Avoid overhead of memory allocation and useless referene-counting in implode()

diff --git a/ext/standard/string.c b/ext/standard/string.c
index 1146f170c0958e889d77cefb7af89a2419c456a2..3aee626ef75e47b9c53290740b3c3457c315d4fc 100644 (file)
--- a/ext/standard/string.c
+++ b/ext/standard/string.c
@@ -1213,7 +1213,11 @@ PHPAPI void php_implode(const zend_string *glue, zval *pieces, zval *return_valu
        zend_string  *str;
        char         *cptr;
        size_t        len = 0;
-       zend_string **strings, **strptr;
+       struct {
+               zend_string *str;
+               zend_long    lval;
+       } *strings, *ptr;
+       ALLOCA_FLAG(use_heap)
 
        numelems = zend_hash_num_elements(Z_ARRVAL_P(pieces));
 
@@ -1226,15 +1230,20 @@ PHPAPI void php_implode(const zend_string *glue, zval *pieces, zval *return_valu
                } ZEND_HASH_FOREACH_END();
        }
 
-       strings = emalloc((sizeof(zend_long) + sizeof(zend_string *)) * numelems);
-       strptr = strings - 1;
+       ptr = strings = do_alloca((sizeof(*strings)) * numelems, use_heap);
 
        ZEND_HASH_FOREACH_VAL(Z_ARRVAL_P(pieces), tmp) {
-               if (Z_TYPE_P(tmp) == IS_LONG) {
+               if (EXPECTED(Z_TYPE_P(tmp) == IS_STRING)) {
+                       ptr->str = Z_STR_P(tmp);
+                       len += ZSTR_LEN(ptr->str);
+                       ptr->lval = 0;
+                       ptr++;
+               } else if (UNEXPECTED(Z_TYPE_P(tmp) == IS_LONG)) {
                        zend_long val = Z_LVAL_P(tmp);
 
-                       *++strptr = NULL;
-                       ((zend_long *) (strings + numelems))[strptr - strings] = Z_LVAL_P(tmp);
+                       ptr->str = NULL;
+                       ptr->lval = val;
+                       ptr++;
                        if (val <= 0) {
                                len++;
                        }
@@ -1243,43 +1252,42 @@ PHPAPI void php_implode(const zend_string *glue, zval *pieces, zval *return_valu
                                len++;
                        }
                } else {
-                       *++strptr = zval_get_string(tmp);
-                       len += ZSTR_LEN(*strptr);
+                       ptr->str = zval_get_string_func(tmp);
+                       len += ZSTR_LEN(ptr->str);
+                       ptr->lval = 1;
+                       ptr++;
                }
        } ZEND_HASH_FOREACH_END();
+
        /* numelems can not be 0, we checked above */
        str = zend_string_safe_alloc(numelems - 1, ZSTR_LEN(glue), len, 0);
        cptr = ZSTR_VAL(str) + ZSTR_LEN(str);
        *cptr = 0;
 
-       do {
-               if (*strptr) {
-                       cptr -= ZSTR_LEN(*strptr);
-                       memcpy(cptr, ZSTR_VAL(*strptr), ZSTR_LEN(*strptr));
-                       zend_string_release(*strptr);
+       while (1) {
+               ptr--;
+               if (EXPECTED(ptr->str)) {
+                       cptr -= ZSTR_LEN(ptr->str);
+                       memcpy(cptr, ZSTR_VAL(ptr->str), ZSTR_LEN(ptr->str));
+                       if (ptr->lval) {
+                               zend_string_release(ptr->str);
+                       }
                } else {
                        char *oldPtr = cptr;
                        char oldVal = *cptr;
-                       zend_long val = ((zend_long *) (strings + numelems))[strptr - strings];
-                       cptr = zend_print_long_to_buf(cptr, val);
+                       cptr = zend_print_long_to_buf(cptr, ptr->lval);
                        *oldPtr = oldVal;
                }
 
+               if (ptr == strings) {
+                       break;
+               }
+
                cptr -= ZSTR_LEN(glue);
                memcpy(cptr, ZSTR_VAL(glue), ZSTR_LEN(glue));
-       } while (--strptr > strings);
-
-       if (*strptr) {
-               memcpy(ZSTR_VAL(str), ZSTR_VAL(*strptr), ZSTR_LEN(*strptr));
-               zend_string_release(*strptr);
-       } else {
-               char *oldPtr = cptr;
-               char oldVal = *cptr;
-               zend_print_long_to_buf(cptr, ((zend_long *) (strings + numelems))[strptr - strings]);
-               *oldPtr = oldVal;
        }
 
-       efree(strings);
+       free_alloca(strings, use_heap);
        RETURN_NEW_STR(str);
 }
 /* }}} */