1 files changed, 64 insertions, 9 deletions

diff --git a/runtime/linear_alloc.h b/runtime/linear_alloc.h
index 1d01f84072..c40af8ad46 100644
--- a/runtime/linear_alloc.h
+++ b/runtime/linear_alloc.h
@@ -18,44 +18,99 @@
 #define ART_RUNTIME_LINEAR_ALLOC_H_
 
 #include "base/arena_allocator.h"
+#include "base/casts.h"
 #include "base/mutex.h"
 
 namespace art {
 
 class ArenaPool;
 
-// TODO: Support freeing if we add class unloading.
+enum class LinearAllocKind : uint32_t {
+  kNoGCRoots = 0,  // No GC-root kind should always be 0.
+  kGCRootArray,
+  kArtMethodArray,
+  kArtFieldArray,
+  kDexCacheArray,
+  kArtMethod
+};
+
+// Header for every allocation in LinearAlloc. The header provides the type
+// and size information to the GC for invoking the right visitor.
+class TrackingHeader final {
+ public:
+  static constexpr uint32_t kIs16Aligned = 1;
+  TrackingHeader(size_t size, LinearAllocKind kind, bool is_16_aligned = false)
+      : kind_(kind), size_(dchecked_integral_cast<uint32_t>(size)) {
+    // We need the last bit to store 16-byte alignment flag.
+    CHECK_EQ(size_ & kIs16Aligned, 0u);
+    if (is_16_aligned) {
+      size_ |= kIs16Aligned;
+    }
+  }
+
+  LinearAllocKind GetKind() const { return kind_; }
+  // Since we are linearly allocating and hop from one object to the next during
+  // visits, reading 'size_ == 0' indicates that there are no more objects to
+  // visit in the given page. But ASAN detects it as use-after-poison access.
+  ATTRIBUTE_NO_SANITIZE_ADDRESS size_t GetSize() const { return size_ & ~kIs16Aligned; }
+  bool Is16Aligned() const { return size_ & kIs16Aligned; }
+
+ private:
+  LinearAllocKind kind_;
+  uint32_t size_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(TrackingHeader);
+};
+
+std::ostream& operator<<(std::ostream& os, LinearAllocKind value);
+
 class LinearAlloc {
  public:
-  explicit LinearAlloc(ArenaPool* pool);
+  static constexpr size_t kAlignment = 8u;
+  static_assert(kAlignment >= ArenaAllocator::kAlignment);
+  static_assert(sizeof(TrackingHeader) == ArenaAllocator::kAlignment);
 
-  void* Alloc(Thread* self, size_t size) REQUIRES(!lock_);
-  void* AllocAlign16(Thread* self, size_t size) REQUIRES(!lock_);
+  explicit LinearAlloc(ArenaPool* pool, bool track_allocs)
+      : lock_("linear alloc"), allocator_(pool), track_allocations_(track_allocs) {}
+
+  void* Alloc(Thread* self, size_t size, LinearAllocKind kind) REQUIRES(!lock_);
+  void* AllocAlign16(Thread* self, size_t size, LinearAllocKind kind) REQUIRES(!lock_);
 
   // Realloc never frees the input pointer, it is the caller's job to do this if necessary.
-  void* Realloc(Thread* self, void* ptr, size_t old_size, size_t new_size) REQUIRES(!lock_);
+  void* Realloc(Thread* self, void* ptr, size_t old_size, size_t new_size, LinearAllocKind kind)
+      REQUIRES(!lock_);
 
   // Allocate an array of structs of type T.
   template<class T>
-  T* AllocArray(Thread* self, size_t elements) REQUIRES(!lock_) {
-    return reinterpret_cast<T*>(Alloc(self, elements * sizeof(T)));
+  T* AllocArray(Thread* self, size_t elements, LinearAllocKind kind) REQUIRES(!lock_) {
+    return reinterpret_cast<T*>(Alloc(self, elements * sizeof(T), kind));
   }
 
   // Return the number of bytes used in the allocator.
   size_t GetUsedMemory() const REQUIRES(!lock_);
 
   ArenaPool* GetArenaPool() REQUIRES(!lock_);
+  // Force arena allocator to ask for a new arena on next allocation. This
+  // is to preserve private/shared clean pages across zygote fork.
+  void SetupForPostZygoteFork(Thread* self) REQUIRES(!lock_);
 
-  // Return true if the linear alloc contrains an address.
+  // Return true if the linear alloc contains an address.
   bool Contains(void* ptr) const REQUIRES(!lock_);
 
   // Unsafe version of 'Contains' only to be used when the allocator is going
   // to be deleted.
-  bool ContainsUnsafe(void* ptr) const NO_THREAD_SAFETY_ANALYSIS;
+  bool ContainsUnsafe(void* ptr) const NO_THREAD_SAFETY_ANALYSIS {
+    return allocator_.Contains(ptr);
+  }
+
+  // Set the given object as the first object for all the pages where the
+  // page-beginning overlaps with the object.
+  void SetFirstObject(void* begin, size_t bytes) const REQUIRES(lock_);
 
  private:
   mutable Mutex lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
   ArenaAllocator allocator_ GUARDED_BY(lock_);
+  const bool track_allocations_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(LinearAlloc);
 };