Remove ConditionalStore barrier

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Mark Hahnenberg]

ConditionalStoreBarrier was created when barriers were much more expensive. Now that they're cheap(er), we can get rid of them. This also allows us to get rid of the write barrier logic in emitPutTransitionStub because we always will have executed a write barrier on the base object in the case where we are allocating and storing a new Butterfly into it. Previously, a ConditionalStoreBarrier might or might not have barrier-ed the base object, so we'd have to emit a write barrier in the transition case.

[Mark Hahnenberg]

Created attachment 226334 [details]
Patch

[Geoffrey Garen]

Comment on attachment 226334 [details]
Patch

r=me

[Mark Hahnenberg]

Committed r165407: <http://trac.webkit.org/changeset/165407>

[Ryosuke Niwa]

Looks like this caused a crash on DYEBench.

http://build.webkit.org/builders/Apple%20MountainLion%20Release%20%28Perf%29/builds/8249
http://build.webkit.org/builders/Apple%20Mavericks%20Release%20%28Perf%29/builds/843

I've built r165406 and 165407 locally and only r165407 reproduces the crash quite reliably.  It appears, however, that this crash doesn't always occur.

While

Tools/Scripts/run-perf-tests PerformanceTests/DoYouEvenBench/Full.html --test-runner-count=4 --reset-results

reproduces the crash quite reliably,

Tools/Scripts/run-perf-tests PerformanceTests/DoYouEvenBench/Full.html --test-runner-count=1 --reset-results

doesn't.

[Ryosuke Niwa]

Filed the bug 130066 to track the crash.