/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ /* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this file, * You can obtain one at http://mozilla.org/MPL/2.0/. */ #ifndef gc_heap_h___ #define gc_heap_h___ #include "mozilla/Attributes.h" #include "mozilla/StandardInteger.h" #include #include "jstypes.h" #include "jsutil.h" #include "ds/BitArray.h" struct JSCompartment; extern "C" { struct JSRuntime; } namespace js { class FreeOp; namespace gc { struct Arena; struct ArenaHeader; struct Chunk; /* * Live objects are marked black. How many other additional colors are available * depends on the size of the GCThing. Objects marked gray are eligible for * cycle collection. */ static const uint32_t BLACK = 0; static const uint32_t GRAY = 1; /* The GC allocation kinds. */ enum AllocKind { FINALIZE_OBJECT0, FINALIZE_OBJECT0_BACKGROUND, FINALIZE_OBJECT2, FINALIZE_OBJECT2_BACKGROUND, FINALIZE_OBJECT4, FINALIZE_OBJECT4_BACKGROUND, FINALIZE_OBJECT8, FINALIZE_OBJECT8_BACKGROUND, FINALIZE_OBJECT12, FINALIZE_OBJECT12_BACKGROUND, FINALIZE_OBJECT16, FINALIZE_OBJECT16_BACKGROUND, FINALIZE_OBJECT_LAST = FINALIZE_OBJECT16_BACKGROUND, FINALIZE_SCRIPT, FINALIZE_SHAPE, FINALIZE_BASE_SHAPE, FINALIZE_TYPE_OBJECT, #if JS_HAS_XML_SUPPORT FINALIZE_XML, #endif FINALIZE_SHORT_STRING, FINALIZE_STRING, FINALIZE_EXTERNAL_STRING, FINALIZE_IONCODE, FINALIZE_LAST = FINALIZE_IONCODE }; static const unsigned FINALIZE_LIMIT = FINALIZE_LAST + 1; static const unsigned FINALIZE_OBJECT_LIMIT = FINALIZE_OBJECT_LAST + 1; /* * This must be an upper bound, but we do not need the least upper bound, so * we just exclude non-background objects. */ static const size_t MAX_BACKGROUND_FINALIZE_KINDS = FINALIZE_LIMIT - FINALIZE_OBJECT_LIMIT / 2; /* * A GC cell is the base class for all GC things. */ struct Cell { static const size_t CellShift = 3; static const size_t CellSize = size_t(1) << CellShift; static const size_t CellMask = CellSize - 1; inline uintptr_t address() const; inline ArenaHeader *arenaHeader() const; inline Chunk *chunk() const; inline AllocKind getAllocKind() const; MOZ_ALWAYS_INLINE bool isMarked(uint32_t color = BLACK) const; MOZ_ALWAYS_INLINE bool markIfUnmarked(uint32_t color = BLACK) const; MOZ_ALWAYS_INLINE void unmark(uint32_t color) const; inline JSCompartment *compartment() const; #ifdef DEBUG inline bool isAligned() const; #endif }; /* * Page size must be static to support our arena pointer optimizations, so we * are forced to support each platform with non-4096 pages as a special case. * Note: The freelist supports a maximum arena shift of 15. * Note: Do not use JS_CPU_SPARC here, this header is used outside JS. * Bug 692267: Move page size definition to gc/Memory.h and include it * directly once jsgc.h is no longer an installed header. */ #if (defined(SOLARIS) || defined(__FreeBSD__)) && \ (defined(__sparc) || defined(__sparcv9) || defined(__ia64)) const size_t PageShift = 13; const size_t ArenaShift = PageShift; #elif defined(__powerpc64__) const size_t PageShift = 16; const size_t ArenaShift = 12; #else const size_t PageShift = 12; const size_t ArenaShift = PageShift; #endif const size_t PageSize = size_t(1) << PageShift; const size_t ArenaSize = size_t(1) << ArenaShift; const size_t ArenaMask = ArenaSize - 1; const size_t ChunkShift = 20; const size_t ChunkSize = size_t(1) << ChunkShift; const size_t ChunkMask = ChunkSize - 1; /* * This is the maximum number of arenas we allow in the FreeCommitted state * before we trigger a