Always compile functions in the snapshot with deoptimization support.

src/compiler.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/compiler.h"
 
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
@@ skipping 147 matching lines @@
     dependencies_[i] = NULL;
   }
   if (mode == STUB) {
     mode_ = STUB;
     return;
   }
   mode_ = mode;
   if (!script_.is_null() && script_->type()->value() == Script::TYPE_NATIVE) {
     MarkAsNative();
   }
+  // Compiling for the snapshot typically results in different code than
+  // compiling later on. This means that code recompiled with deoptimization
+  // support won't be "equivalent" (as defined by SharedFunctionInfo::
+  // EnableDeoptimizationSupport), so it will replace the old code and all
+  // its type feedback. To avoid this, always compile functions in the snapshot
+  // with deoptimization support.
+  if (isolate_->serializer_enabled()) EnableDeoptimizationSupport();
+
   if (isolate_->debug()->is_active()) MarkAsDebug();
   if (FLAG_context_specialization) MarkAsContextSpecializing();
   if (FLAG_turbo_inlining) MarkAsInliningEnabled();
   if (FLAG_turbo_types) MarkAsTypingEnabled();
 
   if (!shared_info_.is_null()) {
     DCHECK(strict_mode() == SLOPPY);
     SetStrictMode(shared_info_->strict_mode());
   }
   bailout_reason_ = kUnknown;
@@ skipping 1260 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 &&
       base::OS::StrChr(const_cast<char*>(FLAG_trace_phase), name_[0]) != NULL);
 }
 
 } }  // namespace v8::internal