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

src/deoptimizer.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 81 matching lines @@
   ASSERT(isolate->deoptimizer_data()->current_ == NULL);
   isolate->deoptimizer_data()->current_ = deoptimizer;
   return deoptimizer;
 }
 
 
 Deoptimizer* Deoptimizer::Grab(Isolate* isolate) {
   ASSERT(isolate == Isolate::Current());
   Deoptimizer* result = isolate->deoptimizer_data()->current_;
   ASSERT(result != NULL);
+  if (isolate->optimized_handler_patch_buffer() != NULL) {
+    ASSERT(result->bailout_type_ == LAZY);
+    // Before allowing allocation, patch the optimized code back.  The
+    // patched code has relocation info that does not agree with the code,
+    // so the patched code should not be seen by the garbage collector.
+    Code* code = result->optimized_code_;
+    DeoptimizationInputData* deopt_data =
+        DeoptimizationInputData::cast(code->deoptimization_data());
+    int deopt_index = isolate->optimized_handler_deopt_index();
+    byte* patch_address =
+        code->instruction_start() + deopt_data->Pc(deopt_index)->value();
+    memcpy(patch_address, isolate->optimized_handler_patch_buffer(),
+           patch_size());
+    // FIXME(mmassi): why doesn't it clear immediately also the patch buffer?
+    isolate->ClearOptimizedHandlerByDeopt(code);
+  }
   result->DeleteFrameDescriptions();
   isolate->deoptimizer_data()->current_ = NULL;
   return result;
 }
 
 
 int Deoptimizer::ConvertJSFrameIndexToFrameIndex(int jsframe_index) {
   if (jsframe_index == 0) return 0;
 
   int frame_index = 0;
@@ skipping 21 matching lines @@
   // Get the function and code from the frame.
   JSFunction* function = JSFunction::cast(frame->function());
   Code* code = frame->LookupCode();
 
   // Locate the deoptimization point in the code. As we are at a call the
   // return address must be at a place in the code with deoptimization support.
   SafepointEntry safepoint_entry = code->GetSafepointEntry(frame->pc());
   int deoptimization_index = safepoint_entry.deoptimization_index();
   ASSERT(deoptimization_index != Safepoint::kNoDeoptimizationIndex);
 
+  // Find the size of exception handlers.
+  DeoptimizationInputData* deoptimization_data =
+      DeoptimizationInputData::cast(code->deoptimization_data());
+  unsigned handler_count =
+      deoptimization_data->HandlerCount(deoptimization_index)->value();
+  unsigned handler_size = handler_count * StackHandlerConstants::kSize;
+
   // Always use the actual stack slots when calculating the fp to sp
   // delta adding two for the function and context.
   unsigned stack_slots = code->stack_slots();
-  unsigned fp_to_sp_delta = ((stack_slots + 2) * kPointerSize);
+  unsigned fp_to_sp_delta = ((stack_slots + 2) * kPointerSize) + handler_size;
 
   Deoptimizer* deoptimizer = new Deoptimizer(isolate,
                                              function,
                                              Deoptimizer::DEBUGGER,
                                              deoptimization_index,
                                              frame->pc(),
                                              fp_to_sp_delta,
                                              code);
   Address tos = frame->fp() - fp_to_sp_delta;
   deoptimizer->FillInputFrame(tos, frame);
@@ skipping 403 matching lines @@
   TranslationIterator iterator(translations, translation_index);
   Translation::Opcode opcode =
       static_cast<Translation::Opcode>(iterator.Next());
   ASSERT(Translation::BEGIN == opcode);
   USE(opcode);
   // Read the number of output frames and allocate an array for their
   // descriptions.
   int count = iterator.Next();
   iterator.Next();  // Drop JS frames count.
   ASSERT(output_ == NULL);
+
+  // If this deoptimization is needed to transfer control to a catch clause
+  // only the first frame is relevant.
+  if (isolate_->optimized_handler_patch_buffer() != NULL) {
+    count = 1;
+  }
+
   output_ = new FrameDescription*[count];
   for (int i = 0; i < count; ++i) {
     output_[i] = NULL;
   }
   output_count_ = count;
 
