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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [AMDGPU][MC][DISASSEMBLER][GFX8+] 64-bit instructions cannot be reassembled when used with a 1/2pi literal"
href="https://bugs.llvm.org/show_bug.cgi?id=39332">39332</a>
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<th>Summary</th>
<td>[AMDGPU][MC][DISASSEMBLER][GFX8+] 64-bit instructions cannot be reassembled when used with a 1/2pi literal
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<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>enhancement
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Backend: AMDGPU
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>dpreobrazhensky@luxoft.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<p>
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<pre>To use 1/2pi literal with 64-bit instructions, it is necessary to specify this
literal as 0.159154943091895317852646485335 or use a hex constant. However
disassembler decodes it as 0.15915494 so the disassembled code cannot be
assembled again.
An example:
v_add_f64 v[0:1], v[0:1], 0.159154943091895317852646485335
Correctly encoded as
0x00,0x00,0x80,0xd2,0x00,0xf1,0x01,0x00
However, when disassembled, the code results in
v_add_f64 v[0:1], v[0:1], 0.15915494
This is a different constant and the code will fail to assemble.</pre>
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