<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/108331>108331</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Possible Partial redundancy optimization using code duplication
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          anirudha-commits
      </td>
    </tr>
</table>

<pre>
    Consider this case
```
if (condition1)
 C1
else
 C2
end if

if (condition2)
 C1
else
 C2
end if
```
Now we have a path where we have redundancy of C1 when both conditions are true. However llvm is unable to optimize this and computes C1 again. Godbolt example: https://godbolt.org/z/nvYq7dcee

Clubbing the conditions solves this problem
```
if (condition1)
 C1
  if (condition2)
   C1
 else
   C2
  end if
else
 C2
 if (condition2)
  C1
 else
  C2
 end if
end if
```
in this case, the values can be stored in registers.
Refer to section 2 in https://www.brainkart.com/article/Partial-Redundancy-Elimination_8195/ for elaboration: 



</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJycVMGO2zYQ_RrqMpAhjiVbOuiw8dbtqQhy66kYkSOLLUW6JGU3-fqCsut4i02ABhAkash5fHxvhhSjOTnmXjQfRPNa0JImH3pyJix6olL5eTYpFoPXn_uDd9FoDpAmE0FRZFG9iupF7Kr7s_6aEQS2yjttkvFOCuxuE3CQtwHbf1PhgPeQ02DGO957MPj_Yd7S-tVf4cow0YWB4ExpguvEgR_BwHpxmpz6DH6Eg8zTDgafJniwiECBIYWFN_CLv_KFA1h7mcFEWBwNliF58OdkZvOFb0KR06D8fF4SxwxLJzJuAz97PXibgP-m-WxZbF9gSukcxfZF4FHg8XRbsPHhJPD4ReDRXX77a68V87NOB7sMg3EnSBM_E43eXjjeKJyDHyzPP2gXwLe9gK-rnuyAhyEAz5a849j3sN-FfiS-Af6278Y91SseVpkuZBfOIQcDQ0w-sAbjIPDJxMQhbm65n3jM5e4hssrkAPOqtzZdr9fNEMi4PymkjfKzwCOFZJRlgcePeUi2_PQorvIna2bjKOP93squEXiE0QdgS4MPazwXw_0wKEXzwcx0YtG8Cmz_UyMmTctw33WJHEpKidQ0s0sxE4mR10GHsmq3lS7HXbct67FVZafbuux0jePYbLUkeij__C50v9XdtqOCe7nHnZQtdvti6vVe6UYNsuEBla40MakWWxzrgZh4X5geK6yrTmLVyFbuN129q9umqXiUcsQdibrimYzd5A7KZV6YGBfuM9OtLCwNbON6MyE6vsI6KxDzRRX6nFQOyymKurImpvgVJplkuf_oYzS5I-8evGnwW4euYsMSc_sorxn0crZGreFiCbb_jtp5t_unPAf_B6sk8LhyzILfD3Hp8Z8AAAD__8JLpsI">