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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [DebugInfo@O2][Dexter] Return value unprintable in func with vectorized loop"
href="https://bugs.llvm.org/show_bug.cgi?id=39019">39019</a>
</td>
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<tr>
<th>Summary</th>
<td>[DebugInfo@O2][Dexter] Return value unprintable in func with vectorized loop
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Keywords</th>
<td>wrong-debug
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>new bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>jeremy.morse.llvm@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>chackz0x12@gmail.com, greg.bedwell@sony.com, international.phantom@gmail.com, llvm-bugs@lists.llvm.org, paul_robinson@playstation.sony.com
</td>
</tr>
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<th>Blocks</th>
<td>38768
</td>
</tr></table>
<p>
<div>
<pre>The vectorized-and-reduced summation below in variable 'sum' is reported as
optimized out on the return line, according to debug info. Given the value is
available in $rax we can almost certainly do better. My test setup is using
clang/llvm r342527, compiling "-O2 -g -fno-inline" targeting x86_64, and
running under gdb or lldb.
If you change BUFSZ to be 193 then the vectorized loop gets a scalar tail,
which contains the original body with dbg.value's, and the 'sum' variable is
printable on the return line.
(This is the same code as in <a class="bz_bug_link
bz_status_NEW "
title="NEW - [DebugInfo@O2][Dexter] Vectorized loop presents constant-valued iterator to debugger"
href="show_bug.cgi?id=39018">bug 39018</a>, but a different issue).
-------->8--------
#include <string.h>
#define BUFSZ 192
int
main()
{
int foo[BUFSZ];
int bar[BUFSZ];
memset(foo, 0, sizeof(foo));
memset(bar, 1, sizeof(bar));
for (int i = 0; i < BUFSZ; i++)
foo[i] += bar[i];
unsigned int sum = 0;
for (int j = 0; j < BUFSZ; j++)
sum += foo[j];
return sum;
}
--------8<--------</pre>
</div>
</p>
<div id="referenced">
<hr style="border: 1px dashed #969696">
<b>Referenced Bugs:</b>
<ul>
<li>
[<a class="bz_bug_link
bz_status_NEW "
title="NEW - [meta][DebugInfo] Umbrella bug for poor debug experiences"
href="https://bugs.llvm.org/show_bug.cgi?id=38768">Bug 38768</a>] [meta][DebugInfo] Umbrella bug for poor debug experiences
</li>
</ul>
</div>
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