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+#ifndef JEMALLOC_INTERNAL_SIZE_H
+#define JEMALLOC_INTERNAL_SIZE_H
+
+#include "jemalloc/internal/bit_util.h"
+#include "jemalloc/internal/pages.h"
+#include "jemalloc/internal/sc.h"
+#include "jemalloc/internal/util.h"
+
+/*
+ * sz module: Size computations.
+ *
+ * Some abbreviations used here:
+ * p: Page
+ * ind: Index
+ * s, sz: Size
+ * u: Usable size
+ * a: Aligned
+ *
+ * These are not always used completely consistently, but should be enough to
+ * interpret function names. E.g. sz_psz2ind converts page size to page size
+ * index; sz_sa2u converts a (size, alignment) allocation request to the usable
+ * size that would result from such an allocation.
+ */
+
+/* Page size index type. */
+typedef unsigned pszind_t;
+
+/* Size class index type. */
+typedef unsigned szind_t;
+
+/*
+ * sz_pind2sz_tab encodes the same information as could be computed by
+ * sz_pind2sz_compute().
+ */
+extern size_t sz_pind2sz_tab[SC_NPSIZES + 1];
+/*
+ * sz_index2size_tab encodes the same information as could be computed (at
+ * unacceptable cost in some code paths) by sz_index2size_compute().
+ */
+extern size_t sz_index2size_tab[SC_NSIZES];
+/*
+ * sz_size2index_tab is a compact lookup table that rounds request sizes up to
+ * size classes. In order to reduce cache footprint, the table is compressed,
+ * and all accesses are via sz_size2index().
+ */
+extern uint8_t sz_size2index_tab[];
+
+/*
+ * Padding for large allocations: PAGE when opt_cache_oblivious == true (to
+ * enable cache index randomization); 0 otherwise.
+ */
+extern size_t sz_large_pad;
+
+extern void sz_boot(const sc_data_t *sc_data, bool cache_oblivious);
+
+JEMALLOC_ALWAYS_INLINE pszind_t
+sz_psz2ind(size_t psz) {
+ assert(psz > 0);
+ if (unlikely(psz > SC_LARGE_MAXCLASS)) {
+ return SC_NPSIZES;
+ }
+ /* x is the lg of the first base >= psz. */
+ pszind_t x = lg_ceil(psz);
+ /*
+ * sc.h introduces a lot of size classes. These size classes are divided
+ * into different size class groups. There is a very special size class
+ * group, each size class in or after it is an integer multiple of PAGE.
+ * We call it first_ps_rg. It means first page size regular group. The
+ * range of first_ps_rg is (base, base * 2], and base == PAGE *
+ * SC_NGROUP. off_to_first_ps_rg begins from 1, instead of 0. e.g.
+ * off_to_first_ps_rg is 1 when psz is (PAGE * SC_NGROUP + 1).
+ */
+ pszind_t off_to_first_ps_rg = (x < SC_LG_NGROUP + LG_PAGE) ?
+ 0 : x - (SC_LG_NGROUP + LG_PAGE);
+
+ /*
+ * Same as sc_s::lg_delta.
+ * Delta for off_to_first_ps_rg == 1 is PAGE,
+ * for each increase in offset, it's multiplied by two.
+ * Therefore, lg_delta = LG_PAGE + (off_to_first_ps_rg - 1).
+ */
+ pszind_t lg_delta = (off_to_first_ps_rg == 0) ?
+ LG_PAGE : LG_PAGE + (off_to_first_ps_rg - 1);
+
+ /*
+ * Let's write psz in binary, e.g. 0011 for 0x3, 0111 for 0x7.
+ * The leftmost bits whose len is lg_base decide the base of psz.
+ * The rightmost bits whose len is lg_delta decide (pgz % PAGE).
+ * The middle bits whose len is SC_LG_NGROUP decide ndelta.
+ * ndelta is offset to the first size class in the size class group,
+ * starts from 1.
+ * If you don't know lg_base, ndelta or lg_delta, see sc.h.
+ * |xxxxxxxxxxxxxxxxxxxx|------------------------|yyyyyyyyyyyyyyyyyyyyy|
+ * |<-- len: lg_base -->|<-- len: SC_LG_NGROUP-->|<-- len: lg_delta -->|
+ * |<-- ndelta -->|
+ * rg_inner_off = ndelta - 1
+ * Why use (psz - 1)?
+ * To handle case: psz % (1 << lg_delta) == 0.
