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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 - LVI-CFI overwrites register used for return value"
href="https://bugs.llvm.org/show_bug.cgi?id=47740">47740</a>
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<th>Summary</th>
<td>LVI-CFI overwrites register used for return value
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
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<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>new bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>llvm-bugzilla@jbeekman.nl
</td>
</tr>
<tr>
<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>The following code:
target datalayout =
"e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
define { i64, i128 } @ret_i64_i128() #0 {
ret { i64, i128 } { i64 1, i128 36893488147419103235 }
}
attributes #0 = { "target-features"="+lvi-cfi" }
Generates the following assembly:
ret_i64_i128: # @ret_i64_i128
.cfi_startproc
# %bb.0:
movl $1, %eax
movl $3, %edx
movl $2, %ecx
popq %rcx
lfence
jmpq *%rcx
.Lfunc_end0:
.size ret_i64_i128, .Lfunc_end0-ret_i64_i128
.cfi_endproc
As you can tell, the LVI-CFI pass is using RCX although that register was used
for part of the return value.</pre>
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