--- BytecodeCompiler.cpp
+++ BytecodeCompiler.cpp
@@ -22,16 +22,36 @@
 
 #include "frontend/Parser-inl.h"
 #include "vm/ScopeObject-inl.h"
 
 using namespace js;
 using namespace js::frontend;
 using mozilla::Maybe;
 
+class MOZ_STACK_CLASS AutoCompilationTraceLogger
+{
+  public:
+    AutoCompilationTraceLogger(ExclusiveContext* cx, const TraceLoggerTextId id);
+
+  private:
+    TraceLoggerThread* logger;
+    TraceLoggerEvent event;
+    AutoTraceLog scriptLogger;
+    AutoTraceLog typeLogger;
+};
+
+AutoCompilationTraceLogger::AutoCompilationTraceLogger(ExclusiveContext* cx, const TraceLoggerTextId id)
+  : logger(cx->isJSContext() ? TraceLoggerForMainThread(cx->asJSContext()->runtime())
+                             : TraceLoggerForCurrentThread()),
+    event(logger, TraceLogger_AnnotateScripts),
+    scriptLogger(logger, event),
+    typeLogger(logger, id)
+{}
+
 static bool
 CheckLength(ExclusiveContext* cx, SourceBufferHolder& srcBuf)
 {
     // Note this limit is simply so we can store sourceStart and sourceEnd in
     // JSScript as 32-bits. It could be lifted fairly easily, since the compiler
     // is using size_t internally already.
     if (srcBuf.length() > UINT32_MAX) {
         if (cx->isJSContext())
@@ -218,24 +238,17 @@ frontend::CompileScript(ExclusiveContext
                         JSString* source_ /* = nullptr */,
                         unsigned staticLevel /* = 0 */,
                         SourceCompressionTask* extraSct /* = nullptr */)
 {
     MOZ_ASSERT(srcBuf.get());
 
     RootedString source(cx, source_);
 
-    js::TraceLoggerThread* logger = nullptr;
-    if (cx->isJSContext())
-        logger = TraceLoggerForMainThread(cx->asJSContext()->runtime());
-    else
-        logger = TraceLoggerForCurrentThread();
-    js::TraceLoggerEvent event(logger, TraceLogger_AnnotateScripts, options);
-    js::AutoTraceLog scriptLogger(logger, event);
-    js::AutoTraceLog typeLogger(logger, TraceLogger_ParserCompileScript);
+    AutoCompilationTraceLogger traceLogger(cx, TraceLogger_ParserCompileScript);
 
     /*
      * The scripted callerFrame can only be given for compile-and-go scripts
      * and non-zero static level requires callerFrame.
      */
     MOZ_ASSERT_IF(evalCaller, options.isRunOnce);
     MOZ_ASSERT_IF(evalCaller, options.forEval);
     MOZ_ASSERT_IF(evalCaller && evalCaller->strict(), options.strictOption);
@@ -467,20 +480,17 @@ frontend::CompileLazyFunction(JSContext*
 
     CompileOptions options(cx, lazy->version());
     options.setMutedErrors(lazy->mutedErrors())
            .setFileAndLine(lazy->filename(), lazy->lineno())
            .setColumn(lazy->column())
            .setNoScriptRval(false)
            .setSelfHostingMode(false);
 
-    js::TraceLoggerThread* logger = js::TraceLoggerForMainThread(cx->runtime());
-    js::TraceLoggerEvent event(logger, TraceLogger_AnnotateScripts, options);
-    js::AutoTraceLog scriptLogger(logger, event);
-    js::AutoTraceLog typeLogger(logger, TraceLogger_ParserCompileLazy);
+    AutoCompilationTraceLogger traceLogger(cx, TraceLogger_ParserCompileLazy);
 
     Parser<FullParseHandler> parser(cx, &cx->tempLifoAlloc(), options, chars, length,
                                     /* foldConstants = */ true, nullptr, lazy);
     if (!parser.checkOptions())
         return false;
 
     uint32_t staticLevel = lazy->staticLevel(cx);
 
@@ -534,20 +544,17 @@ frontend::CompileLazyFunction(JSContext*
 // handler attribute in an HTML <INPUT> tag, or in a Function() constructor.
 static bool
 CompileFunctionBody(JSContext* cx, MutableHandleFunction fun, const ReadOnlyCompileOptions& options,
                     const AutoNameVector& formals, SourceBufferHolder& srcBuf,
                     HandleObject enclosingStaticScope, GeneratorKind generatorKind)
 {
     MOZ_ASSERT(!options.isRunOnce);
 
-    js::TraceLoggerThread* logger = js::TraceLoggerForMainThread(cx->runtime());
-    js::TraceLoggerEvent event(logger, TraceLogger_AnnotateScripts, options);
-    js::AutoTraceLog scriptLogger(logger, event);
-    js::AutoTraceLog typeLogger(logger, TraceLogger_ParserCompileFunction);
+    AutoCompilationTraceLogger traceLogger(cx, TraceLogger_ParserCompileFunction);
 
     // FIXME: make Function pass in two strings and parse them as arguments and
     // ProgramElements respectively.
 
     if (!CheckLength(cx, srcBuf))
         return false;
 
     RootedScriptSource sourceObject(cx, CreateScriptSourceObject(cx, options));