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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Code generation problem with Altivec vec_sel intrinsic"
href="http://llvm.org/bugs/show_bug.cgi?id=16641">16641</a>
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<th>Summary</th>
<td>Code generation problem with Altivec vec_sel intrinsic
</td>
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<th>Product</th>
<td>new-bugs
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>Other
</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>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>new bugs
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>schnetter@gmail.com
</td>
</tr>
<tr>
<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>I am encountering a code generation problem likely related to the Altivec
vec_sel intrinsic.
I am using
$ /home/projects/llvm/bin/clang++ -v
clang version 3.4 (login1.mcs.anl.gov:src/llvm-trunk/tools/clang
0a67b3629eee1e58a45415e07d1bfcd908d73c77) (login1.mcs.anl.gov:src/llvm-trunk
faa6fb57b03395c8b716b8c7523b4be2760a7820)
Target: powerpc64-unknown-linux-gnu
Thread model: posix
on a Power 7 system. The failing program is a test suite for Vecmathlib
<<a href="http://bitbucket.org/eschnett/vecmathlib/">http://bitbucket.org/eschnett/vecmathlib/</a>>, a library for SIMD vectorization.
When I build it with the options
$ /home/projects/llvm/bin/clang++ -faltivec -o test test.cc
it produces the output
$ ./test | head -n 20
Testing math functions:
Vecmathlib configuration: [conf-DEBUG-Altivec]
Testing math functions for type <Altivec:4*float>:
testing boolean operations...
Error in ifthen(bool):
x=[0,1,0,0] [0x00000fffdfb681800000000010003918]
y=[0,0,0,0] [0x00000000000000000000000000000000]
z=[0,0,1,1] [0xffffffffffffffff0000000000000000]
fstd(x,y,z)=[0,0,1,1] [0x00000000000000000000000000000000]
fvml(x,y,z)=[0,0,0,0] [0x00000000000000000000000000000000]
error(x,y,z)=[0,0,1,1] [0x00000000000000000000000000000000]
isbad(x,y,z)=[0,0,1,1]
indicating that a self-test fails; there should be no output starting with
"Error in ...". This particular self-test checks an "ifthen(x,y,z)" function,
which is for Altivec a wrapper around vec_sel, which x the condition (vector of
bool), and y and z the then- and else-values, respectively. As you can see, the
value for x is bogus; this should be a boolean vector, which is on Altivec a
vector of unsigned integers with either all bits unset or all bits set. I
assume there is a code generation problem that corrupts the value for x.
I attach the original source code (files test.cc and vec_altivec_float4.h) as
well as the pre-processed source code test.i.
I expect this pre-processed source code to be built with the command
$ /home/projects/llvm/bin/clang++ -faltivec -o test -x c++-cpp-output test.i
but this leads to the error
In file included from <built-in>:163:
<command line>:1:10: fatal error: 'altivec.h' file not found
#include "altivec.h"
^
1 error generated.
which is bogus since there is no #include statement at all in test.i. I hope
that test.i is nevertheless useful.</pre>
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