<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/144795>144795</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [LoopVectorizePass] 40% regression on neoverse-v1 after #141865
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            vectorizers,
            vectorization
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
            lukel97,
            vzakhari
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          vzakhari
      </td>
    </tr>
</table>

<pre>
    Performance comes back when reverting 7ef77eb9984d1fb537a409cf4be89560fbb681fe

Before the change:
```
           2124.44 msec task-clock                       # 0.997 CPUs utilized
        5510839431      cycles #    2.594 GHz
        6419270661      instructions                     # 1.16  insn per cycle
```

After the change:
```
           3101.06 msec task-clock                       #    0.997 CPUs utilized
 8045294105      cycles                           #    2.594 GHz
 5452469574      instructions                     #    0.68  insn per cycle
```

Attaching LLVM IR dumps before and after the change, and the assembly.

[before.s.gz](https://github.com/user-attachments/files/20804283/before.s.gz)

[before.log.gz](https://github.com/user-attachments/files/20804285/before.log.gz)

[after.s.gz](https://github.com/user-attachments/files/20804286/after.s.gz)

[after.log.gz](https://github.com/user-attachments/files/20804288/after.log.gz)
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJyslNGL4zYQxv8a-UXESGPJlh78kN0lbWELS6H3LttjW41sBUlO2fz1xYnvNt3eljtYERAZPN-n78cwJkY7zIg1kQ8EwC1HdLoiAAQeCcD5Yo6jCXYtyKfMLGn0of5azRrfvdYvGHofJjO3SFs_YaSNaY_07xFnGvCMIdl5oBX2VYWN1kp0vG9kURnBdNuLBpWWJeubplS8R8L2hO0fsPcBaRqRtqOZByTFWiYl235sT98OcBC5EHSK2NJk4nHXOt8e6fcPgYKyXOuKPr78GemSrLMX7O4kpeRMFVoU_Pa_fW0dxmvj6pZLLegvv17uOkrBNVSsLLcOO8cUljZZP8cPH8FzXl4_nekJw83lXUjC9vs-YfhREgVnPGflT5Cg9CMYigkJWnAm_0Xh4_M9PlJIEKWWlfgJMNc3leoH2KRk2nEdr-fnL7_T3_6g3TKdIm1u42Pmjpr3-ODxWl8rJkacGvea39SIfLg15jEfLkQ-EVBjSqe4IocDgcNg07g0eesnAoclYtiZ6wsmnFMkcOitw_UGppgAVRA43CuCfm_k_PA5VvLNatO8M7sy-KxQJYHDneB_bD4tkvpm9C1R1tVFpwttMqx5JRkoLkBlY81B9MqAlpyripmq4k0nu76rmAJleJPZGhhIVnIFnFdM5Rw1VEUHDVO9bNqeCIaTsS537jzlPgyZjXHBmgtRaZk506CL25Y8Y5t8sBcM8W1TbjWzjva2LkO9iu2aZYhEMGdjim_yySZ3XbvP3p--fFV8MTES-UQFIyBpwCFgjNbP1M90Rn_GEHF35ttYEyi44KqU2RJc_T-0V9ft2p2C_wvbROBwTbgS30Kea_gnAAD__4IFv9E">