Enable optimization of top-level code.

src/runtime-profiler.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 214 matching lines @@
       Code* unoptimized = function->shared()->code();
       int nesting = unoptimized->allow_osr_at_loop_nesting_level();
       if (nesting == 0) AttemptOnStackReplacement(function);
       int new_nesting = Min(nesting + 1, Code::kMaxLoopNestingMarker);
       unoptimized->set_allow_osr_at_loop_nesting_level(new_nesting);
     }
 
     // Do not record non-optimizable functions.
     if (!function->IsOptimizable()) continue;
 
+    // Only record top-level code on top of the execution stack and
+    // avoid optimizing excessively large scripts since top-level code
+    // will be executed only once.
+    const int kMaxToplevelSourceSize = 10 * 1024;
+    if (function->shared()->is_toplevel()
+        && (frame_count > 1
+            || function->shared()->SourceSize() > kMaxToplevelSourceSize)) {
+      continue;
+    }
+
     if (FLAG_watch_ic_patching) {
       int ticks = function->shared()->profiler_ticks();
 
       if (ticks >= kProfilerTicksBeforeOptimization) {
         // If this particular function hasn't had any ICs patched for enough
         // ticks, optimize it now.
         Optimize(function, "hot and stable");
       } else if (!any_ic_changed_ &&
           function->shared()->code()->instruction_size() < kMaxSizeEarlyOpt) {
         // If no IC was patched since the last tick and this function is very
@@ skipping 160 matching lines @@
 
 bool RuntimeProfilerRateLimiter::SuspendIfNecessary() {
   if (!RuntimeProfiler::IsSomeIsolateInJS()) {
     return RuntimeProfiler::WaitForSomeIsolateToEnterJS();
   }
   return false;
 }
 
 
 } }  // namespace v8::internal