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Make dlmalloc a little faster

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This change also documents the libc arena allocator.
This commit is contained in:
Justine Tunney 2022-06-09 18:48:15 -07:00
parent fa1e8a3e65
commit a41669dec6
5 changed files with 59 additions and 19 deletions
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12
third_party/dlmalloc/dlmalloc.c vendored
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@ -1,4 +1,5 @@
#include "libc/assert.h"
#include "libc/bits/likely.h"
#include "libc/bits/weaken.h"
#include "libc/calls/calls.h"
#include "libc/dce.h"
@ -22,7 +23,7 @@
#define HAVE_MMAP 1
#define HAVE_MREMAP 0
#define HAVE_MORECORE 0
#define USE_LOCKS 1
#define USE_SPIN_LOCKS 1
#define MORECORE_CONTIGUOUS 0
#define MALLOC_INSPECT_ALL 1
@ -820,12 +821,7 @@ void dlfree(void* mem) {
void* dlcalloc(size_t n_elements, size_t elem_size) {
void* mem;
size_t req = 0;
if (n_elements != 0) {
req = n_elements * elem_size;
if (((n_elements | elem_size) & ~(size_t)0xffff) &&
(req / n_elements != elem_size))
req = MAX_SIZE_T; /* force downstream failure on overflow */
}
if (__builtin_mul_overflow(n_elements, elem_size, &req)) req = -1;
mem = dlmalloc(req);
if (mem != 0 && calloc_must_clear(mem2chunk(mem)))
bzero(mem, req);
@ -1216,7 +1212,7 @@ void* dlrealloc(void* oldmem, size_t bytes) {
if (oldmem == 0) {
mem = dlmalloc(bytes);
}
else if (bytes >= MAX_REQUEST) {
else if (UNLIKELY(bytes >= MAX_REQUEST)) {
MALLOC_FAILURE_ACTION;
}
#ifdef REALLOC_ZERO_BYTES_FREES