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<base href="https://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Condition not evaluated correctly on integer (long long) overflow for optimized builds"
href="https://llvm.org/bugs/show_bug.cgi?id=25385">25385</a>
</td>
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<tr>
<th>Summary</th>
<td>Condition not evaluated correctly on integer (long long) overflow for optimized builds
</td>
</tr>
<tr>
<th>Product</th>
<td>compiler-rt
</td>
</tr>
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<th>Version</th>
<td>3.5
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<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>
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<th>Component</th>
<td>compiler-rt
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>jhallmann@tableau.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</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=15205" name="attach_15205" title="Code to repo the defect">attachment 15205</a> <a href="attachment.cgi?id=15205&action=edit" title="Code to repo the defect">[details]</a></span>
Code to repo the defect
Staring with llvm 3.5 the optimizer is not correctly evaluation the condition
if an overflow happens.
# Compile
clang++ test.cpp -O3 -o testr && clang++ test.cpp -o testd
# Run and the outputs should match
./testd && ./testr
overflows 1
overflows 0
llvm 3.4
.Ltmp16:
#DEBUG_VALUE: delta <- ECX
.loc 1 24 0
setl r9b
setg r10b
.loc 1 21 0
test ecx, ecx
.loc 1 22 0
setg al
.loc 1 23 0
shr ecx, 31
llvm 3.5 - 3.7
.Ltmp13:
#DEBUG_VALUE: value <- R8D
.loc 6 22 17
mov ecx, r8d
sub ecx, r9d
setg r9b
.loc 6 24 17
setl al
.loc 6 23 17
shr ecx, 31</pre>
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