Partial ia32 implementation of optimized try/catch (by Kevin Millikin)

src/isolate.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 83 matching lines @@
   current_vm_state_ = EXTERNAL;
   try_catch_handler_address_ = NULL;
   context_ = NULL;
   thread_id_ = ThreadId::Invalid();
   external_caught_exception_ = false;
   failed_access_check_callback_ = NULL;
   save_context_ = NULL;
   catcher_ = NULL;
   top_lookup_result_ = NULL;
 
+  optimized_handler_patch_buffer_ = NULL;
+  optimized_pending_exception_ = NULL;
+  optimized_handler_handler_index_ = -1;
+  optimized_handler_deopt_index_ = -1;
+  optimized_handler_frame_pc_offset_ = -1;
+
   // These members are re-initialized later after deserialization
   // is complete.
   pending_exception_ = NULL;
   has_pending_message_ = false;
   pending_message_obj_ = NULL;
   pending_message_script_ = NULL;
   scheduled_exception_ = NULL;
 }
 
 
@@ skipping 832 matching lines @@
   DoThrow(exception, location);
   return Failure::Exception();
 }
 
 
 Failure* Isolate::ReThrow(MaybeObject* exception) {
   bool can_be_caught_externally = false;
   bool catchable_by_javascript = is_catchable_by_javascript(exception);
   ShouldReportException(&can_be_caught_externally, catchable_by_javascript);
 
-  thread_local_top()->catcher_ = can_be_caught_externally ?
-      try_catch_handler() : NULL;
+  thread_local_top()->catcher_ =
+      can_be_caught_externally ? try_catch_handler() : NULL;
 
   // Set the exception being re-thrown.
   set_pending_exception(exception);
-  if (exception->IsFailure()) return exception->ToFailureUnchecked();
-  return Failure::Exception();
+
+  // Try to prepare the optimized code for catching only if there is not
+  // an optimized handler ready to catch from the previous throw.
+  if (!is_handling_optimized_catch_statement()) {
+    PrepareForOptimizedHandler();
+  }
+
+  return exception->IsFailure()
+      ? exception->ToFailureUnchecked()
+      : Failure::Exception();
 }
 
 
 Failure* Isolate::ThrowIllegalOperation() {
   return Throw(heap_.illegal_access_symbol());
 }
 
 
 void Isolate::ScheduleThrow(Object* exception) {
   // When scheduling a throw we first throw the exception to get the
@@ skipping 198 matching lines @@
             line_number + 1);
       }
     }
   }
 
   // Save the message for reporting if the the exception remains uncaught.
   thread_local_top()->has_pending_message_ = report_exception;
 
   // Do not forget to clean catcher_ if currently thrown exception cannot
   // be caught.  If necessary, ReThrow will update the catcher.
-  thread_local_top()->catcher_ = can_be_caught_externally ?
-      try_catch_handler() : NULL;
+  thread_local_top()->catcher_ =
+      can_be_caught_externally ? try_catch_handler() : NULL;
 
   set_pending_exception(*exception_handle);
+
+  // If the top-most handler is an optimized JS handler, we need to do
+  // some work to prepare the optimized code for catching.
+  PrepareForOptimizedHandler();
 }
 
