Moved zones and zone related stuff in its own directory.

src/zone.cc

Index: src/zone.cc
diff --git a/src/zone.cc b/src/zone.cc
deleted file mode 100644
index a10b63612e484962870ab2004c6bf2a7ff44f49a..0000000000000000000000000000000000000000
--- a/src/zone.cc
+++ /dev/null
@@ -1,280 +0,0 @@
-// Copyright 2012 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/zone.h"
-
-#include <cstring>
-
-#include "src/v8.h"
-
-#ifdef V8_USE_ADDRESS_SANITIZER
-#include <sanitizer/asan_interface.h>
-#endif  // V8_USE_ADDRESS_SANITIZER
-
-namespace v8 {
-namespace internal {
-
-namespace {
-
-#if V8_USE_ADDRESS_SANITIZER
-
-const size_t kASanRedzoneBytes = 24;  // Must be a multiple of 8.
-
-#else
-
-#define ASAN_POISON_MEMORY_REGION(start, size) \
-  do {                                         \
-    USE(start);                                \
-    USE(size);                                 \
-  } while (false)
-
-#define ASAN_UNPOISON_MEMORY_REGION(start, size) \
-  do {                                           \
-    USE(start);                                  \
-    USE(size);                                   \
-  } while (false)
-
-const size_t kASanRedzoneBytes = 0;
-
-#endif  // V8_USE_ADDRESS_SANITIZER
-
-}  // namespace
-
-
-// Segments represent chunks of memory: They have starting address
-// (encoded in the this pointer) and a size in bytes. Segments are
-// chained together forming a LIFO structure with the newest segment
-// available as segment_head_. Segments are allocated using malloc()
-// and de-allocated using free().
-
-class Segment {
- public:
-  void Initialize(Segment* next, size_t size) {
-    next_ = next;
-    size_ = size;
-  }
-
-  Segment* next() const { return next_; }
-  void clear_next() { next_ = nullptr; }
-
-  size_t size() const { return size_; }
-  size_t capacity() const { return size_ - sizeof(Segment); }
-
-  Address start() const { return address(sizeof(Segment)); }
-  Address end() const { return address(size_); }
-
- private:
-  // Computes the address of the nth byte in this segment.
-  Address address(size_t n) const { return Address(this) + n; }
-
-  Segment* next_;
-  size_t size_;
-};
-
-Zone::Zone(base::AccountingAllocator* allocator)
-    : allocation_size_(0),
-      segment_bytes_allocated_(0),
-      position_(0),
-      limit_(0),
-      allocator_(allocator),
-      segment_head_(nullptr) {}
-
-Zone::~Zone() {
-  DeleteAll();
-  DeleteKeptSegment();
-
-  DCHECK(segment_bytes_allocated_ == 0);
-}
-
-
-void* Zone::New(size_t size) {
-  // Round up the requested size to fit the alignment.
-  size = RoundUp(size, kAlignment);
-
-  // If the allocation size is divisible by 8 then we return an 8-byte aligned
-  // address.
-  if (kPointerSize == 4 && kAlignment == 4) {
-    position_ += ((~size) & 4) & (reinterpret_cast<intptr_t>(position_) & 4);
-  } else {
-    DCHECK(kAlignment >= kPointerSize);
-  }
-
-  // Check if the requested size is available without expanding.
-  Address result = position_;
-
-  const size_t size_with_redzone = size + kASanRedzoneBytes;
-  const uintptr_t limit = reinterpret_cast<uintptr_t>(limit_);
-  const uintptr_t position = reinterpret_cast<uintptr_t>(position_);
-  // position_ > limit_ can be true after the alignment correction above.
-  if (limit < position || size_with_redzone > limit - position) {
-    result = NewExpand(size_with_redzone);
-  } else {
-    position_ += size_with_redzone;
-  }
-
-  Address redzone_position = result + size;
-  DCHECK(redzone_position + kASanRedzoneBytes == position_);
-  ASAN_POISON_MEMORY_REGION(redzone_position, kASanRedzoneBytes);
-
-  // Check that the result has the proper alignment and return it.
-  DCHECK(IsAddressAligned(result, kAlignment, 0));
-  allocation_size_ += size;
-  return reinterpret_cast<void*>(result);
-}
-
-
-void Zone::DeleteAll() {
-#ifdef DEBUG
-  // Constant byte value used for zapping dead memory in debug mode.
-  static const unsigned char kZapDeadByte = 0xcd;
-#endif
-
-  // Find a segment with a suitable size to keep around.
-  Segment* keep = nullptr;
-  // Traverse the chained list of segments, zapping (in debug mode)
-  // and freeing every segment except the one we wish to keep.
-  for (Segment* current = segment_head_; current;) {
-    Segment* next = current->next();
-    if (!keep && current->size() <= kMaximumKeptSegmentSize) {
-      // Unlink the segment we wish to keep from the list.
-      keep = current;
-      keep->clear_next();
-    } else {
-      size_t size = current->size();
-#ifdef DEBUG
-      // Un-poison first so the zapping doesn't trigger ASan complaints.
-      ASAN_UNPOISON_MEMORY_REGION(current, size);
-      // Zap the entire current segment (including the header).
