[Webkit-unassigned] [Bug 248023] New: For-of should perform toPrimitive(done) in the interpreter before checking the iteration is done.
bugzilla-daemon at webkit.org
bugzilla-daemon at webkit.org
Wed Nov 16 22:52:41 PST 2022
https://bugs.webkit.org/show_bug.cgi?id=248023
Bug ID: 248023
Summary: For-of should perform toPrimitive(done) in the
interpreter before checking the iteration is done.
Product: WebKit
Version: WebKit Local Build
Hardware: PC
OS: Linux
Status: NEW
Severity: Normal
Priority: P2
Component: JavaScriptCore
Assignee: webkit-unassigned at lists.webkit.org
Reporter: entryhii at gmail.com
var it=0
var iterator_fn = new Proxy(function () {
}, {
apply() {
print('2')
return it;
}
});
var obj = new Proxy({}, {
get: function (target, name) {
it = obj;
print('1')
return iterator_fn;
}
});
for (var v of obj) {
print('3')
}
With the above script as input to JSC, run JSC with the following parameters:
./jsc test.js --useConcurrentJIT=0
According to ECMA, the correct result should be '12121', but JSC prints '121211'. I alse test the script in Safari, the result is alse '121211'. However, the result is '12121' in Google. If I set the JITPolicyScale to 0. JSC JIT will print '12121'.
The problem may be in LowLevelInterpreter64.asm. In op_iterator_next, m_done is JSValue from _llint_slow_path_iterator_next_get_done. In the scripts, m_done is a Proxy Object. This value should perform toPrimitive before btqnz, otherwise it will iterate one more time and print '1' wrongly.
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