include/jemalloc/internal/rtree.h - platform/external/jemalloc - Git at Google

 /*
  * This radix tree implementation is tailored to the singular purpose of
  * associating metadata with chunks that are currently owned by jemalloc.
  *
  *******************************************************************************
  */
 #ifdef JEMALLOC_H_TYPES

 typedef struct rtree_node_elm_s rtree_node_elm_t;
 typedef struct rtree_level_s rtree_level_t;
 typedef struct rtree_s rtree_t;

 /*
  * RTREE_BITS_PER_LEVEL must be a power of two that is no larger than the
  * machine address width.
  */
 #define	LG_RTREE_BITS_PER_LEVEL	4
 #define	RTREE_BITS_PER_LEVEL	(1U << LG_RTREE_BITS_PER_LEVEL)
 /* Maximum rtree height. */
 #define	RTREE_HEIGHT_MAX						\
     ((1U << (LG_SIZEOF_PTR+3)) / RTREE_BITS_PER_LEVEL)

 /* Used for two-stage lock-free node initialization. */
 #define	RTREE_NODE_INITIALIZING	((rtree_node_elm_t *)0x1)

 /*
  * The node allocation callback function's argument is the number of contiguous
  * rtree_node_elm_t structures to allocate, and the resulting memory must be
  * zeroed.
  */
 typedef rtree_node_elm_t *(rtree_node_alloc_t)(size_t);
 typedef void (rtree_node_dalloc_t)(rtree_node_elm_t *);

 #endif /* JEMALLOC_H_TYPES */
 /******************************************************************************/
 #ifdef JEMALLOC_H_STRUCTS

 struct rtree_node_elm_s {
 	union {
 		void			*pun;
 		rtree_node_elm_t	*child;
 		extent_node_t		*val;
 	};
 };

 struct rtree_level_s {
 	/*
 	 * A non-NULL subtree points to a subtree rooted along the hypothetical
 	 * path to the leaf node corresponding to key 0.  Depending on what keys
 	 * have been used to store to the tree, an arbitrary combination of
 	 * subtree pointers may remain NULL.
 	 *
 	 * Suppose keys comprise 48 bits, and LG_RTREE_BITS_PER_LEVEL is 4.
 	 * This results in a 3-level tree, and the leftmost leaf can be directly
 	 * accessed via subtrees[2], the subtree prefixed by 0x0000 (excluding
 	 * 0x00000000) can be accessed via subtrees[1], and the remainder of the
 	 * tree can be accessed via subtrees[0].
 	 *
 	 *   levels[0] : [<unused> | 0x0001******** | 0x0002******** | ...]
 	 *
 	 *   levels[1] : [<unused> | 0x00000001**** | 0x00000002**** | ... ]
 	 *
 	 *   levels[2] : [val(0x000000000000) | val(0x000000000001) | ...]
 	 *
 	 * This has practical implications on x64, which currently uses only the
 	 * lower 47 bits of virtual address space in userland, thus leaving
 	 * subtrees[0] unused and avoiding a level of tree traversal.
 	 */
 	union {
 		void			*subtree_pun;
 		rtree_node_elm_t	*subtree;
 	};
 	/* Number of key bits distinguished by this level. */
 	unsigned		bits;
 	/*
 	 * Cumulative number of key bits distinguished by traversing to
 	 * corresponding tree level.
 	 */
 	unsigned		cumbits;
 };

 struct rtree_s {
 	rtree_node_alloc_t	*alloc;
 	rtree_node_dalloc_t	*dalloc;
 	unsigned		height;
 	/*
 	 * Precomputed table used to convert from the number of leading 0 key
 	 * bits to which subtree level to start at.
 	 */
 	unsigned		start_level[RTREE_HEIGHT_MAX];
 	rtree_level_t		levels[RTREE_HEIGHT_MAX];
 };

 #endif /* JEMALLOC_H_STRUCTS */
 /******************************************************************************/
 #ifdef JEMALLOC_H_EXTERNS

 bool rtree_new(rtree_t *rtree, unsigned bits, rtree_node_alloc_t *alloc,
     rtree_node_dalloc_t *dalloc);
 void	rtree_delete(rtree_t *rtree);
 rtree_node_elm_t	*rtree_subtree_read_hard(rtree_t *rtree,
     unsigned level);
 rtree_node_elm_t	*rtree_child_read_hard(rtree_t *rtree,
     rtree_node_elm_t *elm, unsigned level);

