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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - assembly files do not preserve order of use lists"
href="http://llvm.org/bugs/show_bug.cgi?id=20515">20515</a>
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<th>Summary</th>
<td>assembly files do not preserve order of use lists
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<th>Product</th>
<td>libraries
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<th>Version</th>
<td>trunk
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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>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>LLVM assembly language parser
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>dexonsmith@apple.com
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
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<pre><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - bitcode files do not preserve order of use lists"
href="show_bug.cgi?id=5680">Bug 5680</a> allows use-list order to be preserved when round-tripping to bitcode.
Now that it's wrapping up, the next job is to add support for assembly, which I
imagine can work quite similarly. My initial idea is to add an assembly
construct that looks something like this:
shuffleuselist i8* %a, [4 x i32] [i32 0, i32 3, i32 1, i32 2]
shuffleuselist i64 0, [4 x i32] [i32 0, i32 3, i32 1, i32 2]
This construct can be at the function or global level. The first argument is a
Value and the second is a use-list shuffle-vector. The LLParser would apply
these at the point they're encountered.
I'm (naively?) assuming the same approach will work here -- predict in the
AssemblyWriter how the LLParser will see the use-lists, and write out shuffles
at a point where the full use-list will have been reconstructed. Once I've had
a chance to read the LLParser (and AsmWriter) to confirm just how naive this
idea is I'll throw a post on llvmdev to bikeshed the instruction format.</pre>
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