+ */
+ pszind_t rg_inner_off = (((psz - 1)) >> lg_delta) & (SC_NGROUP - 1);
+
+ pszind_t base_ind = off_to_first_ps_rg << SC_LG_NGROUP;
+ pszind_t ind = base_ind + rg_inner_off;
+ return ind;
+}
+
+static inline size_t
+sz_pind2sz_compute(pszind_t pind) {
+ if (unlikely(pind == SC_NPSIZES)) {
+ return SC_LARGE_MAXCLASS + PAGE;
+ }
+ size_t grp = pind >> SC_LG_NGROUP;
+ size_t mod = pind & ((ZU(1) << SC_LG_NGROUP) - 1);
+
+ size_t grp_size_mask = ~((!!grp)-1);
+ size_t grp_size = ((ZU(1) << (LG_PAGE + (SC_LG_NGROUP-1))) << grp)
+ & grp_size_mask;
+
+ size_t shift = (grp == 0) ? 1 : grp;
+ size_t lg_delta = shift + (LG_PAGE-1);
+ size_t mod_size = (mod+1) << lg_delta;
+
+ size_t sz = grp_size + mod_size;
+ return sz;
+}
+
+static inline size_t
+sz_pind2sz_lookup(pszind_t pind) {
+ size_t ret = (size_t)sz_pind2sz_tab[pind];
+ assert(ret == sz_pind2sz_compute(pind));
+ return ret;
+}
+
+static inline size_t
+sz_pind2sz(pszind_t pind) {
+ assert(pind < SC_NPSIZES + 1);
+ return sz_pind2sz_lookup(pind);
+}
+
+static inline size_t
+sz_psz2u(size_t psz) {
+ if (unlikely(psz > SC_LARGE_MAXCLASS)) {
+ return SC_LARGE_MAXCLASS + PAGE;
+ }
+ size_t x = lg_floor((psz<<1)-1);
+ size_t lg_delta = (x < SC_LG_NGROUP + LG_PAGE + 1) ?
+ LG_PAGE : x - SC_LG_NGROUP - 1;
+ size_t delta = ZU(1) << lg_delta;
+ size_t delta_mask = delta - 1;
+ size_t usize = (psz + delta_mask) & ~delta_mask;
+ return usize;
+}
+
+static inline szind_t
+sz_size2index_compute(size_t size) {
+ if (unlikely(size > SC_LARGE_MAXCLASS)) {
+ return SC_NSIZES;
+ }
+
+ if (size == 0) {
+ return 0;
+ }
+#if (SC_NTINY != 0)
+ if (size <= (ZU(1) << SC_LG_TINY_MAXCLASS)) {
+ szind_t lg_tmin = SC_LG_TINY_MAXCLASS - SC_NTINY + 1;
+ szind_t lg_ceil = lg_floor(pow2_ceil_zu(size));
+ return (lg_ceil < lg_tmin ? 0 : lg_ceil - lg_tmin);
+ }
+#endif
+ {
+ szind_t x = lg_floor((size<<1)-1);
+ szind_t shift = (x < SC_LG_NGROUP + LG_QUANTUM) ? 0 :
+ x - (SC_LG_NGROUP + LG_QUANTUM);
+ szind_t grp = shift << SC_LG_NGROUP;
+
+ szind_t lg_delta = (x < SC_LG_NGROUP + LG_QUANTUM + 1)
+ ? LG_QUANTUM : x - SC_LG_NGROUP - 1;
+
+ size_t delta_inverse_mask = ZU(-1) << lg_delta;
+ szind_t mod = ((((size-1) & delta_inverse_mask) >> lg_delta)) &
+ ((ZU(1) << SC_LG_NGROUP) - 1);
+
+ szind_t index = SC_NTINY + grp + mod;
+ return index;
+ }
+}
+
+JEMALLOC_ALWAYS_INLINE szind_t
+sz_size2index_lookup_impl(size_t size) {
+ assert(size <= SC_LOOKUP_MAXCLASS);
+ return sz_size2index_tab[(size + (ZU(1) << SC_LG_TINY_MIN) - 1)
+ >> SC_LG_TINY_MIN];
+}
+
+JEMALLOC_ALWAYS_INLINE szind_t
+sz_size2index_lookup(size_t size) {
+ szind_t ret = sz_size2index_lookup_impl(size);
+ assert(ret == sz_size2index_compute(size));
+ return ret;
+}
+
+JEMALLOC_ALWAYS_INLINE szind_t
+sz_size2index(size_t size) {
+ if (likely(size <= SC_LOOKUP_MAXCLASS)) {
+ return sz_size2index_lookup(size);
+ }
+ return sz_size2index_compute(size);
+}
+
+static inline size_t
+sz_index2size_compute(szind_t index) {
+#if (SC_NTINY > 0)
+ if (index < SC_NTINY) {
+ return (ZU(1) << (SC_LG_TINY_MAXCLASS - SC_NTINY + 1 + index));
+ }
+#endif
+ {
+ size_t reduced_index = index - SC_NTINY;
+ size_t grp = reduced_index >> SC_LG_NGROUP;
+ size_t mod = reduced_index & ((ZU(1) << SC_LG_NGROUP) -
+ 1);
+
+ size_t grp_size_mask = ~((!!grp)-1);
+ size_t grp_size = ((ZU(1) << (LG_QUANTUM +
+ (SC_LG_NGROUP-1))) << grp) & grp_size_mask;
+
+ size_t shift = (grp == 0) ? 1 : grp;
+ size_t lg_delta = shift + (LG_QUANTUM-1);
+ size_t mod_size = (mod+1) << lg_delta;
