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<base href="https://bugs.llvm.org/">
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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 - attribute target syntax doesn't match -march options"
href="https://bugs.llvm.org/show_bug.cgi?id=43448">43448</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>attribute target syntax doesn't match -march options
</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>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>C
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>ndesaulniers@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, echristo@gmail.com, erich.keane@intel.com, erik.pilkington@gmail.com, florian_hahn@apple.com, kristof.beyls@arm.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk, srhines@google.com
</td>
</tr>
<tr>
<th>Blocks</th>
<td>4068
</td>
</tr></table>
<p>
<div>
<pre>When looking into an ISA-extension-assembler-directive related issue in
assembling the Linux kernel w/ Clang
(<a href="https://github.com/ClangBuiltLinux/linux/issues/671">https://github.com/ClangBuiltLinux/linux/issues/671</a>,
<a href="https://github.com/ClangBuiltLinux/linux/issues/573">https://github.com/ClangBuiltLinux/linux/issues/573</a>), I ran into some issue
with the ARMv8.1 lse extensions.
It seems that we can either:
1. use an assembler `.arch armv8-a+lse` directive
2. use a command line arg `-march=armv8-a+lse`
3. use a function level attribute
Unfortunately, 3 gets a little complicated in terms of our "compatibility w/
GCC" which is a constraint for compiling the Linux kernel w/ Clang.
__attribute__((target("arch=armv8-a+lse")))
void foo (void){}
produces a warning in Clang, but is accepted by GCC.
__attribute__((target("lse")))
void foo (void){}
produces an error in GCC, but is accepted by Clang.
I find the current behavior in Clang for 3 inconsistent with 1+2.</pre>
</div>
</p>
<div id="referenced">
<hr style="border: 1px dashed #969696">
<b>Referenced Bugs:</b>
<ul>
<li>
[<a class="bz_bug_link
bz_status_CONFIRMED "
title="CONFIRMED - [Meta] Compiling the Linux kernel with clang"
href="https://bugs.llvm.org/show_bug.cgi?id=4068">Bug 4068</a>] [Meta] Compiling the Linux kernel with clang
</li>
</ul>
</div>
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