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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - simple-loop-unswitch asserts after nontrivial unswitch: Assertion `use_empty() && "Uses remain when a value is destroyed!"' failed."
href="https://bugs.llvm.org/show_bug.cgi?id=38778">38778</a>
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<th>Summary</th>
<td>simple-loop-unswitch asserts after nontrivial unswitch: Assertion `use_empty() && "Uses remain when a value is destroyed!"' failed.
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Loop Optimizer
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>fedor.v.sergeev@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Yet another assert on simple loop unswitch:
] cat bad-unswitch-reduced.ll
define void @Test(i32) {
br label %loop
loop:
switch i32 %0, label %continue [
i32 -2147483648, label %check
i32 98, label %guarded1
i32 99, label %guarded2
]
guarded1:
br i1 undef, label %continue, label %leave
guarded2:
br label %continue
check:
%val = add i32 0, 1
br i1 undef, label %continue, label %leave
continue:
br label %loop
leave:
%local = phi i32 [ 0, %guarded1 ], [ %val, %check ]
ret void
}
] DEBUG/bin/opt -passes=unswitch -enable-nontrivial-unswitch
bad-unswitch-reduced.ll 2>&1 -disable-output | head
While deleting: i32 %val
Use still stuck around after Def is destroyed: %.us-phi5 = phi i32 [ %val,
%leave.split.split ], [ %local.us4, %leave.split.split.us ]
opt: /home/fsergeev/work/orca/lib/IR/Value.cpp:92: llvm::Value::~Value():
Assertion `use_empty() && "Uses remain when a value is destroyed!"' failed.
Stack dump:
0. Program arguments:
/home/fsergeev/work/sandbox/fromorca/installDA/bin/opt -passes=unswitch
-enable-nontrivial-unswitch bad-unswitch-reduced.ll -disable-output
#0 0x00007f520b8f4a68 llvm::sys::PrintStackTrace(llvm::raw_ostream&)
/home/fsergeev/work/orca/lib/Support/Unix/Signals.inc:490:0
#1 0x00007f520b8f4af9 PrintStackTraceSignalHandler(void*)
/home/fsergeev/work/orca/lib/Support/Unix/Signals.inc:554:0
#2 0x00007f520b8f2b09 llvm::sys::RunSignalHandlers()
/home/fsergeev/work/orca/lib/Support/Signals.cpp:67:0
#3 0x00007f520b8f4509 SignalHandler(int)
/home/fsergeev/work/orca/lib/Support/Unix/Signals.inc:353:0
#4 0x00007f52092fa390 __restore_rt
(/lib/x86_64-linux-gnu/libpthread.so.0+0x11390)
]
It happens during deleteDeadBlocksFromLoop cleanup.
Recent change for 38737 does not affect this failure.</pre>
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