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<head>
<base href="https://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [globalopt] Crash after dropping user that still has debug value"
href="https://llvm.org/bugs/show_bug.cgi?id=26786">26786</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[globalopt] Crash after dropping user that still has debug value
</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>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Interprocedural Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>mattias.v.eriksson@ericsson.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=15965" name="attach_15965" title="Reduced input file with crash in globalopt">attachment 15965</a> <a href="attachment.cgi?id=15965&action=edit" title="Reduced input file with crash in globalopt">[details]</a></span>
Reduced input file with crash in globalopt
With the attached file running:
opt -globalopt -o /dev/null bugpoint-reduced-simplified.ll
crashes like this:
opt: ../include/llvm/Support/Casting.h:81: static bool
llvm::isa_impl_cl<llvm::BasicBlock, llvm::Value *>::doit(const From *) [To =
llvm::BasicBlock, From = llvm::Value *]: Assertion `Val && "isa<> used on a
null pointer"' failed.
0 opt 0x00000000023c542e
llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 46
1 opt 0x00000000023c5839
2 opt 0x00000000023c4143 llvm::sys::RunSignalHandlers() + 131
3 opt 0x00000000023c5c7f
4 libpthread.so.0 0x00007f88d8f5e340
5 libc.so.6 0x00007f88d8186cc9 gsignal + 57
6 libc.so.6 0x00007f88d818a0d8 abort + 328
7 libc.so.6 0x00007f88d817fb86
8 libc.so.6 0x00007f88d817fc32
9 opt 0x0000000000ea11ae
10 opt 0x0000000000ea1158
11 opt 0x0000000000ea1132
12 opt 0x0000000000ea10d5
13 opt 0x0000000001937277
llvm::ValueEnumerator::EnumerateValue(llvm::Value const*) + 471
14 opt 0x000000000193789d
llvm::ValueEnumerator::EnumerateMetadata(llvm::Metadata const*) + 301
15 opt 0x000000000193638e
llvm::ValueEnumerator::ValueEnumerator(llvm::Module const&, bool) + 2702
16 opt 0x0000000001909052
17 opt 0x0000000001908bff llvm::WriteBitcodeToFile(llvm::Module
const*, llvm::raw_ostream&, bool, bool) + 335
18 opt 0x0000000001908a90
19 opt 0x0000000001dca9e1
20 opt 0x0000000001dca4db
llvm::legacy::PassManagerImpl::run(llvm::Module&) + 347
21 opt 0x0000000001dcaf21
llvm::legacy::PassManager::run(llvm::Module&) + 33
22 opt 0x000000000091f2ec main + 8588
23 libc.so.6 0x00007f88d8171ec5 __libc_start_main + 245
24 opt 0x00000000008f3748
Stack dump:
0. Program arguments: build-master/bin/opt -globalopt -o /dev/null
bugpoint-reduced-simplified.ll
1. Running pass 'Bitcode Writer' on module
'bugpoint-reduced-simplified.ll'.
Aborted
I have been debugging this for a while and found that globalopt tries to
extract the bitcast from:
store i16 0, i16* bitcast (i16** @a.1 to i16*), align 8, !dbg !11
This bitcast also exists in debug info:
tail call void @llvm.dbg.value(metadata i16* bitcast (i16** @a.1 to i16*),
i64 0, metadata !1, metadata !9), !dbg !10
In makeAllConstantUsesInstructions(Constant *C) dropAllReferences is called on
the bitcast expression and this seems to break the instruction with the
llvm.dbg.value</pre>
</div>
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