From 6e1f628f19c1ed0ccd2b12a86d09a78ad34767bb Mon Sep 17 00:00:00 2001
From: Liam Appelbe <liama@google.com>
Date: Thu, 23 May 2019 19:10:46 +0000
Subject: [PATCH] Outline the StackZone's Zone

Bug: https://github.com/dart-lang/sdk/issues/36100
Change-Id: I17cdf438c19fcc66ceb09c23348654eb752dd3cb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/103560
Commit-Queue: Liam Appelbe <liama@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
---
 runtime/vm/zone.cc | 17 ++++++++++-------
 runtime/vm/zone.h  | 10 +++++-----
 2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/runtime/vm/zone.cc b/runtime/vm/zone.cc
index 595871ada1c..cdb8ba424da 100644
--- a/runtime/vm/zone.cc
+++ b/runtime/vm/zone.cc
@@ -331,19 +331,20 @@ char* Zone::VPrint(const char* format, va_list args) {
   return OS::VSCreate(this, format, args);
 }
 
-StackZone::StackZone(ThreadState* thread) : StackResource(thread), zone_() {
+StackZone::StackZone(ThreadState* thread)
+    : StackResource(thread), zone_(new Zone()) {
   if (FLAG_trace_zones) {
     OS::PrintErr("*** Starting a new Stack zone 0x%" Px "(0x%" Px ")\n",
                  reinterpret_cast<intptr_t>(this),
-                 reinterpret_cast<intptr_t>(&zone_));
+                 reinterpret_cast<intptr_t>(zone_));
   }
 
   // This thread must be preventing safepoints or the GC could be visiting the
   // chain of handle blocks we're about the mutate.
   ASSERT(Thread::Current()->MayAllocateHandles());
 
-  zone_.Link(thread->zone());
-  thread->set_zone(&zone_);
+  zone_->Link(thread->zone());
+  thread->set_zone(zone_);
 }
 
 StackZone::~StackZone() {
@@ -351,13 +352,15 @@ StackZone::~StackZone() {
   // chain of handle blocks we're about the mutate.
   ASSERT(Thread::Current()->MayAllocateHandles());
 
-  ASSERT(thread()->zone() == &zone_);
-  thread()->set_zone(zone_.previous_);
+  ASSERT(thread()->zone() == zone_);
+  thread()->set_zone(zone_->previous_);
   if (FLAG_trace_zones) {
     OS::PrintErr("*** Deleting Stack zone 0x%" Px "(0x%" Px ")\n",
                  reinterpret_cast<intptr_t>(this),
-                 reinterpret_cast<intptr_t>(&zone_));
+                 reinterpret_cast<intptr_t>(zone_));
   }
+
+  delete zone_;
 }
 
 }  // namespace dart
diff --git a/runtime/vm/zone.h b/runtime/vm/zone.h
index b4aba7f7f05..88e1ef99d7f 100644
--- a/runtime/vm/zone.h
+++ b/runtime/vm/zone.h
@@ -177,19 +177,19 @@ class StackZone : public StackResource {
   explicit StackZone(ThreadState* thread);
 
   // Delete all memory associated with the zone.
-  ~StackZone();
+  virtual ~StackZone();
 
   // Compute the total size of this zone. This includes wasted space that is
   // due to internal fragmentation in the segments.
-  uintptr_t SizeInBytes() const { return zone_.SizeInBytes(); }
+  uintptr_t SizeInBytes() const { return zone_->SizeInBytes(); }
 
   // Computes the used space in the zone.
-  intptr_t CapacityInBytes() const { return zone_.CapacityInBytes(); }
+  intptr_t CapacityInBytes() const { return zone_->CapacityInBytes(); }
 
-  Zone* GetZone() { return &zone_; }
+  Zone* GetZone() { return zone_; }
 
  private:
-  Zone zone_;
+  Zone* zone_;
 
   template <typename T>
   friend class GrowableArray;