Make top and limit field in AllocationInfo private, assert on non-aligned setting of these fields, …

src/spaces.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1299 matching lines @@
 
 
 // -----------------------------------------------------------------------------
 // A space has a circular list of pages. The next page can be accessed via
 // Page::next_page() call.
 
 // An abstraction of allocation and relocation pointers in a page-structured
 // space.
 class AllocationInfo {
  public:
-  AllocationInfo() : top(NULL), limit(NULL) {
+  AllocationInfo() : top_(NULL), limit_(NULL) {
   }
 
-  Address top;  // Current allocation top.
-  Address limit;  // Current allocation limit.
+  INLINE(void set_top(Address top)) {
+    ASSERT(top == NULL ||

[Michael Starzinger, 2013/10/25 08:34:56]

nit: As discussed offline, maybe consider making all of these SLOW_ASSERTs
instead.

[Hannes Payer (out of office), 2013/11/20 09:58:47]

Done.

+           (reinterpret_cast<intptr_t>(top) & HeapObjectTagMask()) == 0);
+    top_ = top;
+  }
+
+  INLINE(Address top()) const {
+    ASSERT(top_ == NULL ||
+           (reinterpret_cast<intptr_t>(top_) & HeapObjectTagMask()) == 0);
+    return top_;
+  }
+
+  Address* top_address() {
+    return &top_;
+  }
+
+  INLINE(void set_limit(Address limit)) {
+    ASSERT(limit == NULL ||
+           (reinterpret_cast<intptr_t>(limit) & HeapObjectTagMask()) == 0);
+    limit_ = limit;
+  }
+
+  INLINE(Address limit()) const {
+    ASSERT(limit_ == NULL ||
+           (reinterpret_cast<intptr_t>(limit_) & HeapObjectTagMask()) == 0);
+    return limit_;
+  }
+
+  Address* limit_address() {
+    return &limit_;
+  }
 
 #ifdef DEBUG
   bool VerifyPagedAllocation() {
-    return (Page::FromAllocationTop(top) == Page::FromAllocationTop(limit))
-        && (top <= limit);
+    return (Page::FromAllocationTop(top_) == Page::FromAllocationTop(limit_))
+        && (top_ <= limit_);
   }
 #endif
+
+ private:
+  // Current allocation top.
+  Address top_;
+  // Current allocation limit.
+  Address limit_;
 };
 
 
 // An abstraction of the accounting statistics of a page-structured space.
 // The 'capacity' of a space is the number of object-area bytes (i.e., not
 // including page bookkeeping structures) currently in the space. The 'size'
 // of a space is the number of allocated bytes, the 'waste' in the space is
 // the number of bytes that are not allocated and not available to
 // allocation without reorganizing the space via a GC (e.g. small blocks due
 // to internal fragmentation, top of page areas in map space), and the bytes
@@ skipping 358 matching lines @@
   // As size, but the bytes in lazily swept pages are estimated and the bytes
   // in the current linear allocation area are not included.
   virtual intptr_t SizeOfObjects();
 
   // Wasted bytes in this space.  These are just the bytes that were thrown away
   // due to being too small to use for allocation.  They do not include the
   // free bytes that were not found at all due to lazy sweeping.
   virtual intptr_t Waste() { return accounting_stats_.Waste(); }
 
   // Returns the allocation pointer in this space.
-  Address top() { return allocation_info_.top; }
-  Address limit() { return allocation_info_.limit; }
+  Address top() { return allocation_info_.top(); }
+  Address limit() { return allocation_info_.limit(); }
 
-  // The allocation top and limit addresses.
-  Address* allocation_top_address() { return &allocation_info_.top; }
-  Address* allocation_limit_address() { return &allocation_info_.limit; }
+  // The allocation top address.
+  Address* allocation_top_address() {
+    return allocation_info_.top_address();
+  }
+
+  // The allocation limit address.
+  Address* allocation_limit_address() {
+    return allocation_info_.limit_address();
+  }
 
   enum AllocationType {
     NEW_OBJECT,
     MOVE_OBJECT
   };
 
   // Allocate the requested number of bytes in the space if possible, return a
   // failure object if not.
   MUST_USE_RESULT inline MaybeObject* AllocateRaw(
       int size_in_bytes,
@@ skipping 12 matching lines @@
   }
 
   void ResetFreeList() {
     free_list_.Reset();
   }
 
   // Set space allocation info.
   void SetTop(Address top, Address limit) {
     ASSERT(top == limit ||
            Page::FromAddress(top) == Page::FromAddress(limit - 1));
-    MemoryChunk::UpdateHighWaterMark(allocation_info_.top);
-    allocation_info_.top = top;
-    allocation_info_.limit = limit;
+    MemoryChunk::UpdateHighWaterMark(allocation_info_.top());
+    allocation_info_.set_top(top);
+    allocation_info_.set_limit(limit);
   }
 
   void Allocate(int bytes) {
     accounting_stats_.AllocateBytes(bytes);
   }
 
   void IncreaseCapacity(int size) {
     accounting_stats_.ExpandSpace(size);
   }
 
@@ skipping 620 matching lines @@
   }
 
   // Returns the initial capacity of a semispace.
   int InitialCapacity() {
     ASSERT(to_space_.InitialCapacity() == from_space_.InitialCapacity());
     return to_space_.InitialCapacity();
   }
 
