions.cc

Index: runtime/vm/exceptions.cc
diff --git a/runtime/vm/exceptions.cc b/runtime/vm/exceptions.cc
index 7c9d71dccbb5327f3db5be3086ee36e0ccd85f13..f5f66aee6c59fff91e118b2307996e7cda5ca393 100644
--- a/runtime/vm/exceptions.cc
+++ b/runtime/vm/exceptions.cc
@@ -21,6 +21,7 @@
 
 namespace dart {
 
+DECLARE_FLAG(bool, trace_deoptimization);
 DEFINE_FLAG(bool, print_stacktrace_at_throw, false,
             "Prints a stack trace everytime a throw occurs.");
 
@@ -128,6 +129,7 @@ static void BuildStackTrace(StacktraceBuilder* builder) {
   while (frame != NULL) {
     if (frame->IsDartFrame()) {
       code = frame->LookupDartCode();
+      ASSERT(code.ContainsInstructionAt(frame->pc()));
       offset = Smi::New(frame->pc() - code.PayloadStart());
       builder->AddFrame(code, offset);
     }
@@ -214,6 +216,35 @@ static void JumpToExceptionHandler(Thread* thread,
   RawObject* raw_exception = exception_object.raw();
   RawObject* raw_stacktrace = stacktrace_object.raw();
 
+#if !defined(TARGET_ARCH_DBC)
+  MallocGrowableArray<PendingLazyDeopt>* pending_deopts =
+      thread->isolate()->pending_deopts();
+  for (intptr_t i = pending_deopts->length() - 1; i >= 0; i--) {
+    if ((*pending_deopts)[i].fp() == frame_pointer) {
+      // Frame is scheduled for lazy deopt.
+
+      // Deopt should now resume in the catch handler instead of after the call.
+      (*pending_deopts)[i].set_pc(program_counter);
+
+      // Jump to the deopt stub instead of the catch handler.
+      program_counter =
+          StubCode::DeoptimizeLazyFromThrow_entry()->EntryPoint();
+      if (FLAG_trace_deoptimization) {
+        THR_Print("Throwing to frame scheduled for lazy deopt fp=%" Pp "\n",
+                  frame_pointer);
+      }
+      break;
+    }
+  }
+  for (intptr_t i = pending_deopts->length() - 1; i >= 0; i--) {
+    // Leave the mapping at fp itself for use in DeoptimizeCopyFrame.
+    if ((*pending_deopts)[i].fp() < frame_pointer) {
+      pending_deopts->RemoveAt(i);
+    }
+  }
+#endif  // !DBC
+
+
 #if defined(USING_SIMULATOR)
   // Unwinding of the C++ frames and destroying of their stack resources is done
   // by the simulator, because the target stack_pointer is a simulated stack