Bug 3965 – IndexToNameMap::IndexToNameMap has n-squared behavior

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Geoffrey Garen]

For each argument, it searches through each argument to check for duplicate parameter names.

A better solution would move FunctionImp::getParameterName into IndexToNameMap::IndexToNameMap, 
and use a hash table to keep track of already seen parameter names --> better modularity and O(1) 
behavior.

[David Kilzer (:ddkilzer)]

Created attachment 20224 [details]
Sample SunSpider test

SunSpider-0.9 doesn't use the "arguments" object from within a function, so it can't be used to test the performance of the IndexToNameMap constructor code.

This is a test that may be dropped into the SunSpider directory to be run.  I'm sure it doesn't mimic any real-world usage of arguments, but it does exercise the code in the IndexToNameMap constructor.

[David Kilzer (:ddkilzer)]

Created attachment 20370 [details]
Script to generate function args test suite

This script generates tests for use with SunSpider.  It tests passing 0 to 10 arguments to eleven different functions, each of which have 0 to 10 arguments, for a total of 121 tests.

The script should be run from the checked-out SunSpider directory, and generates files of the form:

function-args-M-N.js

where "M" is the number arguments the function is defined with and N is the number of arguments actually passed to that function.

Note that the script outputs a list of function names to stdout, which need to be added to tests/LIST before running SunSpider:

$ ./sunspider --shell ../WebKitBuild/Release/testkjs --tests function-args --run 25

[David Kilzer (:ddkilzer)]

See Bug 20815 Comment #7.

[Darin Adler]

I eliminated IndexToNameMap in http://trac.webkit.org/changeset/36743 and I believe this bug is fixed now.

[David Kilzer (:ddkilzer)]

(In reply to comment #4)
> I eliminated IndexToNameMap in http://trac.webkit.org/changeset/36743 and I
> believe this bug is fixed now.

See Bug 20972.