Do not compile with Turbofan if we cannot deopt for debugging.

src/compiler.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/compiler.h"
 
 #include "src/ast-numbering.h"
 #include "src/bootstrapper.h"
@@ skipping 827 matching lines @@
   CompilationInfoWithZone info(function);
   Handle<Code> result;
   ASSIGN_RETURN_ON_EXCEPTION(info.isolate(), result,
                              GetUnoptimizedCodeCommon(&info),
                              Code);
   return result;
 }
 
 
 MaybeHandle<Code> Compiler::GetLazyCode(Handle<JSFunction> function) {
-  DCHECK(!function->GetIsolate()->has_pending_exception());
+  Isolate* isolate = function->GetIsolate();
+  DCHECK(!isolate->has_pending_exception());
   DCHECK(!function->is_compiled());
-
-  if (FLAG_turbo_asm && function->shared()->asm_function()) {
+  // If the debugger is active, do not compile with turbofan unless we can
+  // deopt from turbofan code.
+  if (FLAG_turbo_asm && function->shared()->asm_function() &&
+      (FLAG_turbo_deoptimization || !isolate->debug()->is_active())) {
     CompilationInfoWithZone info(function);
 
-    VMState<COMPILER> state(info.isolate());
-    PostponeInterruptsScope postpone(info.isolate());
+    VMState<COMPILER> state(isolate);
+    PostponeInterruptsScope postpone(isolate);
 
     info.SetOptimizing(BailoutId::None(),
                        Handle<Code>(function->shared()->code()));
 
     info.MarkAsContextSpecializing();
     info.MarkAsTypingEnabled();
     info.MarkAsInliningDisabled();
 
-    if (GetOptimizedCodeNow(&info)) return info.code();
+    if (GetOptimizedCodeNow(&info)) {
+      DCHECK(function->shared()->is_compiled());
+      return info.code();
+    }
   }
 
   if (function->shared()->is_compiled()) {
     return Handle<Code>(function->shared()->code());
   }
 
   CompilationInfoWithZone info(function);
   Handle<Code> result;
-  ASSIGN_RETURN_ON_EXCEPTION(info.isolate(), result,
-                             GetUnoptimizedCodeCommon(&info), Code);
+  ASSIGN_RETURN_ON_EXCEPTION(isolate, result, GetUnoptimizedCodeCommon(&info),
+                             Code);
 
-  if (FLAG_always_opt &&
-      info.isolate()->use_crankshaft() &&
+  if (FLAG_always_opt && isolate->use_crankshaft() &&
       !info.shared_info()->optimization_disabled() &&
-      !info.isolate()->DebuggerHasBreakPoints()) {
+      !isolate->DebuggerHasBreakPoints()) {
     Handle<Code> opt_code;
     if (Compiler::GetOptimizedCode(
             function, result,
             Compiler::NOT_CONCURRENT).ToHandle(&opt_code)) {
       result = opt_code;
     }
   }
 
   return result;
 }
@@ skipping 578 matching lines @@
   AllowHandleDereference allow_deref;
   bool tracing_on = info()->IsStub()
       ? FLAG_trace_hydrogen_stubs
       : (FLAG_trace_hydrogen &&
          info()->closure()->PassesFilter(FLAG_trace_hydrogen_filter));
   return (tracing_on &&
       base::OS::StrChr(const_cast<char*>(FLAG_trace_phase), name_[0]) != NULL);
 }
 
 } }  // namespace v8::internal