project-base/server-skynet-source-3rd-jemalloc
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Optimize compute_size_with_overflow().

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Do not check for overflow unless it is actually a possibility.
This commit is contained in:
Jason Evans 2017-02-03 15:33:37 -08:00
parent 767ffa2b5f
commit 1bac516aaa
1 changed files with 16 additions and 5 deletions
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21
src/jemalloc.c
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@ -1362,6 +1362,8 @@ malloc_init_hard(void) {
*/
typedef struct static_opts_s static_opts_t;
struct static_opts_s {
/* Whether or not allocation size may overflow. */
bool may_overflow;
/* Whether or not allocations of size 0 should be treated as size 1. */
bool bump_empty_alloc;
/*
@ -1400,6 +1402,7 @@ struct static_opts_s {
JEMALLOC_ALWAYS_INLINE_C void
static_opts_init(static_opts_t *static_opts) {
static_opts->may_overflow = false;
static_opts->bump_empty_alloc = false;
static_opts->assert_nonempty_alloc = false;
static_opts->null_out_result_on_error = false;
@ -1514,12 +1517,19 @@ imalloc_sample(static_opts_t *sopts, dynamic_opts_t *dopts, tsd_t *tsd,
* *size to the product either way.
*/
JEMALLOC_ALWAYS_INLINE_C bool
compute_size_with_overflow(dynamic_opts_t *dopts, size_t *size) {
compute_size_with_overflow(bool may_overflow, dynamic_opts_t *dopts,
size_t *size) {
/*
* This function is just num_items * item_size, except that we have to
* check for overflow.
* This function is just num_items * item_size, except that we may have
* to check for overflow.
*/
if (!may_overflow) {
assert(dopts->num_items == 1);
*size = dopts->item_size;
return false;
}
/* A size_t with its high-half bits all set to 1. */
const static size_t high_bits = SIZE_T_MAX << (sizeof(size_t) * 8 / 2);
@ -1572,8 +1582,8 @@ imalloc_body(static_opts_t *sopts, dynamic_opts_t *dopts) {
}
/* Compute the amount of memory the user wants. */
bool overflow = compute_size_with_overflow(dopts, &size);
if (unlikely(overflow)) {
if (unlikely(compute_size_with_overflow(sopts->may_overflow, dopts,
&size))) {
goto label_oom;
}
@ -1843,6 +1853,7 @@ je_calloc(size_t num, size_t size) {
static_opts_init(&sopts);
dynamic_opts_init(&dopts);
sopts.may_overflow = true;
sopts.bump_empty_alloc = true;
sopts.null_out_result_on_error = true;
sopts.set_errno_on_error = true;