 #endif /* JEMALLOC_H_EXTERNS */
 /******************************************************************************/
 #ifdef JEMALLOC_H_INLINES

 #ifndef JEMALLOC_ENABLE_INLINE
 unsigned	rtree_start_level(rtree_t *rtree, uintptr_t key);
 uintptr_t	rtree_subkey(rtree_t *rtree, uintptr_t key, unsigned level);

 bool	rtree_node_valid(rtree_node_elm_t *node);
 rtree_node_elm_t	*rtree_child_tryread(rtree_node_elm_t *elm,
     bool dependent);
 rtree_node_elm_t	*rtree_child_read(rtree_t *rtree, rtree_node_elm_t *elm,
     unsigned level, bool dependent);
 extent_node_t	*rtree_val_read(rtree_t *rtree, rtree_node_elm_t *elm,
     bool dependent);
 void	rtree_val_write(rtree_t *rtree, rtree_node_elm_t *elm,
     const extent_node_t *val);
 rtree_node_elm_t	*rtree_subtree_tryread(rtree_t *rtree, unsigned level,
     bool dependent);
 rtree_node_elm_t	*rtree_subtree_read(rtree_t *rtree, unsigned level,
     bool dependent);

 extent_node_t	*rtree_get(rtree_t *rtree, uintptr_t key, bool dependent);
 bool	rtree_set(rtree_t *rtree, uintptr_t key, const extent_node_t *val);
 #endif

 #if (defined(JEMALLOC_ENABLE_INLINE) || defined(JEMALLOC_RTREE_C_))
 JEMALLOC_ALWAYS_INLINE unsigned
 rtree_start_level(rtree_t *rtree, uintptr_t key)
 {
 	unsigned start_level;

 	if (unlikely(key == 0))
 		return (rtree->height - 1);

 	start_level = rtree->start_level[lg_floor(key) >>
 	    LG_RTREE_BITS_PER_LEVEL];
 	assert(start_level < rtree->height);
 	return (start_level);
 }

 JEMALLOC_ALWAYS_INLINE uintptr_t
 rtree_subkey(rtree_t *rtree, uintptr_t key, unsigned level)
 {

 	return ((key >> ((ZU(1) << (LG_SIZEOF_PTR+3)) -
 	    rtree->levels[level].cumbits)) & ((ZU(1) <<
 	    rtree->levels[level].bits) - 1));
 }

 JEMALLOC_ALWAYS_INLINE bool
 rtree_node_valid(rtree_node_elm_t *node)
 {

 	return ((uintptr_t)node > (uintptr_t)RTREE_NODE_INITIALIZING);
 }

 JEMALLOC_ALWAYS_INLINE rtree_node_elm_t *
 rtree_child_tryread(rtree_node_elm_t *elm, bool dependent)
 {
 	rtree_node_elm_t *child;

 	/* Double-checked read (first read may be stale. */
 	child = elm->child;
 	if (!dependent && !rtree_node_valid(child))
 		child = atomic_read_p(&elm->pun);
 	assert(!dependent || child != NULL);
 	return (child);
 }

 JEMALLOC_ALWAYS_INLINE rtree_node_elm_t *
 rtree_child_read(rtree_t *rtree, rtree_node_elm_t *elm, unsigned level,
     bool dependent)
 {
 	rtree_node_elm_t *child;

 	child = rtree_child_tryread(elm, dependent);
 	if (!dependent && unlikely(!rtree_node_valid(child)))
 		child = rtree_child_read_hard(rtree, elm, level);
 	assert(!dependent || child != NULL);
 	return (child);
 }

