mirror of https://github.com/rui314/chibicc
Add string hashmap
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24
chibicc.h
24
chibicc.h
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@ -409,6 +409,30 @@ bool is_ident1(uint32_t c);
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bool is_ident2(uint32_t c);
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int display_width(char *p, int len);
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//
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// hashmap.c
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//
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typedef struct {
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char *key;
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int keylen;
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void *val;
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} HashEntry;
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typedef struct {
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HashEntry *buckets;
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int capacity;
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int used;
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} HashMap;
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void *hashmap_get(HashMap *map, char *key);
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void *hashmap_get2(HashMap *map, char *key, int keylen);
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void hashmap_put(HashMap *map, char *key, void *val);
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void hashmap_put2(HashMap *map, char *key, int keylen, void *val);
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void hashmap_delete(HashMap *map, char *key);
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void hashmap_delete2(HashMap *map, char *key, int keylen);
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void hashmap_test(void);
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//
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// main.c
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//
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@ -0,0 +1,165 @@
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// This is an implementation of the open-addressing hash table.
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#include "chibicc.h"
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// Initial hash bucket size
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#define INIT_SIZE 16
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// Rehash if the usage exceeds 70%.
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#define HIGH_WATERMARK 70
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// We'll keep the usage below 50% after rehashing.
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#define LOW_WATERMARK 50
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// Represents a deleted hash entry
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#define TOMBSTONE ((void *)-1)
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static uint64_t fnv_hash(char *s, int len) {
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uint64_t hash = 0xcbf29ce484222325;
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for (int i = 0; i < len; i++) {
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hash *= 0x100000001b3;
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hash ^= (unsigned char)s[i];
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}
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return hash;
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}
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// Make room for new entires in a given hashmap by removing
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// tombstones and possibly extending the bucket size.
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static void rehash(HashMap *map) {
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// Compute the size of the new hashmap.
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int nkeys = 0;
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for (int i = 0; i < map->capacity; i++)
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if (map->buckets[i].key && map->buckets[i].key != TOMBSTONE)
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nkeys++;
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int cap = map->capacity;
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while ((nkeys * 100) / cap >= LOW_WATERMARK)
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cap = cap * 2;
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assert(cap > 0);
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// Create a new hashmap and copy all key-values.
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HashMap map2 = {};
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map2.buckets = calloc(cap, sizeof(HashEntry));
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map2.capacity = cap;
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for (int i = 0; i < map->capacity; i++) {
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HashEntry *ent = &map->buckets[i];
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if (ent->key && ent->key != TOMBSTONE)
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hashmap_put2(&map2, ent->key, ent->keylen, ent->val);
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}
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assert(map2.used == nkeys);
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*map = map2;
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}
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static bool match(HashEntry *ent, char *key, int keylen) {
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return ent->key && ent->key != TOMBSTONE &&
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ent->keylen == keylen && memcmp(ent->key, key, keylen) == 0;
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}
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static HashEntry *get_entry(HashMap *map, char *key, int keylen) {
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if (!map->buckets)
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return NULL;
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uint64_t hash = fnv_hash(key, keylen);
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for (int i = 0; i < map->capacity; i++) {
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HashEntry *ent = &map->buckets[(hash + i) % map->capacity];
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if (match(ent, key, keylen))
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return ent;
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if (ent->key == NULL)
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return NULL;
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}
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unreachable();
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}
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static HashEntry *get_or_insert_entry(HashMap *map, char *key, int keylen) {
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if (!map->buckets) {
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map->buckets = calloc(INIT_SIZE, sizeof(HashEntry));
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map->capacity = INIT_SIZE;
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} else if ((map->used * 100) / map->capacity >= HIGH_WATERMARK) {
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rehash(map);
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}
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uint64_t hash = fnv_hash(key, keylen);
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for (int i = 0; i < map->capacity; i++) {
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HashEntry *ent = &map->buckets[(hash + i) % map->capacity];
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if (match(ent, key, keylen))
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return ent;
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if (ent->key == TOMBSTONE) {
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ent->key = key;
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ent->keylen = keylen;
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return ent;
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}
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if (ent->key == NULL) {
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ent->key = key;
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ent->keylen = keylen;
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map->used++;
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return ent;
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}
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}
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unreachable();
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}
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void *hashmap_get(HashMap *map, char *key) {
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return hashmap_get2(map, key, strlen(key));
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}
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void *hashmap_get2(HashMap *map, char *key, int keylen) {
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HashEntry *ent = get_entry(map, key, keylen);
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return ent ? ent->val : NULL;
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}
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void hashmap_put(HashMap *map, char *key, void *val) {
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hashmap_put2(map, key, strlen(key), val);
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}
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void hashmap_put2(HashMap *map, char *key, int keylen, void *val) {
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HashEntry *ent = get_or_insert_entry(map, key, keylen);
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ent->val = val;
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}
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void hashmap_delete(HashMap *map, char *key) {
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hashmap_delete2(map, key, strlen(key));
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}
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void hashmap_delete2(HashMap *map, char *key, int keylen) {
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HashEntry *ent = get_entry(map, key, keylen);
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if (ent)
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ent->key = TOMBSTONE;
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}
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void hashmap_test(void) {
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HashMap *map = calloc(1, sizeof(HashMap));
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for (int i = 0; i < 5000; i++)
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hashmap_put(map, format("key %d", i), (void *)(size_t)i);
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for (int i = 1000; i < 2000; i++)
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hashmap_delete(map, format("key %d", i));
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for (int i = 1500; i < 1600; i++)
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hashmap_put(map, format("key %d", i), (void *)(size_t)i);
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for (int i = 6000; i < 7000; i++)
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hashmap_put(map, format("key %d", i), (void *)(size_t)i);
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for (int i = 0; i < 1000; i++)
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assert((size_t)hashmap_get(map, format("key %d", i)) == i);
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for (int i = 1000; i < 1500; i++)
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assert(hashmap_get(map, "no such key") == NULL);
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for (int i = 1500; i < 1600; i++)
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assert((size_t)hashmap_get(map, format("key %d", i)) == i);
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for (int i = 1600; i < 2000; i++)
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assert(hashmap_get(map, "no such key") == NULL);
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for (int i = 2000; i < 5000; i++)
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assert((size_t)hashmap_get(map, format("key %d", i)) == i);
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for (int i = 5000; i < 6000; i++)
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assert(hashmap_get(map, "no such key") == NULL);
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for (int i = 6000; i < 7000; i++)
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hashmap_put(map, format("key %d", i), (void *)(size_t)i);
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assert(hashmap_get(map, "no such key") == NULL);
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printf("OK\n");
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}
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5
main.c
5
main.c
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@ -191,6 +191,11 @@ static void parse_args(int argc, char **argv) {
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continue;
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}
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if (!strcmp(argv[i], "-hashmap-test")) {
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hashmap_test();
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exit(0);
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}
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// These options are ignored for now.
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if (!strncmp(argv[i], "-O", 2) ||
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!strncmp(argv[i], "-W", 2) ||
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@ -218,4 +218,7 @@ echo 'void foo(); void bar(); int main() { foo(); bar(); }' > $tmp/main.c
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$chibicc -o $tmp/foo $tmp/main.c $tmp/foo.so
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check '.so'
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$chibicc -hashmap-test
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check 'hashmap'
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echo OK
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