use libdivide for substantially faster division
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63b0c39343
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c7b24f63f1
File diff suppressed because it is too large
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19
malloc.c
19
malloc.c
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@ -12,6 +12,8 @@
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#include <malloc.h>
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#include "libdivide.h"
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#include "malloc.h"
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#include "random.h"
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#include "util.h"
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@ -186,6 +188,8 @@ static struct size_class {
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struct slab_metadata *slab_info;
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struct slab_metadata *partial_slabs;
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struct slab_metadata *free_slabs;
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struct libdivide_u32_t size_divisor;
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struct libdivide_u64_t slab_size_divisor;
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struct random_state rng;
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size_t metadata_allocated;
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size_t metadata_count;
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@ -285,14 +289,9 @@ static void *get_slab(struct size_class *c, size_t slab_size, struct slab_metada
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return (char *)c->class_region_start + (index * slab_size);
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}
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static struct slab_metadata *get_metadata(struct size_class *c, size_t slab_size, void *p) {
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static struct slab_metadata *get_metadata(struct size_class *c, void *p) {
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size_t offset = (char *)p - (char *)c->class_region_start;
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size_t index;
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if (slab_size == PAGE_SIZE) {
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index = offset >> PAGE_SHIFT;
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} else {
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index = offset / slab_size;
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}
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size_t index = libdivide_u64_do(offset, &c->slab_size_divisor);
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// still caught without this check either as a read access violation or "double free"
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if (index >= c->metadata_allocated) {
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fatal_error("invalid free within a slab yet to be used");
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@ -401,9 +400,9 @@ static void slab_free(void *p) {
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pthread_mutex_lock(&c->mutex);
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struct slab_metadata *metadata = get_metadata(c, slab_size, p);
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struct slab_metadata *metadata = get_metadata(c, p);
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void *slab = get_slab(c, slab_size, metadata);
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size_t slot = ((char *)p - (char *)slab) / size;
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size_t slot = libdivide_u32_do((char *)p - (char *)slab, &c->size_divisor);
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if (slot_pointer(size, slab, slot) != p) {
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fatal_error("invalid unaligned free");
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@ -637,6 +636,8 @@ COLD static void init_slow_path(void) {
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if (size == 0) {
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size = 16;
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}
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c->size_divisor = libdivide_u32_gen(size);
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c->slab_size_divisor = libdivide_u64_gen(get_slab_size(size_class_slots[i], size));
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size_t slots = size_class_slots[i];
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size_t metadata_max = get_metadata_max(get_slab_size(slots, size));
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c->slab_info = allocate_pages(metadata_max * sizeof(struct slab_metadata), PAGE_SIZE, false);
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