574834 - jsparse deoptimizes |arguments| var-binding too eagerly

Status: RESOLVED DUPLICATE of bug 740446

(Core :: JavaScript Engine, defect)

Description

[Dave Herman [:dherman]]

This shouldn't need to deoptimize for the |arguments| array:

    function foo(arguments) {
        var arguments = ...
    }

since the explicit parameter precludes the |arguments| array. But jsparse.cpp currently does anyway. See:

http://hg.mozilla.org/tracemonkey/file/b8461ef5fc81/js/src/jsparse.cpp#l5810

Trivial to fix. I'll post a patch in a minute, but someone should definitely check my thinking.

Dave

Comment 1

[Dave Herman [:dherman]]

Attachment: avoids deoptimizing if function has a parameter called "arguments"

Easy fix.

Dave

Comment 2

[Jeff Walden [:Waldo]]

This appears not to have been committed, but the changes in the patch look like something I saw while working on the analysis portion of strict mode arguments.  Did this get fixed elsewhere since original filing?

Comment 3

[Dave Herman [:dherman]]

Hm, good question. Looks like I forgot to ask for a review? I'll ask around tomorrow. If it didn't get fix can I r? you?

Dave

Comment 4

[Jeff Walden [:Waldo]]

Sounds good to me.

Comment 5

[Jeff Walden [:Waldo]]

Did you forget to ask for a review again?  ;-)

Comment 6

[Luke Wagner [:luke]]

This just sorta fell out of the simple way of handling 'arguments'...

js> function f(arguments) { return 3 }
js> dis(f)
flags: NULL_CLOSURE
loc     op
-----   --
main:
00000:  int8 3
00002:  return
00003:  stop

Comment 7

[Gary Kwong [:gkw] [:nth10sd] (NOT official MoCo now)]

Comment on attachment 454235 [details] [diff] [review]
avoids deoptimizing if function has a parameter called "arguments"

Obsoleted by dupe.