Add (debug) printing when IC is used in optimized code (must eliminate it).

runtime/vm/code_generator_ia32.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/globals.h"  // Needed here to get TARGET_ARCH_IA32.
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/code_generator.h"
 
 #include "lib/error.h"
 #include "vm/ast_printer.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
 #include "vm/ic_data.h"
 #include "vm/longjump.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/parser.h"
 #include "vm/resolver.h"
 #include "vm/stub_code.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, print_ast, false, "Print abstract syntax tree.");
 DEFINE_FLAG(bool, print_scopes, false, "Print scopes of local variables.");
 DEFINE_FLAG(bool, trace_functions, false, "Trace entry of each function.");
+DEFINE_FLAG(bool, print_ic_in_optimized, false,
+    "Debugging helper to identify potential performance pitfalls.");
 DEFINE_FLAG(int, optimization_invocation_threshold, 1000,
     "number of invocations before a function is optimized, -1 means never.");
 DECLARE_FLAG(bool, enable_type_checks);
 DECLARE_FLAG(bool, report_invocation_count);
 DECLARE_FLAG(bool, trace_compiler);
 
 #define __ assembler_->
 
 
 CodeGeneratorState::CodeGeneratorState(CodeGenerator* codegen)
@@ skipping 383 matching lines @@
 }
 
 
 void CodeGenerator::GenerateInstanceCall(
     intptr_t node_id,
     intptr_t token_index,
     const String& function_name,
     int num_arguments,
     const Array& optional_arguments_names,
     intptr_t num_args_checked) {
+  if (FLAG_print_ic_in_optimized && IsOptimizing()) {
+    OS::Print("Generate IC in optimized code: id %d name: '%s'\n",
+        node_id, function_name.ToCString());
+  }
   ASSERT(num_args_checked > 0);  // At least receiver check is necessary.
   // Set up the function name and number of arguments (including the receiver)
   // to the InstanceCall stub which will resolve the correct entrypoint for
   // the operator and call it.
   ICData ic_data(function_name, num_args_checked);
   ASSERT(ic_data.NumberOfArgumentsChecked() == num_args_checked);
   __ LoadObject(ECX, Array::ZoneHandle(ic_data.data()));
   __ LoadObject(EDX, ArgumentsDescriptor(num_arguments,
                                          optional_arguments_names));
   uword label_address = 0;
@@ skipping 2343 matching lines @@
                         message_buffer, kMessageBufferSize,
                         format, args);
   va_end(args);
   Isolate::Current()->long_jump_base()->Jump(1, message_buffer);
   UNREACHABLE();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32