<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/85281>85281</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            SIGSEGV under DenseMapBase::erase after std::bad_alloc
        </td>
    </tr>

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

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

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

<pre>
    Ref: https://github.com/rust-lang/rust/issues/121305

In that Rust issue, running on an `i686` host, I found that `DenseMap::allocateBuckets` -> `llvm::allocate_buffer` -> `operator new` was throwing `std::bad_alloc`. Then when unwinding runs the destructors into `LLVMContextDispose`, we get back into `DenseMapBase::erase` and hit `SIGSEGV`, presumably in the same instance that failed allocation.

Maybe `allocate_buffer` should catch and call `report_bad_alloc_error` like the `safe_*alloc` functions do? But even so, it seems that some part of `DenseMap` is not exception safe.
</pre>
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