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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW " title="NEW --- - Performance regression versus GCC 4.9.1 -- test case and ASM attached" href="https://urldefense.proofpoint.com/v2/url?u=https-3A__llvm.org_bugs_show-5Fbug.cgi-3Fid-3D23619&d=AwMBaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=pF93YEPyB-J_PERP4DUZOJDzFVX5ZQ57vQk33wu0vio&m=QqCjc4lxf3C1Ll6h6E_q3p9re-Mru6vkImeAzCA37vQ&s=Cj5hVtLw8F0w8jl1Pe5oK3E0V0szMAUQ1ecb0tWUM4Y&e=">23619</a>
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<th>Summary</th>
<td>Performance regression versus GCC 4.9.1 -- test case and ASM attached
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>3.6
</td>
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<th>Hardware</th>
<td>Macintosh
</td>
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<th>OS</th>
<td>MacOS X
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>LLVM Codegen
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>learnopengles@gmail.com
</td>
</tr>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=14358" name="attach_14358" title="Compiler-generated ASM">attachment 14358</a> <a href="attachment.cgi?id=14358&action=edit" title="Compiler-generated ASM">[details]</a></span>
Compiler-generated ASM
With the attached code, the gcc version is 20% faster than the clang version.
clang++
--------
clang++ --version
Apple LLVM version 6.1.0 (clang-602.0.49) (based on LLVM 3.6.0svn)
Target: x86_64-apple-darwin14.3.0
Thread model: posix
clang++ -std=c++11 -O2 dsp.cpp main.cpp -o dsp && ./dsp
85,758,063 shorts/second
gcc
--------
gcc-mp-4.9 --version
gcc-mp-4.9 (MacPorts gcc49 4.9.2_1) 4.9.2
gcc-mp-4.9 -std=c++11 -O2 dsp.cpp main.cpp -o dsp && ./dsp
102,104,163 shorts/second
Source code: <a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__gist.github.com_anonymous_fd213a7b8ffdcfd219dc&d=AwMBaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=pF93YEPyB-J_PERP4DUZOJDzFVX5ZQ57vQk33wu0vio&m=QqCjc4lxf3C1Ll6h6E_q3p9re-Mru6vkImeAzCA37vQ&s=ob5nBbKH0yA1cEsY5y8AEL3FIecMFVkgWoSrquFhxeE&e=">https://gist.github.com/anonymous/fd213a7b8ffdcfd219dc</a>
Compiler-generated ASM attached.</pre>
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</p>
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