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    <head>
      <base href="http://llvm.org/bugs/" />
    </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 --- - Codegen Compile Time increase after r211900"
   href="http://llvm.org/bugs/show_bug.cgi?id=20641">20641</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Codegen Compile Time increase after r211900
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>tools
          </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>normal
          </td>
        </tr>

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

        <tr>
          <th>Component</th>
          <td>llc
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>bruno.cardoso@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvmbugs@cs.uiuc.edu
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=12888" name="attach_12888" title="Codegen-only compile time for each separated source code">attachment 12888</a> <a href="attachment.cgi?id=12888&action=edit" title="Codegen-only compile time for each separated source code">[details]</a></span>
Codegen-only compile time for each separated source code

As mentioned in llvmdev
(<a href="https://groups.google.com/forum/#!topic/llvm-dev/9B2j3LKEF0I">https://groups.google.com/forum/#!topic/llvm-dev/9B2j3LKEF0I</a>), commit r211900
introduced compile time regression:

    Re-apply r211287: Remove support for LLVM runtime multi-threading.
...
    git-svn-id: <a href="https://llvm.org/svn/llvm-project/llvm/trunk@211900">https://llvm.org/svn/llvm-project/llvm/trunk@211900</a>

I reproduced the problem by reverting the patch and extracting codegen only
compile time for each separated source code (10x run for each source). Bellow
the top 5 (sorted by descending total time), the rest is attached.

cpp,CodeGen Compile Time Increase (User), Total time FE+BE (sec)
bullet-btSoftBody.cpp,1.15565,2.1502
bullet-BenchmarkDemo.cpp,1.13269,1.1308
bullet-btDiscreteDynamicsWorld.cpp,1.16331,0.7851
bullet-btSoftBodyHelpers.cpp,1.12274,0.5422
bullet-btSequentialImpulseConstraintSolver.cpp,1.17394,0.5338

Command line example:
$ /usr/bin/clang -DNO_TIME -c -Xclang -emit-codegen-only -I
/Users/bruno/Dev/srcs/test-suite/MultiSource/Benchmarks/Bullet/include
/Users/bruno/Dev/srcs/test-suite/MultiSource/Benchmarks/Bullet/btSoftBody.cpp
-O3 -o /tmp/x.o</pre>
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