Wrong condition caused repeated deoptimizations and performance degradation especially on Meteor.

runtime/vm/code_generator.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/code_generator.h"
 
 #include "vm/code_index_table.h"
 #include "vm/code_patcher.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 900 matching lines @@
         continue_at_pc);
   }
   caller_frame->set_pc(continue_at_pc);
   // Clear invocation counter so that the function gets optimized after
   // types/classes have been collected.
   function.set_invocation_counter(0);
   function.set_deoptimization_counter(function.deoptimization_counter() + 1);
 
   // We have to skip the following otherwise the compiler will complain
   // when it attempts to install unoptimized code into a function that
   // was already deoptimized.

[ngeoffray, 2011/10/19 08:30:51]

Shouldn't you also change the comment?

[srdjan, 2011/10/19 08:43:25]

The comment is correct, the code was wrong: now we skip if the function's code
is already deoptimized (is_optimized == false).

[ngeoffray, 2011/10/19 08:49:40]

I see, thanks. Maybe a 'If the method is deoptimized, ...' at the beginning of
the comment would be clearer. Your call.

-  if (!Code::Handle(function.code()).is_optimized()) {
+  if (Code::Handle(function.code()).is_optimized()) {
     // Get unoptimized code. Compilation restores (reenables) the entry of
     // unoptimized code.
     Compiler::CompileFunction(function);
 
     DisableOldCode(function, optimized_code, unoptimized_code);
   }
   // TODO(srdjan): Handle better complex cases, e.g. when an older optimized
   // code is alive on frame and gets deoptimized after the function was
   // optimized a second time.
   if (FLAG_trace_deopt) {
@@ skipping 75 matching lines @@
       }
     }
   }
   // The cache is null terminated, therefore the loop above should never
   // terminate by itself.
   UNREACHABLE();
   return Code::null();
 }
 
 }  // namespace dart