   // Return the address of the allocation pointer in the active semispace.
   Address top() {
-    ASSERT(to_space_.current_page()->ContainsLimit(allocation_info_.top));
-    return allocation_info_.top;
+    ASSERT(to_space_.current_page()->ContainsLimit(allocation_info_.top()));
+    return allocation_info_.top();
   }
+
+  void set_top(Address top) {
+    ASSERT(to_space_.current_page()->ContainsLimit(top));
+    allocation_info_.set_top(top);
+  }
+
   // Return the address of the first object in the active semispace.
   Address bottom() { return to_space_.space_start(); }
 
   // Get the age mark of the inactive semispace.
   Address age_mark() { return from_space_.age_mark(); }
   // Set the age mark in the active semispace.
   void set_age_mark(Address mark) { to_space_.set_age_mark(mark); }
 
   // The start address of the space and a bit mask. Anding an address in the
   // new space with the mask will result in the start address.
   Address start() { return start_; }
   uintptr_t mask() { return address_mask_; }
 
   INLINE(uint32_t AddressToMarkbitIndex(Address addr)) {
     ASSERT(Contains(addr));
     ASSERT(IsAligned(OffsetFrom(addr), kPointerSize) ||
            IsAligned(OffsetFrom(addr) - 1, kPointerSize));
     return static_cast<uint32_t>(addr - start_) >> kPointerSizeLog2;
   }
 
   INLINE(Address MarkbitIndexToAddress(uint32_t index)) {
     return reinterpret_cast<Address>(index << kPointerSizeLog2);
   }
 
-  // The allocation top and limit addresses.
-  Address* allocation_top_address() { return &allocation_info_.top; }
-  Address* allocation_limit_address() { return &allocation_info_.limit; }
+  // The allocation top and limit address.
+  Address* allocation_top_address() {
+    return allocation_info_.top_address();
+  }
+
+  // The allocation limit address.
+  Address* allocation_limit_address() {
+    return allocation_info_.limit_address();
+  }
 
   MUST_USE_RESULT INLINE(MaybeObject* AllocateRaw(int size_in_bytes));
 
   // Reset the allocation pointer to the beginning of the active semispace.
   void ResetAllocationInfo();
 
   void LowerInlineAllocationLimit(intptr_t step) {
     inline_allocation_limit_step_ = step;
     if (step == 0) {
-      allocation_info_.limit = to_space_.page_high();
+      allocation_info_.set_limit(to_space_.page_high());
     } else {
-      allocation_info_.limit = Min(
-          allocation_info_.top + inline_allocation_limit_step_,
-          allocation_info_.limit);
+      Address new_limit = Min(
+          allocation_info_.top() + inline_allocation_limit_step_,
+          allocation_info_.limit());
+      allocation_info_.set_limit(new_limit);
     }
-    top_on_previous_step_ = allocation_info_.top;
+    top_on_previous_step_ = allocation_info_.top();
   }
 
   // Get the extent of the inactive semispace (for use as a marking stack,
   // or to zap it). Notice: space-addresses are not necessarily on the
   // same page, so FromSpaceStart() might be above FromSpaceEnd().
   Address FromSpacePageLow() { return from_space_.page_low(); }
   Address FromSpacePageHigh() { return from_space_.page_high(); }
   Address FromSpaceStart() { return from_space_.space_start(); }
   Address FromSpaceEnd() { return from_space_.space_end(); }
 
@@ skipping 126 matching lines @@
   }
 
  public:
   TRACK_MEMORY("OldSpace")
 };
 
 
 // For contiguous spaces, top should be in the space (or at the end) and limit
 // should be the end of the space.
 #define ASSERT_SEMISPACE_ALLOCATION_INFO(info, space) \
-  SLOW_ASSERT((space).page_low() <= (info).top             \
-              && (info).top <= (space).page_high()         \
-              && (info).limit <= (space).page_high())
+  SLOW_ASSERT((space).page_low() <= (info).top() \
+              && (info).top() <= (space).page_high() \
+              && (info).limit() <= (space).page_high())
 
 
 // -----------------------------------------------------------------------------
 // Old space for objects of a fixed size
 
 class FixedSpace : public PagedSpace {
  public:
   FixedSpace(Heap* heap,
              intptr_t max_capacity,
              AllocationSpace id,
@@ skipping 307 matching lines @@
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_SPACES_H_