Fix materialization of arguments objects with unknown values.

src/deoptimizer.cc

Index: src/deoptimizer.cc
diff --git a/src/deoptimizer.cc b/src/deoptimizer.cc
index 98c4ac2c89141a4b0c3e54193166a72a65880b31..a825ebe5eeb777a9775a957175ba632c7764c6b2 100644
--- a/src/deoptimizer.cc
+++ b/src/deoptimizer.cc
@@ -885,8 +885,9 @@ void Deoptimizer::MaterializeHeapObjects(JavaScriptFrameIterator* it) {
         frame->SetExpression(i, *arguments);
         ASSERT_EQ(Memory::Object_at(descriptor.slot_address()), *arguments);
         if (trace_) {
-          PrintF("Materializing %sarguments object for %p: ",
+          PrintF("Materializing %sarguments object of length %d for %p: ",
                  frame->has_adapted_arguments() ? "(adapted) " : "",
+                 arguments->elements()->length(),
                  reinterpret_cast<void*>(descriptor.slot_address()));
           arguments->ShortPrint();
           PrintF("\n");
@@ -1180,6 +1181,7 @@ void Deoptimizer::DoTranslateCommand(TranslationIterator* iterator,
     }
 
     case Translation::ARGUMENTS_OBJECT: {
+      bool args_known = iterator->Next();
       int args_index = iterator->Next() + 1;  // Skip receiver.
       int args_length = iterator->Next() - 1;  // Skip receiver.
       if (trace_) {
@@ -1187,7 +1189,7 @@ void Deoptimizer::DoTranslateCommand(TranslationIterator* iterator,
                output_[frame_index]->GetTop() + output_offset,
                output_offset);
         isolate_->heap()->arguments_marker()->ShortPrint();
-        PrintF(" ; arguments object\n");
+        PrintF(" ; %sarguments object\n", args_known ? "" : "dummy ");
       }
       // Use the arguments marker value as a sentinel and fill in the arguments
       // object after the deoptimized frame is built.
@@ -1200,7 +1202,9 @@ void Deoptimizer::DoTranslateCommand(TranslationIterator* iterator,
       // actual arguments object after the deoptimized frame is built.
       for (int i = 0; i < args_length; i++) {
         unsigned input_offset = input_->GetOffsetFromSlotIndex(args_index + i);
-        intptr_t input_value = input_->GetFrameSlot(input_offset);
+        intptr_t input_value = args_known
+            ? input_->GetFrameSlot(input_offset)
+            : reinterpret_cast<intptr_t>(isolate_->heap()->the_hole_value());
         AddArgumentsObjectValue(input_value);
       }
       return;
@@ -1841,8 +1845,11 @@ void Translation::StoreLiteral(int literal_id) {
 }
 
 
-void Translation::StoreArgumentsObject(int args_index, int args_length) {
+void Translation::StoreArgumentsObject(bool args_known,
+                                       int args_index,
+                                       int args_length) {
   buffer_->Add(ARGUMENTS_OBJECT, zone());
+  buffer_->Add(args_known, zone());
   buffer_->Add(args_index, zone());
   buffer_->Add(args_length, zone());
 }
@@ -1873,9 +1880,9 @@ int Translation::NumberOfOperandsFor(Opcode opcode) {
     case BEGIN:
     case ARGUMENTS_ADAPTOR_FRAME:
     case CONSTRUCT_STUB_FRAME:
-    case ARGUMENTS_OBJECT:
       return 2;
     case JS_FRAME:
+    case ARGUMENTS_OBJECT:
       return 3;
   }
   UNREACHABLE();