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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - -Os increases size because it includes -inline"
href="http://llvm.org/bugs/show_bug.cgi?id=15561">15561</a>
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<th>Summary</th>
<td>-Os increases size because it includes -inline
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>3.2
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</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>Driver
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>antoinep92@gmail.com
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=10218" name="attach_10218" title="Generates huge binary with -Os">attachment 10218</a> <a href="attachment.cgi?id=10218&action=edit" title="Generates huge binary with -Os">[details]</a></span>
Generates huge binary with -Os
Optimization levels -Os and -Oz are supposed to optimize for size, but they are
exactly equivalent to -O2 (as from llvm-as < /dev/null | opt -O...
-disable-output -debug-pass=Arguments)
The problem is that these optimization levels include the -inline optimization
pass which increases the executable size.
For instance, the attached file produces 40x *bigger* binary when compiled with
-Os than with -O0.
clang -Wall -std=c++11 -fconstexpr-depth=65536 -ftemplate-depth=65536 -g0 -s
-O0
<span class="quote">> 96408 bytes (96K)</span >
clang -Wall -std=c++11 -fconstexpr-depth=65536 -ftemplate-depth=65536 -g0 -s
-Os
<span class="quote">> 4024472 bytes (4M)</span >
Trying different optimization options, I found that the origin of the increased
size is (excessive?) inlining from (-inilne). Although this test-case is
extreme, I don't think -inline should be included in -Os.</pre>
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