Add support for javascript incompatibility warnings.

runtime/vm/flow_graph_compiler.cc

 // Copyright (c) 2013, 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_XXX.
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/cha.h"
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
 #include "vm/deopt_instructions.h"
+#include "vm/exceptions.h"
 #include "vm/flow_graph_allocator.h"
 #include "vm/il_printer.h"
 #include "vm/intrinsifier.h"
 #include "vm/locations.h"
 #include "vm/longjump.h"
 #include "vm/object_store.h"
 #include "vm/parser.h"
 #include "vm/stack_frame.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
 
 namespace dart {
 
 DECLARE_FLAG(bool, code_comments);
 DECLARE_FLAG(bool, disassemble);
 DECLARE_FLAG(bool, disassemble_optimized);
 DECLARE_FLAG(bool, enable_type_checks);
 DECLARE_FLAG(bool, intrinsify);
 DECLARE_FLAG(bool, propagate_ic_data);
 DECLARE_FLAG(bool, report_usage_count);
 DECLARE_FLAG(int, optimization_counter_threshold);
 DECLARE_FLAG(bool, use_cha);
 DECLARE_FLAG(bool, use_osr);
 DECLARE_FLAG(int, stacktrace_every);
 DECLARE_FLAG(charp, stacktrace_filter);
 DECLARE_FLAG(int, deoptimize_every);
 DECLARE_FLAG(charp, deoptimize_filter);
+DECLARE_FLAG(bool, warn_on_javascript_compatibility);
 
 DEFINE_FLAG(bool, enable_simd_inline, true,
     "Enable inlining of SIMD related method calls.");
 DEFINE_FLAG(bool, source_lines, false, "Emit source line as assembly comment.");
 
 // Assign locations to incoming arguments, i.e., values pushed above spill slots
 // with PushArgument.  Recursively allocates from outermost to innermost
 // environment.
 void CompilerDeoptInfo::AllocateIncomingParametersRecursive(
     Environment* env,
@@ skipping 281 matching lines @@
   set_current_block(NULL);
 }
 
 
 void FlowGraphCompiler::Bailout(const char* reason) {
   const Function& function = parsed_function_.function();
   const Error& error = Error::Handle(
       LanguageError::NewFormatted(Error::Handle(),  // No previous error.
                                   Script::Handle(function.script()),
                                   function.token_pos(),
-                                  LanguageError::kError,
+                                  LanguageError::kBailout,
                                   Heap::kNew,
                                   "FlowGraphCompiler Bailout: %s %s",
                                   String::Handle(function.name()).ToCString(),
                                   reason));
   Isolate::Current()->long_jump_base()->Jump(1, error);
+  UNREACHABLE();
 }
 
 
 void FlowGraphCompiler::EmitTrySync(Instruction* instr, intptr_t try_index) {
   ASSERT(is_optimizing());
   Environment* env = instr->env();
   CatchBlockEntryInstr* catch_block =
       flow_graph().graph_entry()->GetCatchEntry(try_index);
   const GrowableArray<Definition*>* idefs = catch_block->initial_definitions();
 
@@ skipping 464 matching lines @@
         break;
       default:
         UNIMPLEMENTED();
     }
     ExternalLabel target_label("InlineCache", label_address);
     EmitOptimizedInstanceCall(&target_label, ic_data,
                               argument_count, deopt_id, token_pos, locs);
     return;
   }
 
-  if (is_optimizing()) {
+  if (is_optimizing() &&
+      // Do not make the instance call megamorphic if the callee needs to decode
+      // the calling code sequence to lookup the ic data and verify if a JS
+      // warning has already been issued or not.
+      (!FLAG_warn_on_javascript_compatibility ||
+       !ic_data.MayCheckForJSWarning())) {
     EmitMegamorphicInstanceCall(ic_data, argument_count,
                                 deopt_id, token_pos, locs);
     return;
   }
 
   switch (ic_data.NumArgsTested()) {
     case 1:
       label_address = StubCode::OneArgCheckInlineCacheEntryPoint();
       break;
     case 2:
@@ skipping 475 matching lines @@
 
   for (int i = 0; i < len; i++) {
     sorted->Add(CidTarget(ic_data.GetReceiverClassIdAt(i),
                           &Function::ZoneHandle(ic_data.GetTargetAt(i)),
                           ic_data.GetCountAt(i)));
   }
   sorted->Sort(HighestCountFirst);
 }
 
 }  // namespace dart