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[ruby/prism] Make the locals set switch from list to hash dynamically
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ruby/prism@c977c4c98a
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@kddnewton @matzbot
kddnewton authored and matzbot committed Apr 5, 2024
1 parent 358aeb1 commit 540cc88
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Showing 2 changed files with 83 additions and 45 deletions.
126 changes: 82 additions & 44 deletions prism/prism.c
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Expand Up @@ -676,6 +676,11 @@ pm_parser_warn_node(pm_parser_t *parser, const pm_node_t *node, pm_diagnostic_id
/* Local variable-related functions */
/******************************************************************************/

/**
* The point at which the set of locals switches from being a list to a hash.
*/
#define PM_LOCALS_HASH_THRESHOLD 9

static void
pm_locals_free(pm_locals_t *locals) {
if (locals->capacity > 0) {
Expand All @@ -699,21 +704,31 @@ pm_locals_hash(pm_constant_id_t name) {

static void
pm_locals_rehash(pm_locals_t *locals) {
uint32_t next_capacity = locals->capacity == 0 ? 8 : (locals->capacity * 2);
pm_local_t *next_locals;
uint32_t next_capacity = locals->capacity == 0 ? 4 : (locals->capacity * 2);
assert(next_capacity > locals->capacity);

pm_local_t *next_locals = xcalloc(next_capacity, sizeof(pm_local_t));
if (next_locals == NULL) abort();
if (next_capacity < PM_LOCALS_HASH_THRESHOLD) {
next_locals = xmalloc(next_capacity * sizeof(pm_local_t));
if (next_locals == NULL) abort();

uint32_t mask = next_capacity - 1;
for (uint32_t index = 0; index < locals->capacity; index++) {
pm_local_t *local = &locals->locals[index];
if (locals->size > 0) {
memcpy(next_locals, locals->locals, locals->size * sizeof(pm_local_t));
}
} else {
next_locals = xcalloc(next_capacity, sizeof(pm_local_t));
if (next_locals == NULL) abort();

if (local->name != PM_CONSTANT_ID_UNSET) {
uint32_t hash = local->hash;
uint32_t mask = next_capacity - 1;
for (uint32_t index = 0; index < locals->capacity; index++) {
pm_local_t *local = &locals->locals[index];

while (next_locals[hash & mask].name != PM_CONSTANT_ID_UNSET) hash++;
next_locals[hash & mask] = *local;
if (local->name != PM_CONSTANT_ID_UNSET) {
uint32_t hash = local->hash;

while (next_locals[hash & mask].name != PM_CONSTANT_ID_UNSET) hash++;
next_locals[hash & mask] = *local;
}
}
}

Expand All @@ -734,27 +749,45 @@ pm_locals_write(pm_locals_t *locals, pm_constant_id_t name) {
pm_locals_rehash(locals);
}

uint32_t mask = locals->capacity - 1;
uint32_t hash = pm_locals_hash(name);
uint32_t initial_hash = hash;
if (locals->capacity < PM_LOCALS_HASH_THRESHOLD) {
for (uint32_t index = 0; index < locals->capacity; index++) {
pm_local_t *local = &locals->locals[index];

do {
pm_local_t *local = &locals->locals[hash & mask];

if (local->name == PM_CONSTANT_ID_UNSET) {
*local = (pm_local_t) {
.name = name,
.index = locals->size++,
.reads = 0,
.hash = hash
};
return true;
} else if (local->name == name) {
return false;
} else {
hash++;
if (local->name == PM_CONSTANT_ID_UNSET) {
*local = (pm_local_t) {
.name = name,
.index = locals->size++,
.reads = 0,
.hash = pm_locals_hash(name)
};
return true;
} else if (local->name == name) {
return false;
}
}
} while ((hash & mask) != initial_hash);
} else {
uint32_t mask = locals->capacity - 1;
uint32_t hash = pm_locals_hash(name);
uint32_t initial_hash = hash;

do {
pm_local_t *local = &locals->locals[hash & mask];

if (local->name == PM_CONSTANT_ID_UNSET) {
*local = (pm_local_t) {
.name = name,
.index = locals->size++,
.reads = 0,
.hash = hash
};
return true;
} else if (local->name == name) {
return false;
} else {
hash++;
}
} while ((hash & mask) != initial_hash);
}

assert(false && "unreachable");
}
Expand All @@ -765,23 +798,28 @@ pm_locals_write(pm_locals_t *locals, pm_constant_id_t name) {
*/
static uint32_t
pm_locals_find(pm_locals_t *locals, pm_constant_id_t name) {
if (locals->capacity == 0) return UINT32_MAX;

uint32_t mask = locals->capacity - 1;
uint32_t hash = pm_locals_hash(name);
uint32_t initial_hash = hash & mask;
if (locals->capacity < PM_LOCALS_HASH_THRESHOLD) {
for (uint32_t index = 0; index < locals->size; index++) {
pm_local_t *local = &locals->locals[index];
if (local->name == name) return index;
}
} else {
uint32_t mask = locals->capacity - 1;
uint32_t hash = pm_locals_hash(name);
uint32_t initial_hash = hash & mask;

do {
pm_local_t *local = &locals->locals[hash & mask];
do {
pm_local_t *local = &locals->locals[hash & mask];

if (local->name == PM_CONSTANT_ID_UNSET) {
return UINT32_MAX;
} else if (local->name == name) {
return hash & mask;
} else {
hash++;
}
} while ((hash & mask) != initial_hash);
if (local->name == PM_CONSTANT_ID_UNSET) {
return UINT32_MAX;
} else if (local->name == name) {
return hash & mask;
} else {
hash++;
}
} while ((hash & mask) != initial_hash);
}

return UINT32_MAX;
}
Expand Down
2 changes: 1 addition & 1 deletion prism/util/pm_constant_pool.c
View file
Expand Up @@ -15,7 +15,7 @@ pm_constant_id_list_init(pm_constant_id_list_t *list) {
*/
void
pm_constant_id_list_init_capacity(pm_constant_id_list_t *list, size_t capacity) {
list->ids = xmalloc(sizeof(pm_constant_id_t) * capacity);
list->ids = xcalloc(capacity, sizeof(pm_constant_id_t));
if (list->ids == NULL) abort();

list->size = 0;
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