[Webkit-unassigned] [Bug 165401] New: GetByID IC is using the wrong value for value.__proto__ when the value is the global object.

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=165401

            Bug ID: 165401
           Summary: GetByID IC is using the wrong value for
                    value.__proto__ when the value is the global object.
    Classification: Unclassified
           Product: WebKit
           Version: WebKit Local Build
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: JavaScriptCore
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: mark.lam at apple.com

Here's the test case:

function test(x) {
    x.__proto__
}

for (var i = 0; i < 10000; i++)
    test(this);


As soon as test is JIT compiled and the GetById IC gets optimized, we'll get an exception:
    TypeError: Object.prototype.__proto__ called on null or undefined

This should never be the case because x (in the test above) is never null or undefined.

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