Bug 1568543 - Don't report that an incremental GC is in progress when we're verifiying pre barriers r=sfink

Differential Revision: https://phabricator.services.mozilla.com/D39221

js/src/gc/GC.cpp

@@ -8908,8 +8908,7 @@ JS_PUBLIC_API bool JS::IsIncrementalGCEnabled(JSContext* cx) {
 }
 
 JS_PUBLIC_API bool JS::IsIncrementalGCInProgress(JSContext* cx) {
-  return cx->runtime()->gc.isIncrementalGCInProgress() &&
+  return cx->runtime()->gc.isIncrementalGCInProgress();
-         !cx->runtime()->gc.isVerifyPreBarriersEnabled();
 }
 
 JS_PUBLIC_API bool JS::IsIncrementalGCInProgress(JSRuntime* rt) {

js/src/gc/GCRuntime.h

@@ -354,7 +354,9 @@ class GCRuntime {
             mode == JSGC_MODE_ZONE_INCREMENTAL) &&
            incrementalAllowed;
   }
-  bool isIncrementalGCInProgress() const { return state() != State::NotActive; }
+  bool isIncrementalGCInProgress() const {
+    return state() != State::NotActive && !isVerifyPreBarriersEnabled();
+  }
   bool hasForegroundWork() const;
 
   bool isCompactingGCEnabled() const;
@@ -489,7 +491,7 @@ class GCRuntime {
   void startVerifyPreBarriers();
   void endVerifyPreBarriers();
   void finishVerifier();
-  bool isVerifyPreBarriersEnabled() const { return !!verifyPreData; }
+  bool isVerifyPreBarriersEnabled() const { return verifyPreData; }
   bool shouldYieldForZeal(ZealMode mode);
 #else
   bool isVerifyPreBarriersEnabled() const { return false; }

js/src/gc/Verifier.cpp

@@ -218,6 +218,7 @@ void gc::GCRuntime::startVerifyPreBarriers() {
   /* Create the root node. */
   trc->curnode = MakeNode(trc, nullptr, JS::TraceKind(0));
 
+  MOZ_ASSERT(incrementalState == State::NotActive);
   incrementalState = State::MarkRoots;
 
   /* Make all the roots be edges emanating from the root node. */
@@ -359,6 +360,7 @@ void gc::GCRuntime::endVerifyPreBarriers() {
   number++;
 
   verifyPreData = nullptr;
+  MOZ_ASSERT(incrementalState == State::Mark);
   incrementalState = State::NotActive;
 
   if (!compartmentCreated && IsIncrementalGCUnsafe(rt) == AbortReason::None &&