H-BuildIncrement should make use of available type feedback

src/hydrogen.cc

 // Copyright 2013 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 7476 matching lines @@
     }
     Push(number_input);
   }
 
   // The addition has no side effects, so we do not need
   // to simulate the expression stack after this instruction.
   // Any later failures deopt to the load of the input or earlier.
   HConstant* delta = (expr->op() == Token::INC)
       ? graph()->GetConstant1()
       : graph()->GetConstantMinus1();
-  HInstruction* instr = Add<HAdd>(Top(), delta);
+  HInstruction* instr = AddUncasted<HAdd>(Top(), delta);
+  if (instr->IsAdd()) {
+    HAdd* add = HAdd::cast(instr);
+    add->set_observed_input_representation(1, rep);
+    add->set_observed_input_representation(2, Representation::Smi());
+  }
   instr->SetFlag(HInstruction::kCannotBeTagged);
   instr->ClearAllSideEffects();
   return instr;
 }
 
 
 void HOptimizedGraphBuilder::VisitCountOperation(CountOperation* expr) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
@@ skipping 2341 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal