/usr/include/mozjs-24/js/HeapAPI.h is in libmozjs-24-dev 24.2.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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* vim: set ts=8 sts=4 et sw=4 tw=99:
* 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 js_HeapAPI_h
#define js_HeapAPI_h
#include "jspubtd.h"
/* These values are private to the JS engine. */
namespace js {
namespace gc {
const size_t ArenaShift = 12;
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;
const size_t CellShift = 3;
const size_t CellSize = size_t(1) << CellShift;
const size_t CellMask = CellSize - 1;
/* These are magic constants derived from actual offsets in gc/Heap.h. */
const size_t ChunkMarkBitmapOffset = 1032368;
const size_t ChunkMarkBitmapBits = 129024;
const size_t ChunkRuntimeOffset = ChunkSize - sizeof(void*);
/*
* 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;
} /* namespace gc */
} /* namespace js */
namespace JS {
struct Zone;
} /* namespace JS */
namespace JS {
namespace shadow {
struct ArenaHeader
{
js::Zone *zone;
};
struct Zone
{
bool needsBarrier_;
Zone() : needsBarrier_(false) {}
};
} /* namespace shadow */
} /* namespace JS */
namespace js {
namespace gc {
static JS_ALWAYS_INLINE uintptr_t *
GetGCThingMarkBitmap(const void *thing)
{
uintptr_t addr = uintptr_t(thing);
addr &= ~js::gc::ChunkMask;
addr |= js::gc::ChunkMarkBitmapOffset;
return reinterpret_cast<uintptr_t *>(addr);
}
static JS_ALWAYS_INLINE JS::shadow::Runtime *
GetGCThingRuntime(const void *thing)
{
uintptr_t addr = uintptr_t(thing);
addr &= ~js::gc::ChunkMask;
addr |= js::gc::ChunkRuntimeOffset;
return *reinterpret_cast<JS::shadow::Runtime **>(addr);
}
static JS_ALWAYS_INLINE void
GetGCThingMarkWordAndMask(const void *thing, uint32_t color,
uintptr_t **wordp, uintptr_t *maskp)
{
uintptr_t addr = uintptr_t(thing);
size_t bit = (addr & js::gc::ChunkMask) / js::gc::CellSize + color;
JS_ASSERT(bit < js::gc::ChunkMarkBitmapBits);
uintptr_t *bitmap = GetGCThingMarkBitmap(thing);
*maskp = uintptr_t(1) << (bit % JS_BITS_PER_WORD);
*wordp = &bitmap[bit / JS_BITS_PER_WORD];
}
static JS_ALWAYS_INLINE JS::shadow::ArenaHeader *
GetGCThingArena(void *thing)
{
uintptr_t addr = uintptr_t(thing);
addr &= ~js::gc::ArenaMask;
return reinterpret_cast<JS::shadow::ArenaHeader *>(addr);
}
} /* namespace gc */
} /* namespace js */
namespace JS {
static JS_ALWAYS_INLINE Zone *
GetGCThingZone(void *thing)
{
JS_ASSERT(thing);
return js::gc::GetGCThingArena(thing)->zone;
}
static JS_ALWAYS_INLINE Zone *
GetObjectZone(JSObject *obj)
{
return GetGCThingZone(obj);
}
static JS_ALWAYS_INLINE bool
GCThingIsMarkedGray(void *thing)
{
uintptr_t *word, mask;
js::gc::GetGCThingMarkWordAndMask(thing, js::gc::GRAY, &word, &mask);
return *word & mask;
}
static JS_ALWAYS_INLINE bool
IsIncrementalBarrierNeededOnGCThing(shadow::Runtime *rt, void *thing, JSGCTraceKind kind)
{
if (!rt->needsBarrier_)
return false;
js::Zone *zone = GetGCThingZone(thing);
return reinterpret_cast<shadow::Zone *>(zone)->needsBarrier_;
}
} /* namespace JS */
#endif /* js_HeapAPI_h */
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