KeyAccumulator: tweaking parameters for benchmarks

src/objects.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/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <sstream>
 
@@ skipping 6774 matching lines @@
   ElementsAccessor* accessor = array_like->GetElementsAccessor();
   accessor->AddElementsToKeyAccumulator(array_like, this, filter);
 }
 
 
 void KeyAccumulator::PrepareForComparisons(int count) {
   // Depending on how many comparisons we do we should switch to the
   // hash-table-based checks which have a one-time overhead for
   // initializing but O(1) for HasKey checks.
   if (!set_.is_null()) return;
-  // This limit was obtained through evaluation of a microbench.
-  if (length_ * count < 50) return;
+  // These limit were obtained through evaluation of several microbenchmarks.

[Igor Sheludko, 2015/10/01 06:41:22]

s/limit/limits/g

+  if (length_ * count < 100) return;
+  // Don't use a set for few elements
+  if (length_ < 100 && count < 20) return;
   set_ = OrderedHashSet::Allocate(isolate_, length_);
   for (int i = 0; i < length_; i++) {
     Handle<Object> value(keys_->get(i), isolate_);
     set_ = OrderedHashSet::Add(set_, value);
   }
 }
 
 
 void KeyAccumulator::EnsureCapacity(int capacity) {
   if (keys_.is_null() || keys_->length() <= capacity) {
@@ skipping 9981 matching lines @@
   if (cell->value() != *new_value) {
     cell->set_value(*new_value);
     Isolate* isolate = cell->GetIsolate();
     cell->dependent_code()->DeoptimizeDependentCodeGroup(
         isolate, DependentCode::kPropertyCellChangedGroup);
   }
 }
 
 }  // namespace internal
 }  // namespace v8