1.1 --- a/src/share/vm/oops/markOop.hpp Thu Jun 05 15:57:56 2008 -0700
1.2 +++ b/src/share/vm/oops/markOop.hpp Thu Jun 12 13:50:55 2008 -0700
1.3 @@ -29,8 +29,10 @@
1.4 //
1.5 // Bit-format of an object header (most significant first):
1.6 //
1.7 -//
1.8 -// unused:0/25 hash:25/31 age:4 biased_lock:1 lock:2 = 32/64 bits
1.9 +// 32 bits: unused:0 hash:25 age:4 biased_lock:1 lock:2
1.10 +// 64 bits: unused:24 hash:31 cms:2 age:4 biased_lock:1 lock:2
1.11 +// unused:20 size:35 cms:2 age:4 biased_lock:1 lock:2 (if cms
1.12 +// free chunk)
1.13 //
1.14 // - hash contains the identity hash value: largest value is
1.15 // 31 bits, see os::random(). Also, 64-bit vm's require
1.16 @@ -91,6 +93,7 @@
1.17 biased_lock_bits = 1,
1.18 max_hash_bits = BitsPerWord - age_bits - lock_bits - biased_lock_bits,
1.19 hash_bits = max_hash_bits > 31 ? 31 : max_hash_bits,
1.20 + cms_bits = LP64_ONLY(1) NOT_LP64(0),
1.21 epoch_bits = 2
1.22 };
1.23
1.24 @@ -106,7 +109,8 @@
1.25 enum { lock_shift = 0,
1.26 biased_lock_shift = lock_bits,
1.27 age_shift = lock_bits + biased_lock_bits,
1.28 - hash_shift = lock_bits + biased_lock_bits + age_bits,
1.29 + cms_shift = age_shift + age_bits,
1.30 + hash_shift = cms_shift + cms_bits,
1.31 epoch_shift = hash_shift
1.32 };
1.33
1.34 @@ -118,7 +122,9 @@
1.35 age_mask = right_n_bits(age_bits),
1.36 age_mask_in_place = age_mask << age_shift,
1.37 epoch_mask = right_n_bits(epoch_bits),
1.38 - epoch_mask_in_place = epoch_mask << epoch_shift
1.39 + epoch_mask_in_place = epoch_mask << epoch_shift,
1.40 + cms_mask = right_n_bits(cms_bits),
1.41 + cms_mask_in_place = cms_mask << cms_shift
1.42 #ifndef _WIN64
1.43 ,hash_mask = right_n_bits(hash_bits),
1.44 hash_mask_in_place = (address_word)hash_mask << hash_shift
1.45 @@ -348,4 +354,40 @@
1.46
1.47 // see the definition in markOop.cpp for the gory details
1.48 bool should_not_be_cached() const;
1.49 +
1.50 + // These markOops indicate cms free chunk blocks and not objects.
1.51 + // In 64 bit, the markOop is set to distinguish them from oops.
1.52 + // These are defined in 32 bit mode for vmStructs.
1.53 + const static uintptr_t cms_free_chunk_pattern = 0x1;
1.54 +
1.55 + // Constants for the size field.
1.56 + enum { size_shift = cms_shift + cms_bits,
1.57 + size_bits = 35 // need for compressed oops 32G
1.58 + };
1.59 + // These values are too big for Win64
1.60 + const static uintptr_t size_mask = LP64_ONLY(right_n_bits(size_bits))
1.61 + NOT_LP64(0);
1.62 + const static uintptr_t size_mask_in_place =
1.63 + (address_word)size_mask << size_shift;
1.64 +
1.65 +#ifdef _LP64
1.66 + static markOop cms_free_prototype() {
1.67 + return markOop(((intptr_t)prototype() & ~cms_mask_in_place) |
1.68 + ((cms_free_chunk_pattern & cms_mask) << cms_shift));
1.69 + }
1.70 + uintptr_t cms_encoding() const {
1.71 + return mask_bits(value() >> cms_shift, cms_mask);
1.72 + }
1.73 + bool is_cms_free_chunk() const {
1.74 + return is_neutral() &&
1.75 + (cms_encoding() & cms_free_chunk_pattern) == cms_free_chunk_pattern;
1.76 + }
1.77 +
1.78 + size_t get_size() const { return (size_t)(value() >> size_shift); }
1.79 + static markOop set_size_and_free(size_t size) {
1.80 + assert((size & ~size_mask) == 0, "shouldn't overflow size field");
1.81 + return markOop(((intptr_t)cms_free_prototype() & ~size_mask_in_place) |
1.82 + (((intptr_t)size & size_mask) << size_shift));
1.83 + }
1.84 +#endif // _LP64
1.85 };
