f5cf9b19c8
Rather than dynamically building a table to aid per level computations, define a constant table at compile time. Omit both high and low insignificant bits. Use one to three tree levels, depending on the number of significant bits.
230 lines
7.0 KiB
C
230 lines
7.0 KiB
C
#ifndef JEMALLOC_INTERNAL_RTREE_INLINES_H
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#define JEMALLOC_INTERNAL_RTREE_INLINES_H
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#ifndef JEMALLOC_ENABLE_INLINE
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uintptr_t rtree_leafkey(uintptr_t key);
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uintptr_t rtree_subkey(uintptr_t key, unsigned level);
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extent_t *rtree_elm_read(rtree_elm_t *elm, bool dependent);
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void rtree_elm_write(rtree_elm_t *elm, const extent_t *extent);
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rtree_elm_t *rtree_elm_lookup(tsdn_t *tsdn, rtree_t *rtree,
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rtree_ctx_t *rtree_ctx, uintptr_t key, bool dependent, bool init_missing);
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bool rtree_write(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
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uintptr_t key, const extent_t *extent);
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extent_t *rtree_read(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
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uintptr_t key, bool dependent);
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rtree_elm_t *rtree_elm_acquire(tsdn_t *tsdn, rtree_t *rtree,
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rtree_ctx_t *rtree_ctx, uintptr_t key, bool dependent, bool init_missing);
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extent_t *rtree_elm_read_acquired(tsdn_t *tsdn, const rtree_t *rtree,
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rtree_elm_t *elm);
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void rtree_elm_write_acquired(tsdn_t *tsdn, const rtree_t *rtree,
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rtree_elm_t *elm, const extent_t *extent);
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void rtree_elm_release(tsdn_t *tsdn, const rtree_t *rtree, rtree_elm_t *elm);
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void rtree_clear(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
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uintptr_t key);
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#endif
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#if (defined(JEMALLOC_ENABLE_INLINE) || defined(JEMALLOC_RTREE_C_))
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JEMALLOC_ALWAYS_INLINE uintptr_t
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rtree_leafkey(uintptr_t key) {
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unsigned ptrbits = ZU(1) << (LG_SIZEOF_PTR+3);
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unsigned cumbits = (rtree_levels[RTREE_HEIGHT-1].cumbits -
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rtree_levels[RTREE_HEIGHT-1].bits);
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unsigned maskbits = ptrbits - cumbits;
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uintptr_t mask = ~((ZU(1) << maskbits) - 1);
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return (key & mask);
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}
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JEMALLOC_ALWAYS_INLINE uintptr_t
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rtree_subkey(uintptr_t key, unsigned level) {
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unsigned ptrbits = ZU(1) << (LG_SIZEOF_PTR+3);
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unsigned cumbits = rtree_levels[level].cumbits;
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unsigned shiftbits = ptrbits - cumbits;
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unsigned maskbits = rtree_levels[level].bits;
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unsigned mask = (ZU(1) << maskbits) - 1;
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return ((key >> shiftbits) & mask);
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}
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JEMALLOC_ALWAYS_INLINE extent_t *
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rtree_elm_read(rtree_elm_t *elm, bool dependent) {
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extent_t *extent;
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if (dependent) {
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/*
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* Reading a value on behalf of a pointer to a valid allocation
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* is guaranteed to be a clean read even without
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* synchronization, because the rtree update became visible in
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* memory before the pointer came into existence.
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*/
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extent = elm->extent;
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} else {
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/*
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* An arbitrary read, e.g. on behalf of ivsalloc(), may not be
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* dependent on a previous rtree write, which means a stale read
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* could result if synchronization were omitted here.
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*/
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extent = (extent_t *)atomic_read_p(&elm->pun);
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}
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/* Mask the lock bit. */
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extent = (extent_t *)((uintptr_t)extent & ~((uintptr_t)0x1));
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return extent;
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}
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JEMALLOC_INLINE void
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rtree_elm_write(rtree_elm_t *elm, const extent_t *extent) {
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atomic_write_p(&elm->pun, extent);
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}
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JEMALLOC_ALWAYS_INLINE rtree_elm_t *
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rtree_elm_lookup(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
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uintptr_t key, bool dependent, bool init_missing) {
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assert(!dependent || !init_missing);
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if (likely(key != 0)) {
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uintptr_t leafkey = rtree_leafkey(key);
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#define RTREE_CACHE_CHECK(i) do { \
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if (likely(rtree_ctx->cache[i].leafkey == leafkey)) { \
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rtree_elm_t *leaf = rtree_ctx->cache[i].leaf; \
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if (likely(leaf != NULL)) { \
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/* Reorder. */ \
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memmove(&rtree_ctx->cache[1], \
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&rtree_ctx->cache[0], \
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sizeof(rtree_ctx_cache_elm_t) * i); \
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rtree_ctx->cache[0].leafkey = leafkey; \
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rtree_ctx->cache[0].leaf = leaf; \
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\
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uintptr_t subkey = rtree_subkey(key, \
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RTREE_HEIGHT-1); \
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return &leaf[subkey]; \
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} \
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} \
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} while (0)
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/* Check the MRU cache entry. */
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RTREE_CACHE_CHECK(0);
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/*
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* Search the remaining cache elements, and on success move the
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* matching element to the front. Unroll the first iteration to
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* avoid calling memmove() (the compiler typically optimizes it
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* into raw moves).
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*/
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if (RTREE_CTX_NCACHE > 1) {
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RTREE_CACHE_CHECK(1);
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}
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for (unsigned i = 2; i < RTREE_CTX_NCACHE; i++) {
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RTREE_CACHE_CHECK(i);
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}
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#undef RTREE_CACHE_CHECK
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}
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return rtree_elm_lookup_hard(tsdn, rtree, rtree_ctx, key, dependent,
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init_missing);
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}
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JEMALLOC_INLINE bool
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rtree_write(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx, uintptr_t key,
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const extent_t *extent) {
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rtree_elm_t *elm;
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assert(extent != NULL); /* Use rtree_clear() for this case. */
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assert(((uintptr_t)extent & (uintptr_t)0x1) == (uintptr_t)0x0);
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elm = rtree_elm_lookup(tsdn, rtree, rtree_ctx, key, false, true);
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if (elm == NULL) {
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return true;
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}
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assert(rtree_elm_read(elm, false) == NULL);
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rtree_elm_write(elm, extent);
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return false;
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}
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JEMALLOC_ALWAYS_INLINE extent_t *
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rtree_read(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx, uintptr_t key,
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bool dependent) {
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rtree_elm_t *elm;
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elm = rtree_elm_lookup(tsdn, rtree, rtree_ctx, key, dependent, false);
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if (!dependent && elm == NULL) {
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return NULL;
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}
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return rtree_elm_read(elm, dependent);
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}
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JEMALLOC_INLINE rtree_elm_t *
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rtree_elm_acquire(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
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uintptr_t key, bool dependent, bool init_missing) {
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rtree_elm_t *elm;
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elm = rtree_elm_lookup(tsdn, rtree, rtree_ctx, key, dependent,
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init_missing);
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if (!dependent && elm == NULL) {
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return NULL;
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}
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extent_t *extent;
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void *s;
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do {
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extent = rtree_elm_read(elm, false);
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/* The least significant bit serves as a lock. */
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s = (void *)((uintptr_t)extent | (uintptr_t)0x1);
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} while (atomic_cas_p(&elm->pun, (void *)extent, s));
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if (config_debug) {
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rtree_elm_witness_acquire(tsdn, rtree, key, elm);
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}
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return elm;
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}
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JEMALLOC_INLINE extent_t *
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rtree_elm_read_acquired(tsdn_t *tsdn, const rtree_t *rtree, rtree_elm_t *elm) {
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extent_t *extent;
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assert(((uintptr_t)elm->pun & (uintptr_t)0x1) == (uintptr_t)0x1);
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extent = (extent_t *)((uintptr_t)elm->pun & ~((uintptr_t)0x1));
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assert(((uintptr_t)extent & (uintptr_t)0x1) == (uintptr_t)0x0);
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if (config_debug) {
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rtree_elm_witness_access(tsdn, rtree, elm);
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}
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return extent;
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}
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JEMALLOC_INLINE void
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rtree_elm_write_acquired(tsdn_t *tsdn, const rtree_t *rtree, rtree_elm_t *elm,
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const extent_t *extent) {
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assert(((uintptr_t)extent & (uintptr_t)0x1) == (uintptr_t)0x0);
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assert(((uintptr_t)elm->pun & (uintptr_t)0x1) == (uintptr_t)0x1);
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if (config_debug) {
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rtree_elm_witness_access(tsdn, rtree, elm);
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}
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elm->pun = (void *)((uintptr_t)extent | (uintptr_t)0x1);
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assert(rtree_elm_read_acquired(tsdn, rtree, elm) == extent);
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}
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JEMALLOC_INLINE void
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rtree_elm_release(tsdn_t *tsdn, const rtree_t *rtree, rtree_elm_t *elm) {
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rtree_elm_write(elm, rtree_elm_read_acquired(tsdn, rtree, elm));
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if (config_debug) {
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rtree_elm_witness_release(tsdn, rtree, elm);
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}
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}
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JEMALLOC_INLINE void
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rtree_clear(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
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uintptr_t key) {
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rtree_elm_t *elm;
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elm = rtree_elm_acquire(tsdn, rtree, rtree_ctx, key, true, false);
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rtree_elm_write_acquired(tsdn, rtree, elm, NULL);
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rtree_elm_release(tsdn, rtree, elm);
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}
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#endif
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#endif /* JEMALLOC_INTERNAL_RTREE_INLINES_H */
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