 JEMALLOC_ALWAYS_INLINE extent_node_t *
 rtree_val_read(rtree_t *rtree, rtree_node_elm_t *elm, bool dependent)
 {

 	if (dependent) {
 		/*
 		 * Reading a val on behalf of a pointer to a valid allocation is
 		 * guaranteed to be a clean read even without synchronization,
 		 * because the rtree update became visible in memory before the
 		 * pointer came into existence.
 		 */
 		return (elm->val);
 	} else {
 		/*
 		 * An arbitrary read, e.g. on behalf of ivsalloc(), may not be
 		 * dependent on a previous rtree write, which means a stale read
 		 * could result if synchronization were omitted here.
 		 */
 		return (atomic_read_p(&elm->pun));
 	}
 }

 JEMALLOC_INLINE void
 rtree_val_write(rtree_t *rtree, rtree_node_elm_t *elm, const extent_node_t *val)
 {

 	atomic_write_p(&elm->pun, val);
 }

 JEMALLOC_ALWAYS_INLINE rtree_node_elm_t *
 rtree_subtree_tryread(rtree_t *rtree, unsigned level, bool dependent)
 {
 	rtree_node_elm_t *subtree;

 	/* Double-checked read (first read may be stale. */
 	subtree = rtree->levels[level].subtree;
 	if (!dependent && unlikely(!rtree_node_valid(subtree)))
 		subtree = atomic_read_p(&rtree->levels[level].subtree_pun);
 	assert(!dependent || subtree != NULL);
 	return (subtree);
 }

 JEMALLOC_ALWAYS_INLINE rtree_node_elm_t *
 rtree_subtree_read(rtree_t *rtree, unsigned level, bool dependent)
 {
 	rtree_node_elm_t *subtree;

 	subtree = rtree_subtree_tryread(rtree, level, dependent);
 	if (!dependent && unlikely(!rtree_node_valid(subtree)))
 		subtree = rtree_subtree_read_hard(rtree, level);
 	assert(!dependent || subtree != NULL);
 	return (subtree);
 }

 JEMALLOC_ALWAYS_INLINE extent_node_t *
 rtree_get(rtree_t *rtree, uintptr_t key, bool dependent)
 {
 	uintptr_t subkey;
 	unsigned start_level;
 	rtree_node_elm_t *node;

 	start_level = rtree_start_level(rtree, key);

 	node = rtree_subtree_tryread(rtree, start_level, dependent);
 #define	RTREE_GET_BIAS	(RTREE_HEIGHT_MAX - rtree->height)
 	switch (start_level + RTREE_GET_BIAS) {
 #define	RTREE_GET_SUBTREE(level)					\
 	case level:							\
 		assert(level < (RTREE_HEIGHT_MAX-1));			\
 		if (!dependent && unlikely(!rtree_node_valid(node)))	\
 			return (NULL);					\
 		subkey = rtree_subkey(rtree, key, level -		\
 		    RTREE_GET_BIAS);					\
 		node = rtree_child_tryread(&node[subkey], dependent);	\
 		/* Fall through. */
 #define	RTREE_GET_LEAF(level)						\
 	case level:							\
 		assert(level == (RTREE_HEIGHT_MAX-1));			\
 		if (!dependent && unlikely(!rtree_node_valid(node)))	\
 			return (NULL);					\
 		subkey = rtree_subkey(rtree, key, level -		\
 		    RTREE_GET_BIAS);					\
 		/*							\
 		 * node is a leaf, so it contains values rather than	\
 		 * child pointers.					\
 		 */							\
 		return (rtree_val_read(rtree, &node[subkey],		\
 		    dependent));
 #if RTREE_HEIGHT_MAX > 1
 	RTREE_GET_SUBTREE(0)
 #endif
 #if RTREE_HEIGHT_MAX > 2
 	RTREE_GET_SUBTREE(1)
 #endif
 #if RTREE_HEIGHT_MAX > 3
 	RTREE_GET_SUBTREE(2)
 #endif
 #if RTREE_HEIGHT_MAX > 4
 	RTREE_GET_SUBTREE(3)
 #endif
 #if RTREE_HEIGHT_MAX > 5
 	RTREE_GET_SUBTREE(4)
 #endif
 #if RTREE_HEIGHT_MAX > 6
 	RTREE_GET_SUBTREE(5)
 #endif
 #if RTREE_HEIGHT_MAX > 7
 	RTREE_GET_SUBTREE(6)
 #endif
 #if RTREE_HEIGHT_MAX > 8
 	RTREE_GET_SUBTREE(7)
 #endif
 #if RTREE_HEIGHT_MAX > 9
 	RTREE_GET_SUBTREE(8)
 #endif
 #if RTREE_HEIGHT_MAX > 10
 	RTREE_GET_SUBTREE(9)
 #endif
 #if RTREE_HEIGHT_MAX > 11
 	RTREE_GET_SUBTREE(10)
 #endif
 #if RTREE_HEIGHT_MAX > 12
 	RTREE_GET_SUBTREE(11)
 #endif
 #if RTREE_HEIGHT_MAX > 13
 	RTREE_GET_SUBTREE(12)
 #endif
 #if RTREE_HEIGHT_MAX > 14
 	RTREE_GET_SUBTREE(13)
 #endif
 #if RTREE_HEIGHT_MAX > 15
 	RTREE_GET_SUBTREE(14)
 #endif
 #if RTREE_HEIGHT_MAX > 16
 #  error Unsupported RTREE_HEIGHT_MAX
 #endif
 	RTREE_GET_LEAF(RTREE_HEIGHT_MAX-1)
 #undef RTREE_GET_SUBTREE
 #undef RTREE_GET_LEAF
 	default: not_reached();
 	}
 #undef RTREE_GET_BIAS
 	not_reached();
 }

 JEMALLOC_INLINE bool
 rtree_set(rtree_t *rtree, uintptr_t key, const extent_node_t *val)
 {
 	uintptr_t subkey;
 	unsigned i, start_level;
 	rtree_node_elm_t *node, *child;

 	start_level = rtree_start_level(rtree, key);

 	node = rtree_subtree_read(rtree, start_level, false);
 	if (node == NULL)
 		return (true);
 	for (i = start_level; /**/; i++, node = child) {
 		subkey = rtree_subkey(rtree, key, i);
 		if (i == rtree->height - 1) {
 			/*
 			 * node is a leaf, so it contains values rather than
 			 * child pointers.
 			 */
 			rtree_val_write(rtree, &node[subkey], val);
 			return (false);
 		}
 		assert(i + 1 < rtree->height);
 		child = rtree_child_read(rtree, &node[subkey], i, false);
 		if (child == NULL)
 			return (true);
 	}
 	not_reached();
 }
 #endif

 #endif /* JEMALLOC_H_INLINES */
 /******************************************************************************/
	/*
	* This radix tree implementation is tailored to the singular purpose of
	* associating metadata with chunks that are currently owned by jemalloc.
	*
	*******************************************************************************
	*/
	#ifdef JEMALLOC_H_TYPES

	typedef struct rtree_node_elm_s rtree_node_elm_t;
	typedef struct rtree_level_s rtree_level_t;
	typedef struct rtree_s rtree_t;

	/*
	* RTREE_BITS_PER_LEVEL must be a power of two that is no larger than the
	* machine address width.
	*/
	#define LG_RTREE_BITS_PER_LEVEL 4
	#define RTREE_BITS_PER_LEVEL (1U << LG_RTREE_BITS_PER_LEVEL)
	/* Maximum rtree height. */
	#define RTREE_HEIGHT_MAX \
	((1U << (LG_SIZEOF_PTR+3)) / RTREE_BITS_PER_LEVEL)

	/* Used for two-stage lock-free node initialization. */
	#define RTREE_NODE_INITIALIZING ((rtree_node_elm_t *)0x1)

	/*
	* The node allocation callback function's argument is the number of contiguous
	* rtree_node_elm_t structures to allocate, and the resulting memory must be
	* zeroed.
	*/
	typedef rtree_node_elm_t *(rtree_node_alloc_t)(size_t);
	typedef void (rtree_node_dalloc_t)(rtree_node_elm_t *);

	#endif /* JEMALLOC_H_TYPES */
	/******************************************************************************/
	#ifdef JEMALLOC_H_STRUCTS

	struct rtree_node_elm_s {
	union {
	void *pun;
	rtree_node_elm_t *child;
	extent_node_t *val;
	};
	};

	struct rtree_level_s {
	/*
	* A non-NULL subtree points to a subtree rooted along the hypothetical
	* path to the leaf node corresponding to key 0. Depending on what keys
	* have been used to store to the tree, an arbitrary combination of
	* subtree pointers may remain NULL.
	*
	* Suppose keys comprise 48 bits, and LG_RTREE_BITS_PER_LEVEL is 4.
	* This results in a 3-level tree, and the leftmost leaf can be directly
	* accessed via subtrees[2], the subtree prefixed by 0x0000 (excluding
	* 0x00000000) can be accessed via subtrees[1], and the remainder of the
	* tree can be accessed via subtrees[0].
	*
	* levels[0] : [<unused> \| 0x0001****** \| 0x0002****** \| ...]
	*
	* levels[1] : [<unused> \| 0x00000001** \| 0x00000002** \| ... ]
	*
	* levels[2] : [val(0x000000000000) \| val(0x000000000001) \| ...]
	*
	* This has practical implications on x64, which currently uses only the
	* lower 47 bits of virtual address space in userland, thus leaving
	* subtrees[0] unused and avoiding a level of tree traversal.
	*/
	union {
	void *subtree_pun;
	rtree_node_elm_t *subtree;
	};
	/* Number of key bits distinguished by this level. */
	unsigned bits;
	/*
	* Cumulative number of key bits distinguished by traversing to
	* corresponding tree level.
	*/
	unsigned cumbits;
	};

	struct rtree_s {
	rtree_node_alloc_t *alloc;
	rtree_node_dalloc_t *dalloc;
	unsigned height;
	/*
	* Precomputed table used to convert from the number of leading 0 key
	* bits to which subtree level to start at.
	*/
	unsigned start_level[RTREE_HEIGHT_MAX];
	rtree_level_t levels[RTREE_HEIGHT_MAX];
	};

	#endif /* JEMALLOC_H_STRUCTS */
	/******************************************************************************/
	#ifdef JEMALLOC_H_EXTERNS

	bool rtree_new(rtree_t rtree, unsigned bits, rtree_node_alloc_t alloc,
	rtree_node_dalloc_t *dalloc);
	void rtree_delete(rtree_t *rtree);
	rtree_node_elm_t rtree_subtree_read_hard(rtree_t rtree,
	unsigned level);
	rtree_node_elm_t rtree_child_read_hard(rtree_t rtree,
	rtree_node_elm_t *elm, unsigned level);

	#endif /* JEMALLOC_H_EXTERNS */
	/******************************************************************************/
	#ifdef JEMALLOC_H_INLINES

	#ifndef JEMALLOC_ENABLE_INLINE
	unsigned rtree_start_level(rtree_t *rtree, uintptr_t key);
	uintptr_t rtree_subkey(rtree_t *rtree, uintptr_t key, unsigned level);

	bool rtree_node_valid(rtree_node_elm_t *node);
	rtree_node_elm_t rtree_child_tryread(rtree_node_elm_t elm,
	bool dependent);
	rtree_node_elm_t rtree_child_read(rtree_t rtree, rtree_node_elm_t *elm,
	unsigned level, bool dependent);
	extent_node_t rtree_val_read(rtree_t rtree, rtree_node_elm_t *elm,
	bool dependent);
	void rtree_val_write(rtree_t rtree, rtree_node_elm_t elm,
	const extent_node_t *val);
	rtree_node_elm_t rtree_subtree_tryread(rtree_t rtree, unsigned level,
	bool dependent);
	rtree_node_elm_t rtree_subtree_read(rtree_t rtree, unsigned level,
	bool dependent);

	extent_node_t rtree_get(rtree_t rtree, uintptr_t key, bool dependent);
	bool rtree_set(rtree_t rtree, uintptr_t key, const extent_node_t val);
	#endif

	#if (defined(JEMALLOC_ENABLE_INLINE) \|\| defined(JEMALLOC_RTREE_C_))
	JEMALLOC_ALWAYS_INLINE unsigned
	rtree_start_level(rtree_t *rtree, uintptr_t key)
	{
	unsigned start_level;

	if (unlikely(key == 0))
	return (rtree->height - 1);

	start_level = rtree->start_level[lg_floor(key) >>
	LG_RTREE_BITS_PER_LEVEL];
	assert(start_level < rtree->height);
	return (start_level);
	}

