<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/111093>111093</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            ReplaceWithVeclib constructs scalar overload intrinsic name incorrectly
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          tex3d
      </td>
    </tr>
</table>

<pre>
    The ReplaceWithVeclib (replace-with-veclib) pass constructs the scalar overload name used to look up the veclib call by passing all the input argument types (converted to scalar) to `Intrinsic::getName`. 

https://github.com/llvm/llvm-project/blob/e9b7a093417bda7e0bed2bd62bcaeb7c2a662665/llvm/lib/CodeGen/ReplaceWithVeclib.cpp#L132

This is incorrect.  Instead, it should be using `isVectorIntrinsicWithOverloadTypeAtArg` to determine whether an argument type contributes to the overload, including the return argument (-1).

This mostly went unnoticed because most intrinsics supported so far only had one argument, and that argument type matched the return type. For other intrinsics, such as `pow` or `atan2` with two arguments, this would construct a name like `llvm.pow.f64.f64`.  This won't match the name in the table defined in `VecFuncs.def`, causing it to fail replacement silently.

There is a note in `llvm/test/CodeGen/AArch64/replace-with-veclib-armpl.ll` noting the bug above the `llvm.pow` checks, and the checks were written to match the input (no translation).  I didn't see the note until I debugged the pass after running into the bug while trying to implement this for `atan2`.

https://github.com/llvm/llvm-project/blob/e9b7a093417bda7e0bed2bd62bcaeb7c2a662665/llvm/test/CodeGen/AArch64/replace-with-veclib-armpl.ll#L337-L340


</pre>
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