michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
michael@0:  * vim: set ts=8 sts=4 et sw=4 tw=99:
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef js_HeapAPI_h
michael@0: #define js_HeapAPI_h
michael@0: 
michael@0: #include <limits.h>
michael@0: 
michael@0: #include "jspubtd.h"
michael@0: 
michael@0: #include "js/Utility.h"
michael@0: 
michael@0: /* These values are private to the JS engine. */
michael@0: namespace js {
michael@0: 
michael@0: // Whether the current thread is permitted access to any part of the specified
michael@0: // runtime or zone.
michael@0: JS_FRIEND_API(bool)
michael@0: CurrentThreadCanAccessRuntime(JSRuntime *rt);
michael@0: 
michael@0: JS_FRIEND_API(bool)
michael@0: CurrentThreadCanAccessZone(JS::Zone *zone);
michael@0: 
michael@0: namespace gc {
michael@0: 
michael@0: struct Cell;
michael@0: 
michael@0: const size_t ArenaShift = 12;
michael@0: const size_t ArenaSize = size_t(1) << ArenaShift;
michael@0: const size_t ArenaMask = ArenaSize - 1;
michael@0: 
michael@0: const size_t ChunkShift = 20;
michael@0: const size_t ChunkSize = size_t(1) << ChunkShift;
michael@0: const size_t ChunkMask = ChunkSize - 1;
michael@0: 
michael@0: const size_t CellShift = 3;
michael@0: const size_t CellSize = size_t(1) << CellShift;
michael@0: const size_t CellMask = CellSize - 1;
michael@0: 
michael@0: /* These are magic constants derived from actual offsets in gc/Heap.h. */
michael@0: const size_t ChunkMarkBitmapOffset = 1032360;
michael@0: const size_t ChunkMarkBitmapBits = 129024;
michael@0: const size_t ChunkRuntimeOffset = ChunkSize - sizeof(void*);
michael@0: const size_t ChunkLocationOffset = ChunkSize - sizeof(void*) - sizeof(uintptr_t);
michael@0: 
michael@0: /*
michael@0:  * Live objects are marked black. How many other additional colors are available
michael@0:  * depends on the size of the GCThing. Objects marked gray are eligible for
michael@0:  * cycle collection.
michael@0:  */
michael@0: static const uint32_t BLACK = 0;
michael@0: static const uint32_t GRAY = 1;
michael@0: 
michael@0: /*
michael@0:  * Constants used to indicate whether a chunk is part of the tenured heap or the
michael@0:  * nusery.
michael@0:  */
michael@0: const uintptr_t ChunkLocationNursery = 0;
michael@0: const uintptr_t ChunkLocationTenuredHeap = 1;
michael@0: 
michael@0: } /* namespace gc */
michael@0: } /* namespace js */
michael@0: 
michael@0: namespace JS {
michael@0: struct Zone;
michael@0: } /* namespace JS */
michael@0: 
michael@0: namespace JS {
michael@0: namespace shadow {
michael@0: 
michael@0: struct ArenaHeader
michael@0: {
michael@0:     JS::Zone *zone;
michael@0: };
michael@0: 
michael@0: struct Zone
michael@0: {
michael@0:   protected:
michael@0:     JSRuntime *const runtime_;
michael@0:     JSTracer *const barrierTracer_;     // A pointer to the JSRuntime's |gcMarker|.
michael@0: 
michael@0:   public:
michael@0:     bool needsBarrier_;
michael@0: 
michael@0:     Zone(JSRuntime *runtime, JSTracer *barrierTracerArg)
michael@0:       : runtime_(runtime),
michael@0:         barrierTracer_(barrierTracerArg),
michael@0:         needsBarrier_(false)
michael@0:     {}
michael@0: 
michael@0:     bool needsBarrier() const {
michael@0:         return needsBarrier_;
michael@0:     }
michael@0: 
michael@0:     JSTracer *barrierTracer() {
michael@0:         MOZ_ASSERT(needsBarrier_);
michael@0:         MOZ_ASSERT(js::CurrentThreadCanAccessRuntime(runtime_));
michael@0:         return barrierTracer_;
michael@0:     }
michael@0: 
michael@0:     JSRuntime *runtimeFromMainThread() const {
michael@0:         MOZ_ASSERT(js::CurrentThreadCanAccessRuntime(runtime_));
michael@0:         return runtime_;
michael@0:     }
michael@0: 
michael@0:     // Note: Unrestricted access to the zone's runtime from an arbitrary
michael@0:     // thread can easily lead to races. Use this method very carefully.
michael@0:     JSRuntime *runtimeFromAnyThread() const {
michael@0:         return runtime_;
michael@0:     }
michael@0: 
michael@0:     static JS::shadow::Zone *asShadowZone(JS::Zone *zone) {
michael@0:         return reinterpret_cast<JS::shadow::Zone*>(zone);
michael@0:     }
michael@0: };
michael@0: 
michael@0: } /* namespace shadow */
michael@0: } /* namespace JS */
michael@0: 
michael@0: namespace js {
michael@0: namespace gc {
michael@0: 
michael@0: static MOZ_ALWAYS_INLINE uintptr_t *
michael@0: GetGCThingMarkBitmap(const void *thing)
michael@0: {
michael@0:     MOZ_ASSERT(thing);
michael@0:     uintptr_t addr = uintptr_t(thing);
michael@0:     addr &= ~js::gc::ChunkMask;
michael@0:     addr |= js::gc::ChunkMarkBitmapOffset;
michael@0:     return reinterpret_cast<uintptr_t *>(addr);
michael@0: }
michael@0: 
michael@0: static MOZ_ALWAYS_INLINE JS::shadow::Runtime *
michael@0: GetGCThingRuntime(const void *thing)
michael@0: {
michael@0:     MOZ_ASSERT(thing);
michael@0:     uintptr_t addr = uintptr_t(thing);
michael@0:     addr &= ~js::gc::ChunkMask;
michael@0:     addr |= js::gc::ChunkRuntimeOffset;
michael@0:     return *reinterpret_cast<JS::shadow::Runtime **>(addr);
michael@0: }
michael@0: 
michael@0: static MOZ_ALWAYS_INLINE void
michael@0: GetGCThingMarkWordAndMask(const void *thing, uint32_t color,
michael@0:                           uintptr_t **wordp, uintptr_t *maskp)
michael@0: {
michael@0:     uintptr_t addr = uintptr_t(thing);
michael@0:     size_t bit = (addr & js::gc::ChunkMask) / js::gc::CellSize + color;
michael@0:     MOZ_ASSERT(bit < js::gc::ChunkMarkBitmapBits);
michael@0:     uintptr_t *bitmap = GetGCThingMarkBitmap(thing);
michael@0:     const uintptr_t nbits = sizeof(*bitmap) * CHAR_BIT;
michael@0:     *maskp = uintptr_t(1) << (bit % nbits);
michael@0:     *wordp = &bitmap[bit / nbits];
michael@0: }
michael@0: 
michael@0: static MOZ_ALWAYS_INLINE JS::shadow::ArenaHeader *
michael@0: GetGCThingArena(void *thing)
michael@0: {
michael@0:     uintptr_t addr = uintptr_t(thing);
michael@0:     addr &= ~js::gc::ArenaMask;
michael@0:     return reinterpret_cast<JS::shadow::ArenaHeader *>(addr);
michael@0: }
michael@0: 
michael@0: MOZ_ALWAYS_INLINE bool
michael@0: IsInsideNursery(const JS::shadow::Runtime *runtime, const void *p)
michael@0: {
michael@0: #ifdef JSGC_GENERATIONAL
michael@0:     return uintptr_t(p) >= runtime->gcNurseryStart_ && uintptr_t(p) < runtime->gcNurseryEnd_;
michael@0: #else
michael@0:     return false;
michael@0: #endif
michael@0: }
michael@0: 
michael@0: MOZ_ALWAYS_INLINE bool
michael@0: IsInsideNursery(const js::gc::Cell *cell)
michael@0: {
michael@0: #ifdef JSGC_GENERATIONAL
michael@0:     if (!cell)
michael@0:         return false;
michael@0:     uintptr_t addr = uintptr_t(cell);
michael@0:     addr &= ~js::gc::ChunkMask;
michael@0:     addr |= js::gc::ChunkLocationOffset;
michael@0:     uint32_t location = *reinterpret_cast<uint32_t *>(addr);
michael@0:     JS_ASSERT(location == gc::ChunkLocationNursery ||
michael@0:               location == gc::ChunkLocationTenuredHeap);
michael@0:     return location == gc::ChunkLocationNursery;
michael@0: #else
michael@0:     return false;
michael@0: #endif
michael@0: }
michael@0: 
michael@0: } /* namespace gc */
michael@0: 
michael@0: } /* namespace js */
michael@0: 
michael@0: namespace JS {
michael@0: 
michael@0: static MOZ_ALWAYS_INLINE Zone *
michael@0: GetGCThingZone(void *thing)
michael@0: {
michael@0:     MOZ_ASSERT(thing);
michael@0:     return js::gc::GetGCThingArena(thing)->zone;
michael@0: }
michael@0: 
michael@0: static MOZ_ALWAYS_INLINE Zone *
michael@0: GetObjectZone(JSObject *obj)
michael@0: {
michael@0:     return GetGCThingZone(obj);
michael@0: }
michael@0: 
michael@0: static MOZ_ALWAYS_INLINE bool
michael@0: GCThingIsMarkedGray(void *thing)
michael@0: {
michael@0: #ifdef JSGC_GENERATIONAL
michael@0:     /*
michael@0:      * GC things residing in the nursery cannot be gray: they have no mark bits.
michael@0:      * All live objects in the nursery are moved to tenured at the beginning of
michael@0:      * each GC slice, so the gray marker never sees nursery things.
michael@0:      */
michael@0:     JS::shadow::Runtime *rt = js::gc::GetGCThingRuntime(thing);
michael@0:     if (js::gc::IsInsideNursery(rt, thing))
michael@0:         return false;
michael@0: #endif
michael@0:     uintptr_t *word, mask;
michael@0:     js::gc::GetGCThingMarkWordAndMask(thing, js::gc::GRAY, &word, &mask);
michael@0:     return *word & mask;
michael@0: }
michael@0: 
michael@0: static MOZ_ALWAYS_INLINE bool
michael@0: IsIncrementalBarrierNeededOnGCThing(shadow::Runtime *rt, void *thing, JSGCTraceKind kind)
michael@0: {
michael@0:     if (!rt->needsBarrier_)
michael@0:         return false;
michael@0:     JS::Zone *zone = GetGCThingZone(thing);
michael@0:     return reinterpret_cast<shadow::Zone *>(zone)->needsBarrier_;
michael@0: }
michael@0: 
michael@0: } /* namespace JS */
michael@0: 
michael@0: #endif /* js_HeapAPI_h */