Add infrastructure to keep track of references to prototypes.

src/x64/lithium-codegen-x64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 3258 matching lines @@
   Register elements_pointer_reg = ToRegister(elements_pointer);
   int shift_size = ElementsKindToShiftSize(elements_kind);
   if (key->IsConstantOperand()) {
     int32_t constant_value = ToInteger32(LConstantOperand::cast(key));
     if (constant_value & 0xF0000000) {
       Abort(kArrayIndexConstantValueTooBig);
     }
     return Operand(elements_pointer_reg,
                    (constant_value << shift_size) + offset);
   } else {
-    // Take the tag bit into account while computing the shift size.
-    if (key_representation.IsSmi() && (shift_size >= 1)) {
-      DCHECK(SmiValuesAre31Bits());
-      shift_size -= kSmiTagSize;
-    }
+    // Guaranteed by ArrayInstructionInterface::KeyedAccessIndexRequirement().
+    DCHECK(key_representation.IsInteger32());
+
     ScaleFactor scale_factor = static_cast<ScaleFactor>(shift_size);
     return Operand(elements_pointer_reg,
                    ToRegister(key),
                    scale_factor,
                    offset);
   }
 }
 
 
 void LCodeGen::DoLoadKeyedGeneric(LLoadKeyedGeneric* instr) {
@@ skipping 2595 matching lines @@
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64