Unroll more StringDictionary lookup probes both for positive and negative dictionary lookups.

src/x64/stub-cache-x64.cc

Index: src/x64/stub-cache-x64.cc
diff --git a/src/x64/stub-cache-x64.cc b/src/x64/stub-cache-x64.cc
index ef6f7583882016c5133b4706b3cf4047aab6bf79..6c83606f1dc83e5dd61dd365720238b09ff59151 100644
--- a/src/x64/stub-cache-x64.cc
+++ b/src/x64/stub-cache-x64.cc
@@ -93,7 +93,6 @@ static void GenerateDictionaryNegativeLookup(MacroAssembler* masm,
   __ IncrementCounter(counters->negative_lookups(), 1);
   __ IncrementCounter(counters->negative_lookups_miss(), 1);
 
-  Label done;
   __ movq(r0, FieldOperand(receiver, HeapObject::kMapOffset));
 
   const int kInterceptorOrAccessCheckNeededMask =
@@ -117,62 +116,13 @@ static void GenerateDictionaryNegativeLookup(MacroAssembler* masm,
                  Heap::kHashTableMapRootIndex);
   __ j(not_equal, miss_label);
 
-  // Compute the capacity mask.
-  const int kCapacityOffset =
-      StringDictionary::kHeaderSize +
-      StringDictionary::kCapacityIndex * kPointerSize;
-
-  // Generate an unrolled loop that performs a few probes before
-  // giving up.
-  static const int kProbes = 4;
-  const int kElementsStartOffset =
-      StringDictionary::kHeaderSize +
-      StringDictionary::kElementsStartIndex * kPointerSize;
-
-  // If names of slots in range from 1 to kProbes - 1 for the hash value are
-  // not equal to the name and kProbes-th slot is not used (its name is the
-  // undefined value), it guarantees the hash table doesn't contain the
-  // property. It's true even if some slots represent deleted properties
-  // (their names are the null value).
-  for (int i = 0; i < kProbes; i++) {
-    // r0 points to properties hash.
-    // Compute the masked index: (hash + i + i * i) & mask.
-    Register index = r1;
-    // Capacity is smi 2^n.
-    __ SmiToInteger32(index, FieldOperand(properties, kCapacityOffset));
-    __ decl(index);
-    __ and_(index,
-            Immediate(name->Hash() + StringDictionary::GetProbeOffset(i)));
-
-    // Scale the index by multiplying by the entry size.
-    ASSERT(StringDictionary::kEntrySize == 3);
-    __ lea(index, Operand(index, index, times_2, 0));  // index *= 3.
-
-    Register entity_name = r1;
-    // Having undefined at this place means the name is not contained.
-    ASSERT_EQ(kSmiTagSize, 1);
-    __ movq(entity_name, Operand(properties, index, times_pointer_size,
-                                 kElementsStartOffset - kHeapObjectTag));
-    __ Cmp(entity_name, masm->isolate()->factory()->undefined_value());
-    // __ jmp(miss_label);
-    if (i != kProbes - 1) {
-      __ j(equal, &done);
-
-      // Stop if found the property.
-      __ Cmp(entity_name, Handle<String>(name));
-      __ j(equal, miss_label);
-
-      // Check if the entry name is not a symbol.
-      __ movq(entity_name, FieldOperand(entity_name, HeapObject::kMapOffset));
-      __ testb(FieldOperand(entity_name, Map::kInstanceTypeOffset),
-               Immediate(kIsSymbolMask));
-      __ j(zero, miss_label);
-    } else {
-      // Give up probing if still not found the undefined value.
-      __ j(not_equal, miss_label);
-    }
-  }
-
+  Label done;
+  StringDictionaryLookupStub::GenerateNegativeLookup(masm,
+                                                     miss_label,
+                                                     &done,
+                                                     properties,
+                                                     name,
+                                                     r1);
   __ bind(&done);
   __ DecrementCounter(counters->negative_lookups_miss(), 1);
 }