[PA] kOffsetTagNotInDirectMap->kOffsetTagNormalBuckets

Change-Id: Ie2697abd4a3e690bd35b9ce77b291b9fbe2b0d30
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2943381
Commit-Queue: Bartek Nowierski <bartekn@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Takashi Sakamoto <tasak@google.com>
Cr-Commit-Position: refs/heads/master@{#890865}

base/allocator/partition_allocator/partition_alloc_unittest.cc

@@ -3037,12 +3037,11 @@ TEST_F(PartitionAllocTest, RefCountRealloc) {
 #endif  // BUILDFLAG(USE_BACKUP_REF_PTR)
 
 TEST_F(PartitionAllocTest, ReservationOffset) {
-  // For normal buckets, offset should be kOffsetTagNotInDirectMap.
+  // For normal buckets, offset should be kOffsetTagNormalBuckets.
   void* ptr = allocator.root()->Alloc(kTestAllocSize, type_name);
   EXPECT_TRUE(ptr);
   uintptr_t ptr_as_uintptr = reinterpret_cast<uintptr_t>(ptr);
-  EXPECT_EQ(kOffsetTagNotInDirectMap,
+  EXPECT_EQ(kOffsetTagNormalBuckets, *ReservationOffsetPointer(ptr_as_uintptr));
-            *ReservationOffsetPointer(ptr_as_uintptr));
   allocator.root()->Free(ptr);
 
   // For not yet allocated memory, offset should be kOffsetTagNotAllocated.

base/allocator/partition_allocator/partition_bucket.cc

@@ -290,7 +290,7 @@ SlotSpanMetadata<thread_safe>* PartitionDirectMap(
     int offset = 0;
     while (ptr_start < ptr_end) {
       PA_DCHECK(offset_ptr < GetReservationOffsetTableEnd());
-      PA_DCHECK(offset < kOffsetTagNotInDirectMap);
+      PA_DCHECK(offset < kOffsetTagNormalBuckets);
       *offset_ptr++ = offset++;
       ptr_start += kSuperPageSize;
     }
@@ -536,10 +536,8 @@ ALWAYS_INLINE void* PartitionBucket<thread_safe>::AllocNewSuperPage(
   if (UNLIKELY(!super_page))
     return nullptr;
 
-  // Set the reservation offset table entry to NotInDirectMapOffsetTag, to
-  // indicate that it isn't direct-map allocated.
   *ReservationOffsetPointer(reinterpret_cast<uintptr_t>(super_page)) =
-      kOffsetTagNotInDirectMap;
+      kOffsetTagNormalBuckets;
 
   root->total_size_of_super_pages.fetch_add(kSuperPageSize,
                                             std::memory_order_relaxed);

base/allocator/partition_allocator/reservation_offset_table.h

@@ -21,7 +21,7 @@ namespace internal {
 
 static constexpr uint16_t kOffsetTagNotAllocated =
     std::numeric_limits<uint16_t>::max();
-static constexpr uint16_t kOffsetTagNotInDirectMap =
+static constexpr uint16_t kOffsetTagNormalBuckets =
     std::numeric_limits<uint16_t>::max() - 1;
 
 // The main purpose of the reservation offset table is to easily locate the
@@ -50,7 +50,7 @@ static constexpr uint16_t kOffsetTagNotInDirectMap =
 //   ((Z >> kSuperPageShift) - (the entry for Z)) << kSuperPageShift
 //
 // kOffsetTagNotAllocated is a special tag denoting that the super page isn't
-// allocated by PartitionAlloc and kOffsetTagNotInDirectMap denotes that it is
+// allocated by PartitionAlloc and kOffsetTagNormalBuckets denotes that it is
 // used for a normal-bucket allocation, not for a direct-map allocation.
 //
 // *) In 32-bit mode, Y is not used by PartitionAlloc, and cannot be used
@@ -75,8 +75,8 @@ class BASE_EXPORT ReservationOffsetTable {
   static constexpr size_t kReservationOffsetTableLength =
       4 * kGiB / kSuperPageSize;
 #endif
-  static_assert(kReservationOffsetTableLength < kOffsetTagNotInDirectMap,
+  static_assert(kReservationOffsetTableLength < kOffsetTagNormalBuckets,
-                "Offsets should be smaller than kOffsetTagNotInDirectMap.");
+                "Offsets should be smaller than kOffsetTagNormalBuckets.");
 
   static struct _ReservationOffsetTable {
     // Thenumber of table elements is less than MAX_UINT16, so the element type
@@ -123,7 +123,7 @@ ALWAYS_INLINE uintptr_t GetDirectMapReservationStart(void* address) {
   uintptr_t ptr_as_uintptr = reinterpret_cast<uintptr_t>(address);
   uint16_t* offset_ptr = ReservationOffsetPointer(ptr_as_uintptr);
   PA_DCHECK(*offset_ptr != kOffsetTagNotAllocated);
-  if (*offset_ptr == kOffsetTagNotInDirectMap)
+  if (*offset_ptr == kOffsetTagNormalBuckets)
     return 0;
   uintptr_t reservation_start =
       (ptr_as_uintptr & kSuperPageBaseMask) -
@@ -157,7 +157,7 @@ ALWAYS_INLINE bool IsReservationStart(const void* address) {
   uintptr_t address_as_uintptr = reinterpret_cast<uintptr_t>(address);
   uint16_t* offset_ptr = ReservationOffsetPointer(address_as_uintptr);
   PA_DCHECK(*offset_ptr != kOffsetTagNotAllocated);
-  return ((*offset_ptr == kOffsetTagNotInDirectMap) || (*offset_ptr == 0)) &&
+  return ((*offset_ptr == kOffsetTagNormalBuckets) || (*offset_ptr == 0)) &&
          (address_as_uintptr % kSuperPageSize == 0);
 }
 
@@ -167,7 +167,7 @@ ALWAYS_INLINE bool IsManagedByNormalBuckets(const void* address) {
   uintptr_t address_as_uintptr = reinterpret_cast<uintptr_t>(address);
   uint16_t* offset_ptr = ReservationOffsetPointer(address_as_uintptr);
   PA_DCHECK(*offset_ptr != kOffsetTagNotAllocated);
-  return *offset_ptr == kOffsetTagNotInDirectMap;
+  return *offset_ptr == kOffsetTagNormalBuckets;
 }
 
 // Returns true if |address| belongs to a direct map region.
@@ -176,7 +176,7 @@ ALWAYS_INLINE bool IsManagedByDirectMap(const void* address) {
   uintptr_t address_as_uintptr = reinterpret_cast<uintptr_t>(address);
   uint16_t* offset_ptr = ReservationOffsetPointer(address_as_uintptr);
   PA_DCHECK(*offset_ptr != kOffsetTagNotAllocated);
-  return *offset_ptr != kOffsetTagNotInDirectMap;
+  return *offset_ptr != kOffsetTagNormalBuckets;
 }
 
 }  // namespace internal