Do not create a SharedFunctionInfo for closures on each recompilation.

src/hydrogen.cc

 // Copyright 2011 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 2749 matching lines @@
 void HGraphBuilder::VisitTryFinallyStatement(TryFinallyStatement* stmt) {
   BAILOUT("TryFinallyStatement");
 }
 
 
 void HGraphBuilder::VisitDebuggerStatement(DebuggerStatement* stmt) {
   BAILOUT("DebuggerStatement");
 }
 
 
+static Handle<SharedFunctionInfo> SearchSharedFunctionInfo(
+    Code* unoptimized_code, FunctionLiteral* expr) {
+  int start_position = expr->start_position();
+  RelocIterator it(unoptimized_code);
+  for (;!it.done(); it.next()) {
+    RelocInfo* rinfo = it.rinfo();
+    if (rinfo->rmode() != RelocInfo::EMBEDDED_OBJECT) continue;
+    Object* obj = rinfo->target_object();
+    if (obj->IsSharedFunctionInfo()) {
+      SharedFunctionInfo* shared = SharedFunctionInfo::cast(obj);
+      if (shared->start_position() == start_position) {
+        return Handle<SharedFunctionInfo>(shared);
+      }
+    }
+  }
+
+  return Handle<SharedFunctionInfo>();
+}
+
+
 void HGraphBuilder::VisitFunctionLiteral(FunctionLiteral* expr) {
   Handle<SharedFunctionInfo> shared_info =
-      Compiler::BuildFunctionInfo(expr, info()->script());
+      SearchSharedFunctionInfo(info()->shared_info()->code(),
+                               expr);
+  if (shared_info.is_null()) {
+    shared_info = Compiler::BuildFunctionInfo(expr, info()->script());
+  }
   CHECK_BAILOUT;
   HFunctionLiteral* instr =
       new HFunctionLiteral(shared_info, expr->pretenure());
   ast_context()->ReturnInstruction(instr, expr->id());
 }
 
 
 void HGraphBuilder::VisitSharedFunctionInfoLiteral(
     SharedFunctionInfoLiteral* expr) {
   BAILOUT("SharedFunctionInfoLiteral");
@@ skipping 3108 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify();
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal