Clear token streams before compacting the symbol table.

runtime/vm/precompiler.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/precompiler.h"
 
 #include "vm/aot_optimizer.h"
 #include "vm/assembler.h"
 #include "vm/ast_printer.h"
 #include "vm/branch_optimizer.h"
@@ skipping 222 matching lines @@
       I->set_compilation_allowed(false);
 
       TraceForRetainedFunctions();
       DropFunctions();
       DropFields();
       TraceTypesFromRetainedClasses();
       DropTypes();
       DropTypeArguments();
 
       // Clear these before dropping classes as they may hold onto otherwise
-      // dead instances of classes we will remove.
-      DropCompileTimeConstantCaches();
+      // dead instances of classes we will remove or otherwise unused symbols.
+      DropScriptData();
       I->object_store()->set_unique_dynamic_targets(Array::null_array());
       Class& null_class = Class::Handle(Z);
       I->object_store()->set_future_class(null_class);
       I->object_store()->set_completer_class(null_class);
       I->object_store()->set_stream_iterator_class(null_class);
       I->object_store()->set_symbol_class(null_class);
     }
     DropClasses();
     DropLibraries();
 
@@ skipping 1298 matching lines @@
   bool present;
   for (intptr_t i = 0; i < retained_typeargs.Length(); i++) {
     typeargs ^= retained_typeargs.At(i);
     present = typeargs_table.Insert(typeargs);
     ASSERT(!present);
   }
   object_store->set_canonical_type_arguments(typeargs_table.Release());
 }
 
 
-void Precompiler::DropCompileTimeConstantCaches() {
+void Precompiler::DropScriptData() {
   Library& lib = Library::Handle(Z);
   Array& scripts = Array::Handle(Z);
   Script& script = Script::Handle(Z);
+  const TokenStream& null_tokens = TokenStream::Handle(Z);
   for (intptr_t i = 0; i < libraries_.Length(); i++) {
     lib ^= libraries_.At(i);
     scripts = lib.LoadedScripts();
     for (intptr_t j = 0; j < scripts.Length(); j++) {
       script ^= scripts.At(j);
       script.set_compile_time_constants(Array::null_array());
+      script.set_source(String::null_string());
+      script.set_tokens(null_tokens);
     }
   }
 }
 
 
 void Precompiler::TraceTypesFromRetainedClasses() {
   Library& lib = Library::Handle(Z);
   Class& cls = Class::Handle(Z);
   Array& members = Array::Handle(Z);
   Array& constants = Array::Handle(Z);
@@ skipping 1300 matching lines @@
       CompilationPipeline::New(thread->zone(), function);
 
   ASSERT(FLAG_precompiled_mode);
   const bool optimized = function.IsOptimizable();  // False for natives.
   return PrecompileFunctionHelper(pipeline, function, optimized);
 }
 
 #endif  // DART_PRECOMPILER
 
 }  // namespace dart