Bug 1557193 - Enable the assertion in testScriptSourceCompression.cpp verifying that script source was, in fact, compressed off-thread synchronously. r=arai, r=jonco

Differential Revision: https://phabricator.services.mozilla.com/D33890

--HG--
extra : rebase_source : e8f56515747af7c0894f8dc8c63eecff99a725f9

js/src/jsapi-tests/testScriptSourceCompression.cpp

@@ -111,13 +111,9 @@ static void CompressSourceSync(JS::Handle<JSFunction*> fun, JSContext* cx) {
   MOZ_RELEASE_ASSERT(script);
   MOZ_RELEASE_ASSERT(script->scriptSource()->hasSourceText());
 
-  js::RunPendingSourceCompressions(cx->runtime());
+  js::RunPendingSourceCompressions(cx);
 
-  // XXX Temporarily don't assert this because not all builds guarantee it.
-  //     We test behavior that is *affected in its implementation* by this
-  //     condition, but is the same whether or not this assertion actually
-  //     holds.  We'll figure out how to guarantee it in a followup change.
-  // MOZ_RELEASE_ASSERT(script->scriptSource()->hasCompressedSource());
+  MOZ_RELEASE_ASSERT(script->scriptSource()->hasCompressedSource());
 }
 
 static constexpr char FunctionStart[] = "function @() {";

js/src/vm/HelperThreads.cpp

@@ -2329,7 +2329,14 @@ void js::AttachFinishedCompressions(JSRuntime* runtime,
   }
 }
 
-void js::RunPendingSourceCompressions(JSRuntime* runtime) {
+void js::RunPendingSourceCompressions(JSContext* cx) {
+  // |SourceCompressionTask::shouldStart| delays compression until two major GCs
+  // happen.  Bleah.
+  JS_GC(cx);
+  JS_GC(cx);
+
+  JSRuntime* runtime = cx->runtime();
+
   AutoLockHelperThreadState lock;
 
   if (!HelperThreadState().threads) {

js/src/vm/HelperThreads.h

@@ -676,7 +676,7 @@ void AttachFinishedCompressions(JSRuntime* runtime,
                                 AutoLockHelperThreadState& lock);
 
 // Run all pending source compression tasks synchronously, for testing purposes
-void RunPendingSourceCompressions(JSRuntime* runtime);
+void RunPendingSourceCompressions(JSContext* cx);
 
 class MOZ_RAII AutoLockHelperThreadState : public LockGuard<Mutex> {
   using Base = LockGuard<Mutex>;