<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/126827>126827</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Extend clang/utils/creduce-clang-crash.py to reduce middle-end and backend crashes using llvm-reduce
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
      </td>
    </tr>

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

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

<pre>
    [creduce-clang-crash.py](https://github.com/llvm/llvm-project/blob/main/clang/utils/creduce-clang-crash.py) takes a clang command that crashes, creates an interestingness test from it, and passes it off to creduce/cvise. Reducing at the source language level can be quite slow and doesn't produce a nice `opt`/`llc` command with reduced IR for middle-end and backend crashes.

Before deciding to run creduce/cvise, we should try running `opt -On`/`llc -On` on the output IR.

For middle-end crashes, if we see `clang -On -Xclang -disable-llvm-passes -S -emit-llvm -o /tmp/a.ll; opt -On /tmp/a.ll -disable-output` still reproduces the crash, we should reduce `/tmp/a.ll` with `llvm-reduce` using `opt -On /tmp/a.ll` as the interestingness test.

For backend crashes, if we see `clang -On -Xclang -S -emit-llvm -o /tmp/a.ll; llc -On /tmp/a.ll -o /dev/null` still reproduces the crash, we should reduce `/tmp/a.ll` with `llvm-reduce` using `llc -On /tmp/a.ll` as the interestingness test.

(we should also rename the script to `reduce-clang-crash.py`)
</pre>
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