[TurboFan] Reserve space in scheduler node data for split nodes.

When node splitting is enabled new nodes could be created during scheduling.
The Scheduler::node_data_ and Schedule::nodeid_to_block_ zone vectors
reserve enough space for the node count before splitting, however will
have to reallocate space when node splitting occurs. The vectors double
in space by default, meaning the peak zone usage is 3x the required amount
for these vectors as soon as a single node is split. Avoid this in the
common case by reserving 10% extra space for split nodes. The value
10% was choosen since it covers 98.7% of the optimized functions in Octane.

BUG=chromium:700364

Change-Id: Ibabd8d04cffd1eb08cc3b8a12b76892208ef3288
Reviewed-on: https://chromium-review.googlesource.com/458425
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44153}

src/compiler/scheduler.cc

@@ -25,7 +25,8 @@ namespace compiler {
     if (FLAG_trace_turbo_scheduler) PrintF(__VA_ARGS__); \
   } while (false)
 
-Scheduler::Scheduler(Zone* zone, Graph* graph, Schedule* schedule, Flags flags)
+Scheduler::Scheduler(Zone* zone, Graph* graph, Schedule* schedule, Flags flags,
+                     size_t node_count_hint)
     : zone_(zone),
       graph_(graph),
       schedule_(schedule),
@@ -33,15 +34,23 @@ Scheduler::Scheduler(Zone* zone, Graph* graph, Schedule* schedule, Flags flags)
       scheduled_nodes_(zone),
       schedule_root_nodes_(zone),
       schedule_queue_(zone),
-      node_data_(graph_->NodeCount(), DefaultSchedulerData(), zone) {}
-
+      node_data_(zone) {
+  node_data_.reserve(node_count_hint);
+  node_data_.resize(graph->NodeCount(), DefaultSchedulerData());
+}
 
 Schedule* Scheduler::ComputeSchedule(Zone* zone, Graph* graph, Flags flags) {
   Zone* schedule_zone =
       (flags & Scheduler::kTempSchedule) ? zone : graph->zone();
-  Schedule* schedule = new (schedule_zone)
-      Schedule(schedule_zone, static_cast<size_t>(graph->NodeCount()));
-  Scheduler scheduler(zone, graph, schedule, flags);
+
+  // Reserve 10% more space for nodes if node splitting is enabled to try to
+  // avoid resizing the vector since that would triple its zone memory usage.
+  float node_hint_multiplier = (flags & Scheduler::kSplitNodes) ? 1.1 : 1;
+  size_t node_count_hint = node_hint_multiplier * graph->NodeCount();
+
+  Schedule* schedule =
+      new (schedule_zone) Schedule(schedule_zone, node_count_hint);
+  Scheduler scheduler(zone, graph, schedule, flags, node_count_hint);
 
   scheduler.BuildCFG();
   scheduler.ComputeSpecialRPONumbering();

src/compiler/scheduler.h

@@ -74,7 +74,8 @@ class V8_EXPORT_PRIVATE Scheduler {
   SpecialRPONumberer* special_rpo_;      // Special RPO numbering of blocks.
   ControlEquivalence* equivalence_;      // Control dependence equivalence.
 
-  Scheduler(Zone* zone, Graph* graph, Schedule* schedule, Flags flags);
+  Scheduler(Zone* zone, Graph* graph, Schedule* schedule, Flags flags,
+            size_t node_count_hint_);
 
   inline SchedulerData DefaultSchedulerData();
   inline SchedulerData* GetData(Node* node);