[heap] Add debug checks for linear allocation area top and limit.

src/heap/spaces.cc

 // Copyright 2011 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/heap/spaces.h"
 
 #include <utility>
 
 #include "src/base/bits.h"
 #include "src/base/platform/platform.h"
@@ skipping 2545 matching lines @@
   return node;
 }
 
 // Allocation on the old space free list.  If it succeeds then a new linear
 // allocation space has been set up with the top and limit of the space.  If
 // the allocation fails then NULL is returned, and the caller can perform a GC
 // or allocate a new page before retrying.
 HeapObject* FreeList::Allocate(size_t size_in_bytes) {
   DCHECK(size_in_bytes <= kMaxBlockSize);
   DCHECK(IsAligned(size_in_bytes, kPointerSize));
+  DCHECK_LE(owner_->top(), owner_->limit());
+#ifdef DEBUG
+  if (owner_->top() != owner_->limit()) {
+    DCHECK_EQ(Page::FromAddress(owner_->top()),
+              Page::FromAddress(owner_->limit() - 1));
+  }
+#endif
   // Don't free list allocate if there is linear space available.
   DCHECK_LT(static_cast<size_t>(owner_->limit() - owner_->top()),
             size_in_bytes);
 
   // Mark the old linear allocation area with a free space map so it can be
   // skipped when scanning the heap.  This also puts it back in the free list
   // if it is big enough.
   owner_->EmptyAllocationInfo();
 
   owner_->heap()->StartIncrementalMarkingIfAllocationLimitIsReached(
@@ skipping 662 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 }  // namespace internal
 }  // namespace v8