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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - VirtRegRewriter fails to set properties on BUNDLE instructions"
href="https://llvm.org/bugs/show_bug.cgi?id=30798">30798</a>
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<th>Summary</th>
<td>VirtRegRewriter fails to set properties on BUNDLE instructions
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<th>Product</th>
<td>libraries
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
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<th>Status</th>
<td>NEW
</td>
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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>Register Allocator
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>mattias.v.eriksson@ericsson.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
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</tr></table>
<p>
<div>
<pre>In my out-of-tree back-end we run the register allocator after
bundling of instructions. The register allocator handles this mostly
fine, but I think there is a bug related to imp-use on subregister
definitions:
# *** IR Dump Before Virtual Register Rewriter ***:
BUNDLE %vreg1<imp-def>
* %vreg1:hiAcc<def> = ...
%vreg1 is a register pair which consists of hiAcc and loAcc. It is
allocated %a32, in which %a3 is hiAcc. After register allocation
imp-use is added on the bundled instruction but not on the BUNDLE
head.
# *** IR Dump After Virtual Register Rewriter ***:
BUNDLE %a32<imp-def>
* %a3<def> = ... %a32<imp-use>
I think %a32<imp-use> should be added to the BUNDLE head:
BUNDLE %a32<imp-def>, %a32<imp-use>
* %a3<def> = ... %a32<imp-use>
The relevant code is in VirtRegRewriter::rewrite():
// Add any missing super-register kills after rewriting the whole
// instruction.
while (!SuperKills.empty())
MI->addRegisterKilled(SuperKills.pop_back_val(), TRI, true);
while (!SuperDeads.empty())
MI->addRegisterDead(SuperDeads.pop_back_val(), TRI, true);
while (!SuperDefs.empty())
MI->addRegisterDefined(SuperDefs.pop_back_val(), TRI);
Should this be updated to also add the relevant flags on the bundle
head?</pre>
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