Bug 251117

Summary: DFG should not speculate Int32 for NaN constants
Product: WebKit Reporter: David Degazio <d_degazio>
Component: JavaScriptCoreAssignee: David Degazio <d_degazio>
Status: RESOLVED FIXED    
Severity: Normal CC: webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   

Description David Degazio 2023-01-24 15:03:00 PST 
rdar://104608391

Currently, DFG will attempt to speculate Int32 for certain double constants during the fixup phase. If a number constant is an Int32, or falls within a valid range (between ±2^48), it's allowed to be truncated into an integer. However, NaN values cannot be compared and ordered, so unlike other non-finite values like positive or negative Infinity, they can pass this range check and be converted into an Int32 despite clearly being non-integral values. We should add a check for NaN constants and reject Int32 speculation if we come across one during the fixup phase.
Comment 1 David Degazio 2023-01-24 15:14:44 PST 
Pull request: https://github.com/WebKit/WebKit/pull/9077
Comment 2 EWS 2023-01-24 21:04:54 PST 
Committed 259340@main (800a9bf27aa7): <https://commits.webkit.org/259340@main>

Reviewed commits have been landed. Closing PR #9077 and removing active labels.