1.1 --- a/src/share/vm/gc_implementation/concurrentMarkSweep/promotionInfo.hpp Fri May 14 10:28:46 2010 -0700
1.2 +++ b/src/share/vm/gc_implementation/concurrentMarkSweep/promotionInfo.hpp Mon May 17 00:47:28 2010 -0700
1.3 @@ -1,5 +1,5 @@
1.4 /*
1.5 - * Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * Copyright 2010 Sun Microsystems, Inc. All Rights Reserved.
1.7 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.8 *
1.9 * This code is free software; you can redistribute it and/or modify it
1.10 @@ -32,30 +32,75 @@
1.11 displaced_mark = nth_bit(2), // i.e. 0x4
1.12 next_mask = ~(right_n_bits(3)) // i.e. ~(0x7)
1.13 };
1.14 - intptr_t _next;
1.15 +
1.16 + // Below, we want _narrow_next in the "higher" 32 bit slot,
1.17 + // whose position will depend on endian-ness of the platform.
1.18 + // This is so that there is no interference with the
1.19 + // cms_free_bit occupying bit position 7 (lsb == 0)
1.20 + // when we are using compressed oops; see FreeChunk::isFree().
1.21 + // We cannot move the cms_free_bit down because currently
1.22 + // biased locking code assumes that age bits are contiguous
1.23 + // with the lock bits. Even if that assumption were relaxed,
1.24 + // the least position we could move this bit to would be
1.25 + // to bit position 3, which would require 16 byte alignment.
1.26 + typedef struct {
1.27 +#ifdef VM_LITTLE_ENDIAN
1.28 + LP64_ONLY(narrowOop _pad;)
1.29 + narrowOop _narrow_next;
1.30 +#else
1.31 + narrowOop _narrow_next;
1.32 + LP64_ONLY(narrowOop _pad;)
1.33 +#endif
1.34 + } Data;
1.35 +
1.36 + union {
1.37 + intptr_t _next;
1.38 + Data _data;
1.39 + };
1.40 public:
1.41 inline PromotedObject* next() const {
1.42 - return (PromotedObject*)(_next & next_mask);
1.43 + assert(!((FreeChunk*)this)->isFree(), "Error");
1.44 + PromotedObject* res;
1.45 + if (UseCompressedOops) {
1.46 + // The next pointer is a compressed oop stored in the top 32 bits
1.47 + res = (PromotedObject*)oopDesc::decode_heap_oop(_data._narrow_next);
1.48 + } else {
1.49 + res = (PromotedObject*)(_next & next_mask);
1.50 + }
1.51 + assert(oop(res)->is_oop_or_null(true /* ignore mark word */), "Not an oop?");
1.52 + return res;
1.53 }
1.54 inline void setNext(PromotedObject* x) {
1.55 - assert(((intptr_t)x & ~next_mask) == 0,
1.56 - "Conflict in bit usage, "
1.57 - " or insufficient alignment of objects");
1.58 - _next |= (intptr_t)x;
1.59 + assert(((intptr_t)x & ~next_mask) == 0, "Conflict in bit usage, "
1.60 + "or insufficient alignment of objects");
1.61 + if (UseCompressedOops) {
1.62 + assert(_data._narrow_next == 0, "Overwrite?");
1.63 + _data._narrow_next = oopDesc::encode_heap_oop(oop(x));
1.64 + } else {
1.65 + _next |= (intptr_t)x;
1.66 + }
1.67 + assert(!((FreeChunk*)this)->isFree(), "Error");
1.68 }
1.69 inline void setPromotedMark() {
1.70 _next |= promoted_mask;
1.71 + assert(!((FreeChunk*)this)->isFree(), "Error");
1.72 }
1.73 inline bool hasPromotedMark() const {
1.74 + assert(!((FreeChunk*)this)->isFree(), "Error");
1.75 return (_next & promoted_mask) == promoted_mask;
1.76 }
1.77 inline void setDisplacedMark() {
1.78 _next |= displaced_mark;
1.79 + assert(!((FreeChunk*)this)->isFree(), "Error");
1.80 }
1.81 inline bool hasDisplacedMark() const {
1.82 + assert(!((FreeChunk*)this)->isFree(), "Error");
1.83 return (_next & displaced_mark) != 0;
1.84 }
1.85 - inline void clearNext() { _next = 0; }
1.86 + inline void clearNext() {
1.87 + _next = 0;
1.88 + assert(!((FreeChunk*)this)->isFree(), "Error");
1.89 + }
1.90 debug_only(void *next_addr() { return (void *) &_next; })
1.91 };
1.92
