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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 --- - IRCE breaks loop-info"
href="https://llvm.org/bugs/show_bug.cgi?id=28944">28944</a>
</td>
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<tr>
<th>Summary</th>
<td>IRCE breaks loop-info
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<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>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Loop Optimizer
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>michael.v.zolotukhin@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>When trying to improve LoopInfo verifier, I found that one of IRCE tests
started to fail. Looks like it doesn't update LI as it creates new loops, or
something like this.
To reproduce apply a patch from <a href="https://reviews.llvm.org/D23437">https://reviews.llvm.org/D23437</a> and then:
$ cat fail.ll
define void @inner_loop(i32* %arr, i32* %a_len_ptr, i32 %n) {
entry:
%len = load i32, i32* %a_len_ptr, !range !0
%first.itr.check = icmp sgt i32 %n, 0
br i1 %first.itr.check, label %loop, label %exit
loop: ; preds = %in.bounds, %entry
%idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add i32 %idx, 1
%abc = icmp slt i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds: ; preds = %loop
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp slt i32 %idx.next, %n
br i1 %next, label %loop, label %exit
out.of.bounds: ; preds = %loop
ret void
exit: ; preds = %in.bounds, %entry
ret void
}
!0 = !{i32 0, i32 2147483647}
$ opt -verify-loop-info -irce-print-changed-loops -irce < ww.ll -S
irce: in function inner_loop: constrained Loop at depth 1 containing:
%loop<header><exiting>,%in.bounds<latch><exiting>
Assertion failed: (LoopHeaders1.size() == LoopHeaders2.size() && "LoopInfo is
incorrect."), function verifyByRecomputation, file
/Users/mvzolotu/devel/trunk/llvm/include/llvm/Analysis/LoopInfoImpl.h, line
600.
Stack dump:
0. Program arguments: bin/opt -verify-loop-info -irce-print-changed-loops
-irce -S
1. Running pass 'Function Pass Manager' on module '<stdin>'.
2. Running pass 'Loop Pass Manager' on function '@inner_loop'
Abort trap: 6</pre>
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