VM: Avoid allocating strings when disassembling code.

runtime/vm/profiler_service.cc

 // Copyright (c) 2015, 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/profiler_service.h"
 
 #include "vm/growable_array.h"
 #include "vm/hash_map.h"
 #include "vm/log.h"
 #include "vm/native_symbol.h"
@@ skipping 628 matching lines @@
   ProfileFunction* function = NULL;
   if ((kind() == kReusedCode) || (kind() == kCollectedCode)) {
     if (name() == NULL) {
       // Lazily set generated name.
       GenerateAndSetSymbolName("[Collected]");
     }
     // Map these to a canonical unknown function.
     function = table->GetUnknown();
   } else if (kind() == kDartCode) {
     ASSERT(!code_.IsNull());
-    const String& name = String::Handle(code_.QualifiedName());
+    const char* name = code_.QualifiedName();
     const Object& obj = Object::Handle(code_.owner());
     if (obj.IsFunction()) {
       function = table->LookupOrAdd(Function::Cast(obj));
     } else {
       // A stub.
-      function = table->AddStub(start(), name.ToCString());
+      function = table->AddStub(start(), name);
     }
-    SetName(name.ToCString());
+    SetName(name);
   } else if (kind() == kNativeCode) {
     if (name() == NULL) {
       // Lazily set generated name.
       GenerateAndSetSymbolName("[Native]");
     }
     function = table->AddNative(start(), name());
   } else if (kind() == kTagCode) {
     if (name() == NULL) {
       if (UserTags::IsUserTag(start())) {
         const char* tag_name = UserTags::TagName(start());
@@ skipping 2231 matching lines @@
   // Disable thread interrupts while processing the buffer.
   DisableThreadInterruptsScope dtis(thread);
 
   ClearProfileVisitor clear_profile(isolate);
   sample_buffer->VisitSamples(&clear_profile);
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart