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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 --- - Compiling kernel bpf samples with -O0 results in error"
href="https://llvm.org/bugs/show_bug.cgi?id=26108">26108</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Compiling kernel bpf samples with -O0 results in error
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</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>
<tr>
<th>Component</th>
<td>-New Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>prb003@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>compiling samples/bpf/ from linux kernel with change in optimization as -O0
results in following error. Though with -O2 (which is default in Makefile)
works fine.
$ make samples/bpf/
[...]
clang -nostdinc -isystem /usr/lib/gcc/x86_64-linux-gnu/4.9/include
-I./arch/x86/include -Iarch/x86/include/generated/uapi
-Iarch/x86/include/generated -Iinclude -I./arch/x86/include/uapi
-Iarch/x86/include/generated/uapi -I./include/uapi -Iinclude/generated/uapi
-include ./include/linux/kconfig.h \
-D__KERNEL__ -Wno-unused-value -Wno-pointer-sign \
-O0 -emit-llvm -c samples/bpf/tracex1_kern.c -o -| /home/ravi/bin/llc
-march=bpf -filetype=obj -o samples/bpf/tracex1_kern.o
LLVM ERROR: Cannot select: t12: ch,glue = BPFISD::CALL t11, t6, Register:i64
%R1, t11:1
t6: i64,ch = load<LD8[getelementptr inbounds (%struct.smp_ops,
%struct.smp_ops* @smp_ops, i32 0, i32 3)]> t0, t3, undef:i64
t3: i64 = add t16, Constant:i64<24>
t16: i64 = BPFISD::Wrapper TargetGlobalAddress:i64<%struct.smp_ops*
@smp_ops> 0
t15: i64 = TargetGlobalAddress<%struct.smp_ops* @smp_ops> 0
t2: i64 = Constant<24>
t5: i64 = undef
t10: i64 = Register %R1
t11: ch,glue = CopyToReg t9, Register:i64 %R1, Constant:i64<0>
t10: i64 = Register %R1
t4: i64 = Constant<0>
In function: smp_send_stop
samples/bpf/Makefile:66: recipe for target 'samples/bpf/tracex1_kern.o' failed
make[1]: *** [samples/bpf/tracex1_kern.o] Error 1
Makefile:1544: recipe for target 'samples/bpf/' failed
make: *** [samples/bpf/] Error 2
$
Experimented on,
Linux kernel version : 4.4
Architecture : x86
clang version : 3.8.0 (trunk 256744)
llc version : 3.8.0svn</pre>
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