Short term JSON eval cache

src/compiler.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 407 matching lines @@
   if (!info->shared_info().is_null()) {
     Handle<ScopeInfo> scope_info = ScopeInfo::Create(info->scope(),
                                                      info->zone());
     info->shared_info()->set_scope_info(*scope_info);
   }
   return succeeded;
 }
 #endif
 
 
+static bool IsCacheableJSONEval(FunctionLiteral* function) {
+  if (!FLAG_json_eval_cache ||
+      function->body()->length() != 1)
+    return false;
+  ExpressionStatement* body = function->body()->at(0)->AsExpressionStatement();
+  if (body == NULL) return false;
+  bool is_json = CompileTimeValue::IsCompileTimeValue(body->expression());
+  return is_json;
+}
+
+
 static Handle<SharedFunctionInfo> MakeFunctionInfo(CompilationInfo* info) {
   Isolate* isolate = info->isolate();
   ZoneScope zone_scope(info->zone(), DELETE_ON_EXIT);
   PostponeInterruptsScope postpone(isolate);
 
   ASSERT(!isolate->native_context().is_null());
   Handle<Script> script = info->script();
   script->set_context_data((*isolate->native_context())->data());
 
 #ifdef ENABLE_DEBUGGER_SUPPORT
@@ skipping 22 matching lines @@
   // Only allow non-global compiles for eval.
   ASSERT(info->is_eval() || info->is_global());
   ParsingFlags flags = kNoParsingFlags;
   if (info->pre_parse_data() != NULL ||
       String::cast(script->source())->length() > FLAG_min_preparse_length) {
     flags = kAllowLazy;
   }
   if (!ParserApi::Parse(info, flags)) {
     return Handle<SharedFunctionInfo>::null();
   }
+  bool is_json_eval = info->is_eval() && IsCacheableJSONEval(info->function());
 
   // Measure how long it takes to do the compilation; only take the
   // rest of the function into account to avoid overlap with the
   // parsing statistics.
   HistogramTimer* rate = info->is_eval()
       ? info->isolate()->counters()->compile_eval()
       : info->isolate()->counters()->compile();
   HistogramTimerScope timer(rate);
 
   // Compile the code.
   FunctionLiteral* lit = info->function();
   LiveEditFunctionTracker live_edit_tracker(isolate, lit);
   if (!MakeCode(info)) {
     if (!isolate->has_pending_exception()) isolate->StackOverflow();
     return Handle<SharedFunctionInfo>::null();
   }
 
   // Allocate function.
   ASSERT(!info->code().is_null());
   Handle<SharedFunctionInfo> result =
       isolate->factory()->NewSharedFunctionInfo(
           lit->name(),
           lit->materialized_literal_count(),
           info->code(),
           ScopeInfo::Create(info->scope(), info->zone()));
+  if (is_json_eval) {
+    result->set_is_json_eval(true);
+  }
 
   ASSERT_EQ(RelocInfo::kNoPosition, lit->function_token_position());
   Compiler::SetFunctionInfo(result, lit, true, script);
 
   if (script->name()->IsString()) {
     PROFILE(isolate, CodeCreateEvent(
         info->is_eval()
             ? Logger::EVAL_TAG
             : Logger::ToNativeByScript(Logger::SCRIPT_TAG, *script),
         *info->code(),
@@ skipping 542 matching lines @@
     }
   }
 
   GDBJIT(AddCode(Handle<String>(shared->DebugName()),
                  Handle<Script>(info->script()),
                  Handle<Code>(info->code()),
                  info));
 }
 
 } }  // namespace v8::internal