Add flag to disable string externalization

runtime/vm/intermediate_language.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/intermediate_language.h"
 
 #include "vm/bit_vector.h"
 #include "vm/bootstrap.h"
 #include "vm/compiler.h"
 #include "vm/constant_propagator.h"
@@ skipping 18 matching lines @@
 
 namespace dart {
 
 DEFINE_FLAG(bool, propagate_ic_data, true,
     "Propagate IC data from unoptimized to optimized IC calls.");
 DEFINE_FLAG(bool, two_args_smi_icd, true,
     "Generate special IC stubs for two args Smi operations");
 DEFINE_FLAG(bool, unbox_numeric_fields, true,
     "Support unboxed double and float32x4 fields.");
 DECLARE_FLAG(bool, eliminate_type_checks);
+DECLARE_FLAG(bool, support_externalizable_strings);
 
 
 #if defined(DEBUG)
 void Instruction::CheckField(const Field& field) const {
   ASSERT(field.IsZoneHandle());
   ASSERT(!Compiler::IsBackgroundCompilation() || !field.IsOriginal());
 }
 #endif  // DEBUG
 
 
@@ skipping 113 matching lines @@
     // TODO(fschneider): Make sure ic_data are sorted to hit more cases.
     if (unary_checks().GetReceiverClassIdAt(i) !=
         other_check->unary_checks().GetReceiverClassIdAt(i)) {
       return false;
     }
   }
   return true;
 }
 
 
-bool CheckClassInstr::IsImmutableClassId(intptr_t cid) {
-  switch (cid) {
-    case kOneByteStringCid:
-    case kTwoByteStringCid:
-      return false;
-    default:
-      return true;
-  }
-}
-
-
 static bool AreAllChecksImmutable(const ICData& checks) {
   const intptr_t len = checks.NumberOfChecks();
   for (intptr_t i = 0; i < len; i++) {
     if (checks.IsUsedAt(i)) {
-      if (!CheckClassInstr::IsImmutableClassId(
+      if (Field::IsExternalizableCid(
               checks.GetReceiverClassIdAt(i))) {
         return false;
       }
     }
   }
   return true;
 }
 
 
 EffectSet CheckClassInstr::Dependencies() const {
   // Externalization of strings via the API can change the class-id.
   return !AreAllChecksImmutable(unary_checks()) ?
       EffectSet::Externalization() : EffectSet::None();
 }
 
 
 EffectSet CheckClassIdInstr::Dependencies() const {
   // Externalization of strings via the API can change the class-id.
-  return !CheckClassInstr::IsImmutableClassId(cid_) ?
+  return Field::IsExternalizableCid(cid_) ?
       EffectSet::Externalization() : EffectSet::None();
 }
 
 
 bool CheckClassInstr::DeoptIfNull() const {
   if (unary_checks().NumberOfChecks() != 1) {
     return false;
   }
   CompileType* in_type = value()->Type();
   const intptr_t cid = unary_checks().GetCidAt(0);
@@ skipping 3534 matching lines @@
   set_native_c_function(native_function);
   function().SetIsNativeAutoSetupScope(auto_setup_scope);
   Dart_NativeEntryResolver resolver = library.native_entry_resolver();
   bool is_bootstrap_native = Bootstrap::IsBootstapResolver(resolver);
   set_is_bootstrap_native(is_bootstrap_native);
 }
 
 #undef __
 
 }  // namespace dart