+
+ size_t usize = grp_size + mod_size;
+ return usize;
+ }
+}
+
+JEMALLOC_ALWAYS_INLINE size_t
+sz_index2size_lookup_impl(szind_t index) {
+ return sz_index2size_tab[index];
+}
+
+JEMALLOC_ALWAYS_INLINE size_t
+sz_index2size_lookup(szind_t index) {
+ size_t ret = sz_index2size_lookup_impl(index);
+ assert(ret == sz_index2size_compute(index));
+ return ret;
+}
+
+JEMALLOC_ALWAYS_INLINE size_t
+sz_index2size(szind_t index) {
+ assert(index < SC_NSIZES);
+ return sz_index2size_lookup(index);
+}
+
+JEMALLOC_ALWAYS_INLINE void
+sz_size2index_usize_fastpath(size_t size, szind_t *ind, size_t *usize) {
+ *ind = sz_size2index_lookup_impl(size);
+ *usize = sz_index2size_lookup_impl(*ind);
+}
+
+JEMALLOC_ALWAYS_INLINE size_t
+sz_s2u_compute(size_t size) {
+ if (unlikely(size > SC_LARGE_MAXCLASS)) {
+ return 0;
+ }
+
+ if (size == 0) {
+ size++;
+ }
+#if (SC_NTINY > 0)
+ if (size <= (ZU(1) << SC_LG_TINY_MAXCLASS)) {
+ size_t lg_tmin = SC_LG_TINY_MAXCLASS - SC_NTINY + 1;
+ size_t lg_ceil = lg_floor(pow2_ceil_zu(size));
+ return (lg_ceil < lg_tmin ? (ZU(1) << lg_tmin) :
+ (ZU(1) << lg_ceil));
+ }
+#endif
+ {
+ size_t x = lg_floor((size<<1)-1);
+ size_t lg_delta = (x < SC_LG_NGROUP + LG_QUANTUM + 1)
+ ? LG_QUANTUM : x - SC_LG_NGROUP - 1;
+ size_t delta = ZU(1) << lg_delta;
+ size_t delta_mask = delta - 1;
+ size_t usize = (size + delta_mask) & ~delta_mask;
+ return usize;
+ }
+}
+
+JEMALLOC_ALWAYS_INLINE size_t
+sz_s2u_lookup(size_t size) {
+ size_t ret = sz_index2size_lookup(sz_size2index_lookup(size));
+
+ assert(ret == sz_s2u_compute(size));
+ return ret;
+}
+
+/*
+ * Compute usable size that would result from allocating an object with the
+ * specified size.
+ */
+JEMALLOC_ALWAYS_INLINE size_t
+sz_s2u(size_t size) {
+ if (likely(size <= SC_LOOKUP_MAXCLASS)) {
+ return sz_s2u_lookup(size);
+ }
+ return sz_s2u_compute(size);
+}
+
+/*
+ * Compute usable size that would result from allocating an object with the
+ * specified size and alignment.
+ */
+JEMALLOC_ALWAYS_INLINE size_t
+sz_sa2u(size_t size, size_t alignment) {
+ size_t usize;
+
+ assert(alignment != 0 && ((alignment - 1) & alignment) == 0);
+
+ /* Try for a small size class. */
+ if (size <= SC_SMALL_MAXCLASS && alignment <= PAGE) {
+ /*
+ * Round size up to the nearest multiple of alignment.
+ *
+ * This done, we can take advantage of the fact that for each
+ * small size class, every object is aligned at the smallest
+ * power of two that is non-zero in the base two representation
+ * of the size. For example:
+ *
+ * Size | Base 2 | Minimum alignment
+ * -----+----------+------------------
+ * 96 | 1100000 | 32
+ * 144 | 10100000 | 32
+ * 192 | 11000000 | 64
+ */
+ usize = sz_s2u(ALIGNMENT_CEILING(size, alignment));
+ if (usize < SC_LARGE_MINCLASS) {
+ return usize;
+ }
+ }
+
+ /* Large size class. Beware of overflow. */
+
+ if (unlikely(alignment > SC_LARGE_MAXCLASS)) {
+ return 0;
+ }
+
+ /* Make sure result is a large size class. */
+ if (size <= SC_LARGE_MINCLASS) {
+ usize = SC_LARGE_MINCLASS;
+ } else {
+ usize = sz_s2u(size);
+ if (usize < size) {
+ /* size_t overflow. */
+ return 0;
+ }
+ }
+
+ /*
+ * Calculate the multi-page mapping that large_palloc() would need in
+ * order to guarantee the alignment.
+ */
+ if (usize + sz_large_pad + PAGE_CEILING(alignment) - PAGE < usize) {
+ /* size_t overflow. */
+ return 0;
+ }
+ return usize;
+}
+
+size_t sz_psz_quantize_floor(size_t size);
+size_t sz_psz_quantize_ceil(size_t size);
+
+#endif /* JEMALLOC_INTERNAL_SIZE_H */