621072 - TM: Traces shouldn't bake in interruptFlags

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

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

Since web workers can move from one thread to another, and the old thread may disappear, it isn't valid to bake &JS_THREAD_DATA(cx)->interruptFlags into traces.

Comment 1

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

Attachment: patch

This is the simplest way to fix this.

Comment 2

[Nicholas Nethercote [inactive]]

That's an empty patch :)

Comment 3

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

Attachment: updated patch

It's a simple patch, but not that simple. I messed up when I split two changes apart.

Comment 4

[Nicholas Nethercote [inactive]]

I thought this was going to require an extra load per check, glad to see it doesn't!

Comment 5

[Igor Bukanov]

Comment on attachment 499437 [details] [diff] [review]
updated patch

>From: Bill McCloskey <[e-mail]>
>try: -p linux,linux64,win32
>
>diff --git a/js/src/jstracer.cpp b/js/src/jstracer.cpp
>--- a/js/src/jstracer.cpp
>+++ b/js/src/jstracer.cpp
>@@ -2345,17 +2345,22 @@ TraceRecorder::TraceRecorder(JSContext* 
> 
>     if (fragment == fragment->root) {
>         /*
>          * We poll the operation callback request flag. It is updated asynchronously whenever
>          * the callback is to be invoked. We can use w.nameImmpNonGC here as JIT-ed code is per
>          * thread and cannot outlive the corresponding JSThreadData.
>          */
>         w.comment("begin-interruptFlags-check");
>-        LIns* flagptr = w.nameImmpNonGC((void *) &JS_THREAD_DATA(cx)->interruptFlags);
>+#ifdef JS_THREADSAFE
>+        void *interrupt = (void*) &cx->runtime->interruptCounter;
>+#else
>+        void *interrupt = (void*) &JS_THREAD_DATA(cx)->interruptFlags;
>+#endif

Add fixme bug 621140 about per-compartment flag here.

Comment 6

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

http://hg.mozilla.org/tracemonkey/rev/6255a0255dc2

Comment 7

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

http://hg.mozilla.org/mozilla-central/rev/c83c130ce23f