Closed Bug 1438232 Opened 3 years ago Closed 3 years ago
Reuse Script For Clone be optimized more?
CanReuseScriptForClone returns false when we have a lazy script: // We need to clone the script if we're not already marked as having a // non-syntactic scope. If we're lazy, go ahead and clone the script; see // the big comment at the end of CopyScriptInternal for the explanation of // what's going on there. return fun->hasScript() && fun->nonLazyScript()->hasNonSyntacticScope(); This will make the caller clone the function + script (after delazifying). What if we delazify in CanReuseScriptForClone (since we will delazify anyway) and then check hasNonSyntacticScope()? It seems like that could help avoid script clones. I don't know how common this case is though; should instrument a browser build to get some data.
So here's a much nicer patch, thanks to help from Shu. Let's see if this is also green on Try.
(In reply to Jan de Mooij [:jandem] from comment #0) > I don't know how common this case is though; should instrument a browser > build to get some data. For posterity: I instrumented a browser build and this definitely hits many times when starting the browser, even more when opening devtools. So I hope this will improve both perf and memory usage.
Pushed by firstname.lastname@example.org: https://hg.mozilla.org/integration/mozilla-inbound/rev/784c1815c3c4 Handle lazy scripts in CanReuseScriptForClone without forcing a delazify/clone. r=shu
AWSY report below. This was a 2-3% JS memory usage win. mccr8, I think lazy parsing for non-syntactic scopes (bug 1364566) should be a lot more effective now. We no longer unnecessarily delazify + clone scripts when cloning such (lazy) functions. --- == Change summary for alert #11619 (as of Thu, 15 Feb 2018 23:06:33 GMT) == Improvements: 3% JS windows7-32 pgo stylo 87,252,061.99 -> 84,582,935.05 3% JS windows10-64 opt stylo 115,966,089.39 -> 112,636,003.66 3% JS windows7-32 opt stylo 86,772,136.57 -> 84,458,974.43 3% JS linux64-stylo-sequential opt stylo-sequential104,128,567.46 -> 101,451,809.46 2% JS windows10-64 pgo stylo 115,672,796.91 -> 112,963,230.23 2% JS linux64 opt stylo 104,154,544.19 -> 101,914,488.72 2% JS osx-10-10 opt stylo 103,851,712.72 -> 101,649,556.17 For up to date results, see: https://treeherder.mozilla.org/perf.html#/alerts?id=11619
And some perf improvements: == Change summary for alert #11610 (as of Thu, 15 Feb 2018 23:06:33 GMT) == Improvements: 5% cpstartup content-process-startup windows7-32 opt e10s stylo 295.67 -> 280.33 4% cpstartup content-process-startup windows10-64 opt e10s stylo 301.54 -> 288.92 4% cpstartup content-process-startup windows7-32 pgo e10s stylo 263.79 -> 253.33 3% cpstartup content-process-startup linux64 pgo e10s stylo 200.38 -> 194.83 For up to date results, see: https://treeherder.mozilla.org/perf.html#/alerts?id=11610
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