Reviewers: Michael Starzinger,
https://codereview.chromium.org/1302423007/diff/1/src/heap/spaces.h
File src/heap/spaces.h (left):
https://codereview.chromium.org/1302423007/diff/1/src/heap/spaces.h#oldcode558
src/heap/spaces.h:558: 5 * kPointerSize + // free list statistics
5 * kPointerSize implicitly included the memory that was needed to
amount for alignment requirements. (Maybe the author new this, maybe
not.)
Description:
[heap] Fix MemoryChunk::kHeaderSize computation and add some assertions.
[email protected]
Please review this at https://codereview.chromium.org/1302423007/
Base URL: https://chromium.googlesource.com/v8/v8.git@master
Affected files (+46, -21 lines):
M src/heap/spaces.h
Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index
de82164a1332be17c00c5f2c9e239a4284a1e1cb..25c1211329229536ac8ac6ec58288cb03b3c888a
100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -541,23 +541,37 @@ class MemoryChunk {
static const intptr_t kSizeOffset = 0;
static const intptr_t kLiveBytesOffset =
- kSizeOffset + kPointerSize + kPointerSize + kPointerSize +
kPointerSize +
- kPointerSize + kPointerSize + kPointerSize + kPointerSize + kIntSize;
+ kSizeOffset + kPointerSize // size_t size
+ + kIntptrSize // intptr_t flags_
+ + kPointerSize // Address area_start_
+ + kPointerSize // Address area_end_
+ + 2 * kPointerSize // base::VirtualMemory reservation_
+ + kPointerSize // Address owner_
+ + kPointerSize // Heap* heap_
+ + kIntSize; // int store_buffer_counter_
- static const size_t kSlotsBufferOffset = kLiveBytesOffset + kIntSize;
+
+ static const size_t kSlotsBufferOffset =
+ kLiveBytesOffset + kIntSize; // int live_byte_count_
static const size_t kWriteBarrierCounterOffset =
- kSlotsBufferOffset + kPointerSize + kPointerSize;
-
- static const size_t kHeaderSize = kWriteBarrierCounterOffset +
- kPointerSize + //
write_barrier_counter_
- kIntSize + // progress_bar_
- kIntSize + // high_water_mark_
- kPointerSize + // mutex_ page lock
- kPointerSize + // parallel_sweeping_
- 5 * kPointerSize + // free list
statistics
- kPointerSize + // next_chunk_
- kPointerSize; // prev_chunk_
+ kSlotsBufferOffset + kPointerSize // SlotsBuffer* slots_buffer_;
+ + kPointerSize; // SkipList* skip_list_;
+
+ static const size_t kMinHeaderSize =
+ kWriteBarrierCounterOffset +
+ kPointerSize // intptr_t write_barrier_counter_
+ + kIntSize // int progress_bar_
+ + kIntSize // int high_water_mark_
+ + kPointerSize // base::Mutex* mutex_
+ + kPointerSize // base::AtomicWord parallel_sweeping_
+ + 5 * kIntSize // int free-list statistics
+ + kPointerSize // base::AtomicWord next_chunk_
+ + kPointerSize; // base::AtomicWord prev_chunk_
+
+ // We add some more space to the computed header size to amount for
missing
+ // alignment requirements in our computation.
+ static const size_t kHeaderSize = kMinHeaderSize + kPointerSize;
static const int kBodyOffset =
CODE_POINTER_ALIGN(kHeaderSize + Bitmap::kSize);
@@ -727,12 +741,10 @@ class MemoryChunk {
base::AtomicWord prev_chunk_;
friend class MemoryAllocator;
+ friend class MemoryChunkValidator;
};
-STATIC_ASSERT(sizeof(MemoryChunk) <= MemoryChunk::kHeaderSize);
-
-
//
-----------------------------------------------------------------------------
// A page is a memory chunk of a size 1MB. Large object pages may be
larger.
//
@@ -841,9 +853,6 @@ class Page : public MemoryChunk {
};
-STATIC_ASSERT(sizeof(Page) <= MemoryChunk::kHeaderSize);
-
-
class LargePage : public MemoryChunk {
public:
HeapObject* GetObject() { return HeapObject::FromAddress(area_start()); }
@@ -860,7 +869,6 @@ class LargePage : public MemoryChunk {
friend class MemoryAllocator;
};
-STATIC_ASSERT(sizeof(LargePage) <= MemoryChunk::kHeaderSize);
//
----------------------------------------------------------------------------
// Space is the abstract superclass for all allocation spaces.
@@ -914,6 +922,23 @@ class Space : public Malloced {
};
+class MemoryChunkValidator {
+ // Computed offsets should match the compiler generates ones.
+ STATIC_ASSERT(MemoryChunk::kSizeOffset == offsetof(MemoryChunk, size_));
+ STATIC_ASSERT(MemoryChunk::kLiveBytesOffset ==
+ offsetof(MemoryChunk, live_byte_count_));
+ STATIC_ASSERT(MemoryChunk::kSlotsBufferOffset ==
+ offsetof(MemoryChunk, slots_buffer_));
+ STATIC_ASSERT(MemoryChunk::kWriteBarrierCounterOffset ==
+ offsetof(MemoryChunk, write_barrier_counter_));
+
+ // Validate our estimates on the header size.
+ STATIC_ASSERT(sizeof(MemoryChunk) <= MemoryChunk::kHeaderSize);
+ STATIC_ASSERT(sizeof(LargePage) <= MemoryChunk::kHeaderSize);
+ STATIC_ASSERT(sizeof(Page) <= MemoryChunk::kHeaderSize);
+};
+
+
//
----------------------------------------------------------------------------
// All heap objects containing executable code (code objects) must be
allocated
// from a 2 GB range of memory, so that they can call each other using
32-bit
--
--
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