 
+void Isolate::PrepareForOptimizedHandler() {
+  // Look for the topmost handler that is not a of kind JS_ENTRY
+  Address js_handler_address = Isolate::handler(thread_local_top());
+  StackHandler* handler = StackHandler::FromAddress(js_handler_address);
+  while (handler != NULL && handler->is_js_entry()) {
+    handler = handler->next();
+  }
+  // There might not be a JS handler at all.
+  if (handler == NULL) {
+    return;
+  }
+  // There might be an API handler before the top JS handler.
+  Address api_handler_address = thread_local_top()->try_catch_handler_address();
+  if (api_handler_address != NULL && api_handler_address < Address(handler)) {
+    return;
+  }
+  // The top JS handler might not be in optimized code.
+  if (!handler->is_optimized()) {
+    return;
+  }
+
+  set_optimized_handler_handler_index(handler->index());
+
+  // Find the frame corresponding to this handler.
+  JavaScriptFrame* frame = NULL;
+  for (JavaScriptFrameIterator it(this); !it.done(); it.Advance()) {
+    frame = it.frame();
+    if (frame->HasHandler() && frame->fp() > Address(handler)) break;
+  }
+
+  // This will be read by the deopt and put into eax.
+  // FIXME(mmassi): can this be moved by a collection?
+  set_optimized_pending_exception(pending_exception());
+
+  // Set the index of the next safepoint from the current PC.
+  // Runtime_CatchInOptimizedCode will then use it to find the offset where
+  // the code needs to be patched.
+  Code* code = handler->code();
+  SafepointEntry safepoint = code->GetSafepointEntry(frame->pc());
+  int deopt_index = safepoint.deoptimization_index();
+  ASSERT(deopt_index != Safepoint::kNoDeoptimizationIndex);
+  set_optimized_handler_deopt_index(deopt_index);
+  // Also set the offset in "code" where we will need to jump to.
+  set_optimized_handler_frame_pc_offset(
+      frame->pc() - reinterpret_cast<Address>(code));
+}
+
+
+void Isolate::ClearOptimizedHandlerByDeopt(Code* optimized_code) {
+  Deoptimizer::RemoveDeoptimizingCode(optimized_code);
+  clear_optimized_handler_handler_index();
+  clear_optimized_handler_deopt_index();
+  clear_optimized_handler_patch_buffer();
+}
+
+
+void Isolate::ClearOptimizedHandlerByAPI() {
+  clear_optimized_handler_handler_index();
+  clear_optimized_handler_deopt_index();
+  clear_optimized_handler_frame_pc_offset();
+  clear_optimized_pending_exception();
+}
+
+
 bool Isolate::IsExternallyCaught() {
   ASSERT(has_pending_exception());
 
   if ((thread_local_top()->catcher_ == NULL) ||
       (try_catch_handler() != thread_local_top()->catcher_)) {
     // When throwing the exception, we found no v8::TryCatch
     // which should care about this exception.
     return false;
   }
 
@@ skipping 13 matching lines @@
   // There should be no try-catch blocks as they would prohibit us from
   // finding external catcher in the first place (see catcher_ check above).
   //
   // Note, that finally clause would rethrow an exception unless it's
   // aborted by jumps in control flow like return, break, etc. and we'll
   // have another chances to set proper v8::TryCatch.
   StackHandler* handler =
       StackHandler::FromAddress(Isolate::handler(thread_local_top()));
   while (handler != NULL && handler->address() < external_handler_address) {
     ASSERT(!handler->is_catch());
+    // Despite the above ASSERT the handler could come from optimized code.
+    if (handler->is_optimized()) return false;
     if (handler->is_finally()) return false;
 
     handler = handler->next();
   }
 
   return true;
 }
 
 
 void Isolate::ReportPendingMessages() {
@@ skipping 435 matching lines @@
 
 Isolate::~Isolate() {
   TRACE_ISOLATE(destructor);
 
   // Has to be called while counters_ are still alive.
   runtime_zone_.DeleteKeptSegment();
 
   delete[] assembler_spare_buffer_;
   assembler_spare_buffer_ = NULL;
 
+  // FIXME(mmassi): why there was no guard here?
+  if (optimized_handler_patch_buffer() != NULL) {
+    clear_optimized_handler_patch_buffer();
+  }
+
   delete unicode_cache_;
   unicode_cache_ = NULL;
 
   delete date_cache_;
   date_cache_ = NULL;
 
   delete regexp_stack_;
   regexp_stack_ = NULL;
 
   delete descriptor_lookup_cache_;
@@ skipping 372 matching lines @@
 
 #ifdef DEBUG
 #define ISOLATE_FIELD_OFFSET(type, name, ignored)                       \
 const intptr_t Isolate::name##_debug_offset_ = OFFSET_OF(Isolate, name##_);
 ISOLATE_INIT_LIST(ISOLATE_FIELD_OFFSET)
 ISOLATE_INIT_ARRAY_LIST(ISOLATE_FIELD_OFFSET)
 #undef ISOLATE_FIELD_OFFSET
 #endif
 
 } }  // namespace v8::internal