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Port js_allocate_fast_array helper for non-mutating array methods #1456

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Merged
saghul merged 1 commit into from
Apr 21, 2026
+108 −73
Merged

Port js_allocate_fast_array helper for non-mutating array methods #1456

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112 changes: 39 additions & 73 deletions quickjs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10013,6 +10013,35 @@ static int add_fast_array_element(JSContext *ctx, JSObject *p,
return true;
}

/* Allocate a new fast array initialized to JS_UNDEFINED. Its maximum
size is 2^31-1 elements. For convenience, 'len' is a 64 bit
integer. */
static JSValue js_allocate_fast_array(JSContext *ctx, int64_t len)
{
JSValue arr;
JSObject *p;
int i;

if (len > INT32_MAX)
return JS_ThrowRangeError(ctx, "invalid array length");
arr = JS_NewArray(ctx);
if (JS_IsException(arr))
return arr;
if (len > 0) {
p = JS_VALUE_GET_OBJ(arr);
if (expand_fast_array(ctx, p, len) < 0) {
JS_FreeValue(ctx, arr);
return JS_EXCEPTION;
}
p->u.array.count = len;
for(i = 0; i < len; i++)
p->u.array.u.values[i] = JS_UNDEFINED;
/* update the 'length' field */
set_value(ctx, &p->prop[0].u.value, js_int32(len));
}
return arr;
}

static void js_free_desc(JSContext *ctx, JSPropertyDescriptor *desc)
{
JS_FreeValue(ctx, desc->getter);
Expand Down Expand Up @@ -41608,11 +41637,6 @@ static JSValue js_array_with(JSContext *ctx, JSValueConst this_val,
if (js_get_length64(ctx, &len, obj))
goto exception;

if (len > UINT32_MAX) {
JS_ThrowRangeError(ctx, "invalid array length");
goto exception;
}

if (JS_ToInt64Sat(ctx, &idx, argv[0]))
goto exception;

Expand All @@ -41624,15 +41648,11 @@ static JSValue js_array_with(JSContext *ctx, JSValueConst this_val,
goto exception;
}

arr = JS_NewArray(ctx);
arr = js_allocate_fast_array(ctx, len);
if (JS_IsException(arr))
goto exception;

p = JS_VALUE_GET_OBJ(arr);
if (expand_fast_array(ctx, p, len) < 0)
goto exception;
p->u.array.count = len;

i = 0;
pval = p->u.array.u.values;
if (js_get_fast_array(ctx, obj, &arrp, &count32) && count32 == len) {
Expand All @@ -41644,21 +41664,14 @@ static JSValue js_array_with(JSContext *ctx, JSValueConst this_val,
} else {
for (; i < idx; i++, pval++)
if (-1 == JS_TryGetPropertyInt64(ctx, obj, i, pval))
goto fill_and_fail;
goto exception;
*pval = js_dup(argv[1]);
for (i++, pval++; i < len; i++, pval++) {
if (-1 == JS_TryGetPropertyInt64(ctx, obj, i, pval)) {
fill_and_fail:
for (; i < len; i++, pval++)
*pval = JS_UNDEFINED;
if (-1 == JS_TryGetPropertyInt64(ctx, obj, i, pval))
goto exception;
}
}
}

if (JS_SetProperty(ctx, arr, JS_ATOM_length, js_int64(len)) < 0)
goto exception;

ret = arr;
arr = JS_UNDEFINED;

Expand Down Expand Up @@ -42568,20 +42581,12 @@ static JSValue js_array_toReversed(JSContext *ctx, JSValueConst this_val,
if (js_get_length64(ctx, &len, obj))
goto exception;

if (len > UINT32_MAX) {
JS_ThrowRangeError(ctx, "invalid array length");
goto exception;
}

arr = JS_NewArray(ctx);
arr = js_allocate_fast_array(ctx, len);
if (JS_IsException(arr))
goto exception;

if (len > 0) {
p = JS_VALUE_GET_OBJ(arr);
if (expand_fast_array(ctx, p, len) < 0)
goto exception;
p->u.array.count = len;

i = len - 1;
pval = p->u.array.u.values;
Expand All @@ -42591,17 +42596,10 @@ static JSValue js_array_toReversed(JSContext *ctx, JSValueConst this_val,
} else {
// Query order is observable; test262 expects descending order.
for (; i >= 0; i--, pval++) {
if (-1 == JS_TryGetPropertyInt64(ctx, obj, i, pval)) {
// Exception; initialize remaining elements.
for (; i >= 0; i--, pval++)
*pval = JS_UNDEFINED;
if (-1 == JS_TryGetPropertyInt64(ctx, obj, i, pval))
goto exception;
}
}
}

if (JS_SetProperty(ctx, arr, JS_ATOM_length, js_int64(len)) < 0)
goto exception;
}

ret = arr;
Expand Down Expand Up @@ -42727,8 +42725,6 @@ static JSValue js_array_toSpliced(JSContext *ctx, JSValueConst this_val,
int64_t i, j, len, newlen, start, add, del;
uint32_t count32;

pval = NULL;
last = NULL;
ret = JS_EXCEPTION;
arr = JS_UNDEFINED;

Expand All @@ -42753,28 +42749,19 @@ static JSValue js_array_toSpliced(JSContext *ctx, JSValueConst this_val,
add = argc - 2;

newlen = len + add - del;
if (newlen > UINT32_MAX) {
// Per spec: TypeError if newlen >= 2**53, RangeError below
if (newlen > MAX_SAFE_INTEGER) {
JS_ThrowTypeError(ctx, "invalid array length");
} else {
JS_ThrowRangeError(ctx, "invalid array length");
}
if (newlen > MAX_SAFE_INTEGER) {
JS_ThrowTypeError(ctx, "invalid array length");
goto exception;
}

arr = JS_NewArray(ctx);
arr = js_allocate_fast_array(ctx, newlen);
if (JS_IsException(arr))
goto exception;

if (newlen <= 0)
goto done;

p = JS_VALUE_GET_OBJ(arr);
if (expand_fast_array(ctx, p, newlen) < 0)
goto exception;

p->u.array.count = newlen;
pval = &p->u.array.u.values[0];
last = &p->u.array.u.values[newlen];

Expand All @@ -42798,17 +42785,11 @@ static JSValue js_array_toSpliced(JSContext *ctx, JSValueConst this_val,

assert(pval == last);

if (JS_SetProperty(ctx, arr, JS_ATOM_length, js_int64(newlen)) < 0)
goto exception;

done:
ret = arr;
arr = JS_UNDEFINED;

exception:
while (pval != last)
*pval++ = JS_UNDEFINED;

JS_FreeValue(ctx, arr);
JS_FreeValue(ctx, obj);
return ret;
Expand Down Expand Up @@ -43141,38 +43122,23 @@ static JSValue js_array_toSorted(JSContext *ctx, JSValueConst this_val,
if (js_get_length64(ctx, &len, obj))
goto exception;

if (len > UINT32_MAX) {
JS_ThrowRangeError(ctx, "invalid array length");
goto exception;
}

arr = JS_NewArray(ctx);
arr = js_allocate_fast_array(ctx, len);
if (JS_IsException(arr))
goto exception;

if (len > 0) {
p = JS_VALUE_GET_OBJ(arr);
if (expand_fast_array(ctx, p, len) < 0)
goto exception;
p->u.array.count = len;

i = 0;
pval = p->u.array.u.values;
if (js_get_fast_array(ctx, obj, &arrp, &count32) && count32 == len) {
for (; i < len; i++, pval++)
*pval = js_dup(arrp[i]);
} else {
for (; i < len; i++, pval++) {
if (-1 == JS_TryGetPropertyInt64(ctx, obj, i, pval)) {
for (; i < len; i++, pval++)
*pval = JS_UNDEFINED;
if (-1 == JS_TryGetPropertyInt64(ctx, obj, i, pval))
goto exception;
}
}
}

if (JS_SetProperty(ctx, arr, JS_ATOM_length, js_int64(len)) < 0)
goto exception;
}

ret = js_array_sort(ctx, arr, argc, argv);
Expand Down
69 changes: 69 additions & 0 deletions tests/test_array_to_gc.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,69 @@
import * as std from "qjs:std";
import { assert } from "./assert.js";

// The non-mutating array methods (with, toReversed, toSpliced, toSorted)
// allocate a fast array and then populate it by pulling values from the
// source via JS_TryGetPropertyInt64. When the source is an array-like with
// a property getter that triggers GC, the GC must see fully initialized
// slots — otherwise it would walk uninitialized JSValues in the newly
// allocated array. Run under ASAN to catch regressions.

function makeArrayLike(length, getterIndex) {
const obj = { length };
Object.defineProperty(obj, getterIndex, {
configurable: true,
get() {
std.gc();
return 1;
},
});
return obj;
}

// with
{
const obj = makeArrayLike(256, 0);
Object.defineProperty(obj, 1, {
value: 2,
writable: true,
configurable: true,
});
const res = Array.prototype.with.call(obj, 1, 9);
assert(res.length, 256);
assert(res[0], 1);
assert(res[1], 9);
assert(res[2], undefined);
assert(res[255], undefined);
}

// toReversed
{
const obj = makeArrayLike(256, 255);
const res = Array.prototype.toReversed.call(obj);
assert(res.length, 256);
assert(res[0], 1);
assert(res[1], undefined);
assert(res[255], undefined);
}

// toSpliced
{
const obj = makeArrayLike(256, 0);
const res = Array.prototype.toSpliced.call(obj, 1, 0, 7);
assert(res.length, 257);
assert(res[0], 1);
assert(res[1], 7);
assert(res[2], undefined);
assert(res[256], undefined);
}

// toSorted
{
const obj = makeArrayLike(256, 0);
const res = Array.prototype.toSorted.call(obj);
assert(res.length, 256);
// Sort places `undefined` at the end, so the single defined value (1) is first.
assert(res[0], 1);
assert(res[1], undefined);
assert(res[255], undefined);
}
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