diff -r ffce0f5e4840 -r 2aa2b913106c hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/freeBlockDictionary.hpp --- a/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/freeBlockDictionary.hpp Fri Jun 06 11:47:26 2008 -0700 +++ b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/freeBlockDictionary.hpp Mon Jun 09 11:51:19 2008 -0400 @@ -22,88 +22,6 @@ * */ -// -// Free block maintenance for Concurrent Mark Sweep Generation -// -// The main data structure for free blocks are -// . an indexed array of small free blocks, and -// . a dictionary of large free blocks -// - -// No virtuals in FreeChunk (don't want any vtables). - -// A FreeChunk is merely a chunk that can be in a doubly linked list -// and has a size field. NOTE: FreeChunks are distinguished from allocated -// objects in two ways (by the sweeper). The second word (prev) has the -// LSB set to indicate a free chunk; allocated objects' klass() pointers -// don't have their LSB set. The corresponding bit in the CMSBitMap is -// set when the chunk is allocated. There are also blocks that "look free" -// but are not part of the free list and should not be coalesced into larger -// free blocks. These free blocks have their two LSB's set. - -class FreeChunk VALUE_OBJ_CLASS_SPEC { - friend class VMStructs; - FreeChunk* _next; - FreeChunk* _prev; - size_t _size; - - public: - NOT_PRODUCT(static const size_t header_size();) - // Returns "true" if the "wrd", which is required to be the second word - // of a block, indicates that the block represents a free chunk. - static bool secondWordIndicatesFreeChunk(intptr_t wrd) { - return (wrd & 0x1) == 0x1; - } - bool isFree() const { - return secondWordIndicatesFreeChunk((intptr_t)_prev); - } - bool cantCoalesce() const { return (((intptr_t)_prev) & 0x3) == 0x3; } - FreeChunk* next() const { return _next; } - FreeChunk* prev() const { return (FreeChunk*)(((intptr_t)_prev) & ~(0x3)); } - debug_only(void* prev_addr() const { return (void*)&_prev; }) - - void linkAfter(FreeChunk* ptr) { - linkNext(ptr); - if (ptr != NULL) ptr->linkPrev(this); - } - void linkAfterNonNull(FreeChunk* ptr) { - assert(ptr != NULL, "precondition violation"); - linkNext(ptr); - ptr->linkPrev(this); - } - void linkNext(FreeChunk* ptr) { _next = ptr; } - void linkPrev(FreeChunk* ptr) { _prev = (FreeChunk*)((intptr_t)ptr | 0x1); } - void clearPrev() { _prev = NULL; } - void clearNext() { _next = NULL; } - void dontCoalesce() { - // the block should be free - assert(isFree(), "Should look like a free block"); - _prev = (FreeChunk*)(((intptr_t)_prev) | 0x2); - } - void markFree() { _prev = (FreeChunk*)((intptr_t)_prev | 0x1); } - void markNotFree() { _prev = NULL; } - - size_t size() const { return _size; } - void setSize(size_t size) { _size = size; } - - // For volatile reads: - size_t* size_addr() { return &_size; } - - // Return the address past the end of this chunk - HeapWord* end() const { return ((HeapWord*) this) + _size; } - - // debugging - void verify() const PRODUCT_RETURN; - void verifyList() const PRODUCT_RETURN; - void mangleAllocated(size_t size) PRODUCT_RETURN; - void mangleFreed(size_t size) PRODUCT_RETURN; -}; - -// Alignment helpers etc. -#define numQuanta(x,y) ((x+y-1)/y) -enum AlignmentConstants { - MinChunkSize = numQuanta(sizeof(FreeChunk), MinObjAlignmentInBytes) * MinObjAlignment -}; // A FreeBlockDictionary is an abstract superclass that will allow // a number of alternative implementations in the future.