Revert of Replaced different means of zone pooling/reusing by one zone segment pool

src/compiler/zone-pool.cc

Index: src/compiler/zone-pool.cc
diff --git a/src/compiler/zone-pool.cc b/src/compiler/zone-pool.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7681eeb5d17dbc831b96372cddf438cdd0d6906e
--- /dev/null
+++ b/src/compiler/zone-pool.cc
@@ -0,0 +1,138 @@
+// Copyright 2014 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/compiler/zone-pool.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+ZonePool::StatsScope::StatsScope(ZonePool* zone_pool)
+    : zone_pool_(zone_pool),
+      total_allocated_bytes_at_start_(zone_pool->GetTotalAllocatedBytes()),
+      max_allocated_bytes_(0) {
+  zone_pool_->stats_.push_back(this);
+  for (Zone* zone : zone_pool_->used_) {
+    size_t size = static_cast<size_t>(zone->allocation_size());
+    std::pair<InitialValues::iterator, bool> res =
+        initial_values_.insert(std::make_pair(zone, size));
+    USE(res);
+    DCHECK(res.second);
+  }
+}
+
+
+ZonePool::StatsScope::~StatsScope() {
+  DCHECK_EQ(zone_pool_->stats_.back(), this);
+  zone_pool_->stats_.pop_back();
+}
+
+
+size_t ZonePool::StatsScope::GetMaxAllocatedBytes() {
+  return std::max(max_allocated_bytes_, GetCurrentAllocatedBytes());
+}
+
+
+size_t ZonePool::StatsScope::GetCurrentAllocatedBytes() {
+  size_t total = 0;
+  for (Zone* zone : zone_pool_->used_) {
+    total += static_cast<size_t>(zone->allocation_size());
+    // Adjust for initial values.
+    InitialValues::iterator it = initial_values_.find(zone);
+    if (it != initial_values_.end()) {
+      total -= it->second;
+    }
+  }
+  return total;
+}
+
+
+size_t ZonePool::StatsScope::GetTotalAllocatedBytes() {
+  return zone_pool_->GetTotalAllocatedBytes() - total_allocated_bytes_at_start_;
+}
+
+
+void ZonePool::StatsScope::ZoneReturned(Zone* zone) {
+  size_t current_total = GetCurrentAllocatedBytes();
+  // Update max.
+  max_allocated_bytes_ = std::max(max_allocated_bytes_, current_total);
+  // Drop zone from initial value map.
+  InitialValues::iterator it = initial_values_.find(zone);
+  if (it != initial_values_.end()) {
+    initial_values_.erase(it);
+  }
+}
+
+ZonePool::ZonePool(AccountingAllocator* allocator)
+    : max_allocated_bytes_(0), total_deleted_bytes_(0), allocator_(allocator) {}
+
+ZonePool::~ZonePool() {
+  DCHECK(used_.empty());
+  DCHECK(stats_.empty());
+  for (Zone* zone : unused_) {
+    delete zone;
+  }
+}
+
+
+size_t ZonePool::GetMaxAllocatedBytes() {
+  return std::max(max_allocated_bytes_, GetCurrentAllocatedBytes());
+}
+
+
+size_t ZonePool::GetCurrentAllocatedBytes() {
+  size_t total = 0;
+  for (Zone* zone : used_) {
+    total += static_cast<size_t>(zone->allocation_size());
+  }
+  return total;
+}
+
+
+size_t ZonePool::GetTotalAllocatedBytes() {
+  return total_deleted_bytes_ + GetCurrentAllocatedBytes();
+}
+
+
+Zone* ZonePool::NewEmptyZone() {
+  Zone* zone;
+  // Grab a zone from pool if possible.
+  if (!unused_.empty()) {
+    zone = unused_.back();
+    unused_.pop_back();
+  } else {
+    zone = new Zone(allocator_);
+  }
+  used_.push_back(zone);
+  DCHECK_EQ(0u, zone->allocation_size());
+  return zone;
+}
+
+
+void ZonePool::ReturnZone(Zone* zone) {
+  size_t current_total = GetCurrentAllocatedBytes();
+  // Update max.
+  max_allocated_bytes_ = std::max(max_allocated_bytes_, current_total);
+  // Update stats.
+  for (StatsScope* stat_scope : stats_) {
+    stat_scope->ZoneReturned(zone);
+  }
+  // Remove from used.
+  Used::iterator it = std::find(used_.begin(), used_.end(), zone);
+  DCHECK(it != used_.end());
+  used_.erase(it);
+  total_deleted_bytes_ += static_cast<size_t>(zone->allocation_size());
+  // Delete zone or clear and stash on unused_.
+  if (unused_.size() >= kMaxUnusedSize) {
+    delete zone;
+  } else {
+    zone->DeleteAll();
+    DCHECK_EQ(0u, zone->allocation_size());
+    unused_.push_back(zone);
+  }
+}
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8