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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [LoopVectorizer] bad vectorized loop: "Instruction does not dominate all uses!""
href="https://bugs.llvm.org/show_bug.cgi?id=44026">44026</a>
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<th>Summary</th>
<td>[LoopVectorizer] bad vectorized loop: "Instruction does not dominate all uses!"
</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>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Loop Optimizer
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>paulsson@linux.vnet.ibm.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<pre>Created <span class=""><a href="attachment.cgi?id=22819" name="attach_22819" title="reduced testcase">attachment 22819</a> <a href="attachment.cgi?id=22819&action=edit" title="reduced testcase">[details]</a></span>
reduced testcase
clang -cc1 -triple s390x-ibm-linux -S -target-cpu z13 -O3 -w -vectorize-loops
-mllvm -force-target-instruction-cost=1 -mllvm -unroll-full-max-count=1
-faddrsig -x ir tc_insdoesnotdom.ll
Instruction does not dominate all uses!
%27 = phi <4 x i32> [ %21, %pred.load.continue10 ], [ %26, %pred.load.if11 ]
%0 = shufflevector <4 x i32> %vector.recur, <4 x i32> %27, <4 x i32> <i32 3,
i32 4, i32 5, i32 6>
in function func_21
fatal error: error in backend: Broken function found, compilation aborted!
Loop vectorizer seems to build a loop where the use comes before the definition
(%29):
vector.body:
%index = phi i64 [ 0, %vector.ph ], [ %index.next, %pred.store.continue18 ]
%vector.recur = phi <4 x i32> [ %vector.recur.init, %vector.ph ], [ %29,
%pred.store.continue18 ]
%0 = shufflevector <4 x i32> %vector.recur, <4 x i32> %29, <4 x i32> <i32 3,
i32 4, i32 5, i32 6>
...
pred.load.continue12:
%29 = phi <4 x i32> [ %23, %pred.load.continue10 ], [ %28, %pred.load.if11 ]
...
pred.store.continue18:
%index.next = add i64 %index, 4
%43 = icmp eq i64 %index.next, 8
br i1 %43, label %middle.block, label %vector.body, !llvm.loop !0</pre>
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