[turbofan] Allocate SourcePositionTable inside a Zone.

This also removes the destructor of the class in question, which removed
any added decorator from the graph. However the adding of the decorator
happens explicitly, so symmetry suggests that removal should also happen
explicitly instead of implicitly in the destructor.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/1914473002

Cr-Commit-Position: refs/heads/master@{#35732}

src/compiler/pipeline.cc

@@ -104,7 +104,8 @@ class PipelineData {
         register_allocation_data_(nullptr) {
     PhaseScope scope(pipeline_statistics, "init pipeline data");
     graph_ = new (graph_zone_) Graph(graph_zone_);
-    source_positions_.Reset(new SourcePositionTable(graph_));
+    source_positions_ = new (graph_zone_->New(sizeof(SourcePositionTable)))
+        SourcePositionTable(graph_);
     simplified_ = new (graph_zone_) SimplifiedOperatorBuilder(graph_zone_);
     machine_ = new (graph_zone_) MachineOperatorBuilder(
         graph_zone_, MachineType::PointerRepresentation(),
@@ -128,7 +129,8 @@ class PipelineData {
         graph_zone_scope_(zone_pool_),
         graph_zone_(nullptr),
         graph_(graph),
-        source_positions_(new SourcePositionTable(graph_)),
+        source_positions_(new (info->zone()->New(sizeof(SourcePositionTable)))
+                              SourcePositionTable(graph_)),
         loop_assignment_(nullptr),
         simplified_(nullptr),
         machine_(nullptr),
@@ -195,9 +197,7 @@ class PipelineData {
 
   Zone* graph_zone() const { return graph_zone_; }
   Graph* graph() const { return graph_; }
-  SourcePositionTable* source_positions() const {
-    return source_positions_.get();
-  }
+  SourcePositionTable* source_positions() const { return source_positions_; }
   MachineOperatorBuilder* machine() const { return machine_; }
   CommonOperatorBuilder* common() const { return common_; }
   JSOperatorBuilder* javascript() const { return javascript_; }
@@ -238,13 +238,11 @@ class PipelineData {
   }
 
   void DeleteGraphZone() {
-    // Destroy objects with destructors first.
-    source_positions_.Reset(nullptr);
     if (graph_zone_ == nullptr) return;
-    // Destroy zone and clear pointers.
     graph_zone_scope_.Destroy();
     graph_zone_ = nullptr;
     graph_ = nullptr;
+    source_positions_ = nullptr;
     loop_assignment_ = nullptr;
     type_hint_analysis_ = nullptr;
     simplified_ = nullptr;
@@ -317,8 +315,7 @@ class PipelineData {
   ZonePool::Scope graph_zone_scope_;
   Zone* graph_zone_;
   Graph* graph_;
-  // TODO(dcarney): make this into a ZoneObject.
-  base::SmartPointer<SourcePositionTable> source_positions_;
+  SourcePositionTable* source_positions_;
   LoopAssignmentAnalysis* loop_assignment_;
   TypeHintAnalysis* type_hint_analysis_ = nullptr;
   SimplifiedOperatorBuilder* simplified_;

src/compiler/source-position.h

@@ -66,9 +66,6 @@ class SourcePositionTable final {
   };
 
   explicit SourcePositionTable(Graph* graph);
-  ~SourcePositionTable() {
-    if (decorator_) RemoveDecorator();
-  }
 
   void AddDecorator();
   void RemoveDecorator();