[turbofan] compute arguments length in deoptimizer

src/deoptimizer.cc

Index: src/deoptimizer.cc
diff --git a/src/deoptimizer.cc b/src/deoptimizer.cc
index 89a06c2d353f95ddeacd527ce297d18e7a120884..4247e5535b0779c38f6a057c24c4e37564d358a1 100644
--- a/src/deoptimizer.cc
+++ b/src/deoptimizer.cc
@@ -2407,6 +2407,11 @@ void Translation::ArgumentsElements(bool is_rest) {
   buffer_->Add(is_rest);
 }
 
+void Translation::ArgumentsLength(bool is_rest) {
+  buffer_->Add(ARGUMENTS_LENGTH);
+  buffer_->Add(is_rest);
+}
+
 void Translation::BeginCapturedObject(int length) {
   buffer_->Add(CAPTURED_OBJECT);
   buffer_->Add(length);
@@ -2540,6 +2545,7 @@ int Translation::NumberOfOperandsFor(Opcode opcode) {
     case CONSTRUCT_STUB_FRAME:
       return 3;
     case ARGUMENTS_ELEMENTS:
+    case ARGUMENTS_LENGTH:
       return 1;
   }
   FATAL("Unexpected translation type");
@@ -3309,6 +3315,7 @@ TranslatedFrame TranslatedState::CreateNextTranslatedFrame(
     case Translation::DUPLICATED_OBJECT:
     case Translation::ARGUMENTS_OBJECT:
     case Translation::ARGUMENTS_ELEMENTS:
+    case Translation::ARGUMENTS_LENGTH:
     case Translation::CAPTURED_OBJECT:
     case Translation::REGISTER:
     case Translation::INT32_REGISTER:
@@ -3344,38 +3351,48 @@ void TranslatedFrame::AdvanceIterator(
   }
 }
 
-// Creates translated values for an arguments backing store, or the backing
-// store for the rest parameters if {is_rest} is true. The TranslatedValue
-// objects for the fields are not read from the TranslationIterator, but instead
-// created on-the-fly based on dynamic information in the optimized frame.
-void TranslatedState::CreateArgumentsElementsTranslatedValues(
-    int frame_index, Address input_frame_pointer, bool is_rest) {
-  TranslatedFrame& frame = frames_[frame_index];
-
+Address TranslatedState::ComputeArgumentsPosition(Address input_frame_pointer,
+                                                  bool is_rest, int* length) {
   Address parent_frame_pointer = *reinterpret_cast<Address*>(
       input_frame_pointer + StandardFrameConstants::kCallerFPOffset);
   intptr_t parent_frame_type = Memory::intptr_at(
       parent_frame_pointer + CommonFrameConstants::kContextOrFrameTypeOffset);
-  int length;
+
   Address arguments_frame;
   if (parent_frame_type ==
       StackFrame::TypeToMarker(StackFrame::ARGUMENTS_ADAPTOR)) {
-    length = Smi::cast(*reinterpret_cast<Object**>(
-                           parent_frame_pointer +
-                           ArgumentsAdaptorFrameConstants::kLengthOffset))
-                 ->value();
+    if (length)
+      *length = Smi::cast(*reinterpret_cast<Object**>(
+                              parent_frame_pointer +
+                              ArgumentsAdaptorFrameConstants::kLengthOffset))
+                    ->value();
     arguments_frame = parent_frame_pointer;
   } else {
-    length = formal_parameter_count_;
+    if (length) *length = formal_parameter_count_;
     arguments_frame = input_frame_pointer;
   }
 
   if (is_rest) {
     // If the actual number of arguments is less than the number of formal
     // parameters, we have zero rest parameters.
-    length = std::max(0, length - formal_parameter_count_);
+    if (length) *length = std::max(0, *length - formal_parameter_count_);
   }
 
+  return arguments_frame;
+}
+
+// Creates translated values for an arguments backing store, or the backing
+// store for the rest parameters if {is_rest} is true. The TranslatedValue
+// objects for the fields are not read from the TranslationIterator, but instead
+// created on-the-fly based on dynamic information in the optimized frame.
+void TranslatedState::CreateArgumentsElementsTranslatedValues(
+    int frame_index, Address input_frame_pointer, bool is_rest) {
+  TranslatedFrame& frame = frames_[frame_index];
+
+  int length;
+  Address arguments_frame =
+      ComputeArgumentsPosition(input_frame_pointer, is_rest, &length);
+
   int object_index = static_cast<int>(object_positions_.size());
   int value_index = static_cast<int>(frame.values_.size());
   object_positions_.push_back({frame_index, value_index});
@@ -3459,6 +3476,14 @@ int TranslatedState::CreateNextTranslatedValue(
       return 0;
     }
 
+    case Translation::ARGUMENTS_LENGTH: {
+      bool is_rest = iterator->Next();
+      int length;
+      ComputeArgumentsPosition(fp, is_rest, &length);
+      frame.Add(TranslatedValue::NewInt32(this, length));
+      return 0;
+    }
+
     case Translation::CAPTURED_OBJECT: {
       int field_count = iterator->Next();
       int object_index = static_cast<int>(object_positions_.size());