   // Translate each output frame.
   for (int i = 0; i < count; ++i) {
     // Read the ast node id, function, and frame height for this output frame.
     Translation::Opcode opcode =
@@ skipping 237 matching lines @@
       // temporary placeholder in the frame.
       AddDoubleValue(output_[frame_index]->GetTop() + output_offset, value);
       output_[frame_index]->SetFrameSlot(output_offset, kPlaceholder);
       return;
     }
 
     case Translation::STACK_SLOT: {
       int input_slot_index = iterator->Next();
       unsigned input_offset =
           input_->GetOffsetFromSlotIndex(input_slot_index);
-      intptr_t input_value = input_->GetFrameSlot(input_offset);
+      intptr_t input_value;
+      if (isolate_->optimized_handler_patch_buffer() != NULL &&
+          input_offset >= input_->frame_size()) {
+        // Skip stack slots that were above the handler (they must be
+        // arguments that must be thrown away because try is a statement).
+        input_value = 0;
+        if (FLAG_trace_deopt) {
+          PrintF("                SKIPPING SLOT ABOVE HANDLER (ARGUMENT)\n");
+        }
+      } else {
+        input_value = input_->GetFrameSlot(input_offset);
+      }
       if (FLAG_trace_deopt) {
         PrintF("    0x%08" V8PRIxPTR ": ",
                output_[frame_index]->GetTop() + output_offset);
         PrintF("[top + %d] <- 0x%08" V8PRIxPTR " ; [sp + %d] ",
                output_offset,
                input_value,
                input_offset);
         reinterpret_cast<Object*>(input_value)->ShortPrint();
         PrintF("\n");
       }
@@ skipping 181 matching lines @@
 
   switch (opcode) {
     case Translation::BEGIN:
     case Translation::JS_FRAME:
     case Translation::ARGUMENTS_ADAPTOR_FRAME:
     case Translation::CONSTRUCT_STUB_FRAME:
     case Translation::GETTER_STUB_FRAME:
     case Translation::SETTER_STUB_FRAME:
     case Translation::DUPLICATE:
       UNREACHABLE();  // Malformed input.
-       return false;
+      return false;
 
      case Translation::REGISTER: {
        int output_reg = iterator->Next();
        if (FLAG_trace_osr) {
          PrintF("    %s <- 0x%08" V8PRIxPTR " ; [sp + %d]\n",
                 converter.NameOfCPURegister(output_reg),
                 input_value,
                 *input_offset);
        }
        output->SetRegister(output_reg, input_value);
@@ skipping 186 matching lines @@
     RevertStackCheckCodeAt(unoptimized_code,
                            pc_after,
                            check_code,
                            replacement_code);
     stack_check_cursor += 2 * kIntSize;
   }
 }
 
 
 unsigned Deoptimizer::ComputeInputFrameSize() const {
+  // This is the size of the frame that is the same for both optimized and
+  // unoptimized frames---the incoming parameters and the fixed part of the
+  // frame.
   unsigned fixed_size = ComputeFixedSize(function_);
+
   // The fp-to-sp delta already takes the context and the function
   // into account so we have to avoid double counting them (-2).
   unsigned result = fixed_size + fp_to_sp_delta_ - (2 * kPointerSize);
+
 #ifdef DEBUG
   if (bailout_type_ == OSR) {
     // TODO(kasperl): It would be nice if we could verify that the
     // size matches with the stack height we can compute based on the
     // environment at the OSR entry. The code for that his built into
     // the DoComputeOsrOutputFrame function for now.
   } else {
-    unsigned stack_slots = optimized_code_->stack_slots();
-    unsigned outgoing_size = ComputeOutgoingArgumentSize();
-    ASSERT(result == fixed_size + (stack_slots * kPointerSize) + outgoing_size);
+    // Verify the actual frame size matches the expected (fixed part +
+    // spill slots + exception handlers + outgoing arguments).
+    unsigned spill_slots_size = optimized_code_->stack_slots() * kPointerSize;
+    unsigned handlers_size = ComputeHandlersSize();
+    // If we are doing lazy deoptimization for catching in an optimized
+    // frame, one of the handlers in the frame description has already been
+    // dropped by throwing to it.
+    if (isolate_->optimized_handler_patch_buffer() != NULL) {
+      ASSERT(bailout_type_ == LAZY);
+      ASSERT(static_cast<int>(handlers_size) >= StackHandlerConstants::kSize);
+      handlers_size -= StackHandlerConstants::kSize;
+    }
+    unsigned outgoing_arg_size = ComputeOutgoingArgumentSize();
+    ASSERT(result ==
+           fixed_size + spill_slots_size + handlers_size + outgoing_arg_size);
   }
 #endif
   return result;
 }
 
