431540 - TT: obj == null should not call obj.valueOf

Status: RESOLVED FIXED

(Tamarin Graveyard :: Tracing Virtual Machine, defect, P1)

Description

[Edwin Smith]

but it does.  see vm.fs ==vec, calls obj==nonobj which always calls defaultValue

test case:

var o = { valueOf: function() { print("valueOf"); return 0 } }
print(o != null)

this should not print "valueOf"

please add test case to regression suite when fixing.

Comment 1

[Steven Johnson]

Attachment: Patch

I think this has it nailed. Still passes sanities.

Comment 2

[Edwin Smith]

do the obj==ns and ns==obj cases need to check for a hook?

Comment 3

[Edwin Smith]

this fix makes access-binary-trees 2X faster because this function is hot and frequently compares a pointer to null.

TreeNode.prototype.itemCheck = function(){
   if (this.left==null) return this.item;
   else return this.item + this.left.itemCheck() - this.right.itemCheck();
}

Comment 4

[Steven Johnson]

(In reply to comment #2)
> do the obj==ns and ns==obj cases need to check for a hook?

AFAIK, no. If ES4 adds the ability to override operator== (to use C++ terminology) then we might need to do so, but nothing in standard builtin objects needs it that I aware of. (Changing it back wouldn't hurt, this is just a performance optimization)

Comment 5

[Steven Johnson]

pushed as changeset:   361:3b882d257ab0

Comment 6

[Steven Johnson]

marked fixed; added acceptance test in changeset:   376:c9f90e0fd541