Bug 18961 – SQUIRRELFISH: Gmail doesn't load

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Cameron Zwarich (cpst)]

Loading Gmail fails with some undefined value exceptions. I'm going to try to debug this.

[Cameron Zwarich (cpst)]

Created attachment 21033 [details]
Stack trace

Here's a stack trace from the first undefined value exception.

[Cameron Zwarich (cpst)]

I asked gdb to print the bytecode that threw the exception. Here it is:

6 instructions; 84 bytes at 0x1344e460; 1 locals (1 parameters); 15 temporaries

[   0] resolve		 tr0, a(@id0)
[   3] get_by_id	 tr1, tr0, apply(@id1)
[   7] resolve		 tr13, f(@id2)
[  10] resolve		 tr14, arguments(@id3)
[  13] call		 tr0, tr1, tr0, 12, 3
[  19] ret		 tr0

Identifiers:
  id0 = a
  id1 = apply
  id2 = f
  id3 = arguments

[Cameron Zwarich (cpst)]

The value returned by the first resolve is bogus, causing the exception to be thrown when calling toObject() on the base in get_by_id. I'll try to see what is up with that resolve.

[Cameron Zwarich (cpst)]

Google Reader had the least amount of JS out of all of the affected Google products, so I hacked up enough of a local copy to reproduce the error. Using a decent amount of alert debugging, I managed to find the problem. Consider this code:

var o = { };
o = o.Nothere || o;
print(o == undefined);

Trunk prints false, SquirrelFish prints true.

[Cameron Zwarich (cpst)]

Here is the bytecode for my example:

[   0] load		 lr2, undefined(@k0)		
[   3] load		 tr0, undefined(@k0)		
[   6] new_object	 lr2
[   8] get_by_id	 lr2, lr2, Nothere(@id0)
[  12] jtrue		 lr2, 1(->15)
[  15] mov		 tr0, lr2
[  18] resolve_func	 tr0, tr1, print(@id1)
[  22] resolve		 tr14, undefined(@id2)
[  25] eq		 tr13, lr2, tr14
[  29] call		 tr0, tr1, tr0, 12, 2
[  35] end		 tr0

The problem is that LogicalAndNode is using the final destination as a temporary.

[Cameron Zwarich (cpst)]

> The problem is that LogicalAndNode is using the final destination as a
temporary.

Oops, I meant LogicalOrNode, but the problem is in both.

[Cameron Zwarich (cpst)]

Created attachment 21067 [details]
Proposed patch

[Oliver Hunt]

Comment on attachment 21067 [details]
Proposed patch

r=me

woo!

[Cameron Zwarich (cpst)]

Created attachment 21068 [details]
Proposed patch with test

I accidentally didn't add the test to the last patch, and the description was bad. Here's a new patch.

[Cameron Zwarich (cpst)]

Landed in r33031.