 
 unsigned Deoptimizer::ComputeFixedSize(JSFunction* function) const {
   // The fixed part of the frame consists of the return address, frame
   // pointer, function, context, and all the incoming arguments.
   return ComputeIncomingArgumentSize(function) +
       StandardFrameConstants::kFixedFrameSize;
 }
 
 
 unsigned Deoptimizer::ComputeIncomingArgumentSize(JSFunction* function) const {
   // The incoming arguments is the values for formal parameters and
   // the receiver. Every slot contains a pointer.
   unsigned arguments = function->shared()->formal_parameter_count() + 1;
   return arguments * kPointerSize;
 }
 
 
 unsigned Deoptimizer::ComputeOutgoingArgumentSize() const {
+  // Since try is a statement there will not be arguments left on the stack
+  // once we have popped the handler.
+  if (isolate_->optimized_handler_patch_buffer() != NULL) {
+    return 0;
+  }
+
   DeoptimizationInputData* data = DeoptimizationInputData::cast(
       optimized_code_->deoptimization_data());
   unsigned height = data->ArgumentsStackHeight(bailout_id_)->value();
   return height * kPointerSize;
 }
 
 
+unsigned Deoptimizer::ComputeHandlersSize() const {
+  DeoptimizationInputData* data = DeoptimizationInputData::cast(
+      optimized_code_->deoptimization_data());
+  unsigned handler_count = data->HandlerCount(bailout_id_)->value();
+  return handler_count * StackHandlerConstants::kSize;
+}
+
+
 Object* Deoptimizer::ComputeLiteral(int index) const {
   DeoptimizationInputData* data = DeoptimizationInputData::cast(
       optimized_code_->deoptimization_data());
   FixedArray* literals = data->LiteralArray();
   return literals->get(index);
 }
 
 
 void Deoptimizer::AddDoubleValue(intptr_t slot_address,
                                  double value) {
@@ skipping 211 matching lines @@
 
 void Translation::BeginArgumentsAdaptorFrame(int literal_id, unsigned height) {
   buffer_->Add(ARGUMENTS_ADAPTOR_FRAME, zone());
   buffer_->Add(literal_id, zone());
   buffer_->Add(height, zone());
 }
 
 
 void Translation::BeginJSFrame(BailoutId node_id,
                                int literal_id,
-                               unsigned height) {
+                               unsigned height,
+                               int handler_count) {
   buffer_->Add(JS_FRAME, zone());
   buffer_->Add(node_id.ToInt(), zone());
   buffer_->Add(literal_id, zone());
   buffer_->Add(height, zone());
+  buffer_->Add(handler_count, zone());
 }
 
 
 void Translation::StoreRegister(Register reg) {
   buffer_->Add(REGISTER, zone());
   buffer_->Add(reg.code(), zone());
 }
 
 
 void Translation::StoreInt32Register(Register reg) {
@@ skipping 69 matching lines @@
     case INT32_STACK_SLOT:
     case UINT32_STACK_SLOT:
     case DOUBLE_STACK_SLOT:
     case LITERAL:
       return 1;
     case BEGIN:
     case ARGUMENTS_ADAPTOR_FRAME:
     case CONSTRUCT_STUB_FRAME:
       return 2;
     case JS_FRAME:
-      return 3;
+      return 4;
   }
   UNREACHABLE();
   return -1;
 }
 
 
 #if defined(OBJECT_PRINT) || defined(ENABLE_DISASSEMBLER)
 
 const char* Translation::StringFor(Opcode opcode) {
   switch (opcode) {
@@ skipping 239 matching lines @@
 
 void DeoptimizedFrameInfo::Iterate(ObjectVisitor* v) {
   v->VisitPointer(BitCast<Object**>(&function_));
   v->VisitPointers(parameters_, parameters_ + parameters_count_);
   v->VisitPointers(expression_stack_, expression_stack_ + expression_count_);
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal