636544 - Some js/src/tests that check tracemonkey stats fail with just -j -m

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Jason Orendorff [:jorendorff]]

The command line
    python tests/jstests.py -so --args="-j -m" $OBJDIR/js
reports a dozen or so failures on tests that look at tracemonkey stats. Bill says these tests should only run under plain -j or '-j -m -a', not under '-j -m'.

Comment 1

[Bill McCloskey [inactive unless it's an emergency] (:billm)]

Attachment: patch

I noticed two things going wrong here.

The first is a bug in the way that we computed how many iterations to run in the methodjit before trying the trace hook. Before, we took the tracer/profiler's HOTLOOP value and then subtracted the number of iterations we already spent in the interpreter before switching to the methodjit. However, if HOTLOOP is 1 (as it is when the profiler is off), and if we've already spent 15 iterations in the interpreter, we get a negative number. It's unsigned, so it's actually a really big number. So we basically never run the tracer. I fixed it in this case to go directly to the tracer.

The other problem is that there are some jstests that run for a few iterations and then check that we actually traced. I fixed these for the profiler, but I forgot to do it for the adaptive methodjit compilation. So this patch does that, by adding a flag called "adaptive" that you can query. It is true if the profiler is running or if always_methodjit is false.

Comment 2

[Bill McCloskey [inactive unless it's an emergency] (:billm)]

http://hg.mozilla.org/tracemonkey/rev/e8a4bc81a4cb

Comment 3

[Nicholas Nethercote [inactive]]

(In reply to comment #1)
> So we basically never run the tracer.

Does this affect Firefox 4?  Too late to change it if so, but would be good to know.

Comment 4

[Bill McCloskey [inactive unless it's an emergency] (:billm)]

(In reply to comment #3)
> Does this affect Firefox 4?  Too late to change it if so, but would be good to
> know.

Unfortunately, yes, it affects Firefox 4. It's probably only a big deal if we're trying to track down performance faults. But we usually do that on trunk anyway.

Comment 5

[Chris Leary [:cdleary] (not checking bugmail)]

http://hg.mozilla.org/mozilla-central/rev/e8a4bc81a4cb