[heap] Small refactoring to tidy up heap.

Bug: v8:8015
Change-Id: I6b1283f893944ca45ff7816d51e0c7fb26c8a8e1
Reviewed-on: https://chromium-review.googlesource.com/1209785Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Florian Sattler <sattlerf@google.com>
Cr-Commit-Position: refs/heads/master@{#55693}

src/heap/heap.cc

@@ -2488,8 +2488,8 @@ void Heap::ProcessWeakListRoots(WeakObjectRetainer* retainer) {
   set_allocation_sites_list(retainer->RetainAs(allocation_sites_list()));
 }
 
-void Heap::ForeachAllocationSite(Object* list,
-                                 std::function<void(AllocationSite*)> visitor) {
+void Heap::ForeachAllocationSite(
+    Object* list, const std::function<void(AllocationSite*)>& visitor) {
   DisallowHeapAllocation disallow_heap_allocation;
   Object* current = list;
   while (current->IsAllocationSite()) {

src/heap/heap.h

@@ -567,8 +567,8 @@ class Heap {
 
   // Traverse all the allocaions_sites [nested_site and weak_next] in the list
   // and foreach call the visitor
-  void ForeachAllocationSite(Object* list,
-                             std::function<void(AllocationSite*)> visitor);
+  void ForeachAllocationSite(
+      Object* list, const std::function<void(AllocationSite*)>& visitor);
 
   // Number of mark-sweeps.
   int ms_count() const { return ms_count_; }

src/heap/item-parallel-job.cc

@@ -58,7 +58,7 @@ ItemParallelJob::~ItemParallelJob() {
   }
 }
 
-void ItemParallelJob::Run(std::shared_ptr<Counters> async_counters) {
+void ItemParallelJob::Run(const std::shared_ptr<Counters>& async_counters) {
   DCHECK_GT(tasks_.size(), 0);
   const size_t num_items = items_.size();
   const size_t num_tasks = tasks_.size();

src/heap/item-parallel-job.h

@@ -137,7 +137,7 @@ class V8_EXPORT_PRIVATE ItemParallelJob {
 
   // Runs this job. Reporting metrics in a thread-safe manner to
   // |async_counters|.
-  void Run(std::shared_ptr<Counters> async_counters);
+  void Run(const std::shared_ptr<Counters>& async_counters);
 
  private:
   std::vector<Item*> items_;

src/heap/mark-compact.cc

@@ -3426,8 +3426,9 @@ void MarkCompactCollector::MarkingWorklist::PrintWorklist(
     count[obj->map()->instance_type()]++;
   });
   std::vector<std::pair<int, InstanceType>> rank;
-  for (auto i : count) {
-    rank.push_back(std::make_pair(i.second, i.first));
+  rank.reserve(count.size());
+  for (const auto& i : count) {
+    rank.emplace_back(i.second, i.first);
   }
   std::map<InstanceType, std::string> instance_type_name;
 #define INSTANCE_TYPE_NAME(name) instance_type_name[name] = #name;