Testing Clang Builds

Here's a diff which I use to test Clang on OS X and Linux builders: http://pastebin.mozilla.org/1677911. More information here.

The clang binary on Linux builders is in the same path.

And here's the trychooser syntax:

try: -b do -p macosx64,macosx -u reftest,reftest-ipc,reftest-no-accel,crashtest,crashtest-ipc,xpcshell,jsreftest,jetpack,mozmill-all,opengl,peptest,mochitests -t chrome.2,chrome_mac.2,nochrome.2,dirty,tpr_responsiveness,tprow,svg,dromaeo,xperf

Once the Talos jobs finish, here's how you would test the performance.

1. In the TBPL page for your push, click each of the Talos tabs. For each job, click on the + icon on the bottom pane of TBPL 4-5 times in order to trigger a few re-runs of the same test.
2. Wait a few hours until all of those builds finish.
3. Now go to http://perf.snarkfest.net/compare-talos/.
4. In the "New Revision" field, enter the short SHA1 for your try push.
5. Click "Add Another" a few times. Five is a good number.
6. In each of the Original Revision fields, enter the short SHA1 for a job from pushes leading to the base revision from the repository clone from where you pushed your try job. As an example, let's say that you've pushed from mozilla-inbound. In "Original Revision 1", you need to enter the SHA1 for your base revision. In "Original Revision 2", you need to enter the SHA1 for the preceding push of that base revision, and so on. Note that you should choose the revisions *with* Talos runs on the platform you're interested in, otherwise that revision would not provide useful data for compare-talos.
7. Then click Compare, and interpret the results. Improvements will be green, and regressions will be red. The black points are performance numbers within the noise threshold.