GC_SHRINK to release free arenas to the OS. */ const static uint32_t FreeCommittedArenasThreshold = (32 << 20) / ArenaSize; /* * The mark bitmap has one bit per each GC cell. For multi-cell GC things this * wastes space but allows to avoid expensive devisions by thing's size when * accessing the bitmap. In addition this allows to use some bits for colored * marking during the cycle GC. */ const size_t ArenaCellCount = size_t(1) << (ArenaShift - Cell::CellShift); const size_t ArenaBitmapBits = ArenaCellCount; const size_t ArenaBitmapBytes = ArenaBitmapBits / 8; const size_t ArenaBitmapWords = ArenaBitmapBits / JS_BITS_PER_WORD; /* * A FreeSpan represents a contiguous sequence of free cells in an Arena. * |first| is the address of the first free cell in the span. |last| is the * address of the last free cell in the span. This last cell holds a FreeSpan * data structure for the next span unless this is the last span on the list * of spans in the arena. For this last span |last| points to the last byte of * the last thing in the arena and no linkage is stored there, so * |last| == arenaStart + ArenaSize - 1. If the space at the arena end is * fully used this last span is empty and |first| == |last + 1|. * * Thus |first| < |last| implies that we have either the last span with at least * one element or that the span is not the last and contains at least 2 * elements. In both cases to allocate a thing from this span we need simply * to increment |first| by the allocation size. * * |first| == |last| implies that we have a one element span that records the * next span. So to allocate from it we need to update the span list head * with a copy of the span stored at |last| address so the following * allocations will use that span. * * |first| > |last| implies that we have an empty last span and the arena is * fully used. * * Also only for the last span (|last| & 1)! = 0 as all allocation sizes are * multiples of Cell::CellSize. */ struct FreeSpan { uintptr_t first; uintptr_t last; public: FreeSpan() {} FreeSpan(uintptr_t first, uintptr_t last) : first(first), last(last) { checkSpan(); } /* * To minimize the size of the arena header the first span is encoded * there as offsets from the arena start. */ static size_t encodeOffsets(size_t firstOffset, size_t lastOffset) { /* Check that we can pack the offsets into uint16. */ JS_STATIC_ASSERT(ArenaShift < 16); JS_ASSERT(firstOffset <= ArenaSize); JS_ASSERT(lastOffset < ArenaSize); JS_ASSERT(firstOffset <= ((lastOffset + 1) & ~size_t(1))); return firstOffset | (lastOffset << 16); } /* * Encoded offsets for a full arena when its first span is the last one * and empty. */ static const size_t FullArenaOffsets = ArenaSize | ((ArenaSize - 1) << 16); static FreeSpan decodeOffsets(uintptr_t arenaAddr, size_t offsets) { JS_ASSERT(!(arenaAddr & ArenaMask)); size_t firstOffset = offsets & 0xFFFF; size_t lastOffset = offsets >> 16; JS_ASSERT(firstOffset <= ArenaSize); JS_ASSERT(lastOffset < ArenaSize); /* * We must not use | when calculating first as firstOffset is * ArenaMask + 1 for the empty span. */ return FreeSpan(arenaAddr + firstOffset, arenaAddr | lastOffset); } void initAsEmpty(uintptr_t arenaAddr = 0) { JS_ASSERT(!(arenaAddr & ArenaMask)); first = arenaAddr + ArenaSize; last = arenaAddr | (ArenaSize - 1); JS_ASSERT(isEmpty()); } bool isEmpty() const { checkSpan(); return first > last; } bool hasNext() const { checkSpan(); return !