For background compilation we copy ICData so that it is immutable during comnpilation. However, we …

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
index a653a7db208686fc303e3de0abdcd8433a3abd6e..bdb577420a9f0b5cc250d518bbd5bf78c5bbd4f7 100644
--- a/runtime/vm/compiler.cc
+++ b/runtime/vm/compiler.cc
@@ -42,6 +42,7 @@ namespace dart {
 
 DEFINE_FLAG(bool, allocation_sinking, true,
     "Attempt to sink temporary allocations to side exits");
+DEFINE_FLAG(bool, always_clone_ic_descriptor, false, "Testing flag");

[zra, 2015/12/21 19:31:47]

Did you mean to leave this in? If so, is it possible to include a bit more about
what the flag does?

[srdjan, 2015/12/21 20:22:49]

Removing it, once all platforms pass.

 DEFINE_FLAG(bool, common_subexpression_elimination, true,
     "Do common subexpression elimination.");
 DEFINE_FLAG(bool, constant_propagation, true,
@@ -461,7 +462,8 @@ static bool CompileParsedFunctionHelper(CompilationPipeline* pipeline,
 
           // 'Freeze' ICData in background compilation so that it does not
           // change while compiling.
-          const bool clone_descriptors = Compiler::IsBackgroundCompilation();
+          const bool clone_descriptors = FLAG_always_clone_ic_descriptor ||
+              Compiler::IsBackgroundCompilation();
           function.RestoreICDataMap(ic_data_array, clone_descriptors);
 
           if (FLAG_print_ic_data_map) {