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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 --- - PowerPC backend not parsing vector registers correctly"
href="https://llvm.org/bugs/show_bug.cgi?id=31127">31127</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>PowerPC backend not parsing vector registers correctly
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</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>Backend: PowerPC
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>sfantao@us.ibm.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>For the following input `a.s`
```
.text
.abiversion 2
.file "a.c"
.globl foo
.p2align 4
.type foo,@function
foo:
xxswapd 0, 0
xxswapd 0, 0
```
If I run:
```
llvm-mc -triple powerpc64le-linux-gnu -mcpu pwr8 -filetype=obj a.s -o - |
llvm-objdump -disassemble -
```
I get:
```
<stdin>: file format ELF64-ppc64
Disassembly of section .text:
foo:
0: 56 02 00 f0 xxswapd 0, 32
4: 56 02 00 f0 xxswapd 0, 32
```
Looks like the second register operand of the `xxswapd` instruction is being
parsed as vr32 instead of vr0.
This instruction is often used to implement the memcpy intrinsic, making codes
like:
```
#include <stdio.h>
#include <string.h>
int main(void) {
int A[10] = {0,1,2,3,4,5,6,7,8,9};
int B[10];
memcpy(&B[0], &A[0], sizeof(A));
for(int i=0; i<10; ++i)
printf("%d %d\n",A[i], B[i]);
return 0;
}
```
to return incorrect results if compiled with clang and the options -O0 and
-save-temps (or any other combination that separates the compile from the
assemble phases).</pre>
</div>
</p>
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