Fix type propagation rules for count operation....

src/ia32/codegen-ia32.cc

 // Copyright 2010 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 6849 matching lines @@
 
     Result new_value = frame_->Pop();
     new_value.ToRegister();
 
     Result old_value;  // Only allocated in the postfix case.
     if (is_postfix) {
       // Allocate a temporary to preserve the old value.
       old_value = allocator_->Allocate();
       ASSERT(old_value.is_valid());
       __ mov(old_value.reg(), new_value.reg());
+
+      // The old value that is return for postfix operations has the
+      // same type as the input value we got from the frame.
+      old_value.set_number_info(new_value.number_info());
     }
+
     // Ensure the new value is writable.
     frame_->Spill(new_value.reg());
 
     Result tmp;
     if (new_value.is_smi()) {
       if (FLAG_debug_code) {
         __ AbortIfNotSmi(new_value.reg(), "Operand not a smi");
       }
     } else {
       // We don't know statically if the input is a smi.
@@ skipping 43 matching lines @@
         deferred->Branch(not_zero);
       } else {
         // Otherwise we test separately for overflow and smi tag.
         deferred->Branch(overflow);
         __ test(new_value.reg(), Immediate(kSmiTagMask));
         deferred->Branch(not_zero);
       }
     }
     deferred->BindExit();
 
+    // The result of ++ or -- is always a number.
+    new_value.set_number_info(NumberInfo::Number());
 
     // Postfix: store the old value in the allocated slot under the
     // reference.
     if (is_postfix) frame_->SetElementAt(target.size(), &old_value);
 
     frame_->Push(&new_value);
     // Non-constant: update the reference.
     if (!is_const) target.SetValue(NOT_CONST_INIT);
   }
 
@@ skipping 5276 matching lines @@
 
   // Call the runtime; it returns -1 (less), 0 (equal), or 1 (greater)
   // tagged as a small integer.
   __ bind(&runtime);
   __ TailCallRuntime(Runtime::kStringCompare, 2, 1);
 }
 
 #undef __
 
 } }  // namespace v8::internal