[Webkit-unassigned] [Bug 199650] New: Keyword lookup can use memcmp to get around unaligned load undefined behavior

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=199650

            Bug ID: 199650
           Summary: Keyword lookup can use memcmp to get around unaligned
                    load undefined behavior
           Product: WebKit
           Version: WebKit Local Build
          Hardware: Macintosh
                OS: Other
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: New Bugs
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: saagarjha at apple.com

KeywordLookup.h rolls what appears to be its own custom memcmp to do string matches, but it performs unaligned loads, reinterpret_casts, and in general makes UBSan very unhappy. I think we can use just use memcmp instead (someone should check whether I can do this, though: I may be misunderstanding how the character encoding works). I have checked that Clang and GCC produce reasonable-looking assembly for this if we make what we're doing clear enough.

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