Reland: "Use stability to only conditionally flush information from the CheckMaps table."

src/compiler.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 1167 matching lines @@
       return isolate->builtins()->InOptimizationQueue();
     }
   } else {
     if (GetOptimizedCodeNow(info.get())) return info->code();
   }
 
   // Failed.
   if (FLAG_trace_opt) {
     PrintF("[failed to optimize ");
     function->PrintName();
-    PrintF("]\n");
+    PrintF(": %s]\n", GetBailoutReason(info->bailout_reason()));
   }
 
   if (isolate->has_pending_exception()) isolate->clear_pending_exception();
   return Handle<Code>::null();
 }
 
 
 Handle<Code> Compiler::GetConcurrentlyOptimizedCode(OptimizedCompileJob* job) {
   // Take ownership of compilation info.  Deleting compilation info
   // also tears down the zone and the recompile job.
@@ skipping 99 matching lines @@
   AllowHandleDereference allow_deref;
   bool tracing_on = info()->IsStub()
       ? FLAG_trace_hydrogen_stubs
       : (FLAG_trace_hydrogen &&
          info()->closure()->PassesFilter(FLAG_trace_hydrogen_filter));
   return (tracing_on &&
       OS::StrChr(const_cast<char*>(FLAG_trace_phase), name_[0]) != NULL);
 }
 
 } }  // namespace v8::internal