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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Continuous memory fences fail lower into one"
href="https://llvm.org/bugs/show_bug.cgi?id=23339">23339</a>
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<th>Summary</th>
<td>Continuous memory fences fail lower into one
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>All
</td>
</tr>
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<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: AArch64
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>rwindz0@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>We have file test.ll which contains:
define i32 @t1() {
entry:
fence seq_cst
fence seq_cst
fence seq_cst
fence seq_cst
ret i32 0
}
When dealing with arm taret, the output looks like sane:
$llc -O0 -mtriple arm-linux-gnueabi -mcpu cortex-a53 test.ll -o -
.type t1,%function
t1: @ @t1
.fnstart
@ BB#0: @ %entry
movw r0, #0
dmb ish
bx lr
.Lfunc_end0:
.size t1, .Lfunc_end0-t1
.fnend
But with arm64 target:
$llc -O0 -mtriple arm64-linux-gnueabi -mcpu cortex-a53 test.ll -o -
t1: // @t1
.cfi_startproc
// BB#0: // %entry
mov w8, wzr
dmb ish
dmb ish
dmb ish
dmb ish
mov w0, w8
ret
.Lfunc_end0:
.size t1, .Lfunc_end0-t1
.cfi_endproc
We have multiple "dmb ish" instructions here.</pre>
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