Bug 232679 – We need to PreferNumber when calling toPrimitive for negate

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Lukas Bernhard]

During differential testing of webkit I found a sample triggering a miscomputation in FTL related to using Date in a negative integer context.

The sample is invoked as:
WebKitBuild/Release/bin/jsc --validateOptions=true --useConcurrentJIT=false --useConcurrentGC=false --thresholdForJITSoon=10 --thresholdForJITAfterWarmUp=10 --thresholdForOptimizeAfterWarmUp=100 --thresholdForOptimizeAfterLongWarmUp=100 --thresholdForOptimizeSoon=100 --thresholdForFTLOptimizeAfterWarmUp=1000 --thresholdForFTLOptimizeSoon=1000 --validateBCE=true --useFTLJIT=true sample.js


function main() {
    let v1 = 0;
    while (v1++ < 9) { } 
        
    let v19 = 0;
    let v45;
    do {
        function v22() {
            "a".charCodeAt(undefined);
            const v44 = new Date(123);
            v45 = -v44;
            for (let v49 = -4096; v49 < 100; v49++) { } 
        }   
        v22();
    } while (v19++ < 7); 
    print(v45); // -123 without FTL, NaN with FTL (also -123 in spidermonkey)
}
main();

[Saam Barati]

Created attachment 443329 [details]
Patch

[Alexey Shvayka]

Comment on attachment 443329 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=443329&action=review

> JSTests/ChangeLog:8
> +        * stress/negate-prfer-number-to-primitive.js: Added.

(nit) filename typo: "prefer"

[Saam Barati]

Created attachment 443330 [details]
patch for landing

[EWS]

Committed r285406 (243963@main): <https://commits.webkit.org/243963@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 443330 [details].

[Radar WebKit Bug Importer]

<rdar://problem/85157764>