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Unified Diff: src/objects.h

Issue 876613002: Only use FreeSpace objects in the free list. (Closed) Base URL: https://chromium.googlesource.com/v8/v8.git@master
Patch Set: addressed comments Created 5 years, 11 months ago
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Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 51755054cb00a3513faae0b6c5684ce5473f105e..80ab91956b647041532acb280d5e611443c5a303 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -4448,8 +4448,11 @@ class ByteArray: public FixedArrayBase {
};
-// FreeSpace represents fixed sized areas of the heap that are not currently in
-// use. Used by the heap and GC.
+// FreeSpace are fixed-size free memory blocks used by the heap and GC.
+// They look like heap objects (are heap object tagged and have a map) so that
+// the heap remains iterable. They have a size and a next pointer.
+// The next pointer is the raw address of the next FreeSpace object (or NULL)
+// in the free list.
class FreeSpace: public HeapObject {
public:
// [size]: size of the free space including the header.
@@ -4461,7 +4464,12 @@ class FreeSpace: public HeapObject {
inline int Size() { return size(); }
- DECLARE_CAST(FreeSpace)
+ // Accessors for the next field.
+ inline FreeSpace* next();
+ inline FreeSpace** next_address();
+ inline void set_next(FreeSpace* next);
+
+ inline static FreeSpace* cast(HeapObject* obj);
// Dispatched behavior.
DECLARE_PRINTER(FreeSpace)
@@ -4470,9 +4478,7 @@ class FreeSpace: public HeapObject {
// Layout description.
// Size is smi tagged when it is stored.
static const int kSizeOffset = HeapObject::kHeaderSize;
- static const int kHeaderSize = kSizeOffset + kPointerSize;
-
- static const int kAlignedSize = OBJECT_POINTER_ALIGN(kHeaderSize);
+ static const int kNextOffset = POINTER_SIZE_ALIGN(kSizeOffset + kPointerSize);
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(FreeSpace);
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