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    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - LLVM 6.0 compile time regression with large amounts of debuginfo"
   href="https://bugs.llvm.org/show_bug.cgi?id=36417">36417</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>LLVM 6.0 compile time regression with large amounts of debuginfo
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>libraries
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>DebugInfo
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>alex@crichton.co
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>aprantl@apple.com, karl-johan.karlsson@ericsson.com, llvm-bugs@lists.llvm.org, rnk@google.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=19883" name="attach_19883" title="slow bytecode">attachment 19883</a> <a href="attachment.cgi?id=19883&action=edit" title="slow bytecode">[details]</a></span>
slow bytecode

We've recently upgraded to LLVM 6.0 (or at least what's close to the release_60
branch of LLVM) in Rust, but unfortunately we're seeing a regression in compile
time now!

First reported to us [1] it looks like the compile time to emit debug
information has increased dramatically between LLVM 4.0 and LLVM 6.0. Doing
some testing locally I've managed to extract a test case for LLVM I think. The
attached IR completes codegen in ~2s on LLVM 4.0 but takes minutes on LLVM 6.0

I ran a bisection based on the results of the command:

    llc test.bc -filetype=obj -O2 -relocation-model=pic

and this bisection pointed at <a href="https://reviews.llvm.org/D38229">https://reviews.llvm.org/D38229</a>. I've cc'd those
involved with that patch here, would y'all mind helping take a look into this
regression? Also this may also just be rustc not producing debug information
that LLVM is expecting, so if something's off about that please just let us
know!

[1]: <a href="https://github.com/rust-lang/rust/issues/48226">https://github.com/rust-lang/rust/issues/48226</a></pre>
        </div>
      </p>


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