908696 - GenerationalGC: Disable post barrier verification when disabling GGC

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Jon Coppeard (:jonco)]

Attachment: disable-verification-with-ggc

When running jittests with barrier verification turned on, test gc/bug-890048.js fails like this:

Assertion failure: isEnabled(), at /home/jon/work/inbound/js/src/gc/StoreBuffer.cpp:293

Catchpoint 1 (signal SIGSEGV), js::gc::StoreBuffer::mark (this=0x7ffff7fbad50, 
    trc=0x1a64390) at /home/jon/work/inbound/js/src/gc/StoreBuffer.cpp:293
293	    JS_ASSERT(isEnabled());

Catchpoint 1 (signal SIGSEGV), js::gc::StoreBuffer::mark (this=0x7ffff7fbad50, 
    trc=0x1a64390) at /home/jon/work/inbound/js/src/gc/StoreBuffer.cpp:293
293	    JS_ASSERT(isEnabled());
(gdb) bt
#0  js::gc::StoreBuffer::mark (this=0x7ffff7fbad50, trc=0x1a64390)
    at /home/jon/work/inbound/js/src/gc/StoreBuffer.cpp:293
#1  0x00000000006a443a in js::gc::EndVerifyPostBarriers (rt=0x7ffff7f7a010)
    at /home/jon/work/inbound/js/src/gc/Verifier.cpp:748
#2  0x00000000007b70c8 in js::gc::AutoStopVerifyingBarriers::AutoStopVerifyingBarriers (
    this=0x7fffffffad98, rt=0x7ffff7f7a010, isShutdown=false, _notifier=...)
    at ../gc/GCInternals.h:130
#3  0x00000000007b45f4 in js::gc::AutoStopVerifyingBarriers::AutoStopVerifyingBarriers (
    this=0x7fffffffad98, rt=0x7ffff7f7a010, isShutdown=false, _notifier=...)
    at ../gc/GCInternals.h:132
#4  0x000000000079f1f0 in Collect (rt=0x7ffff7f7a010, incremental=false, budget=0, 
    gckind=js::GC_NORMAL, reason=JS::gcreason::DEBUG_GC)
    at /home/jon/work/inbound/js/src/jsgc.cpp:4565
#5  0x00000000007a051d in js::gc::RunDebugGC (cx=0x1a1b970)
    at /home/jon/work/inbound/js/src/jsgc.cpp:4877
#6  0x00000000005e5dce in js::gc::NewGCThing<JSObject, (js::AllowGC)1> (cx=0x1a1b970, 
    kind=js::gc::FINALIZE_OBJECT0_BACKGROUND, thingSize=32, heap=js::gc::DefaultHeap)
    at ../jsgcinlines.h:409


This is because it causes generational GC to be disabled, but doesn't disable post barrier verification, which triggers the isEnabled() assertion the next time it tries to run.

Comment 1

[Terrence Cole [:terrence]]

Comment on attachment 794713 [details] [diff] [review]
disable-verification-with-ggc

Review of attachment 794713 [details] [diff] [review]:
-----------------------------------------------------------------

Good find! r=me

Comment 2

[Jon Coppeard (:jonco)]

Attachment: disable-barrier-verification-with-ggc-2

So I saw there was a simpler fix for this, given that doing a minor collection already calls EndVerifyPreBarriers() via AutoStopVerifyingBarriers.

Comment 3

[Terrence Cole [:terrence]]

Comment on attachment 796007 [details] [diff] [review]
disable-barrier-verification-with-ggc-2

Review of attachment 796007 [details] [diff] [review]:
-----------------------------------------------------------------

Clever! Much cleaner too. r=me

Comment 4

[Jon Coppeard (:jonco)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/df8b1e56e1a6

Comment 5

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/df8b1e56e1a6