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<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>
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<th>Summary</th>
<td>LLVM 6.0 compile time regression with large amounts of debuginfo
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<th>Product</th>
<td>libraries
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>DebugInfo
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>alex@crichton.co
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<th>CC</th>
<td>aprantl@apple.com, karl-johan.karlsson@ericsson.com, llvm-bugs@lists.llvm.org, rnk@google.com
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<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>
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