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Optimize String.fromCharCode and String.fromCodePoint #391

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merged 1 commit into from
Apr 21, 2024
Merged

Optimize String.fromCharCode and String.fromCodePoint #391

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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 @@ -39335,6 +39335,17 @@ static JSValue js_string_fromCharCode(JSContext *ctx, JSValue this_val,
int i;
StringBuffer b_s, *b = &b_s;

// shortcut for single argument common case
if (argc == 1 && JS_VALUE_GET_TAG(argv[0]) == JS_TAG_INT) {
uint16_t c16 = JS_VALUE_GET_INT(argv[0]);
if (c16 < 128) {
uint8_t c8 = c16;
return js_new_string8(ctx, &c8, 1);
} else {
return js_new_string16(ctx, &c16, 1);
}
}

string_buffer_init(ctx, b, argc);

for(i = 0; i < argc; i++) {
Expand All @@ -39352,10 +39363,30 @@ static JSValue js_string_fromCodePoint(JSContext *ctx, JSValue this_val,
{
double d;
int i, c;
StringBuffer b_s, *b = &b_s;
StringBuffer b_s, *b = NULL;

/* XXX: could pre-compute string length if all arguments are JS_TAG_INT */
// shortcut for single argument common case
if (argc == 1 && JS_VALUE_GET_TAG(argv[0]) == JS_TAG_INT) {
c = JS_VALUE_GET_INT(argv[0]);
if (c < 0 || c > 0x10ffff)
goto range_error;
if (c < 128) {
uint8_t c8 = c;
return js_new_string8(ctx, &c8, 1);
}
if (c < 0x10000) {
uint16_t c16 = c;
return js_new_string16(ctx, &c16, 1);
} else {
uint16_t c16[2];
c16[0] = get_hi_surrogate(c);
c16[1] = get_lo_surrogate(c);
return js_new_string16(ctx, c16, 2);
}
}

/* XXX: could pre-compute string length if all arguments are JS_TAG_INT */
b = &b_s;
if (string_buffer_init(ctx, b, argc))
goto fail;
for(i = 0; i < argc; i++) {
Expand All @@ -39377,7 +39408,7 @@ static JSValue js_string_fromCodePoint(JSContext *ctx, JSValue this_val,
range_error:
JS_ThrowRangeError(ctx, "invalid code point");
fail:
string_buffer_free(b);
if (b) string_buffer_free(b);
return JS_EXCEPTION;
}

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