Bug 1282113 - When we're shutting down the runtime, only allow shutdown GCs. r=terrence

devtools/client/locales/en-US/markers.properties

@@ -103,7 +103,6 @@ marker.value.DOMEventBubblingPhase=Bubbling
 marker.gcreason.label.API=API Call
 marker.gcreason.label.EAGER_ALLOC_TRIGGER=Eager Allocation Trigger
 marker.gcreason.label.DESTROY_RUNTIME=Shutdown
-marker.gcreason.label.DESTROY_CONTEXT=Shutdown
 marker.gcreason.label.LAST_DITCH=Out of Memory
 marker.gcreason.label.TOO_MUCH_MALLOC=Too Many Bytes Allocated
 marker.gcreason.label.ALLOC_TRIGGER=Too Many Allocations
@@ -143,7 +142,6 @@ marker.nurseryCollection=Nursery Collection
 marker.gcreason.description.API=There was an API call to force garbage collection.
 marker.gcreason.description.EAGER_ALLOC_TRIGGER=JavaScript returned to the event loop and there were enough bytes allocated since the last GC that a new GC cycle was triggered.
 marker.gcreason.description.DESTROY_RUNTIME=Firefox destroyed a JavaScript runtime or context, and this was the final garbage collection before shutting down.
-marker.gcreason.description.DESTROY_CONTEXT=Firefox destroyed a JavaScript runtime or context, and this was the final garbage collection before shutting down.
 marker.gcreason.description.LAST_DITCH=JavaScript attempted to allocate, but there was no memory available. Doing a full compacting garbage collection as an attempt to free up memory for the allocation.
 marker.gcreason.description.TOO_MUCH_MALLOC=JavaScript allocated too many bytes, and forced a garbage collection.
 marker.gcreason.description.ALLOC_TRIGGER=JavaScript allocated too many times, and forced a garbage collection.

js/public/GCAPI.h

@@ -54,7 +54,7 @@ namespace JS {
     D(API)                                      \
     D(EAGER_ALLOC_TRIGGER)                      \
     D(DESTROY_RUNTIME)                          \
-    D(DESTROY_CONTEXT)                          \
+    D(UNUSED0)                                  \
     D(LAST_DITCH)                               \
     D(TOO_MUCH_MALLOC)                          \
     D(ALLOC_TRIGGER)                            \

js/src/doc/Debugger/Debugger.Memory.md

@@ -161,7 +161,6 @@ compartment.
         * "API"
         * "EAGER_ALLOC_TRIGGER"
         * "DESTROY_RUNTIME"
-        * "DESTROY_CONTEXT"
         * "LAST_DITCH"
         * "TOO_MUCH_MALLOC"
         * "ALLOC_TRIGGER"

js/src/jit-test/tests/gc/bug1282113.js

@@ -0,0 +1,6 @@
+Object.getOwnPropertyNames(this);
+setGCCallback({
+    action: "majorGC",
+    phases: "begin"
+});
+selectforgc(this);

js/src/jsgc.cpp

@@ -6280,6 +6280,11 @@ GCRuntime::checkIfGCAllowedInCurrentState(JS::gcreason::Reason reason)
     if (rt->mainThread.suppressGC)
         return false;
 
+    // Only allow shutdown GCs when we're destroying the runtime. This keeps
+    // the GC callback from triggering a nested GC and resetting global state.
+    if (rt->isBeingDestroyed() && !IsShutdownGC(reason))
+        return false;
+
 #ifdef JS_GC_ZEAL
     if (deterministicOnly && !IsDeterministicGCReason(reason))
         return false;