(last & uintptr_t(1)); } const FreeSpan *nextSpan() const { JS_ASSERT(hasNext()); return reinterpret_cast(last); } FreeSpan *nextSpanUnchecked(size_t thingSize) const { #ifdef DEBUG uintptr_t lastOffset = last & ArenaMask; JS_ASSERT(!(lastOffset & 1)); JS_ASSERT((ArenaSize - lastOffset) % thingSize == 0); #endif return reinterpret_cast(last); } uintptr_t arenaAddressUnchecked() const { return last & ~ArenaMask; } uintptr_t arenaAddress() const { checkSpan(); return arenaAddressUnchecked(); } ArenaHeader *arenaHeader() const { return reinterpret_cast(arenaAddress()); } bool isSameNonEmptySpan(const FreeSpan *another) const { JS_ASSERT(!isEmpty()); JS_ASSERT(!another->isEmpty()); return first == another->first && last == another->last; } bool isWithinArena(uintptr_t arenaAddr) const { JS_ASSERT(!(arenaAddr & ArenaMask)); /* Return true for the last empty span as well. */ return arenaAddress() == arenaAddr; } size_t encodeAsOffsets() const { /* * We must use first - arenaAddress(), not first & ArenaMask as * first == ArenaMask + 1 for an empty span. */ uintptr_t arenaAddr = arenaAddress(); return encodeOffsets(first - arenaAddr, last & ArenaMask); } /* See comments before FreeSpan for details. */ MOZ_ALWAYS_INLINE void *allocate(size_t thingSize) { JS_ASSERT(thingSize % Cell::CellSize == 0); checkSpan(); uintptr_t thing = first; if (thing < last) { /* Bump-allocate from the current span. */ first = thing + thingSize; } else if (JS_LIKELY(thing == last)) { /* * Move to the next span. We use JS_LIKELY as without PGO * compilers mis-predict == here as unlikely to succeed. */ *this = *reinterpret_cast(thing); } else { return NULL; } checkSpan(); return reinterpret_cast(thing); } /* A version of allocate when we know that the span is not empty. */ MOZ_ALWAYS_INLINE void *infallibleAllocate(size_t thingSize) { JS_ASSERT(thingSize % Cell::CellSize == 0); checkSpan(); uintptr_t thing = first; if (thing < last) { first = thing + thingSize; } else { JS_ASSERT(thing == last); *this = *reinterpret_cast(thing); } checkSpan(); return reinterpret_cast(thing); } /* * Allocate from a newly allocated arena. We do not move the free list * from the arena. Rather we set the arena up as fully used during the * initialization so to allocate we simply return the first thing in the * arena and set the free list to point to the second. */ MOZ_ALWAYS_INLINE void *allocateFromNewArena(uintptr_t arenaAddr, size_t firstThingOffset, size_t thingSize) { JS_ASSERT(!(arenaAddr & ArenaMask)); uintptr_t thing = arenaAddr | firstThingOffset; first = thing + thingSize; last = arenaAddr | ArenaMask; checkSpan(); return reinterpret_cast(thing); } void checkSpan() const { #ifdef DEBUG /* We do not allow spans at the end of the address space. */ JS_ASSERT(last != uintptr_t(-1)); JS_ASSERT(first); JS_ASSERT(last); JS_ASSERT(first - 1 <= last); uintptr_t arenaAddr = arenaAddressUnchecked(); if (last & 1) { /* The span is the last. */ JS_ASSERT((last & ArenaMask) == ArenaMask); if (first - 1 == last) { /* The span is last and empty. The above start != 0 check * implies that we are not at the end of the address space. */ return; } size_t spanLength = last - first + 1; JS_ASSERT(spanLength % Cell::CellSize == 0); /* Start and end must belong to the same arena. */ JS_ASSERT((first & ~ArenaMask) == arenaAddr); return; } /* The span is not the last and we have more spans to follow. */ JS_ASSERT(first <= last); size_t spanLengthWithoutOneThing = last - first; JS_ASSERT(spanLengthWithoutOneThing % Cell::CellSize == 0); JS_ASSERT((first & ~ArenaMask) == arenaAddr); /* * If there is not enough space before the arena end to allocate one * more thing, then the span must be marked as the last one to avoid * storing useless empty span reference. */ size_t beforeTail = ArenaSize - (last & ArenaMask); JS_ASSERT(beforeTail >= sizeof(FreeSpan) + Cell::CellSize); FreeSpan *next = reinterpret_cast(last); /* * The GC things on the list of free spans come from one arena * and the spans are linked in ascending address order with * at least one non-free thing between spans. */ JS_ASSERT(last < next->first); JS_ASSERT(arenaAddr == next->arenaAddressUnchecked()); if (next->first > next->last) { /* * The next span is the empty span that terminates the list for * arenas that do not have any free things at the end. */ JS_ASSERT(next->first - 1 == next->last); JS_ASSERT(arenaAddr + ArenaSize == next->first); } #endif } }; /* Every arena has a header. */ struct ArenaHeader { friend struct FreeLists; JSCompartment *compartment; /* * ArenaHeader::next has two purposes: when unallocated, it points to the * next available Arena's header. When allocated, it points to the next * arena of the same size class and compartment. */ ArenaHeader *next; private: /* * The first span of free things in the arena. We encode it as the start * and end offsets within the arena, not as FreeSpan structure, to * minimize the header size. */ size_t firstFreeSpanOffsets; /* * One of AllocKind constants or FINALIZE_LIMIT when the arena does not * contain any GC things and is on the list of empty arenas in the GC * chunk. The latter allows to quickly check if the arena is allocated * during the conservative GC scanning without searching the arena in the * list. * * We use 8 bits for the allocKind so the compiler can use byte-level memory * instructions to access it. */ size_t allocKind : 8; /* * When collecting we sometimes need to keep an auxillary list of arenas, * for which we use the following fields. This happens for several reasons: * * When recursive marking uses too much stack the marking is delayed and the * corresponding arenas are put into a stack. To distinguish the bottom of * the stack from the arenas not present in the stack we use the * markOverflow flag to tag arenas on the stack. * * Delayed marking is also used for arenas that we allocate into during an * incremental GC. In this case, we intend to mark all the objects in the * arena, and it's faster to do this marking in bulk. * * When sweeping we keep track of which arenas have been allocated since the * end of the mark phase. This allows us to tell whether a pointer to an * unmarked object is yet to be finalized or has already been reallocated. * We set the allocatedDuringIncremental flag for this and clear it at the * end of the sweep phase. * * To minimize the ArenaHeader size we record the next linkage as * arenaAddress() >> ArenaShift and pack it with the allocKind field and the * flags. */ public: size_t hasDelayedMarking : 1; size_t allocatedDuringIncremental : 1; size_t markOverflow : 1; size_t auxNextLink : JS_BITS_PER_WORD - 8 - 1 - 1 - 1; static void staticAsserts() { /* We must be able to fit the allockind into uint8_t. */ JS_STATIC_ASSERT(FINALIZE_LIMIT <= 255); /* * auxNextLink packing assumes that ArenaShift has enough bits * to cover allocKind and hasDelayedMarking. */ JS_STATIC_ASSERT(ArenaShift >= 8 + 1 + 1 + 1); } inline uintptr_t address() const; inline Chunk *chunk() const; bool allocated() const { JS_ASSERT(allocKind <= size_t(FINALIZE_LIMIT)); return allocKind < size_t(FINALIZE_LIMIT); } void init(JSCompartment *comp, AllocKind kind) { JS_ASSERT(!allocated()); JS_ASSERT(!markOverflow); JS_ASSERT(!allocatedDuringIncremental); JS_ASSERT(!hasDelayedMarking); compartment = comp; JS_STATIC_ASSERT(FINALIZE_LIMIT <= 255); allocKind = size_t(kind); /* See comments in FreeSpan::allocateFromNewArena. */ firstFreeSpanOffsets = FreeSpan::FullArenaOffsets; } void setAsNotAllocated() { allocKind = size_t(FINALIZE_LIMIT); markOverflow = 0; allocatedDuringIncremental = 0; hasDelayedMarking = 0; auxNextLink = 0; } inline uintptr_t arenaAddress() const; inline Arena *getArena(); AllocKind getAllocKind() const { JS_ASSERT(allocated()); return AllocKind(allocKind); } inline size_t getThingSize() const; bool hasFreeThings() const { return firstFreeSpanOffsets != FreeSpan::FullArenaOffsets; } inline bool isEmpty() const; void setAsFullyUsed() { firstFreeSpanOffsets = FreeSpan::FullArenaOffsets; } inline FreeSpan getFirstFreeSpan() const; inline void setFirstFreeSpan(const FreeSpan *span); #ifdef DEBUG void checkSynchronizedWithFreeList() const; #endif inline ArenaHeader *getNextDelayedMarking() const; inline void setNextDelayedMarking(ArenaHeader *aheader); inline void unsetDelayedMarking(); inline ArenaHeader *getNextAllocDuringSweep() const; inline void setNextAllocDuringSweep(ArenaHeader *aheader); inline void unsetAllocDuringSweep(); }; struct Arena { /* * Layout of an arena: * An arena is 4K in size and 4K-aligned. It starts with the ArenaHeader * descriptor followed by some pad bytes. The remainder of the arena is * filled with the array of T things. The pad bytes ensure that the thing * array ends exactly at the end of the arena. * * +-------------+-----+----+----+-----+----+ * | ArenaHeader | pad | T0 | T1 | ... | Tn | * +-------------+-----+----+----+-----+----+ * * <----------------------------------------> = ArenaSize bytes * <-------------------> = first thing offset */ ArenaHeader aheader; uint8_t data[ArenaSize - sizeof(ArenaHeader)]; private: static JS_FRIEND_DATA(const uint32_t) ThingSizes[]; static JS_FRIEND_DATA(const uint32_t) FirstThingOffsets[]; public: static void staticAsserts(); static size_t thingSize(AllocKind kind) { return ThingSizes[kind]; } static size_t firstThingOffset(AllocKind kind) { return FirstThingOffsets[kind]; } static size_t thingsPerArena(size_t thingSize) { JS_ASSERT(thingSize % Cell::CellSize == 0); /* We should be able to fit FreeSpan in any GC thing. */ JS_ASSERT(thingSize >= sizeof(FreeSpan)); return (ArenaSize - sizeof(ArenaHeader)) / thingSize; } static size_t thingsSpan(size_t thingSize) { return thingsPerArena(thingSize) * thingSize; } static bool isAligned(uintptr_t thing, size_t thingSize) { /* Things ends at the arena end. */ uintptr_t tailOffset = (ArenaSize - thing) & ArenaMask; return tailOffset % thingSize == 0; } uintptr_t address() const { return aheader.address(); } uintptr_t thingsStart(AllocKind thingKind) { return address() | firstThingOffset(thingKind); } uintptr_t thingsEnd() { return address() + ArenaSize; } template bool finalize(FreeOp *fop, AllocKind thingKind, size_t thingSize); }; inline size_t ArenaHeader::getThingSize() const { JS_ASSERT(allocated()); return Arena::thingSize(getAllocKind()); } /* The chunk header (located at the end of the chunk to preserve arena alignment). */ struct ChunkInfo { Chunk *next; Chunk **prevp; /* Free arenas are linked together with aheader.next. */ ArenaHeader *freeArenasHead; /* * Decommitted arenas are tracked by a bitmap in the chunk header. We use * this offset to start our search iteration close to a decommitted arena * that we can allocate. */ uint32_t lastDecommittedArenaOffset; /* Number of free arenas, either committed or decommitted. */ uint32_t numArenasFree; /* Number of free, committed arenas. */ uint32_t numArenasFreeCommitted; /* Number of GC cycles this chunk has survived. */ uint32_t age; }; /* * Calculating ArenasPerChunk: * * In order to figure out how many Arenas will fit in a chunk, we need to know * how much extra space is available after we allocate the header data. This * is a problem because the header size depends on the number of arenas in the * chunk. The two dependent fields are bitmap and decommittedArenas. * * For the mark bitmap, we know that each arena will use a fixed number of full * bytes: ArenaBitmapBytes. The full size of the header data is this number * multiplied by the eventual number of arenas we have in the header. We, * conceptually, distribute this header data among the individual arenas and do * not include it in the header. This way we do not have to worry about its * variable size: it gets attached to the variable number we are computing. * * For the decommitted arena bitmap, we only have 1 bit per arena, so this * technique will not work. Instead, we observe that we do not have enough * header info to fill 8 full arenas: it is currently 4 on 64bit, less on * 32bit. Thus, with current numbers, we need 64 bytes for decommittedArenas. * This will not become 63 bytes unless we double the data required in the * header. Therefore, we just compute the number of bytes required to track * every possible arena and do not worry about slop bits, since there are too * few to usefully allocate. * * To actually compute the number of arenas we can allocate in a chunk, we * divide the amount of available space less the header info (not including * the mark bitmap which is distributed into the arena size) by the size of * the arena (with the mark bitmap bytes it uses). */ const size_t BytesPerArenaWithHeader = ArenaSize + ArenaBitmapBytes; const size_t ChunkDecommitBitmapBytes = ChunkSize / ArenaSize / JS_BITS_PER_BYTE; const size_t ChunkBytesAvailable = ChunkSize - sizeof(ChunkInfo) - ChunkDecommitBitmapBytes; const size_t ArenasPerChunk = ChunkBytesAvailable / BytesPerArenaWithHeader; /* A chunk bitmap contains enough mark bits for all the cells in a chunk. */ struct ChunkBitmap { uintptr_t bitmap[ArenaBitmapWords * ArenasPerChunk]; MOZ_ALWAYS_INLINE void getMarkWordAndMask(const Cell *cell, uint32_t color, uintptr_t **wordp, uintptr_t *maskp); MOZ_ALWAYS_INLINE bool isMarked(const Cell *cell, uint32_t color) { uintptr_t *word, mask; getMarkWordAndMask(cell, color, &word, &mask); return *word & mask; } MOZ_ALWAYS_INLINE bool markIfUnmarked(const Cell *cell, uint32_t color) { uintptr_t *word, mask; getMarkWordAndMask(cell, BLACK, &word, &mask); if (*word & mask) return false; *word |= mask; if (color != BLACK) { /* * We use getMarkWordAndMask to recalculate both mask and word as * doing just mask << color may overflow the mask. */ getMarkWordAndMask(cell, color, &word, &mask); if (*word & mask) return false; *word |= mask; } return true; } MOZ_ALWAYS_INLINE void unmark(const Cell *cell, uint32_t color) { uintptr_t *word, mask; getMarkWordAndMask(cell, color, &word, &mask); *word &= ~mask; } void clear() { PodArrayZero(bitmap); } uintptr_t *arenaBits(ArenaHeader *aheader) { /* * We assume that the part of the bitmap corresponding to the arena * has the exact number of words so we do not need to deal with a word * that covers bits from two arenas. */ JS_STATIC_ASSERT(ArenaBitmapBits == ArenaBitmapWords * JS_BITS_PER_WORD); uintptr_t *word, unused; getMarkWordAndMask(reinterpret_cast(aheader->address()), BLACK, &word, &unused); return word; } }; JS_STATIC_ASSERT(ArenaBitmapBytes * ArenasPerChunk == sizeof(ChunkBitmap)); typedef BitArray PerArenaBitmap; const size_t ChunkPadSize = ChunkSize - (sizeof(Arena) * ArenasPerChunk) - sizeof(ChunkBitmap) - sizeof(PerArenaBitmap) - sizeof(ChunkInfo); JS_STATIC_ASSERT(ChunkPadSize < BytesPerArenaWithHeader); /* * Chunks contain arenas and associated data structures (mark bitmap, delayed * marking state). */ struct Chunk { Arena arenas[ArenasPerChunk]; /* Pad to full size to ensure cache alignment of ChunkInfo. */ uint8_t padding[ChunkPadSize]; ChunkBitmap bitmap; PerArenaBitmap decommittedArenas; ChunkInfo info; static Chunk *fromAddress(uintptr_t addr) { addr &= ~ChunkMask; return reinterpret_cast(addr); } static bool withinArenasRange(uintptr_t addr) { uintptr_t offset = addr & ChunkMask; return offset < ArenasPerChunk * ArenaSize; } static size_t arenaIndex(uintptr_t addr) { JS_ASSERT(withinArenasRange(addr)); return (addr & ChunkMask) >> ArenaShift; } uintptr_t address() const { uintptr_t addr = reinterpret_cast(this); JS_ASSERT(!(addr & ChunkMask)); return addr; } bool unused() const { return info.numArenasFree == ArenasPerChunk; } bool hasAvailableArenas() const { return info.numArenasFree != 0; } inline void addToAvailableList(JSCompartment *compartment); inline void insertToAvailableList(Chunk **insertPoint); inline void removeFromAvailableList(); ArenaHeader *allocateArena(JSCompartment *comp, AllocKind kind); void releaseArena(ArenaHeader *aheader); static Chunk *allocate(JSRuntime *rt); /* Must be called with the GC lock taken. */ static inline void release(JSRuntime *rt, Chunk *chunk); static inline void releaseList(JSRuntime *rt, Chunk *chunkListHead); /* Must be called with the GC lock taken. */ inline void prepareToBeFreed(JSRuntime *rt); /* * Assuming that the info.prevp points to the next field of the previous * chunk in a doubly-linked list, get that chunk. */ Chunk *getPrevious() { JS_ASSERT(info.prevp); return fromPointerToNext(info.prevp); } /* Get the chunk from a pointer to its info.next field. */ static Chunk *fromPointerToNext(Chunk **nextFieldPtr) { uintptr_t addr = reinterpret_cast(nextFieldPtr); JS_ASSERT((addr & ChunkMask) == offsetof(Chunk, info.next)); return reinterpret_cast(addr - offsetof(Chunk, info.next)); } private: inline void init(); /* Search for a decommitted arena to allocate. */ unsigned findDecommittedArenaOffset(); ArenaHeader* fetchNextDecommittedArena(); public: /* Unlink and return the freeArenasHead. */ inline ArenaHeader* fetchNextFreeArena(JSRuntime *rt); inline void addArenaToFreeList(JSRuntime *rt, ArenaHeader *aheader); }; JS_STATIC_ASSERT(sizeof(Chunk) == ChunkSize); inline uintptr_t Cell::address() const { uintptr_t addr = uintptr_t(this); JS_ASSERT(addr % Cell::CellSize == 0); JS_ASSERT(Chunk::withinArenasRange(addr)); return addr; } inline uintptr_t ArenaHeader::address() const { uintptr_t addr = reinterpret_cast(this); JS_ASSERT(!