	JEMALLOC_ALWAYS_INLINE uintptr_t
	rtree_subkey(rtree_t *rtree, uintptr_t key, unsigned level)
	{

	return ((key >> ((ZU(1) << (LG_SIZEOF_PTR+3)) -
	rtree->levels[level].cumbits)) & ((ZU(1) <<
	rtree->levels[level].bits) - 1));
	}

	JEMALLOC_ALWAYS_INLINE bool
	rtree_node_valid(rtree_node_elm_t *node)
	{

	return ((uintptr_t)node > (uintptr_t)RTREE_NODE_INITIALIZING);
	}

	JEMALLOC_ALWAYS_INLINE rtree_node_elm_t *
	rtree_child_tryread(rtree_node_elm_t *elm, bool dependent)
	{
	rtree_node_elm_t *child;

	/* Double-checked read (first read may be stale. */
	child = elm->child;
	if (!dependent && !rtree_node_valid(child))
	child = atomic_read_p(&elm->pun);
	assert(!dependent \|\| child != NULL);
	return (child);
	}

	JEMALLOC_ALWAYS_INLINE rtree_node_elm_t *
	rtree_child_read(rtree_t rtree, rtree_node_elm_t elm, unsigned level,
	bool dependent)
	{
	rtree_node_elm_t *child;

	child = rtree_child_tryread(elm, dependent);
	if (!dependent && unlikely(!rtree_node_valid(child)))
	child = rtree_child_read_hard(rtree, elm, level);
	assert(!dependent \|\| child != NULL);
	return (child);
	}

	JEMALLOC_ALWAYS_INLINE extent_node_t *
	rtree_val_read(rtree_t rtree, rtree_node_elm_t elm, bool dependent)
	{

	if (dependent) {
	/*
	* Reading a val on behalf of a pointer to a valid allocation is
	* guaranteed to be a clean read even without synchronization,
	* because the rtree update became visible in memory before the
	* pointer came into existence.
	*/
	return (elm->val);
	} else {
	/*
	* An arbitrary read, e.g. on behalf of ivsalloc(), may not be
	* dependent on a previous rtree write, which means a stale read
	* could result if synchronization were omitted here.
	*/
	return (atomic_read_p(&elm->pun));
	}
	}

	JEMALLOC_INLINE void
	rtree_val_write(rtree_t rtree, rtree_node_elm_t elm, const extent_node_t *val)
	{

	atomic_write_p(&elm->pun, val);
	}

	JEMALLOC_ALWAYS_INLINE rtree_node_elm_t *
	rtree_subtree_tryread(rtree_t *rtree, unsigned level, bool dependent)
	{
	rtree_node_elm_t *subtree;

	/* Double-checked read (first read may be stale. */
	subtree = rtree->levels[level].subtree;
	if (!dependent && unlikely(!rtree_node_valid(subtree)))
	subtree = atomic_read_p(&rtree->levels[level].subtree_pun);
	assert(!dependent \|\| subtree != NULL);
	return (subtree);
	}

	JEMALLOC_ALWAYS_INLINE rtree_node_elm_t *
	rtree_subtree_read(rtree_t *rtree, unsigned level, bool dependent)
	{
	rtree_node_elm_t *subtree;

	subtree = rtree_subtree_tryread(rtree, level, dependent);
	if (!dependent && unlikely(!rtree_node_valid(subtree)))
	subtree = rtree_subtree_read_hard(rtree, level);
	assert(!dependent \|\| subtree != NULL);
	return (subtree);
	}

