py/qstr: Change qstr hash type from mp_uint_t to size_t.

The hash is either 8 or 16 bits (depending on MICROPY_QSTR_BYTES_IN_HASH)
so will fit in a size_t.

This saves 268 bytes on the unix nanbox build.  Non-nanbox configurations
are unchanged because mp_uint_t is the same size as size_t.

Signed-off-by: Damien George <damien@micropython.org>

py/objstr.h

@@ -30,7 +30,7 @@
 
 typedef struct _mp_obj_str_t {
     mp_obj_base_t base;
-    mp_uint_t hash;
+    size_t hash;
     // len == number of bytes used in data, alloc = len + 1 because (at the moment) we also append a null byte
     size_t len;
     const byte *data;
@@ -41,7 +41,7 @@ typedef struct _mp_obj_str_t {
 // use this macro to extract the string hash
 // warning: the hash can be 0, meaning invalid, and must then be explicitly computed from the data
 #define GET_STR_HASH(str_obj_in, str_hash) \
-    mp_uint_t str_hash; \
+    size_t str_hash; \
     if (mp_obj_is_qstr(str_obj_in)) { \
         str_hash = qstr_hash(MP_OBJ_QSTR_VALUE(str_obj_in)); \
     } else { \

py/qstr.c

@@ -60,9 +60,9 @@
 #define MICROPY_ALLOC_QSTR_ENTRIES_INIT (10)
 
 // this must match the equivalent function in makeqstrdata.py
-mp_uint_t qstr_compute_hash(const byte *data, size_t len) {
+size_t qstr_compute_hash(const byte *data, size_t len) {
     // djb2 algorithm; see http://www.cse.yorku.ca/~oz/hash.html
-    mp_uint_t hash = 5381;
+    size_t hash = 5381;
     for (const byte *top = data + len; data < top; data++) {
         hash = ((hash << 5) + hash) ^ (*data); // hash * 33 ^ data
     }
@@ -181,7 +181,7 @@ STATIC qstr qstr_add(mp_uint_t hash, mp_uint_t len, const char *q_ptr) {
 
 qstr qstr_find_strn(const char *str, size_t str_len) {
     // work out hash of str
-    mp_uint_t str_hash = qstr_compute_hash((const byte *)str, str_len);
+    size_t str_hash = qstr_compute_hash((const byte *)str, str_len);
 
     // search pools for the data
     for (const qstr_pool_t *pool = MP_STATE_VM(last_pool); pool != NULL; pool = pool->prev) {
@@ -254,7 +254,7 @@ qstr qstr_from_strn(const char *str, size_t len) {
         MP_STATE_VM(qstr_last_used) += n_bytes;
 
         // store the interned strings' data
-        mp_uint_t hash = qstr_compute_hash((const byte *)str, len);
+        size_t hash = qstr_compute_hash((const byte *)str, len);
         memcpy(q_ptr, str, len);
         q_ptr[len] = '\0';
         q = qstr_add(hash, len, q_ptr);

py/qstr.h

@@ -78,7 +78,7 @@ typedef struct _qstr_pool_t {
 
 void qstr_init(void);
 
-mp_uint_t qstr_compute_hash(const byte *data, size_t len);
+size_t qstr_compute_hash(const byte *data, size_t len);
 qstr qstr_find_strn(const char *str, size_t str_len); // returns MP_QSTRnull if not found
 
 qstr qstr_from_str(const char *str);