Short term JSON eval cache

src/compiler.cc

Index: src/compiler.cc
===================================================================
--- src/compiler.cc	(revision 12582)
+++ src/compiler.cc	(working copy)
@@ -425,6 +425,17 @@
 #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);
@@ -467,6 +478,7 @@
   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
@@ -492,6 +504,9 @@
           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);