Reset opt count on optimized code map lookup failure.

src/code-stubs-hydrogen.cc

Index: src/code-stubs-hydrogen.cc
diff --git a/src/code-stubs-hydrogen.cc b/src/code-stubs-hydrogen.cc
index dfa5ecd8cf840a75086eb5b0d5bac86b839aceb3..2022cac6404030fdce0af08a91ffb253df1b5b1a 100644
--- a/src/code-stubs-hydrogen.cc
+++ b/src/code-stubs-hydrogen.cc
@@ -1191,6 +1191,23 @@ void CodeStubGraphBuilderBase::BuildInstallFromOptimizedCodeMap(
             loop_builder.Break();
           }
           done_check.Else();
+          {
+            // The optimization count should be tied to the context, e.g. as
+            // entry in optimized code map.  But for simplicity's sake we just
+            // reset the opt count if the optimized code map lookup fails,
+            // because no optimized code exists for the current context.
+            HValue* opt_count_and_bailout_reason = Add<HLoadNamedField>(
+                shared_info, HObjectAccess::ForOptCountAndBailoutReason());
+            int32_t opt_count_mask =

[Jakob Kummerow, 2013/11/05 14:35:05]

BitField has a kMask which you can use. Note that you'll want the
DisabledOptimizationReasonBits::kMask, though, so that opt_count is zeroed out.

+                (1 << SharedFunctionInfo::OptCountBits::kSize - 1)
+                    << SharedFunctionInfo::OptCountBits::kShift;
+            HValue* mask = Add<HConstant>(opt_count_mask);
+            HValue* result = Add<HBitwise>(
+                Token::BIT_AND, opt_count_and_bailout_reason, mask);
+            Add<HStoreNamedField>(shared_info,
+                                  HObjectAccess::ForOptCountAndBailoutReason(),
+                                  result);
+          }
           done_check.End();
         }
         restore_check.End();
@@ -1241,8 +1258,6 @@ HValue* CodeStubGraphBuilder<FastNewClosureStub>::BuildCodeStub() {
                         HObjectAccess::ForSharedFunctionInfoPointer(),
                         shared_info);
   Add<HStoreNamedField>(js_function, HObjectAccess::ForFunctionContextPointer(),
-                        shared_info);
-  Add<HStoreNamedField>(js_function, HObjectAccess::ForFunctionContextPointer(),
                         context());
 
   // Initialize the code pointer in the function to be the one