-      memset(current, kZapDeadByte, size);
-#endif
-      DeleteSegment(current, size);
-    }
-    current = next;
-  }
-
-  // If we have found a segment we want to keep, we must recompute the
-  // variables 'position' and 'limit' to prepare for future allocate
-  // attempts. Otherwise, we must clear the position and limit to
-  // force a new segment to be allocated on demand.
-  if (keep) {
-    Address start = keep->start();
-    position_ = RoundUp(start, kAlignment);
-    limit_ = keep->end();
-    // Un-poison so we can re-use the segment later.
-    ASAN_UNPOISON_MEMORY_REGION(start, keep->capacity());
-#ifdef DEBUG
-    // Zap the contents of the kept segment (but not the header).
-    memset(start, kZapDeadByte, keep->capacity());
-#endif
-  } else {
-    position_ = limit_ = 0;
-  }
-
-  allocation_size_ = 0;
-  // Update the head segment to be the kept segment (if any).
-  segment_head_ = keep;
-}
-
-
-void Zone::DeleteKeptSegment() {
-#ifdef DEBUG
-  // Constant byte value used for zapping dead memory in debug mode.
-  static const unsigned char kZapDeadByte = 0xcd;
-#endif
-
-  DCHECK(segment_head_ == nullptr || segment_head_->next() == nullptr);
-  if (segment_head_ != nullptr) {
-    size_t size = segment_head_->size();
-#ifdef DEBUG
-    // Un-poison first so the zapping doesn't trigger ASan complaints.
-    ASAN_UNPOISON_MEMORY_REGION(segment_head_, size);
-    // Zap the entire kept segment (including the header).
-    memset(segment_head_, kZapDeadByte, size);
-#endif
-    DeleteSegment(segment_head_, size);
-    segment_head_ = nullptr;
-  }
-
-  DCHECK(segment_bytes_allocated_ == 0);
-}
-
-
-// Creates a new segment, sets it size, and pushes it to the front
-// of the segment chain. Returns the new segment.
-Segment* Zone::NewSegment(size_t size) {
-  Segment* result = reinterpret_cast<Segment*>(allocator_->Allocate(size));
-  segment_bytes_allocated_ += size;
-  if (result != nullptr) {
-    result->Initialize(segment_head_, size);
-    segment_head_ = result;
-  }
-  return result;
-}
-
-
-// Deletes the given segment. Does not touch the segment chain.
-void Zone::DeleteSegment(Segment* segment, size_t size) {
-  segment_bytes_allocated_ -= size;
-  allocator_->Free(segment, size);
-}
-
-
-Address Zone::NewExpand(size_t size) {
-  // Make sure the requested size is already properly aligned and that
-  // there isn't enough room in the Zone to satisfy the request.
-  DCHECK_EQ(size, RoundDown(size, kAlignment));
-  DCHECK(limit_ < position_ ||
-         reinterpret_cast<uintptr_t>(limit_) -
-                 reinterpret_cast<uintptr_t>(position_) <
-             size);
-
-  // Compute the new segment size. We use a 'high water mark'
-  // strategy, where we increase the segment size every time we expand
-  // except that we employ a maximum segment size when we delete. This
-  // is to avoid excessive malloc() and free() overhead.
-  Segment* head = segment_head_;
-  const size_t old_size = (head == nullptr) ? 0 : head->size();
-  static const size_t kSegmentOverhead = sizeof(Segment) + kAlignment;
-  const size_t new_size_no_overhead = size + (old_size << 1);
-  size_t new_size = kSegmentOverhead + new_size_no_overhead;
-  const size_t min_new_size = kSegmentOverhead + size;
-  // Guard against integer overflow.
-  if (new_size_no_overhead < size || new_size < kSegmentOverhead) {
-    V8::FatalProcessOutOfMemory("Zone");
-    return nullptr;
-  }
-  if (new_size < kMinimumSegmentSize) {
-    new_size = kMinimumSegmentSize;
-  } else if (new_size > kMaximumSegmentSize) {
-    // Limit the size of new segments to avoid growing the segment size
-    // exponentially, thus putting pressure on contiguous virtual address space.
-    // All the while making sure to allocate a segment large enough to hold the
-    // requested size.
-    new_size = Max(min_new_size, kMaximumSegmentSize);
-  }
-  if (new_size > INT_MAX) {
-    V8::FatalProcessOutOfMemory("Zone");
-    return nullptr;
-  }
-  Segment* segment = NewSegment(new_size);
-  if (segment == nullptr) {
-    V8::FatalProcessOutOfMemory("Zone");
-    return nullptr;
-  }
-
-  // Recompute 'top' and 'limit' based on the new segment.
-  Address result = RoundUp(segment->start(), kAlignment);
-  position_ = result + size;
-  // Check for address overflow.
-  // (Should not happen since the segment is guaranteed to accomodate
-  // size bytes + header and alignment padding)
-  DCHECK(reinterpret_cast<uintptr_t>(position_) >=
-         reinterpret_cast<uintptr_t>(result));
-  limit_ = segment->end();
-  DCHECK(position_ <= limit_);
-  return result;
-}
-
-}  // namespace internal
-}  // namespace v8