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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 --- - RIP-relative memory references" href="https://urldefense.proofpoint.com/v2/url?u=https-3A__llvm.org_bugs_show-5Fbug.cgi-3Fid-3D23986&d=AwMBaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=pF93YEPyB-J_PERP4DUZOJDzFVX5ZQ57vQk33wu0vio&m=CVCchxYYeNjupZscR9R8kMKWBHv6kUKNsgbI8d5zUE8&s=4xXJvF2wWdbIO2MSLmPMFkvuCLJWB6NwfAPXiHj7D-M&e=">23986</a>
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<th>Summary</th>
<td>RIP-relative memory references
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: X86
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>david.l.kreitzer@intel.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>llvm-mc is encoding some RIP-relative instructions incorrectly by failing to
relax arith imm8 instruction forms. For example:
------------- t.s -----------------
bar:
.section imul
imul $foo, bar(%rip), %bx
imul $foo, bar(%rip), %ebx
imul $foo, bar(%rip), %rbx
-----------------------------------
This is the current behavior. Note that in each case, $foo is encoded as an
8-bit immediate even though it is not guaranteed to fit in 8 bits.
bash-4.3$ llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu t.s -o t.o
bash-4.3$ objdump -d --section=imul t.o
t.o: file format elf64-x86-64
Disassembly of section imul:
0000000000000000 <imul>:
0: 66 6b 1d 00 00 00 00 imul $0x0,0x0(%rip),%bx # 8 <imul+0x8>
7: 00
8: 6b 1d 00 00 00 00 00 imul $0x0,0x0(%rip),%ebx # f
<imul+0xf>
f: 48 6b 1d 00 00 00 00 imul $0x0,0x0(%rip),%rbx # 17
<bar+0x17>
16: 00</pre>
</div>
</p>
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