	JEMALLOC_ALWAYS_INLINE extent_node_t *
	rtree_get(rtree_t *rtree, uintptr_t key, bool dependent)
	{
	uintptr_t subkey;
	unsigned start_level;
	rtree_node_elm_t *node;

	start_level = rtree_start_level(rtree, key);

	node = rtree_subtree_tryread(rtree, start_level, dependent);
	#define RTREE_GET_BIAS (RTREE_HEIGHT_MAX - rtree->height)
	switch (start_level + RTREE_GET_BIAS) {
	#define RTREE_GET_SUBTREE(level) \
	case level: \
	assert(level < (RTREE_HEIGHT_MAX-1)); \
	if (!dependent && unlikely(!rtree_node_valid(node))) \
	return (NULL); \
	subkey = rtree_subkey(rtree, key, level - \
	RTREE_GET_BIAS); \
	node = rtree_child_tryread(&node[subkey], dependent); \
	/* Fall through. */
	#define RTREE_GET_LEAF(level) \
	case level: \
	assert(level == (RTREE_HEIGHT_MAX-1)); \
	if (!dependent && unlikely(!rtree_node_valid(node))) \
	return (NULL); \
	subkey = rtree_subkey(rtree, key, level - \
	RTREE_GET_BIAS); \
	/* \
	* node is a leaf, so it contains values rather than \
	* child pointers. \
	*/ \
	return (rtree_val_read(rtree, &node[subkey], \
	dependent));
	#if RTREE_HEIGHT_MAX > 1
	RTREE_GET_SUBTREE(0)
	#endif
	#if RTREE_HEIGHT_MAX > 2
	RTREE_GET_SUBTREE(1)
	#endif
	#if RTREE_HEIGHT_MAX > 3
	RTREE_GET_SUBTREE(2)
	#endif
	#if RTREE_HEIGHT_MAX > 4
	RTREE_GET_SUBTREE(3)
	#endif
	#if RTREE_HEIGHT_MAX > 5
	RTREE_GET_SUBTREE(4)
	#endif
	#if RTREE_HEIGHT_MAX > 6
	RTREE_GET_SUBTREE(5)
	#endif
	#if RTREE_HEIGHT_MAX > 7
	RTREE_GET_SUBTREE(6)
	#endif
	#if RTREE_HEIGHT_MAX > 8
	RTREE_GET_SUBTREE(7)
	#endif
	#if RTREE_HEIGHT_MAX > 9
	RTREE_GET_SUBTREE(8)
	#endif
	#if RTREE_HEIGHT_MAX > 10
	RTREE_GET_SUBTREE(9)
	#endif
	#if RTREE_HEIGHT_MAX > 11
	RTREE_GET_SUBTREE(10)
	#endif
	#if RTREE_HEIGHT_MAX > 12
	RTREE_GET_SUBTREE(11)
	#endif
	#if RTREE_HEIGHT_MAX > 13
	RTREE_GET_SUBTREE(12)
	#endif
	#if RTREE_HEIGHT_MAX > 14
	RTREE_GET_SUBTREE(13)
	#endif
	#if RTREE_HEIGHT_MAX > 15
	RTREE_GET_SUBTREE(14)
	#endif
	#if RTREE_HEIGHT_MAX > 16
	# error Unsupported RTREE_HEIGHT_MAX
	#endif
	RTREE_GET_LEAF(RTREE_HEIGHT_MAX-1)
	#undef RTREE_GET_SUBTREE
	#undef RTREE_GET_LEAF
	default: not_reached();
	}
	#undef RTREE_GET_BIAS
	not_reached();
	}

	JEMALLOC_INLINE bool
	rtree_set(rtree_t rtree, uintptr_t key, const extent_node_t val)
	{
	uintptr_t subkey;
	unsigned i, start_level;
	rtree_node_elm_t node, child;

	start_level = rtree_start_level(rtree, key);

	node = rtree_subtree_read(rtree, start_level, false);
	if (node == NULL)
	return (true);
	for (i = start_level; /**/; i++, node = child) {
	subkey = rtree_subkey(rtree, key, i);
	if (i == rtree->height - 1) {
	/*
	* node is a leaf, so it contains values rather than
	* child pointers.
	*/
	rtree_val_write(rtree, &node[subkey], val);
	return (false);
	}
	assert(i + 1 < rtree->height);
	child = rtree_child_read(rtree, &node[subkey], i, false);
	if (child == NULL)
	return (true);
	}
	not_reached();
	}
	#endif

	#endif /* JEMALLOC_H_INLINES */
	/******************************************************************************/