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Micro-optimisations to perform better on JSON and String processing #1280

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Merged
saghul merged 2 commits into from
Dec 31, 2025
+34 −3
Merged

Micro-optimisations to perform better on JSON and String processing #1280

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d14cc79
* string allocation default increased from 32 to 48
djinn Dec 22, 2025
9b2b021
Changed the indentations
djinn Dec 29, 2025
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37 changes: 34 additions & 3 deletions quickjs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20185,7 +20185,7 @@ typedef struct JSFunctionDef {
bool need_home_object : 1;
bool use_short_opcodes : 1; /* true if short opcodes are used in byte_code */
bool has_await : 1; /* true if await is used (used in module eval) */

JSFunctionKindEnum func_kind : 8;
JSParseFunctionEnum func_type : 7;
uint8_t is_strict_mode : 1;
Expand Down Expand Up @@ -20344,6 +20344,21 @@ static const JSOpCode opcode_info[OP_COUNT + (OP_TEMP_END - OP_TEMP_START)] = {
opcode_info[(op) >= OP_TEMP_START ? \
(op) + (OP_TEMP_END - OP_TEMP_START) : (op)]

static void json_free_token(JSParseState *s, JSToken *token) {
// Only free actual allocated values
switch(token->val) {
case TOK_NUMBER:
JS_FreeValue(s->ctx, token->u.num.val);
break;
case TOK_STRING:
JS_FreeValue(s->ctx, token->u.str.str);
break;
case TOK_IDENT:
JS_FreeAtom(s->ctx, token->u.ident.atom);
break;
}
}

static void free_token(JSParseState *s, JSToken *token)
{
switch(token->val) {
Expand Down Expand Up @@ -21425,14 +21440,30 @@ static int json_parse_string(JSParseState *s, const uint8_t **pp)
uint32_t c;
StringBuffer b_s, *b = &b_s;

if (string_buffer_init(s->ctx, b, 32))
if (string_buffer_init(s->ctx, b, 48))
goto fail;

p = *pp;
for(;;) {
if (p >= s->buf_end) {
goto end_of_input;
}

// Fast path: batch consecutive ASCII characters
const uint8_t *p_start = p;
while (p < s->buf_end && *p != '"' && *p != '\\' && *p >= 0x20 && *p < 0x80) {
p++;
}

// Write batched ASCII in one call
if (p > p_start) {
if (string_buffer_write8(b, p_start, p - p_start))
goto fail;
}

if (p >= s->buf_end)
goto end_of_input;

c = *p++;
if (c == '"')
break;
Expand Down Expand Up @@ -21578,7 +21609,7 @@ static __exception int json_next_token(JSParseState *s)
return -1;
}

free_token(s, &s->token);
json_free_token(s, &s->token);

p = s->last_ptr = s->buf_ptr;
s->last_line_num = s->token.line_num;
Expand Down