<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/136498>136498</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [LSR] Regression in array access with constant stride
        </td>
    </tr>

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

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

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

<pre>
    It appears LSR does not recognize that shift operations could be promoted to operate directly on 64-bit values instead of adding extra 32-bit truncation and sign-extension for ops on loop induction variables. E.g. direct 64-bit shifting compared to `lea r9d, [8*rcx]` then `movsxd r9, r9d` for `i*8` and `i<<3` respectively.

```llvm
%35 = trunc nuw nsw i64 %indvars.iv to i32
%shl = shl i32 %35, 3
%idxprom = sext i32 %shl to i64
%arrayidx = getelementptr inbounds i32, ptr %src, i64 %idxprom
```

[Godbolt test](https://godbolt.org/z/xe6d9Ks69) (timeout on Alive2).
</pre>
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