[stubs] Fix performance regression on x64 caused by modified double hole check.

src/code-stub-assembler.cc

 // Copyright 2016 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/code-stub-assembler.h"
 #include "src/code-factory.h"
 #include "src/frames-inl.h"
 #include "src/frames.h"
 #include "src/ic/handler-configuration.h"
 #include "src/ic/stub-cache.h"
@@ skipping 1133 matching lines @@
       FixedDoubleArray::kHeaderSize + additional_offset - kHeapObjectTag;
   Node* offset = ElementOffsetFromIndex(index_node, FAST_HOLEY_DOUBLE_ELEMENTS,
                                         parameter_mode, header_size);
   return LoadDoubleWithHoleCheck(object, offset, if_hole, machine_type);
 }
 
 Node* CodeStubAssembler::LoadDoubleWithHoleCheck(Node* base, Node* offset,
                                                  Label* if_hole,
                                                  MachineType machine_type) {
   if (if_hole) {
-    Node* element_upper =
-        Load(MachineType::Uint32(), base,
-             IntPtrAdd(offset, IntPtrConstant(kIeeeDoubleExponentWordOffset)));
-    GotoIf(Word32Equal(element_upper, Int32Constant(kHoleNanUpper32)), if_hole);
+    // TODO(ishell): Compare only the upper part for the hole once the
+    // compiler is able to fold addition of already complex |offset| with
+    // |kIeeeDoubleExponentWordOffset| into one addressing mode.
+    if (Is64()) {
+      Node* element = Load(MachineType::Uint64(), base, offset);
+      GotoIf(Word64Equal(element, Int64Constant(kHoleNanInt64)), if_hole);
+    } else {
+      Node* element_upper = Load(
+          MachineType::Uint32(), base,
+          IntPtrAdd(offset, IntPtrConstant(kIeeeDoubleExponentWordOffset)));
+      GotoIf(Word32Equal(element_upper, Int32Constant(kHoleNanUpper32)),
+             if_hole);
+    }
   }
   if (machine_type.IsNone()) {
     // This means the actual value is not needed.
     return nullptr;
   }
   return Load(machine_type, base, offset);
 }
 
 Node* CodeStubAssembler::LoadNativeContext(Node* context) {
   return LoadFixedArrayElement(context,
@@ skipping 3037 matching lines @@
                        Heap::kTheHoleValueRootIndex);
 
   // Store the WeakCell in the feedback vector.
   StoreFixedArrayElement(feedback_vector, slot, cell, UPDATE_WRITE_BARRIER,
                          CodeStubAssembler::SMI_PARAMETERS);
   return cell;
 }
 
 }  // namespace internal
 }  // namespace v8