(addr & ArenaMask)); JS_ASSERT(Chunk::withinArenasRange(addr)); return addr; } inline Chunk * ArenaHeader::chunk() const { return Chunk::fromAddress(address()); } inline uintptr_t ArenaHeader::arenaAddress() const { return address(); } inline Arena * ArenaHeader::getArena() { return reinterpret_cast(arenaAddress()); } inline bool ArenaHeader::isEmpty() const { /* Arena is empty if its first span covers the whole arena. */ JS_ASSERT(allocated()); size_t firstThingOffset = Arena::firstThingOffset(getAllocKind()); return firstFreeSpanOffsets == FreeSpan::encodeOffsets(firstThingOffset, ArenaMask); } FreeSpan ArenaHeader::getFirstFreeSpan() const { #ifdef DEBUG checkSynchronizedWithFreeList(); #endif return FreeSpan::decodeOffsets(arenaAddress(), firstFreeSpanOffsets); } void ArenaHeader::setFirstFreeSpan(const FreeSpan *span) { JS_ASSERT(span->isWithinArena(arenaAddress())); firstFreeSpanOffsets = span->encodeAsOffsets(); } inline ArenaHeader * ArenaHeader::getNextDelayedMarking() const { JS_ASSERT(hasDelayedMarking); return &reinterpret_cast(auxNextLink << ArenaShift)->aheader; } inline void ArenaHeader::setNextDelayedMarking(ArenaHeader *aheader) { JS_ASSERT(!(uintptr_t(aheader) & ArenaMask)); JS_ASSERT(!auxNextLink && !hasDelayedMarking); hasDelayedMarking = 1; auxNextLink = aheader->arenaAddress() >> ArenaShift; } inline void ArenaHeader::unsetDelayedMarking() { JS_ASSERT(hasDelayedMarking); hasDelayedMarking = 0; auxNextLink = 0; } inline ArenaHeader * ArenaHeader::getNextAllocDuringSweep() const { JS_ASSERT(allocatedDuringIncremental); return &reinterpret_cast(auxNextLink << ArenaShift)->aheader; } inline void ArenaHeader::setNextAllocDuringSweep(ArenaHeader *aheader) { JS_ASSERT(!auxNextLink && !allocatedDuringIncremental); allocatedDuringIncremental = 1; auxNextLink = aheader->arenaAddress() >> ArenaShift; } inline void ArenaHeader::unsetAllocDuringSweep() { JS_ASSERT(allocatedDuringIncremental); allocatedDuringIncremental = 0; auxNextLink = 0; } JS_ALWAYS_INLINE void ChunkBitmap::getMarkWordAndMask(const Cell *cell, uint32_t color, uintptr_t **wordp, uintptr_t *maskp) { size_t bit = (cell->address() & ChunkMask) / Cell::CellSize + color; JS_ASSERT(bit < ArenaBitmapBits * ArenasPerChunk); *maskp = uintptr_t(1) << (bit % JS_BITS_PER_WORD); *wordp = &bitmap[bit / JS_BITS_PER_WORD]; } static void AssertValidColor(const void *thing, uint32_t color) { #ifdef DEBUG ArenaHeader *aheader = reinterpret_cast(thing)->arenaHeader(); JS_ASSERT_IF(color, color < aheader->getThingSize() / Cell::CellSize); #endif } inline ArenaHeader * Cell::arenaHeader() const { uintptr_t addr = address(); addr &= ~ArenaMask; return reinterpret_cast(addr); } Chunk * Cell::chunk() const { uintptr_t addr = uintptr_t(this); JS_ASSERT(addr % Cell::CellSize == 0); addr &= ~(ChunkSize - 1); return reinterpret_cast(addr); } AllocKind Cell::getAllocKind() const { return arenaHeader()->getAllocKind(); } bool Cell::isMarked(uint32_t color /* = BLACK */) const { AssertValidColor(this, color); return chunk()->bitmap.isMarked(this, color); } bool Cell::markIfUnmarked(uint32_t color /* = BLACK */) const { AssertValidColor(this, color); return chunk()->bitmap.markIfUnmarked(this, color); } void Cell::unmark(uint32_t color) const { JS_ASSERT(color != BLACK); AssertValidColor(this, color); chunk()->bitmap.unmark(this, color); } JSCompartment * Cell::compartment() const { return arenaHeader()->compartment; } #ifdef DEBUG bool Cell::isAligned() const { return Arena::isAligned(address(), arenaHeader()->getThingSize()); } #endif } /* namespace gc */ } /* namespace js */ #endif /* gc_heap_h___ */