Fix excessive reoptimization (guard test lost somehow). Fixes problems in Dart.

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_api_impl.h"
 #include "vm/dart_entry.h"
 #include "vm/exceptions.h"
 #include "vm/ic_data.h"
 #include "vm/object_store.h"
 #include "vm/resolver.h"
 #include "vm/runtime_entry.h"
 #include "vm/stack_frame.h"
 #include "vm/verifier.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, inline_cache, true, "enable inline caches");
 DEFINE_FLAG(bool, trace_deopt, false, "Trace deoptimization");
 DEFINE_FLAG(bool, trace_ic, false, "trace IC handling");
 DEFINE_FLAG(bool, trace_patching, false, "Trace patching of code.");
 DEFINE_FLAG(bool, trace_runtime_calls, false, "Trace runtime calls.");
+DECLARE_FLAG(bool, deoptimization_counter_threshold);
 
 
 const Array& CodeGenerator::ArgumentsDescriptor(
     int num_arguments,
     const Array& optional_arguments_names) {
   const intptr_t num_named_args =
       optional_arguments_names.IsNull() ? 0 : optional_arguments_names.Length();
   const intptr_t num_pos_args = num_arguments - num_named_args;
 
   // Build the argument descriptor array, which consists of the total number of
@@ skipping 722 matching lines @@
 }
 
 
 // Only unoptimized code has invocation counter threshold checking.
 // Once the invocation counter threshold is reached any entry into the
 // unoptimized code is redirected to this function.
 DEFINE_RUNTIME_ENTRY(OptimizeInvokedFunction, 1) {
   ASSERT(arguments.Count() ==
          kOptimizeInvokedFunctionRuntimeEntry.argument_count());
   const Function& function = Function::CheckedHandle(arguments.At(0));
+  if (function.deoptimization_counter() >=
+      FLAG_deoptimization_counter_threshold) {
+    // TODO(srdjan): Investigate excessive deoptimization.
+    function.set_invocation_counter(0);
+    return;
+  }
   if (function.is_optimizable()) {
     ASSERT(!Code::Handle(function.code()).is_optimized());
     const Code& unoptimized_code = Code::Handle(function.code());
     // Compilation patches the entry of unoptimized code.
     Compiler::CompileOptimizedFunction(function);
     const Code& optimized_code = Code::Handle(function.code());
     ASSERT(!optimized_code.IsNull());
     ASSERT(!unoptimized_code.IsNull());
   } else {
     // TODO(5442338): Abort as this should not happen.
@@ skipping 169 matching lines @@
       }
     }
   }
   // The cache is null terminated, therefore the loop above should never
   // terminate by itself.
   UNREACHABLE();
   return Code::null();
 }
 
 }  // namespace dart